Inability to Maintain Airway Patency and/or Reflexes

Upper Airway Obstruction

• Altered Mental Status (see Obtundation-Coma)
  • Intoxication
    • Central Nervous System Depressants (Such as Ethanol, Benzodiazepines, etc)
  • Procedural Deep Sedation (with/without Pharmacologic Paralysis) (see Sedation)
    • Bronchoscopy (see Bronchoscopy)
    • Cerebral Angiogram (see Cerebral Angiogram)
    • Coronary Angiogram (see Cardiac Catheterization)
    • Colonoscopy (see Colonoscopy)
    • Esophagogastroduodenoscopy (EGD) (see Esophagogastroduodenoscopy)
    • Other Procedures Which Require Prolonged Immobility
  • Procedural General Anesthesia (with/without Pharmacologic Paralysis) (see General Anesthesia)
    • Surgery
• Bilateral Vocal Fold Immobility (BVFI) (see Bilateral Vocal Fold Immobility)
  • Example: Bilateral Vocal Cord Paralysis (see Vocal Cord Paralysis)
  • Example: Laryngospasm (see Laryngospasm)
• Other Etiologies of Upper Airway Obstruction
  • Example: Anaphylaxis (see Anaphylaxis)
  • Example: Angioedema (see Angioedema)

Lower Airway Obstruction

• Airway Mucous Plugging with Inability to Clear Secretions
• Massive Hemoptysis (see Hemoptysis)

Respiratory Failure (see Respiratory Failure)

Type I Hypoxemic Respiratory Failure

• Acute or Chronic Hypoxemic Respiratory Failure
  • Decreased Mixed Venous Oxygen Saturation (Decreased Mixed Venous pO2)
  • Intrapulmonary Right-to-Left Shunt (see Intracardiac and Extracardiac Shunt)
  • Intracardiac Right-to-Left Shunt (see Intracardiac and Extracardiac Shunt)
  • Worsened V/Q Mismatch (Above Levels Observed as Part of Normal Physiology)
  • Diffusion Limitation

Type II Hypoxemic, Hypercapnic Respiratory Failure

• Acute Hypoxemic, Hypercapnic Respiratory Failure (Acute Hypoventilation, Acute Ventilatory Failure)
  • Decreased Ventilatory Drive
  • Decreased Ventilatory Output Due to Neuromuscular Disease
  • Decreased Ventilatory Output Due to Excessive Ventilatory Demand
• Chronic Hypoxemic, Hypercapnic Respiratory Failure (Chronic Hypoventilation, Chronic Ventilatory Failure)
  • Decreased Ventilatory Drive
  • Decreased Ventilatory Output Due to Neuromuscular Disease
  • Decreased Ventilatory Output Due to Excessive Ventilatory Demand

Cardiac Arrest (see Cardiac Arrest)

• Key Determinants of Successful Cardiopulmonary Resuscitation (CPR)
  • Quality Chest Compressions (100-120/min with 2-2.4” Depth and Full Chest Recoil Between Compressions
  • Early Defibrillation
• American Heart Association Guidelines Recommend Maintaining a Chest Compression Fraction of ≥60% (Meaning on Average, Chest Compressions Should Be Withheld<40% of the Intra-Arrest Time ( J Emerg Med, 2018) [MEDLINE]
  • There May Be Additional Benefit with Maintaining a Chest Compression Fraction of ≥80% (Circulation, 2009) [MEDLINE] (Resuscitation, 2011) [MEDLINE]
  • Multiple Interventions May Interrupt Chest Compressions: some of which have unclear benefit
    • Administration of Resuscitation Medications
    • Endotracheal Intubation: supraglottic airway insertion can be quicker than endotracheal intubation, don’t interfere with chest compressions, and have a loer complication than endotracheal intubation
    • Vascular Access Attempts: intraosseous access can be quicker than intravenous access and doesn’t interfere with chest compressions
• In Cardiopulmonary Arrest, Systemic and Pulmonary Vascular Perfusion is Very Low Despite Optimal Cardiopulmonary Resuscitation (CPR)
  • Therefore, Ventilation/Perfusion Relationships Can Be Maintained with Low Minute Ventilation
• Hyperventilation Should Be Avoided During CPR, as Increased Intrathoracic Pressure and Gastric Distention Can Impede Effective Chest Compressions (Circulation, 2015) [MEDLINE]

Airway Management Techniques During Cardiopulmonary Resuscitation

• Bag-Valve-Mask (BVM)
• Endotracheal Intubation (see Endotracheal Intubation)
• Laryngeal Mask Airway (LMA) or Other Similar Supraglottic Airway Device

Clinical Efficacy of Endotracheal Intubation in Out-of-Hospital Cardiac Arrest

• Randomized Trial of Bag-Mask Ventilation vs Endotracheal Intubation During Cardiopulmonary Resuscitation in Out-of-Hospital Cardiac Arrest (JAMA 2018) [MEDLINE]: n= 2043
  • Bag-Mask Ventilation and Endotracheal Intubation were Equivalent in Terms of 28-Day Neurologic Outcome for Out-of-Hospital Cardiac Arrest
• AIRWAYS-2 Randomized Trial of Supraglottic Airway Device vs Tracheal Intubation in Out-of-Hospital Cardiac Arrest ( JAMA, 2018) [MEDLINE]: n = 9296
  • Supraglottic Airway Device and Endotracheal Intubation Were Equivalent in Terms of 30-Day Outcome in Out-of-Hospital Cardiac Arrest
• Trial of Laryngeal Tube Insertion vs Endotracheal Intubation in Out-of-Hospital Cardiac Arrest (JAMA, 2018) [MEDLINE]: n= 3000
  • Laryngeal Tube Insertion was Superior to Endotracheal Intubation in Terms of 72 hr Mortality Rate in Out-of-Hospital Cardiac Arrest

Recommendations (American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, 2015) (Circulation, 2015) [MEDLINE]

• Use the Maximal Feasible Inspired Oxygen Concentration During CPR (Class IIb, LOE C-EO)
• Method of Oxygenation/Ventilation
  • Inadequate Evidence to Demonstrate a Difference in Survival or Favorable Neurologic Outcome with the Use of Bag-Mask Ventilation, as Compared to Endotracheal Intubation During CPR
  • Either a Bag-Mask Device or an Advanced Airway May Be Used for Oxygenation/Ventilation During CPR in Both the In-Hospital and Out-of-Hospital Settings (Class IIb, LOE C-LD)
  • For Healthcare Providers Trained in Their Use, Either an Supraglottic Airway Device or an Endotracheal Tube May Be Used as the Initial Advanced Airway During CPR (Class IIb, LOE C-LD)
• Confirmation of Endotracheal Tube Placement
  • Continuous Waveform Capnography is Recommended in Addition to Clinical Assessment as the Most Reliable Method of Confirming and Monitoring Correct Endotracheal Tube Placement (Class I, LOE C-LD)
  • If Continuous Waveform Capnometry is Not Available, a Nonwaveform CO2 Detector, Esophageal Detector Device, or Ultrasound Used by an Experienced Operator is a Reasonable Alternative (Class IIa, LOE C-LD)
• Ventilation After Advanced Airway Placement
  • After Placement of Advanced Airway, it is Reasonable to Deliver 1 Breath Every 6 sec (10 Breaths/min) While Continuous Chest Compressions are Being Performed (Class IIb, LOE C-LD)

Types of Upper Airway Obstruction

• Foreign Body Airway Obstruction (see Airway Foreign Body)
  • Types
    • Blood Clots
    • Dentures/Bridges/Fractured Teeth
    • Emesis
    • Food Material
    • Ingested Objects
    • Injured Tissue
    • Secretions
• Soft Tissue Upper Airway Obstruction
  • Commonly Associated with Altered Mental Status (Due to Deep Sedation, General Anesthesia, Intoxication, etc)
  • Mechanisms (Anaesth Intensive Care, 1994) [MEDLINE]
    • Loss of Muscular Tone of the Soft Palate
    • Prolapse of the Tongue into the Posterior Pharynx

Clinical Features of Upper Airway Obstruction

• Accessory Muscle (Intercostal, Subcostal, Suprasternal, and Supraclavicular) Retractions
  • Retractions May Be the Only Clinical Sign of Upper Airway Obstruction in Cases with Complete Upper Airway Obstruction
• Cyanosis (see Cyanosis)
  • Cyanosis May Be the Only Clinical Sign of Upper Airway Obstruction in Cases with Complete Upper Airway Obstruction
• Gurgling
• Snoring (see Snoring)
• Stridor (see Stridor)

Management of Foreign Body Airway Obstruction

• Maneuvers to Clear Airway Obstruction
  • Abdominal Thrusts (Heimlich Maneuver)
    • May Be Complicated by Gastric Rupture in Some Cases (Am J Emerg Med, 1993) [MEDLINE]
  • Back Blows
  • Chest Thrusts
• Clinical Efficacy
  • Efficacy of a Single Maneuver is 50% at Best, with the Highest Efficacy Observed When Using Multiple Maneuvers (Crit Care Med, 1979) [MEDLINE]
• Recommendations for Responsive Patient (2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care) (Circulation, 2010) [MEDLINE] (2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care) (Circulation, 2015) [MEDLINE]
  • In a Patient with Severe Airway Obstruction by a Foreign Body, Multiple Rapid-Sequence Abdominal Thrusts Followed by Chest Thrusts is Recommended
  • If the Abdomen Cannot Be Encircled or the Patient is in the Late Stages of Pregnancy, Chest Thrusts are the Initial Recommended Maneuver
• Recommendations for Unresponsive Patient (2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care) (Circulation, 2010) [MEDLINE]
  • Blind Finger Sweep is Not Recommended, Unless Solid Material Becomes Visible in the Upper Airway During the Course of CPR
  • Cardiopulmonary Resuscitation (CPR): since chest compressions may produce higher airway pressures than abdominal thrusts in unresponsive patients (Resuscitation, 2000) [MEDLINE]

General Comments

• Airway Maneuvers Decrease Soft Tissue Upper Airway Obstruction and Establish Upper Airway Patency)

Head-Tilt Chin-Lift Maneuver

• Background
  • Head-Tilt Chin-Lift is Frequently the First Maneuver to Utilized in a Patient without a Concern About Possible Cervical Cord Spinal Injury
• Technique
  • Use 2 Hands to Apply Downward Pressure to the Forehead and Use Tips of Index and Middle Fingers to Extend Neck by Lifting Jaw Forward at the Mentum: this maneuver moves the tongue anteriorly out of the posterior pharynx (JACEP, 1976) [MEDLINE]

Jaw-Thrust Maneuver

• Background
  • Jaw Thrust Maneuver Can Be Utilized in a Patient Even if There is a Concern About Possible Cervical Spinal Cord Injury
  • However, Since Airway Maneuvers are Usually Associated with at Least Some Movement of the Cervical Spine, Caution Must Be Exercised in Any Patient in Whom There is a Concern About Potential Cervical Spinal Cord Injury (Spine; Phila Pa 1976) [MEDLINE] (Anesth Analg, 2000) [MEDLINE]
• Technique
  • With Hands on Parieto-Occipital Skull, Thrusting Jaw Forward (Importantly, without Extending the Neck) Moves the Tongue Anteriorly Out of the Posterior Pharynx (ORL J Otorhinolaryngol Relat Spec, 2005) [MEDLINE]

General Comments

• After Establishment of Upper Airway Patency by the Above Upper Airway Maneuvers, Airway Adjuncts Serve to Maintain Patency

Oropharyngeal Airway

• Design
  • Oropharyngeal Airway is a Tube-Like Plastic Device Which Prevents the Tongue and Oropharyngeal Soft Tissues from Obstructing the Upper Airway
• Clinical Use
  • Oropharyngeal Airway Should Only Be Used in a Patient Under Deep Sedation (Due to the Risk of Vomiting and/or Aspiration)
• Sizing
  • When Held Next to the Patients Face with the Flat End in Line with the Patient’s Mouth, the Tip of a Properly-Sized Oropharyngeal Airway Should Just Reach the Angle of the Mandible
• Insertion
  • Insert the Oropharyngeal Airway Upside Down to Avoid Pushing the Tongue Posteriorly into the Oropharynx
  • Then Carefully Rotate the Oropharyngeal Airway 180 Degrees While Advancing It into the Posterior Pharynx
• Adverse Effects/Complications
  • Capture of Lips/Tongue Between the Oropharyngeal Airway and Teeth (Causing Injury)
  • Oropharyngeal Mucosal Injury (May Occur During Rotation): may cause bleeding in a patient with coagulopathy
  • Inadvertent Displacement of the Tongue into the Posterior Pharynx (Worsening Upper Airway Obstruction)
  • Use of Incorrectly Size Oropharyngeal Airway
    • Too Large Oropharyngeal Airway: may push the epiglottis into the airway, worsening upper airway obstruction
    • Too Small Oropharyngeal Airway: may be ineffective and/or become lost in the oropharynx
  • Vomiting (with/without Aspiration): may occur in a patient who is not adequately sedated prior to oropharyngeal device insertion

Nasopharyngeal Airway (Nasal Trumpet)

• Design
  • Nasopharyngeal Airway is a Soft Rubber or Plastic Tube Which is Passed Through the Nose into the Posterior Pharynx
• Clinical Use
  • Nasopharyngeal Airway May Be Used in a Patient with Clenched Jaw or Inability to Tolerate an Oropharyngeal Airway (Due to Inadequate Sedation)
• Sizing
  • Nasopharyngeal Airway Comes Sizing is Based on the Internal Diameter: with the larger internal diameter = longer length
    • Small Adult: 6-7 cm
    • Medium Adult: 7-8 cm
    • Large Adult: 8-9 cm
  • Size Should Be Selected Based on Length of the Nasopharyngeal Airway (Emerg Med J, 2005) [MEDLINE]
  • When Holding the Nasopharyngeal Airway Next to Patient’s Mandible with the Flared End at the Patient’s Mouth, the Distal Tip of a Properly-Sized Nasopharyngeal Airway Should Just Reach the Angle of the Patient’s Mandible
• Insertion
  • Lubricate the Nasopharyngeal Airway (with Water-Soluble Lubricant or Lidocaine Jelly) and Insert Along the Floor of the Nares into the Posterior Pharynx (Following a Downward Angle of Approximately 15 Degrees): note that the contact time for lidocaine jelly is insufficient to provide anesthesia during the insertion, but it may provide anesthesia after the nasopharyngeal airway is already in place
• Adverse Effects/Complications
  • Inadvertent Intracranial Nasopharyngeal Airway Incursion: has been rarely described in patients with basilar skull fractures
  • Nasopharyngeal Mucosal Injury: may cause epistaxis in up to 30% of cases (Anaesthesia, 1993) [MEDLINE]
    • Epistaxis May Be Severe in a Patient with Coagulopathy
  • Use of Excessively Long Nasopharyngeal Airway (Which May Extend into the Esophagus and Cause Gastric Distention During Subsequent Bag-Valve-Mask Ventilation)

American Society of Anesthesiologists (ASA) Physical Status Classification

• ASA 1: Normal Healthy Patient
  • Example: varicose veins in otherwise healthy patient
• ASA 2: Mild Systemic Disease That Does Not Impair Normal Activity
  • Example: controlled hypertension, controlled diabetes mellitus, chronic bronchitis, etc
• ASA 3: Severe Systemic Disease That is Not Incapacitating
  • Example: insulin-dependent diabetes mellitus, angina, pulmonary insufficiency, etc
• ASA 4: Severe Systemic Disease That is a Constant Threat to Life
  • Example: CHF, major organ insufficiency, etc
• ASA 5: Moribund Patient Who is Not Expected to Survive for 24 hrs With or Without Surgery
  • Example: intracranial hemorrhage in coma, etc
• ASA 6: Declared Brain Dead with Plan for Organ Donation

Assessment for Physiologic Factors Which May Increase the Risk of Intubation

• Physiologic Risk Factors Which Increase the Risk of Cardiovascular Compromise During or After Airway Management, Regardless of Anatomic Difficulty with Endotracheal Intubation (West J Emerg Med. 2015;16(7):1109 [MEDLINE]
  • Arrhythmias
    • Atrial Fibrillation (AF) (see Atrial Fibrillation)
    • Ventricular Tachycardia (VT) (see Ventricular Tachycardia)
  • Bronchospasm (see Obstructive Lung Disease)
  • Hypotension (see Hypotension)
  • Hypoxemia (see Hypoxemia)
  • Myocardial Ischemia (see Coronary Artery Disease)
  • Right Ventricular Failure (see Congestive Heart Failure)
  • Severe Anemia (see Anemia)
  • Severe Electrolyte Disturbance (Hypokalemia, etc)
  • Severe Metabolic Acidosis (see Metabolic Acidosis-General)
• Selected Techniques for Preintubation Optimization: these should be performed as required and as time allows
  • Correction of Anemia with Packed Red Blood Cell Transfusion (Especially in the Setting of Hemorrhagic Shock) (see Anemia)
  • Correction of Coagulopathy (see Coagulopathy)
    • Cryoprecipitate (see Cryoprecipitate)
    • Fresh Frozen Plasma (FFP) (see Fresh Frozen Plasma)
    • Platelet Transfusion (see Platelet Transfusion)
    • Prothrombin Complex Concentrate (PCC) (see Prothrombin Complex Concentrate-4 Factor)
  • Correction of Electrolyte Disturbances (Especially in the Setting of Arrhythmias and/or Hemodynamic Instability)
  • Correction of Intravascular Volume Status with Intravenous Fluids
    • Post-Intubation Hypotension is the Most Common Complication of Intubation
  • Treatment of Metabolic Acidosis by Addressing Underlying Etiology, Administering Bicarbonate, etc) (see Metabolic Acidosis-General)
  • Treatment of Bronchospasm with Bronchodilators
  • Treatment of Hemothorax/Pneumothorax with Chest Tube Placement (see Pleural Effusion-Hemothorax and Pneumothorax)

Airway Assessment Methods

Mallampati Airway Class/Score

• Technique: assessed in upright patient with mouth wide open and tongue out -> allows assessment of oral size and anatomy of tongue and oropharynx
  • Class I: hard palate, soft palate, entire uvula, fauces, and pillars visible
  • Class II: hard palate, soft palate, part of uvula, and fauces visible
  • Class III: hard palate, soft palate, and base of uvula visible -> predicts difficult mask ventilation and difficult intubation
  • Class IV: only hard palate visible -> predicts difficult mask ventilation and difficult intubation

• Clinical Efficacy
  • In Non-Cardiac Arrest Emergency Department Intubations, Only 32% of Patients were Able to Follow Simple Commands (Allowing Mallampati Assessment) and Not Cervical Spine Immobilized (Allowing Neck Mobility and Thyromental Measurement) (Ann Emerg Med, 2004) [MEDLINE]
  • In Emergency Department Intubations, Mallampati Could Be Performed in Only 26% of Patients, Due to Lack of Patient Cooperation and Clinical Instability (J Emerg Med, 2010) [MEDLINE]
  • In Terms of Predicting Difficulty to Intubate, Modified Mallampati Score (≥3) had a Positive Likelihood Ratio 4.1 (95% CI: 3.0-5.6) and Specificity 0.87 (95% CI: 0.81-0.91) (JAMA, 2019) [MEDLINE]

Upper Lip Bite Test

• Technique
  • Easy to Perform Assessment of Patient’s Ability of Lower Incisors to Extend and Reach the Upper Lip
• Clinical Efficacy
  • Systematic Review of Upper Lip Bite Test to Predict Difficult Intubation (JAMA, 2019) [MEDLINE]: n= 33, 559 Patients (62 High-Quality Studies)
    • Approximately 10% (95% CI: 8.2%-12%) of Patients were Difficult to Intubate in the Systematic Review
    • In Terms of Predicting Difficulty to Intubate, Grade of Class 3 on the Upper Lip Bite Test Had a Positive Likelihood Ratio of 14 (95% CI: 8.9-22) and Specificity 0.96 (95% CI: 0.93-0.97)
    • In Terms of Predicting Difficulty to Intubate, Shorter Hyomental Distance Had a Range of <3-5.5 cm, Positive Likelihood Ratio 6.4 (95% CI: 4.1-10), and Specificity 0.97 (95% CI: 0.94-0.98)
    • In Terms of Predicting Difficulty to Intubate, Retrognathia (Mandible Measuring <9 cm from the Angle of the Jaw to the Tip of the Chin or Subjectively Short) Had a Positive Likelihood Ratio 6.0 (95% CI, 3.1-11) and Specificity 0.98 (95% CI: 0.90-1.0)
    • In Terms of Predicting Difficulty to Intubate, Combination of Physical Findings Based on the Wilson Score Had a Positive Likelihood Ratio 9.1 (95% CI: 5.1-16) and Specificity 0.95 [95% CI: 0.90-0.98)
    • In Terms of Predicting Difficulty to Intubate, Modified Mallampati Score (≥3) had a Positive Likelihood Ratio 4.1 (95% CI: 3.0-5.6) and Specificity 0.87 (95% CI: 0.81-0.91)
    • An Abnormal Upper Lip Bite Test Raises the Probability of Difficult Intubation from 10% to >60% for the Average Risk Patient

Naguib Airway Assessment Method

• Commonly Utilized in Operative Settings
• Uses Measurements in an Equation to Predict Difficult Intubation
  • Positive = Difficult Laryngoscopy
  • Negative = Easy Laryngoscopy
• Clinical Efficacy
  • Study of Diagnostic Validity of Multivariate Airway Scoring Systems to Predict Difficult Laryngoscopy (J Intl Med Res, 2016) [MEDLINE]
    • All Three Scoring Systems (Naguib, LEMON, and MACOCHA) Demonstrated Inconclusive Zones Which Limit Their Clinical Utility in Predicting Difficult Intubations

LEMON Airway Assessment Score

• Scoring System
  • Look
    • Facial Trauma: 1 pt
    • Large Incisors: 1 pt
    • Beard/Mustache: 1 pt
    • Large Tongue: 1 pt
    • Dentition: assess for dentures, prominent maxillary incisors, broken/loose teeth, and crowns
    • Scars
  • Evaluate Using the 3-3-2 Rule
    • Inter-Incisor Distance <3 Fingers: 1 pt
    • Hyoid-Mental Distance <3 Fingers: 1 pt
      • Distance Between the Hyoid Bone (Just Above the Thyroid Cartilage) and Point of Chin (Mentum)
    • Thyromental Distance (or Thyroid-Floor of Mouth Distance) <2 Fingers: 1 pt
      • Distance from Thyroid Prominence to the Point of Chin (Mentum) with Next Extended
      • Thyromental Distance is Considered Important Because During Direct Laryngoscopy, the Tongue is Displaced by the Laryngoscope into the Thyromental Space
      • A Short Thyromental Distance Indicates Less Space for the Tongue to Be Displaced by the Laryngoscope Blade
  • Mallampati Airway Class/Score ≥3: 1 pt
  • Obstruction of Airway (Epiglottitis, Peritonsillar Abscess, Trauma, etc): 1 pt
  • Limited Neck Mobility (Through Flexion and Extension): 1 pt
    • Neck Extension May Be Limited with History of C-Spine Surgery
    • Presence of C-Collar Indicates No C-Spine Mobility
    • Neck Extension May Be limited Due to Rheumatoid Arthritis (RA) (see Rheumatoid Arthritis): neck extension during intubation in some patients with RA may result in atlanto-axial subluxation, resulting in spinal cord injury
  • Scoring
    • Maximum: 10 pts
• Clinical Efficacy
  • Study of LEMON Score for Prediction of Difficult Airway in the Emergency Department (Emerg Med J, 2005) [MEDLINE]
    • LEMON Score was Able to Successfully Stratify the Risk of Intubation Difficulty in the Emergency Department
    • Patients with Large Incisors, a Decreased Inter-Incisor Distance, and a Decreased Thyroid to Floor of Mouth Distance were More Likely to Have a Poor Laryngoscopic View (grades 2, 3, or 4)
  • Study of LEMON and LEON Scores in the Emergency Department ( J Emerg Med, 2009)
    • The Thyroid-to-Hyoid Distance <2 Fingers was the Only Independent Variable Which Predicted Difficult Intubation
    • Mallampati Score was Not a Useful Tool in Predicting the Difficulty intubation in the Emergency Department, Such that “LEMON” Can Be Modified to “LEON”
  • Prospective Validation of the LEMON Score in the Emergency Department (Am J Emerg Med, 2015) [MEDLINE]
    • Type of Laryngoscope: 84% direct larynogoscope, 16% video laryngoscope
    • Difficult Intubation: 5.4% with direct larynogoscope, 7.4% with video laryngoscope
    • Sensitivity: 85.7% with direct laryngoscope, 94.9% with video laryngoscope
    • Specificity: 47.6% with direct laryngoscope, 40.3% with video laryngoscope
    • Negative Predictive Value: 98.2% with direct laryngoscope, 9% with video laryngoscope
  • Study of Diagnostic Validity of Multivariate Airway Scoring Systems to Predict Difficult Laryngoscopy (J Intl Med Res, 2016) [MEDLINE]
    • All Three Scoring Systems (Naguib, LEMON, and MACOCHA) Demonstrated Inconclusive Zones Which Limit Their Clinical Utility in Predicting Difficult Intubations
  • Study of the Modified LEMON Score in Patients Undergoing Intubation for Emergency Surgery for Trauma (J Emerg Surg, 2018) [MEDLINE]
    • Modified LEMON Score (the LEON Score, Omitting the Mallampati Score Component) was Correlated with Difficult Intubation in Adult Trauma Patients Undergoing Emergency Surgery
  • Systematic Review of Airway Assessment Methods to Predict Difficult Intubation (JAMA, 2019) [MEDLINE]: n= 33, 559 Patients (62 High-Quality Studies)
    • Approximately 10% (95% CI: 8.2%-12%) of Patients were Difficult to Intubate in the Systematic Review
    • In Terms of Predicting Difficulty to Intubate, Grade of Class 3 on the Upper Lip Bite Test Had a Positive Likelihood Ratio of 14 (95% CI: 8.9-22) and Specificity 0.96 (95% CI: 0.93-0.97)
    • In Terms of Predicting Difficulty to Intubate, Shorter Hyomental Distance Had a Range of <3-5.5 cm, Positive Likelihood Ratio 6.4 (95% CI: 4.1-10), and Specificity 0.97 (95% CI: 0.94-0.98)
    • In Terms of Predicting Difficulty to Intubate, Retrognathia (Mandible Measuring <9 cm from the Angle of the Jaw to the Tip of the Chin or Subjectively Short) Had a Positive Likelihood Ratio 6.0 (95% CI, 3.1-11) and Specificity 0.98 (95% CI: 0.90-1.0)
    • In Terms of Predicting Difficulty to Intubate, Combination of Physical Findings Based on the Wilson Score Had a Positive Likelihood Ratio 9.1 (95% CI: 5.1-16) and Specificity 0.95 [95% CI: 0.90-0.98)
    • In Terms of Predicting Difficulty to Intubate, Modified Mallampati Score (≥3) had a Positive Likelihood Ratio 4.1 (95% CI: 3.0-5.6) and Specificity 0.87 (95% CI: 0.81-0.91)
    • An Abnormal Upper Lip Bite Test Raises the Probability of Difficult Intubation from 10% to >60% for the Average Risk Patient

MACOCHA Airway Assessment Score

• Scoring System (Am J Respir Crit Care Med, 2013) [MEDLINE]
  • Patient Factors
    • Mallampati Class III/IV: 5 points
    • Obstructive Sleep Apnea (OSA): 2 points
    • Decreased C-Spine Mobility: 1 point
    • Limited Mouth Opening (≤3 cm): 1 point
  • Physiology Factors
    • Coma: 1 point
    • Severe Hypoxemia (SaO2 <80%): 1 point
  • Operator Factors:
    • Non-Anesthesiologist: 1 point
  • Scoring
    • 0 = easy airway
    • 12 = difficult airway
• Clinical Efficacy
  • MACOCHA Score Predicts Difficult Intubation (Am J Respir Crit Care Med, 2013) [MEDLINE]
    • Performance
      • Sensitivity: 73%
      • Specificity: 83%
      • Negative Predictive Value: 98%
      • Positive Predictive Value: 36%
    • Scoring Stratification
      • MACOCHA 6-7: 45% are difficult
      • MACOCHA 8-9: >50% are difficult
      • MACOCHA 12: 100% are difficult
  • MACOCHA Score Can Be Used to Predict Intubation Failure in Non-Anesthesiologist Trainees (J Crit Care, 2015) [MEDLINE]
  • Study of Diagnostic Validity of Multivariate Airway Scoring Systems to Predict Difficult Laryngoscopy (J Intl Med Res, 2016) [MEDLINE]
    • All Three Scoring Systems (Naguib, LEMON, and MACOCHA) Demonstrated Inconclusive Zones Which Limit Their Clinical Utility in Predicting Difficult Intubations
  • Systematic Review of Airway Assessment Methods to Predict Difficult Intubation (JAMA, 2019) [MEDLINE]: n= 33, 559 Patients (62 High-Quality Studies)
    • Approximately 10% (95% CI: 8.2%-12%) of Patients were Difficult to Intubate in the Systematic Review
    • In Terms of Predicting Difficulty to Intubate, Grade of Class 3 on the Upper Lip Bite Test Had a Positive Likelihood Ratio of 14 (95% CI: 8.9-22) and Specificity 0.96 (95% CI: 0.93-0.97)
    • In Terms of Predicting Difficulty to Intubate, Shorter Hyomental Distance Had a Range of <3-5.5 cm, Positive Likelihood Ratio 6.4 (95% CI: 4.1-10), and Specificity 0.97 (95% CI: 0.94-0.98)
    • In Terms of Predicting Difficulty to Intubate, Retrognathia (Mandible Measuring <9 cm from the Angle of the Jaw to the Tip of the Chin or Subjectively Short) Had a Positive Likelihood Ratio 6.0 (95% CI, 3.1-11) and Specificity 0.98 (95% CI: 0.90-1.0)
    • In Terms of Predicting Difficulty to Intubate, Combination of Physical Findings Based on the Wilson Score Had a Positive Likelihood Ratio 9.1 (95% CI: 5.1-16) and Specificity 0.95 [95% CI: 0.90-0.98)
    • In Terms of Predicting Difficulty to Intubate, Modified Mallampati Score (≥3) had a Positive Likelihood Ratio 4.1 (95% CI: 3.0-5.6) and Specificity 0.87 (95% CI: 0.81-0.91)
    • An Abnormal Upper Lip Bite Test Raises the Probability of Difficult Intubation from 10% to >60% for the Average Risk Patient

Specific Preoperative Airway Assessment of Patients with Known/Suspected Obstructive Sleep Apnea (OSA) (see Obstructive Sleep Apnea)

Recommendations (American Society of Anesthesiologists Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea 2014) (Anesthesiology, 2014) [MEDLINE]

• See Obstructive Sleep Apnea (OSA) (see Obstructive Sleep Apnea)

Specific Preoperative Airway Assessment of Patients with a Potential Difficult Airway

Recommendations (2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway) (Anesthesiology, 2022) [MEDLINE]

Recommendations for Airway Evaluation

• Before Initiation of Anesthetic Care/Airway Management, Airway Risk Assessment Should Be Performed by the Person(s) Responsible for Airway Management (Whenever Feasible) to Identify Patient, Medical, Surgical, Environmental, and Anesthetic Factors (Risk of Aspiration, etc) Which May Indicate the Potential for a Difficult Airway
  • When Available in the Patient’s Medical Record, Evaluate Demographic Information, Clinical Conditions, Diagnostic Test Findings, Patient/Family Interviews, and Questionnaire Responses
  • Assess Multiple Demographic and Clinical Characteristics to Determine a Patient’s Potential for a Difficult Airway or Aspiration
• Before Initiation of Anesthetic Care/Airway Management, Conduct an Airway Physical Examination to Identify Physical Characteristics Which May Indicate the Potential for a Difficult Airway
  • Physical Examination May Include Assessment of Facial Features, Anatomical Measurements, and Landmarks
  • Additional Evaluation to Characterize the Likelihood or Nature of the Anticipated Airway Difficulty May Include Bedside Endoscopy, Virtual Laryngoscopy/Bronchoscopy, or Three-Dimensional Printing
  • Assess Multiple Airway Features to Determine a Patient’s Potential for Difficult Airway or Aspiration

Recommendations for Preparation for Difficult Airway Management

• Ensure that Airway Management Equipment is Available in the Room
• Ensure that a Portable Storage Unit Which Contains Specialized Equipment for Difficult Airway Management is Immediately Available
• If a Difficult Airway is Known or Suspected
  • Ensure that a Skilled Individual is Present or Immediately Available to Assist with Airway Management (When Feasible)
  • Inform the Patient (or Responsible Person) of the Special Risks and Procedures Pertaining to Management of the Difficult Airway
  • Properly Position the Patient, Administer Supplemental Oxygen Before Initiating Management of the Difficult Airway, and Continue to Deliver Supplemental Oxygen (Whenever Feasible) throughout the Process of Difficult Airway Management (including Extubation
• At a Minimum, Ensure that Monitoring According to the ASA Standards for Basic Anesthesia Monitoring is Performed Before/During/After Airway Management of All Patients

Recommendations for Anticipated Difficult Airway Management

• Have a Preformulated Strategy for Management of the Anticipated Difficult Airway
  • Strategy Will Depend on the Anticipated Surgery, Condition of the Patient, Patient Cooperation/Consent, Patient Age, and Skills/Preferences of the Anesthesiologist
  • Develop a Strategy for the Following
    • Awake Intubation
    • Patient Who Can Be Adequately Ventilate, But is Difficult to Intubate
    • Patient Who Cannot Be Ventilated or Intubated
    • Patient Expected to Demonstrate Difficulty with Emergency Invasive Airway Rescue
  • When Appropriate, Perform Awake Intubation if the Patient is Suspected to Be a Difficult Intubation and ≥1 of the Following Apply
    • Patient Expected to Be Difficult to Ventilate (with Face Mask or Supraglottic Airway)
    • Increased Risk of Aspiration
    • Patient Expected to Be Intolerant of a Brief Apneic Episode
    • Patient Expected to Demonstrate Difficulty with Emergency Invasive Airway Rescue
  • The Uncooperative or Pediatric Patient May Restrict the Options for Difficult Airway Management (Particularly Options Which Involve Awake Intubation)
  • Airway Management in the Uncooperative or Pediatric Patient May Require an Approach (Such as Intubation Attempts After Induction of General Anesthesia) Which Might Not Be Regarded as a Primary Approach in a Cooperative Patient
  • Proceed with Airway Management After Induction of General Anesthesia When the Benefits are Judged to Outweigh the Risks
  • For Either Awake or Anesthetized Intubation, Airway Maneuvers May Be Attempted to Facilitate Intubation
  • Before Attempting Intubation of the Anticipated Difficult Airway, Determine the Benefit of a Noninvasive vs Invasive Approach to Airway Management
    • If Noninvasive Approach is Selected, Identify a Preferred Sequence of Noninvasive Airway Management Devices
      • If Difficulty is Encountered with a Technique, Combination Techniques May Be Used
      • Be Aware of the Passage of Time, the Number of Attempts, and Oxygen Saturation
      • Provide and Test Mask Ventilation After Each Attempt (When Feasible)
      • Limit the Number of Attempts at Endotracheal Intubation or Supraglottic Airway Placement to Avoid Potential Injury and Complications
    • If Elective Invasive Approach is Selected, Identify a Preferred Intervention
      • Ensure that an Invasive Airway is Performed by an Individual Trained in Invasive Airway Techniques (Whenever Possible)
      • If the Selected Approach Fails or is Not Feasible, Identify an Alternative Invasive Intervention
      • Initiate VV-ECMO When/if Appropriate and Available

Recommendations for Unanticipated and Emergency Difficult Airway Management

• Call for Help
• Optimize Oxygenation
• When Appropriate, Refer to an Algorithm and/or Cognitive Aid
• When Encountering an Unanticipated Difficult Airway
  • Determine the Benefit of Waking and/or Restoring Spontaneous Breathing
  • Determine the Benefit of a Noninvasive vs Invasive Approach to Airway Management
  • If a Noninvasive Approach is Selected, Identify a Preferred Sequence of Noninvasive Airway ManagementDevices to Use
    • If Difficulty is Encountered with Individual Techniques, Combination techniques May Be Performed
    • Be Aware of the Passage of Time, the Number of Attempts, and Oxygen Saturation
    • Provide and Test Mask Ventilation After Each Attempt (When Feasible)
    • Limit the Number of Attempts at Endotracheal Intubation or Supraglottic Airway Placement to Avoid Potential Injury and Complications
• If an Invasive approach to the Airway is Necessary (Due to “Cannot Intubate, Cannot Ventilate” Scenario), Identify a Preferred Intervention
  • Ensure that an Invasive Airway is Performed by an Individual Trained in Invasive Airway Techniques (Whenever Possible)
  • Ensure that an Invasive Airway is Performed as Rapidly as Possible
  • If the Selected Invasive Approach Fails or is Not Feasible, Identify an Alternative Invasive Intervention
    • Initiate VV-ECMO When/if Appropriate and Available

General Comments

• Proper Bag-Valve-Mask Ventilation Allows for Adequate Oxygenation and Ventilation, Giving the Provider Time to Prepare for a Well-Controlled Endotracheal Intubation (see Endotracheal Intubation)
• Requirements for Effective Bag-Valve-Mask Ventilation
  • Proper Mask Seal
  • Upper Airway Patency
  • Ability to Provide the Proper Respiratory Rate, Tidal Volume, and Cadence to Achieve Ventilation

Types of Ventilation Bags

Self-Inflating Ventilation Bag (Ambu Bag)

• Technique
  • Bag Has a Recoil Mechanism, Allowing Self-Inflation: does not require an oxygen flow to reinflate
  • Ambu Bag Has a One-Way Valve to Prevent Rebreathing: however, with a tight mask seal, some spontaneously breathing patients may be able to generate adequate inspiratory pressure to overcome the one-way valve
  • Oxygen Flows to the Patient When the Bag is Squeezed
• Range of Oxygen Delivery: 95-100% FIO2 (with reservoir)
• Considerations
  • Allows Assisted Ventilation in Combination with Supplemental Oxygen: assisted ventilation is useful for patient who may be hypoxemic in combination with hypercapnic (i.e. in type II hypoxemic, hypercapnic respiratory failure)
  • Should Not Use to Provide Blow By
  • Requires a Reservoir to Achieve Higher FIO2

Flow-Inflating Ventilation Bag (Anesthesia Bag)

• Technique
  • Flow-Inflating Bag Provides a Constant Flow of Oxygen (When Connected to an Oxygen Source): bag requires a constant oxygen flow to remain inflated
• Range of Oxygen Delivery: up to 100% FIO2
• Considerations
  • Allows Assisted Ventilation in Combination with Supplemental Oxygen: assisted ventilation is useful for patient who may be hypoxemic in combination with hypercapnic (i.e. in type II hypoxemic, hypercapnic respiratory failure)
  • May Use to Provide Blow By
  • Requires Expertise to Use Effectively (Pediatr Emerg Care, 1997) [MEDLINE]

Technique

General Comments

• Position the Mask So that the Top of the Mask is on the Bridge of the Nose and the Bottom of the Mask Covers the Mandibular Alveolar Ridge
• Operator Should Not Rest Wrists or the Upper Part of the Mask on the Patients Eyes (to Avoid Inducing a Vagal Response or Causing Corneal Damage

Mask Size

• Ensure that Airway Adjunct and Corners of the Mouth are Within the Mask and Allow a Proper Seal

Manual Techniques

• Single-Handed Bag-Valve-Mask Ventilation Technique
  • Requires Only a Single Provider to Perform Both Mask Sealing and Bag Ventilation
  • Place Hand with Thumb Web Resting Against the Mask Connector Tube and Three Fingers Along the Mandible (Using Fingers to Advance the Mandible Forward)
• Double-Handed Bag-Valve-Mask Ventilation Technique: generally considered the more effective method (Anesthesiology, 2010) [MEDLINE]
  • Requires a Second Person to Perform Bag Ventilation
  • Place Thumb and Index Finger on the Top of Mask and Other Three Fingers Along the Mandible (Using Fingers to Advance the Mandible Forward)
    • Alternately, the Provider Can Place Their Thenar Eminences on the Top of the Mask and the Other Four Fingers Along the Mandible (Using Fingers to Advance the Mandible Forward): this method may be less fatiguing and provide superior ventilation (Clin Anesth, 2013) [MEDLINE]

Respiratory Rate

• Generally, the Respiratory Rate During Bag Ventilation Should Correspond to the Patient’s Expected Acid-Base Status (with Caution to Avoid High Respiratory Rates in the Setting of Hemodynamic Compromise)
  • During Cardiopulmonary Resuscitation (CPR), Respiratory Rate Should Be <10-12 Breaths/min to Avoid Creating Unnecessary Auto-PEEP Which May Increased Intrathoracic Pressure, Resulting in Decreased Venous Return to the Right Side of the Heart and Decreased Cardiac Output ( Circulation, 2004) [MEDLINE] (Crit Care Med, 2004) [MEDLINE]
  • During CPR, the Standard Compression:Ventilation Ratio of 30:2 Would Result in a Respiratory Rate of Approximately 8 Breaths/min

Tidal Volume

• Generally, a Tidal Volume of 8-10 mL/kg is Adequate
  • During CPR, Tidal Volume of 5-6 mL/kg is Adequate, Due to Presence of Decreased Cardiac Output (Circulation, 1989) [MEDLINE]

Cricoid Pressure (Sellick’s Maneuver)

• Definition
  • Cricoid Pressure Applied During Bag-Valve-Mask Ventilation Decrease Gastric Insufflation
  • Cricoid Pressure Applied During Rapid Sequence Intubation Theoretically Decreases Emesis with Aspiration
    • Maintain Cricoid Pressure Until the Endotracheal Tube Cuff is Inflated
• Cautions
  • Cricoid Pressure is Frequently Applied Improperly and Inconsistently
  • Cricoid Pressure May Impair Lower Esophageal Sphincter Function
  • Cricoid Pressure May Result in Esophageal Injury
  • Cricoid Pressure May Result in Undesirable Movement of the Cervical Spine in Patients with Cervical Spinal Cord Injury
  • Cricoid Pressure May Contribute to Airway Obstruction, Even When Using a Video Laryngoscope (Ann Emerg Med, 2006) [MEDLINE] (Ann Emerg Med, 2013) [MEDLINE]
• Clinical Efficacy
  • Review of Cricoid Pressure to Prevent Aspiration During Endotracheal Intubation (Emerg Med J, 2005) [MEDLINE]
    • There is Little Evidence that Cricoid Pressure Decreases the Incidence of Aspiration During Rapid Sequence Intubation
  • Cochrane Database Systematic Review of Cricoid Pressure During Rapid Sequence Endotracheal Intubation (Cochrane Database Syst Rev, 2015) [MEDLINE]
    • No Randomized Trials are Available to Evaluate the Efficacy of Cricoid Pressure During Rapid Sequence Endotracheal Intubation
    • Non-Randomized Trials Suggest that Cricoid Pressure is Not Required to Safely Perform Rapid Sequence Endotracheal Intubation
• Recommendations
  • While Cricoid Pressure May Decrease Gastric Insufflation During Bag-Valve-Mask Ventilation, it is No Longer Recommended for Use During Rapid Sequence Endotracheal Intubation

Difficult Mask Ventilation

General Comments

• Difficult Mask Ventilation Occurs in Approximately 5% of Adults (Anesthesiology, 2000) [MEDLINE] and (Anesthesiology, 2006) [MEDLINE]
• Difficult Mask Ventilation is Associated with Difficult Intubation
  • Difficult Intubation Occurs in 30% of Patients with Difficult Mask Ventilation, as Compared to Only 8% of Patients without Difficult Mask Ventilation (Anesthesiology, 2000) [MEDLINE]
  • Difficult Mask Ventilation is Associated with a “Can’t Intubate, Can’t Ventilate” Scenario
• Predictors of Difficult Mask Ventilation: the presence of two of these factors had a 72% sensitivity and 73% specificity (Anesthesiology, 2000) [MEDLINE] and (Anesthesiology, 2006) [MEDLINE]
  • Age >55 y/o: age is associated with increased pharyngeal resistance to airflow (from choanae to epiglottis) in men, but not in women
  • BMI >26 kg/m2: obesity is associated with decreased posterior airway space behind the base of the tongue, impaired airway patency during sleep, and is a risk factor for OSA
  • Lack of Teeth
  • Presence of Beard
  • History of Snoring
  • Limited Mandibular Protrusion

Etiology of Difficult Mask Ventilation (Respir Care, 2015) [MEDLINE]

• Inadequate Mask Seal
  • Edentulism
  • Facial Hair
  • Improper Mask Size
  • Maxillomandibular Deformity
    • Micrognathia (see Micrognathia)
  • Upper Airway Foreign Body (see Airway Foreign Body)
• Increased Airway Resistance
  • Upper Airway
    • Enlarged Epiglottis
    • External Upper Airway Compression
      • Large Neck Mass
      • Neck Hematoma
    • Laryngospasm (see Laryngospasm)
    • Macroglossia (see Macroglossia)
    • Oropharyngeal Tumors
    • Redundant Upper Airway Soft Tissue
    • Tonsillar/Adenoidal Hypertrophy
    • Upper Airway Edema
  • Lower Airway
    • Airway Foreign Body (see Airway Foreign Body)
    • Airway Mass
    • Airway Secretions
    • Bronchospasm (see Obstructive Lung Disease)
    • Excessively Applied Cricoid Pressure
    • Mediastinal Mass (see Mediastinal Mass)
    • Tracheomalacia (see Tracheobronchomalacia)
    • Tracheal Stenosis (see Tracheal Stenosis)
• Decreased Respiratory System Compliance (Due to Lungs or Chest Wall)
  • Abdominal Abnormality
    • Abdominal Compartment Syndrome (see Abdominal Compartment Syndrome)
    • Ascites (see Ascites)
    • Pregnancy (see Pregnancy)
  • Chest Wall Abnormality
    • Orthotic with External Chest Compression
    • Severe Kyphoscoliosis (see Kyphoscoliosis)
  • Obesity (see Obesity)
  • Restrictive Lung Disease
    • Acute Respiratory Distress Syndrome (ARDS) (see Acute Respiratory Distress Syndrome)
    • Severe Interstitial Lung Disease (ILD) (see Interstitial Lung Disease)
    • Severe Pneumonia (see Pneumonia)
  • Tension Pneumothorax (see Pneumothorax)

Management of Difficult Bag-Valve-Mask Ventilation the Edentulous Patient

• Reinsert False Teeth in the Edentulous Patient to Improve Mask Seal (Anesth Analg, 2007) [MEDLINE]
• Changing Location of the Lower Edge of the Mask to Between the Lower Lip and the Alveolar Ridge May Improve Mask Seal in the Edentulous Patient (Anesthesiology, 2010) [MEDLINE]

Hemodynamic Optimization

• Since Sedative Medications and Positive-Pressure Ventilation Can Both Induce Hypotension During and/or Soon After Endotracheal Intubation, Attention Should Be Paid to Intravenous Volume Resuscitation Prior to Intubation
  • In Most Cases, Preemptive Intravenous Volume Resuscitation and Vasopressors Can Be Utilized Prior to and/or During Endotracheal Intubation to Mitigate or Completely Avoid the Occurrence of Intubation-Associated Hypotension

Body Positioning for Intubation

Body Positions

• Sniffing Position: classical position used for intubation
  • Atlanto-Occipital Extension with Head Elevation of 3-7 cm
• Ramped Position
  • Use of Towels/Blankets to Elevate the Head and Upper Torso, Creating Horizontal Alignment of the External Auditory Meatus with the Sternal Notch

Clinical Efficacy

• Comparison of Sniff and Ramped Positions for Laryngoscopic Intubation in Morbidly Obese Patients (Obes Surg, 2004) [MEDLINE]: randomized trial (n = 60)
  • Sniffing Position was Achieved by Placing a Firm 7 cm Cushion Under the Patient’s Head: this raised the occiput a standard distance from the table
  • Ramped Position was Achieved by Placing Blankets Under the Upper Body and Head to Horizontally Align the External Auditory Meatus with the Sternal Notch
  • Ramped Position Significantly Improved the Laryngeal View, as Compared to the Standard Sniffing Position
• Study of Head-Elevated Position During Endotracheal Intubation in Decreasing Airway-Related Complications (Anesth Analg, 2016) [MEDLINE]: retrospective study (n = 528)
  • Back-Up, Head-Elevated Position During Endotracheal Intubation Decreased Airway-Related Complications (Aspiration, Difficult Intubation, Hypoxemia, Esophageal Intubation), as Compared to Supine Positioning

Preparation of the Endotracheal Tube (ETT)

Purposes of the Endotracheal Tube

• Maintenance of Airway Patency in in Patient Who Cannot Do So Independently
• Maintenance of Upper Airway Patency During Positive-Pressure Mechanical Ventilation
  • While Negative-Pressure Ventilation May Induce Upper Airway Collapse (Requiring an Endotracheal Tube to Maintain Airway Patency with Large Negative Airway Pressures), Maintenance of Airway Patency During Positive-Pressure Ventilation is Also Critically Important
• Pulmonary Toilet
  • Maintenance of the Ability to Therapeutically Clear Airways (i.e. Suctioning of Secretions and Blood)

Choice of Endotracheal Tube

• Standard Single-Lumen Endotracheal Tube
• Rusch Endotracheal Tube
  • Rusch Endotracheal Tube is a Reinforced Tube
    • Commonly Used When Flexibility of the Endotracheal Tube is Desired without Compromise of Tube Patency (Either During Intubation or Following Intubation During a Surgical Procedure)
    • Commonly Used for Surgical Procedures Involving the Upper Airway, Cervical Spine, etc
• Subglottic Suction Port Endotracheal Tube
  • Subglottic Suction Port Endotracheal Tubes are Designed to Allow Suctioning of Secretions from Above the Endotracheal Tube Cuff and Theoretically Decrease the Risk of Ventilator-Associated Pneumonia (VAP) (see Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)
• Silver-Coated Endotracheal Tube
  • Silver Coating is Designed to Decrease Bacterial Growth and Theoretically Decrease the Risk of Ventilator-Associated Pneumonia (VAP) (see Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)
• Double-Lumen Endotracheal Tube
  • Dual-Lumen Endotracheal Tube May Be Used for Single-Lung Isolation/Ventilation (During Cardiothoracic Surgery, for the Management of Severe Hemoptysis, etc)

Structure of the Endotracheal Tube

Anatomic Relationships of the Endotracheal Tube

Physical Preparation of the Endotracheal Tube

• Push Top Endotracheal Tube Connector Piece Firmly into the Endotracheal Tube: this is important since insertion of this piece deeper into the endotracheal tube after intubation can be difficult in some cases
• Determine if Stylet Will Be Utilized (and if it Should Be Loaded in the Endotracheal Tube)
  • Standard Aluminum Stylet
  • Gum Elastic Bougie with Bent Tip
  • Stiff Metal Stylet (Glidescope Stylet, etc)
• Check Endotracheal Tube Cuff Balloon for Integrity: keep the 10 mL syringe available for cuff inflation after intubation
• Lubricate Endotracheal Tube Cuff: avoid lubricating endotracheal tube above the cuff, as this can make handling of the tube difficult during intubation
• Assure that a Colorimetric Carbon Dioxide Detector is Present

Confirmation of Functioning Suction Set-Up

• Yankauer Suction Set-Up Should Be Tested for Function: in some cases with large volumes of anticipated orla material, a second suction set-up should be prepared

Preparation of Backup Airway Management Devices and Personnel with Airway Expertise

• Prior to Intubation, Other Airway Devices (Including Bronchoscope, Laryngeal Mask Airway, etc) and Personnel Should Be Readily Available, Should Difficulty Be Encountered During Intubation
  • Pre-Intubation Airway Assessment is Crucial to Predict the Risk of a Difficult Airway Prior to Intubation, Triggering More Robust Advance Preparation
  • However, Since a Difficult Intubation Can Be Encountered Unexpectedly in Some Cases, Routine Preparation of Other Equipment is Always Advisable

Confirmation of Adequate Intravenous Access and Intravenous Fluids

• Ensure that Patient Has at Least Two Functional Intravenous Lines in Place
  • Adequate Intravenous Access is Critical to Deliver Sedative and Paralytic Medications Which are Standardly Used to Facilitate Endotracheal Intubation
  • Loss of Functional Intravenous Lines During the Course of Endotracheal Intubation Can Significantly Delay the Performance of Rapid Sequence Intubation, Resulting in Undesired Prolonged Bag-Valve-Mask Ventilation and Gastric Insufflation
• Intravenous Fluids and Vasopressors Should Be Available to Manage Post-Intubation Hypotension

Confirmation of Preparation of Sedative and Paralytic Medications for Intubation

• In Addition to Below, Additional Sedatives (Propofol Drip, etc) May Be Desired to Manage Sedation After Intubation: this is critical when a short-acting sedative (such as etomidate) is used in conjunction with a long-acting paralytic agent (such as rocuronium, etc)

Team-Oriented Approach with Protocol/Checklist/Cognitive Aids

• Prospective Multicenter Study of a Bundle to Decrease Endotracheal Intubation Complications in the ICU (Intensive Care Med, 2010) [MEDLINE]: n = 244 intubations
  • Bundle Components
    • Capnography
    • Cricoid Pressure
    • Fluid Loading
    • Preoxygenation with Noninvasive Positive Pressure Ventilation
    • Preparation and Early Administration of Sedation and Vasopressor Use if Needed
    • Presence of two operators, rapid sequence induction
    • Protective Ventilation
  • Intubation Management Protocol Decreased Immediate Severe Life-Threatening Complications (Cardiac Arrest or Death, Severe Cardiovascular Collapse, and Hypoxemia Occurring within 60 min of Endotracheal Intubation of ICU Patients
• Single-Center, Prospective Observational Trial of Team Approach, Mandatory Checklist, Use of Crew Resource Management Tactics, and Postevent Debriefing to Improve the Quality of Endotracheal Intubation by Pulmonary/Critical Care Fellows (J Intensive Care Med, 2011) [MEDLINE]: n- 101 intubations
  • Emergency Endotracheal Intubation Could Be Performed by Pulmonary/Critical Care Fellows with Safety Comparable to Other Providers
• Literature Review of Cognitive Aids in the Assistance of Anesthetic Management (Anesth Analg, 2013) [MEDLINE]
  • Cognitive Aids are Prompts (Posters, Flowcharts, Checklists, or Mnemonics) Designed to Assist Users Complete a Task or Series of Tasks _ Ten Studies Using Simulation Suggested that Technical Performance Improved with the Use of Cognitive Aids in Some Anesthetic Emergencies (Malignant Hyperthermia, Cardiopulmonary Resuscitation, and Airway Management)
  • Cognitive Aids Would Benefit from More Extensive Simulation-Based Usability Testing Before Use
• Study of Implementation of a Difficult Airway Response Team (DART) at the Johns Hopkins Hospital (Anesth Analg, 2015) [MEDLINE]
  • DART is a Comprehensive Program for Improving Difficult Airway Management
  • Between July, 2008-June, 2013, DART Managed 360 Adult Difficult Airway Events, Comprising 8% of All Code Blue Activations
  • Predisposing Patient Factors Included BMI >40, History of Head and Neck Tumor, Prior Difficult Intubation, Cervical Spine Injury, Airway Edema, Airway Bleeding, and Previous or Current Tracheostomy
  • There Were No Airway Management Related Deaths, Sentinel Events, or Malpractice Claims in Adult Patients Managed by DART
• Study of the Vortex Tool for Emergency Airway Management in “Can’t Intubate, Can’t Oxygenate” (CICO) Scenarios (Br J Anaesth, 2016) [MEDLINE]
  • Vortex Approach ([LINK]
  • The Vortex is Flexible Enough for the Same Tool to Be Applied to Any Circumstance in which Airway Management Takes Place, Independent of Context, Patient Type, or the Intended Airway Device
• Multicenter Randomized Trial of a Checklist for Endotracheal Intubation of Critically Ill Adults (Chest, 2018) [MEDLINE]: n = 262
  • The Verbal Performance of a Written, Preprocedure Checklist Did Not Increase the Lowest Arterial Oxygen Saturation or Lowest Systolic Blood Pressure During Endotracheal Intubation of Critically Ill Adults, as Compared to Usual Care
• Comprehensive Systematic Review of Randomized Trials for Endotracheal Intubation in Critically Ill Patients (Crit Care, 2018) [MEDLINE]
  • No Effect was Found for Use of a Pre-Intubation Checklist (Although Only 1 Trial was Reviewed)
• Review of Difficult Airway Management Team (DART Experience at the Johns Hopkins Hospital (Crit Care Clin, 2018) [MEDLINE]
  • Article Details the Lessons Learned and Recommendations for Initiating a DART Program
• Study of Simulation-Based Airway Management Training of Critical Care Fellows Using a Checklist (Chest 2020) [MEDLINE]
  • Simulation-Based Airway Management Training of Early Critical Care Fellows (Using a Checklist) Transferred Well to Real-Life Critical Care Airway Management Skills Later in Fellowship

Rapid Sequence Intubation (RSI)

Definition and Background

• Definition of Rapid Sequence Intubation: period of preoxygenation, folllowed by the nearly simultaneous administration of a sedative and paralytic agent to facilitate rapid and effective endotracheal intubation (with a minimal risk of aspiration)
  • RSI is the Most Common Emergency Intubation Technique in a Patient Who is Not Anticipated to Have a Difficult Airway: approximately 85% of first endotracheal intubation attempts in emergency departments are performed using RSI (Ann Emerg Med, 2015) [MEDLINE]

Clinical Efficacy

• RSI Has Been Demonstrated to Decrease Procedure-Related Complications and Increase the Probability of First-Pass Endotracheal Intubation Success (Crit Care Med, 2012) [MEDLINE] (Ann Am Thorac Soc, 2015) [MEDLINE] (Int J Emerg Med, 2017)[MEDLINE]
• RSI Has Been Demonstrated to Have High First-Pass Endotracheal Intubation Success Rates (90%) with Video Laryngoscopy in Patients with Anticipated Difficult Airways: 11% of non-arrest patients had a predicted difficult airway in this study and none required a surgical airway ( J Emerg Med, 2017) [MEDLINE]

Physiologic Basis of Rapid Sequence Intubation

• RSI is Based Upon the Observation that, After Preoxygenation, an Average 70 kg Adult Will Maintain SaO2 >90% for 8 min During Apnea (Anesthesiology, 1997) [MEDLINE]
  • Importantly, Even with Adequate Preoxygenation, this Period of Time is <3 min in Critically Ill, Obese, and Third Trimester Pregnant Patients
  • This Period of Time is <4 min in Children
• Preoxygenation (with the Highest Possible Oxygen Concentration for a Minimum of 3 min) Replaces Nitrogen and Other Gases in the Functional Residual Capacity, Creating an Oxygen Reservoir Which is Depleted During the Subsequent RSI Apneic Period (Anesth Analg, 2017) [MEDLINE]
• Importantly, in its Pure Form, RSI Utilizes an Apneic Period Following Administration of Pharmacologic Sedation/Paralytic (Up to the Point of Endotracheal Tube Placement): bag ventilation is avoided during this period, if possible, to avoid gastric insufflation (which may result in aspiration)

Cautions

• Since RSI Utilizes the Monitoring of Oxygen Saturation During Apnea, Finger Probe Pulse Oximetry May Lag Behind that of the Central Arterial Circulation in Critically Ill Patients (Can J Anaesth, 1992) [MEDLINE]: for this reason, pulse oximetry must be used with judicious caution during RSI
• In Patients with Right-to-Left Shunt (Usually Intrapulmonary Shunt Resulting from Pneumonia, ARDS, etc), Standard Attempts at Preoxygenation May Be Ineffective: these patients may require positive-pressure ventilation with PEEP to promote alveolar recruitment and facilitate adequate preoxygenation
  • Bag-Valve Mask Ventilation, Noninvasive Positive-Pressure Ventilation, or High-Flow Nasal Cannula Can Be Used to Facilitate Prexoygenation in this Setting

Relative Contraindications to Rapid-Sequence Intubation

• Anticipated Difficult Intubation (Especially if Rescue is Anticipated to Be Difficult or Impossible)
• Inability to Tolerate Apneic Period During RSI (Due to Severe Hypoxemia, Acidosis, etc)

Seven P’s of Rapid Sequence Intubation

• Preparation: 10 min before intubation
• Preoxygenation: 5 min before intubation
• Pre-Intubation Optimization: 3 min before intubation
• Paralysis with Induction: induction
• Protection: 30 sec after induction
• Placement (Intubation): 45 sec after induction
• Post-Intubation Management: 60 sec after induction

Physiologic Basis of Rapid Sequence Intubation

• Rapid Sequence Intubation is Based Upon the Observation that, After Preoxygenation, an Average 70 kg Adult Will Maintain SaO2 >90% for 8 min During Apnea (Anesthesiology, 1997) [MEDLINE]
  • Importantly, Even with Adequate Preoxygenation, this Period of Time is <3 min in Critically Ill, Obese, and Third Trimester Pregnant Patients
  • This Period of Time is <4 min in Children
• Preoxygenation (with the Highest Possible Oxygen Concentration for a Minimum of 3 min) Replaces Nitrogen and Other Gases in the Functional Residual Capacity of the Lung, Creating an Oxygen Reservoir Which is Subsequently Depleted During the Subsequent Rapid Sequence Intubation Apneic Period (Anesth Analg, 2017) [MEDLINE]
  • Since Rapid Sequence Intubation Utilizes the Monitoring of Oxygen Saturation Using Finger Probe Pulse Oximetry During Apnea, Pulse Oximetry Readings May Lag Behind that of the Central Arterial Circulation in Critically Ill Patients (Can J Anaesth, 1992) [MEDLINE]
    • Consequently, Pulse Oximetry Must Be Used Judiciously During Rapid Sequence Intubation
• Effect on Obesity on Apneic Time (see Obesity)
  • Because Obesity is Characterized by Increased Oxygen Consumption and Increased Carbon Dioxide Production, the Time to Desaturation (and the “Safe Apnea Period” During Rapid Sequence Intubation) are Decreased (Anesthesiology, 1997) [MEDLINE]

Preoxygenation Technique

• Methods to Increase the Reservoir Size During Preoxygenation
  • Use of Bag-Valve-Mask Ventilation or Noninvasive Positive-Pressure Ventilation, Both of Which Increase the Mean Airway Pressure
  • Use of 20 Degree Head-Up Patient Positioning, Which Decreases Dependent Atelectasis (Anaesthesia, 2005) [MEDLINE]
• Preoxygenation Techniques Based on Patient Type
  • Patient with Adequate Spontaneous Ventilation and Cooperative
    • Bag-Valve-Mask Ventilation with Oxygen at 15 L/min
      • Squeezing the Bag is Not Necessary, But a Tight Mask Seal Must Be Maintained to Ensure a High FIO2
      • If the Time is Critically Short and the Bag is Squeezed, Eight Vital Capacity Breaths Can Achieve Adequate Preoxygenation in <1 min
  • Patient with Adequate Spontaneous Ventilation and Uncooperative/Intolerant of Bag-Valve-Mask Ventilation
    • Non-Rebreather Mask with Flush Rate Oxygen (≥50 L/min): note that standard 15 L/minflow rates are inadequate for preoxygenation due to entrainment of room air (and decrease in the effective FIO2)
    • High-Flow Nasal Cannula: can also be considered
  • Patient with Inadequate Spontaneous Ventilation
    • Bag-Valve-Mask Ventilation with Oxygen at 15 L/min (Synchronized with Patient’s Respiratory Efforts): avoid pressure >20 cm H2O to minimize the degree of gastric insufflation
• In its Pure Form, Rapid Sequence Intubation Utilizes Administration of Pharmacologic Sedation (Induction) and Paralysis, Followed by an Apneic Period without Bag-Valve-Mask Ventilation Up to the Point of Endotracheal Tube Placement
  • Bag-Valve-Mask Ventilation is Avoided, if Possible, to Avoid Gastric Insufflation (Which May Result in Aspiration)
• However, In Patients with Right-to-Left Shunt (Usually Intrapulmonary Shunt Resulting from Pneumonia, ARDS, etc), Standard Attempts at Preoxygenation May Be Ineffective
  • These Patients May Require Positive-Pressure Ventilation with PEEP to Promote Alveolar Recruitment and Facilitate Adequate Preoxygenation
  • Bag-Valve Mask Ventilation, Noninvasive Positive-Pressure Ventilation, or High-Flow Nasal Cannula Can Be Used to Facilitate Prexoygenation in this Setting

Continuous Passive Oxygenation During Apnea (“Apneic Oxygenation”)

• Continuous Passive Oxygenation Can Be Used During the Rapid Sequence Intubation Apneic Period for Patients Who Cannot Tolerate the Apneic Period without Developing Hypoxemia
  • Continuous Passive Oxygenation Slows Depletion of the Oxygen Reservoir Created During Preoxygenation
  • Apneic Oxygenation Can Potentially Induce Worsening Hypercapnia in Patients with Chronic Hypoventilation (in this Setting, Predominantly Due to the Worsening of V/Q Mismatch)
    • The Resulting Hypercapnia Can Be Deleterious in Specific Patient Populations, Such as Those with Increased Intracranial Pressure, Metabolic Acidosis, or Pulmonary Hypertension
• Continuous Passive Oxygenation Techniques
  • High-Flow Nasal Cannula (HFNC)
  • Standard Nasal Cannula (at a High Flow Rate): at flow rate ≥15 L/min

Clinical Efficacy-Preoxygenation and Continuous Passive Oxygenation During Apnea (“Apneic Oxygenation”)

• Study of Nasopharyngeal Apneic Oxygenation Using the Four Breath Technique in Surgical Patients (Anaesthesia, 2006) [MEDLINE]
  • Apneic Oxygenation (Following Preoxygenation Using the Four Breath Technique) Delayed the Onset of Oxygen Desaturation During Apnea
    • Study of Apneic Oxygenation in During Simulated Laryngoscopy in Obese Patients (J Clin Anesth, 2010) [MEDLINE]
  • Nasal Apneic Oxygenation Improved the Frequency/Duration of SpO2 ≥95% and Increased the Minimal SpO2 During Prolonged Laryngoscopy in Obese Patients
• Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) Increases Apnea Time During Endotracheal Intubation (Anaesthesia, 2015) [MEDLINE]
  • High-Nasal Cannula Oxygenation (During Preoxygenation and Continuing as Post-Oxygenation During Intravenous Induction of Anaesthesia and Neuromuscular Blockade Until Airway was Secured) Increases the Apnea Time During Endotracheal Intubation
  • Proposed Mechanism: combines the benefits of classical apneic oxygenation with continuous positive airway pressure and gaseous exchange through flow-dependent deadspace flushing
• French PREOXYFLOW Multicenter Randomized Trial of High-Flow Nasal Cannula in Hypoxemic Patients Undergoing Intubation (Intensive Care Med, 2015) [MEDLINE]: multicenter, randomized opne-labelled, controlled trial in 6 French ICU’s (n = 124)
  • In Terms of the Lowest Level of Oxygen Desaturation, High-Flow Nasal Cannula (Maintained Throughout the Procedure) was Comparable to High-Flow Face Mask Preoxygenation (Removed at End of General Anesthesia Induction)
  • No Differences were Observed in Difficult Intubations, Ventilator-Free Days, intubation-Related Events, or Mortality Rate
• Trial of High-Flow Nasal Cannula During Endotracheal Intubation in ICU Patients (Crit Care Med, 2015) [MEDLINE]: n = 101
  • High-Flow Nasal Cannula Oxygen Significantly Improved Preoxygenation and Reduced the Prevalence of Severe Hypoxemia, as Compared to Non-Rebreathing Bag Reservoir Facemask Oxygen
• Australian Study of Apneic Oxygenation in Helicopter Emergency Service (Ann Emerg Med, 2015) [MEDLINE]
  • Apneic Oxygenation Decreased the Incidence of Oxygen Desaturation in Patients Undergoing Rapid Sequence Intubation
• Study of Apneic Oxygenation in Adult Patients the Emergency Department (Acad Emerg Med, 2016) [MEDLINE]
  • Apneic Oxygenation Increased First-Pass Intubation Success without Hypoxemia
• Randomized Trial of Apneic Oxygenation During Intubation in Critically Ill Adult Patients in the Medical ICU (Am J Respir Crit Care Med, 2016) [MEDLINE]: n= 150
  • Apneic Oxygenation Had No Effect on the Lowest Oxygen Saturation in Critically Ill Patients
• German Randomized Trial of Flow Nasal Cannula Versus Bag-Valve-Mask for Preoxygenation Before Intubation in Subjects With Hypoxemic Respiratory Failure (Respir Care, 2016) [MEDLINE]: n = 40
  • No Significant Difference in the Mean Lowest Oxygen Saturation During intubation Between the High-Flow Nasal Cannula Group and the Bag-Valve-Mask-Ventilation Group in Patients with Mild-Moderate Hypoxemic Respiratory Failure
  • However, On Continuous Monitoring, There was a Significant Decrease in Oxygen Saturation During the Apnea Phase Before Intubation in the Bag-Valve-Mask-Ventilation Group, which was Not Observed in the High-Flow Nasal Cannula Group
• French OPTINIV Trial of High-Flow Nasal Cannula Combined with Noninvasive Positive-Pressure Ventilation vs Noninvasive Positive-Pressure Ventilation Alone for Preoxygenation Prior to Intubation (Intensive Care Med, 2016) [MEDLINE]: single-center, blinded, randomized trial
  • Use of Combined High-Flow Nasal Cannula and Noninvasive Positive-Pressure Ventilation for Preoxygenation Prior to Intubation was More Effective in Decreasing Oxygen Desaturation, as Compared to Noninvasive Positive-Pressure Ventilation Alone
• Trial of Apneic Oxygenation During Rapid Sequence Intubation in the Emergency Department (Acad Emerg Med, 2016) [MEDLINE]
  • Apneic Oxygenation During RSI Increased the First Pass Success (without Hypoxemia) Rate: defined as successful intubation with SaO2 remaining ≥90%
• Randomized Trial of Apneic Oxygenation During Intubation in a Medical ICU (Am J Respir Crit Care Med, 2016) [MEDLINE]: n = 150
  • Apneic Oxygenation with High-Flow Nasal Cannula (15 L/min) During Intubation Did Not Increase the Lowest SaO2, as Compared to Usual Care
• Systematic Review and Meta-Analysis of Support Techniques to Prevent Oxygen Desaturation in Critically Ill Patients Requiring Endotracheal Intubation ( J Crit Care, 2017) [MEDLINE]
  • Apneic Oxygenation was Significantly Associated with Higher Minimum Oxygen Saturation During Intubation, as Compared to No Apneic Oxygenation: but there were no significant differences in severe hypoxemia and intubation related-complications
  • Further Study is Required to Evaluate the Role of Noninvasive Positive-Pressure Ventilation (NIPPV) and High-Flow Nasal Cannula (HFNC)
• Systematic Review/Meta-Analysis of Apneic Oxygenation During Emergency Intubation (Am J Emerg Med, 2017) [MEDLINE]
  • Apneic Oxygenation Significantly Decreased the Incidence of Hypoxemia During Emergency Intubation
• Systematic Review/Meta-Analysis of Apneic Oxygenation (J Crit Care, 2017) [MEDLINE]
  • In Patients Being Intubated for Any Indication Other than Respiratory Failure, Apneic Oxygenation at Any Flow Rate >15 L/min Decreased the Incidence of Desaturation (<90%) and Critical Desaturation (<80%)
  • Further Trials are Required, Given the Degree of Heterogeneity in Outcomes and Subgroup Analyses
• Systematic Review/Meta-Analysis of Apneic Oxygenation (Ann Emerg Med, 2017 [MEDLINE]
  • Apneic Oxygenation Increased Peri-Intubation Oxygen Saturation, Decreased the Rate of Hypoxemia, and Increased First-Pass Success Rate
• Randomized ENDAO Trial of Apneic Oxygenation During Rapid Sequence Intubation in the Emergency Department (Acad Emerg Med, 2017) [MEDLINE]: n = 200
  • Apneic Oxygenation Had No Effect on the Lowest Mean Oxygen Saturation
  • However, All Patients were Intubated within 120 sec in this Trial, Likely Diluting Out Any Effect that Apneic Oxygenation Might Have Had
• Study of Risk Factors for and Prediction of Hypoxemia During Endotracheal Intubation of Critically Ill Adults (Ann Am Thorac Soc, 2018) [MEDLINE]: n = 426
  • Predictors of Severe Hypoxemia During Endotracheal Intubation of Critically Ill Adult
    • Hypoxemic Respiratory Failure as Indication for Intubation (Odds Ratio 2.70; 95% CI: 1.58-4.60)
    • Lower Oxygen Saturation at Induction (Odds Ratio 0.92 Per 1% Increase; 95% CI: 0.89-0.96 Per 1% Increase)
    • Younger Age (Odds Ratio 0.97 Per 1-Year Increase in Age; 95% CI: 0.95-0.99 Per 1-Year Increase in Age)
    • Higher Body Mass Index (Odds Ratio 1.03 Per 1 kg/m2; 95% CI: 1.00-1.06 Per 1 kg/m2)
    • Race (Odds Ratio 4.58 for White vs Black; 95% CI, 1.97-10.67; Odds Ratio 4.47 for Other vs Black; 95% CI: 1.19-16.84)
    • Operator with <100 Prior Intubations (Odds Ratio 2.83; 95% CI: 1.37-5.85)
• Comprehensive Systematic Review of Randomized Trials for Endotracheal Intubation in Critically Ill Patients (Crit Care, 2018) [MEDLINE]: n = 22 trials
  • Analyzed 1 Trial Using Pre-Procedure Checklist, 6 Trials of Preoxygenation or Apneic Oxygenation, 3 Trials of Sedatives, 1 Trial of Neuromuscular Blocking Agents, 1 Trial of Patient Positioning, 9 Trials of Video Laryngoscopy, and 1 Trial of Post-Intubation Lung Recruitment
  • Preoxygenation with Noninvasive Positive-Pressure Ventilation and/or High-Flow Nasal Cannula Before Endotracheal Intubation was Beneficial
  • Post-Intubation Lung Recruitment Maneuvers May Increase Post-Intubation Oxygenation
  • No Effect was Found for Use of a Pre-Intubation Checklist, Apneic Oxygenation (on Oxygenation and Hemodynamics), Video Laryngoscopy (on Number and Length of Intubation Attempts), Sedatives and Neuromuscular Blockers (on Hemodynamics)
  • Video Laryngoscopy was Associated with Severe Adverse Effects in Multiple Trials
  • Ramped Position Increased the Number of Intubation Attempts
  • Thiopental Had Negative Hemodynamic Effects
• Multicenter, Randomized PreVent Trial of Bag-Valve-Mask Ventilation During Endotracheal Intubation in Critically Ill Patients (NEJM, 2019) [MEDLINE]: n = 401 (7 intensive care units in the US)
  • Bag-Valve-Mask Ventilation During Endotracheal Intubation Resulted in Improved Oxygenation, as Compared to Apnea Between Induction and Laryngoscopy
  • Operator-Reported Aspiration Occurred During 2.5% of Intubations in the Bag-Valve-Mask Ventilation Group and During 4.0% of Intubations in the No-Ventilation Group (P = 0.41)
  • Incidence of New Opacity on Chest X-Ray in the 48 hrs After Endotracheal Intubation was 16.4% in the Bag-Valve-Mask Ventilation Group and 14.8% in the No Ventilation Group (P = 0.73)
• Randomized PROTRACH Trial of Nasal High-Flow Preoxygenation for Endotracheal Intubation in the Critically Ill Patient (Intensive Care Med, 2019) [MEDLINE]: n = 192 randomized, n = 184 in intent-to-treat analysis
  • Compared with Standard Bag-Valve-Mask Oxygenation, Preoxygenation with High-Flow Nasal Cannula Did Not improve the Lowest Oxygen Saturation During Intubation in the Non-Severely Hypoxemic Patients, But Led to a Decrease in Intubation-Related Adverse Events

Cricoid Pressure (Sellick’s Maneuver)

• Definition
  • Cricoid Pressure Applied During Bag-Valve-Mask Ventilation Decrease Gastric Insufflation
  • Cricoid Pressure Applied During Rapid Sequence Intubation (and Maintained Until the Endotracheal Tube Cuff is Inflated) Theoretically Decreases Emesis with Aspiration
• Cautions
  • Cricoid Pressure is Frequently Applied Improperly and Inconsistently
  • Cricoid Pressure May Impair Lower Esophageal Sphincter Function
  • Cricoid Pressure May Result in Esophageal Injury
  • Cricoid Pressure May Result in Undesirable Movement of the Cervical Spine in Patients with Cervical Spinal Cord Injury
  • Cricoid Pressure May Contribute to Airway Obstruction, Even When Using a Video Laryngoscope (Ann Emerg Med, 2006) [MEDLINE] (Ann Emerg Med, 2013) [MEDLINE]
• Clinical Efficacy
  • Review of Cricoid Pressure to Prevent Aspiration During Endotracheal Intubation (Emerg Med J, 2005) [MEDLINE]
    • There is Little Evidence that Cricoid Pressure Decreases the Incidence of Aspiration During Rapid Sequence Intubation
  • Cadaver Study of Airway Maneuvers During Laryngoscopy (Ann Emerg Med, 2006) [MEDLINE]
    • Bimanual Laryngoscopy Improved the Laryngoscopic View, as Compared to Cricoid Pressure, BURP, and No Manipulation
    • Cricoid Pressure and BURP Frequently Worsen the Laryngoscopic View
  • Anatomic MRI Study of the Effects of Cricoid Pressure During Endotracheal Intubation (Anesth Analg, 2009) [MEDLINE]
    • Cricoid Pressure Results in Compression of the Postcricoid Hypopharynx (Hypopharynx and Cricoid Ring Move Together as an Anatomic Unit)
    • The Location and Movement of the Esophagus is Irrelevant to the Efficiency of Cricoid Pressure in Regard to Prevention of Gastric Regurgitation into the Pharynx
    • Compression of the Esophagus Occurs with Midline and Lateral Displacement of the Cricoid Cartilage Relative to the Underlying Vertebral Body
  • Intubation Bundles Can Decrease the Incidence of Post-Intubation Adverse Effects/Complications in the Intensive Care Unit (Intensive Care Med, 2010) [MEDLINE]: n = 244
    • Bundle Components
      • Capnography
      • Cricoid Pressure
      • Intravenous Fluid Loading
      • Preoxygenation with Noninvasive Positive-Pressure Ventilation
      • Preparation and Early Administration of Sedation
      • Presence of Two Operators
      • Protective Ventilation
      • Rapid Sequence Induction
      • Vasopressor Use (If Required)
  • Observational Study of Identification of the Cricothyroid Membrane in Female Subjects Using Palpation (Anesth Analg, 2012) [MEDLINE]
    • Misidentification of the Cricothyroid Membrane in Female Patients is Common and its Localization is Less Precise in Those Who are Obese
  • Cochrane Database Systematic Review of Cricoid Pressure During Rapid Sequence Endotracheal Intubation (Cochrane Database Syst Rev, 2015) [MEDLINE]
    • No Randomized Trials are Available to Evaluate the Efficacy of Cricoid Pressure During Rapid Sequence Endotracheal Intubation
    • Non-Randomized Trials Suggest that Cricoid Pressure is Not Required to Safely Perform Rapid Sequence Endotracheal Intubation
  • Randomized IRIS Trial of Cricoid Pressure in Operating Room Rapid Sequence Intubation (JAMA Surg, 2019) [MEDLINE]: n = 3472
    • Cricoid Pressure Had No Clinical Benefit in Preventing Aspiration, as Compared to Sham Cricoid Procedure
    • Secondary End Points (Pneumonia, Length of Stay, Mortality) Were Similar Between the Two Groups
    • Intubation Time was Longer in the Cricoid Pressure Group
• Recommendations
  • While Cricoid Pressure May Decrease Gastric Insufflation During Bag-Valve-Mask Ventilation, it is No Longer Recommended for Use During Rapid Sequence Endotracheal Intubation

Backward-Upward-Rightward (BURP) Maneuver

• Definition:
  • Backward-Upward-Rightward Movement of Larynx by Manipulating the Thyroid Cartilage
• Clinical Efficacy
  • Cadaver Study of Airway Maneuvers During Laryngoscopy (Ann Emerg Med, 2006) [MEDLINE]
    • Bimanual Laryngoscopy Improved the Laryngoscopic View, as Compared to Cricoid Pressure, BURP, and No Manipulation
    • Cricoid Pressure and BURP Frequently Worsen the Laryngoscopic View

Mandibular Advancement

• May Improve the Laryngoscopic View
• Clinical Efficacy
  • Mandibular Advancement May Improve the Laryngoscopic View During Intubation Performed by Inexperienced Operators (Anesthesiology, 2004) [MEDLINE]

Gum Elastic Bougie

• Clinical Efficacy
  • Randomized Trial of Gum Elastic Bougie vs Endotracheal Tube and Stylet in Difficult Emergency Intubation in the Emergency Department (JAMA, 2018) [MEDLINE]
    • Gum Elastic Bougie Increased First-Pass Success Rate in Emergency Difficult Intubation, as Compared to Endotracheal Tube and Stylet

Induction and Paralytic Medications for Rapid Sequence Intubation

• Sedatives
  • Etomidate (Amidate) (see Etomidate)
    • Dose (Intravenous): 0.3 mg/kg IVP (Usual Dose: 20 mg)
    • Onset: 30-60 sec
    • Duration: 3-5 min
    • Comments
      • Provides Excellent Sedation
      • Minimal Hypotension
      • May Cause Adrenal Suppression
  • Ketamine (see Ketamine)
    • Dose (Intravenous):: 1-2 mg/kg
    • Onset: 30 sec
    • Duration: 45 min
    • Comments
      • Stimulates Catecholamine Release
      • Bronchodilator
      • Controversial to Use for RSI in the Setting of Increased Intracranial pressure or Hypertension
  • Midazolam (Versed) (see Midazolam)
    • Dose (Intravenous): 2-10 mg IVP (recommended: 0.2-0.3 mg/kg)
    • Onset: 2-5 min
    • Duration: 3-11 hrs (usual range: 1.8-6.4 hrs)
    • Comments
      • Amnestic Properties
      • Dose-Related Myocardial Depression May Result in Hypotension
  • Propofol (Diprivan) (see Propofol)
    • Intravenous Bolus (Induction)
      • Healthy, Age <55 y/o: 2-2.5 mg/kg (given as 40 mg q10 min)
      • Elderly, Debilitated or ASA P3-P: 1-1.5 mg/kg (given as 20 mg q10 min)
    • Onset: 9-51 sec (usual: 30 sec)
    • Duration: 3-10 min (after bolus dose)
    • Comments
      • Bronchodilator
      • Induces Dose-Related Hypotension
• Paralytics
  • Vecuronium (Norcuron) (see Vecuronium)
    • Dose (Intravenous): 0.08-0.1 mg/kg IVP (Usual Dose: 10 mg)
    • Onset: 2.5-3.0 min
    • Duration: 25-40 min (95% Recovery within 45-60 min)
  • Rocuronium (Zemuron) (see Rocuronium)
    • Dose (Intravenous):: 0.6-1.2 mg/kg IVP (Usual Dose: 100 mg)
    • Onset: 75 sec
    • Duration: 33 min
  • Succinylcholine (see Succinylcholine)
    • Dose (Intravenous):: 1-1.5 mg/kg IVP
    • Onset: 5-10 min
    • Duration: 7-10 min
    • Contraindications to Use of Succinylcholine
      • Burns within 24 h-2 yrs (see Burns)
      • History of Malignant Hyperthermia (see Malignant Hyperthermia)
      • Ischemic Cerebrovascular Accident (CVA) within 1 wk-6 mo (see Ischemic Cerebrovascular Accident)
      • Muscle Crush Injury within 7-90 days
      • Neuromuscular Disease
      • Amyotrophic Lateral Sclerosis (ALS) (see Amyotrophic Lateral Sclerosis)
      • Multiple Sclerosis (see Multiple Sclerosis)
      • Penetrating Eye Trauma
      • Spinal Cord Injury (SCI) within 1 wk-6 mo (see Acute Spinal Cord Injury and Chronic Spinal Cord Injury)

Laryngoscopy Blades

Direct Laryngoscopy Blades

• Macintosh Blade
  • Curved Blade
  • Tip is Inserted into the Vallecula
  • Size: 3 or 4 for adults
• Miller Blade
  • Straight Blade
  • Tip is Inserted on Top of Epiglottis
  • Size: 3 or 4 for adults

Video Laryngoscope (Glidescope, etc)

Technique

• Tip is Inserted into the Vallecula

Clinical Utility

• Video Laryngoscopy is Being Increasingly Used (27% of Cases) as the First Emergency Adult Endotracheal Intubation Attempt Method in Emergency Departments: presumably replacing direct laryngoscopy (Ann Emerg Med, 2015) [MEDLINE]

Advantages

• Video Laryngoscope Provides a Superior View, as Compared to Direct Laryngoscopy
• Video Laryngoscope Results in Less Cervical Spinal Motion, as Compared to Direct Laryngoscopy: beneficial in patients with unsecured cervical spinal cord injury (J Emerg Med, 2013) [MEDLINE]

Disadvantages

• Failure of Video Laryngoscopy is Typically Related to Inability to Pass the Endotracheal Tube Despite Visualization of the Glottis
  • In Contrast, Failure of Direct Laryngoscopy is Typically Related to Inability to Visualize the Glottis
• Secretions/Blood in the Airway May Obscure the View of the Video Laryngoscope

Clinical Efficacy

• Systematic Review/Meta-Analysis of Video Laryngoscopic vs Direct Laryngoscopic Endotracheal Intubation in the ICU (Intensive Care Med, 2014) [MEDLINE]: 9 trials (n = 2133) comparing direct laryngoscopic vs video laryngoscopic intubation
  • Compared to Direct Laryngoscopy, Video Laryngoscopy Reduced the Risk of Difficult Orotracheal Intubation [OR 0.29 (95% confidence interval (CI) 0.20-0.44, p < 0.001)], Cormack 3/4 Grade Airways [OR 0.26 (95% CI 0.17-0.41, p < 0.001)], and Esophageal Intubation [0.14 (95% CI 0.02-0.81, p = 0.03)]
  • Compared to Direct Laryngoscopy, Video Laryngoscopy Increased the First-Attempt Success Rate [OR 2.07 (95% CI 1.35-3.16, p < 0.001)]
  • No Statistically Significant Difference was Found for Severe Hypoxemia, Severe Cardiovascular Collapse, or Airway Injury
• Randomized Trial of Glidescope Video Laryngoscopy (Crit Care Med, 2015) [MEDLINE]
  • Glidescope Video Laryngoscopy Improved First-Pass Intubation Success Rates for Urgent Endotracheal Intubation Performed by Pulmonary and Critical Care Medicine Fellow, as Compared to Direct Laryngoscopy
• Secondary Analysis of Predictors of Difficult Video Laryngoscopy with GlideScope or C-MAC® with D-Blade (Br J Anaesth, 2016) [MEDLINE]
  • Characteristics Associated with Greater Risk for Difficult Video Laryngoscopy
    • Head and Neck Position of “Supine Sniffing” vs “Supine Neutral” (Odds Ratio 1.63; 95% CI: 1.1-2.31)
    • Undergoing Otolaryngologic or Cardiac Surgery vs General Surgery (Odds Ratio 1.89; 95% CI: 1.19, 3.01 and Odds Ratio 6.13; 95% CI: 1.85-20.37], respectively)
    • Intubation Performed by an attending anaesthestist vs a supervised resident (Odds Ratio 1.83, 95% CI: 1.14-2.92)
    • Small Mouth (Odds Ratio 1.18; 95% CI: 1.02-1.36)
• Single-Center Observational Study of Video Laryngoscopy and Difficult Airway Characteristics in the ICU (Ann Am Thorac Soc, 2017) [MEDLINE]
  • Presence of Blood in the Airway, Airway Edema, Cervical Immobility, and Obesity are Associated with Higher Odds of First-Attempt Failure with Video Laryngoscopy
• Emergency Department Study of Combined Rapid Sequence Intubation and Video Laryngoscopy (J Emerg Med, 2017) [MEDLINE]
  • Approximately 11% of Patients (n = 50) Had a Predicted Difficult Airway
  • Rapid Sequence Intubation was Demonstrated to Have High First-Pass Endotracheal Intubation Success Rates (90%) with Video Laryngoscopy in Patients with Anticipated Difficult Airways
  • None of the Patients with Difficult Airway Required Placement of a Surgical Airway
• Randomized Trial of Video Laryngoscopy vs Direct Laryngoscopy on Successful First-Pass Orotracheal Intubation in ICU Patients (JAMA, 2017) [MEDLINE]: n = 371
  • In ICU Requiring Intubation, Video Laryngoscopy, as Compared to Direct Laryngoscopy, Did Not Improve First-Pass Orotracheal Intubation Rates
  • In Post-Hoc Analysis, Video Laryngoscopy was Associated with Higher Rates of Severe Life-Threatening Complications, But Not with Mild-Moderate Life-Threatening Complications
  • The Proportion of First-Attempt Intubations Performed by Non-Experts (Primarily Residents, n = 290) Did Not Differ Between the Groups (84.4% with Video Laryngoscopy vs 83.2% with Direct Laryngoscopy; Absolute Difference 1.2% [95% CI, -6.3% to 8.6%]; P = .76)
  • The Median Time to Successful intubation was 3 min (range, 2-4 min) for Both Video Laryngoscopy and Direct Laryngoscopy (Absolute Difference, 0 [95% CI, 0 to 0]; P = .95)
• Rapid Sequence Intubation Has High First-Pass Endotracheal Intubation Success Rate with Video Laryngoscopy (90%) in Patients with Anticipated Difficult Airways (J Emerg Med, 2017) [MEDLINE]
  • Only 11% of Non-Cardiac Arrest Patients Had a Predicted Difficult Airway in this Study and None Required a Surgical Airway
• Comprehensive Systematic Review of Randomized Trials for Endotracheal Intubation in Critically Ill Patients (Crit Care, 2018) [MEDLINE]: n = 22 trials
  • Analyzed 1 Trial Using Pre-Procedure Checklist, 6 Trials of Preoxygenation or Apneic Oxygenation, 3 Trials of Sedatives, 1 Trial of Neuromuscular Blocking Agents, 1 Trial of Patient Positioning, 9 Trials of Video Laryngoscopy, and 1 Trial of Post-Intubation Lung Recruitment
  • Preoxygenation with Noninvasive Positive-Pressure Ventilation and/or High-Flow Nasal Cannula Before Endotracheal Intubation was Beneficial
  • Post-Intubation Lung Recruitment Maneuvers May Increase Post-Intubation Oxygenation
  • No Effect was Found for Use of a Pre-Intubation Checklist, Apneic Oxygenation (on Oxygenation and Hemodynamics), Video Laryngoscopy (on Number and Length of Intubation Attempts), Sedatives and Neuromuscular Blockers (on Hemodynamics)
  • Video Laryngoscopy was Associated with Severe Adverse Effects in Multiple Trials
  • Ramped Position Increased the Number of Intubation Attempts
  • Thiopental Had Negative Hemodynamic Effects
• Australian/New Zealand Survey Study of Intubation Practices in the Intensive Care Unit (Crit Care Resusc, 2019)[MEDLINE]
  • Propofol was the Preferred Induction Agent (67% of Respondents) and rocuronium was the Preferred Neuromuscular Blocking Agent (58% of Respondents)
  • Video Laryngoscopes were Immediately available in 97% of the ICU’s and were Used as the First-Line Device by 43% of Respondents
• DEVICE Trial of Video Laryngoscopy in Critically Ill Adults in Emergency Department and Intensive Care Unit Settings (NEJM, 2023) [MEDLINE]: n = 1,417
  • Successful First-Attempt Intubation Occurred in 85.1% of Patients in the Video Laryngoscope Group and 70.8% of Patients in the Direct Laryngoscope Group (Absolute Risk Difference of 14.3 Percentage Points; 95% CI: 9.9 to 18.7; P < 0.001)
  • A Total of 21.4% of Patients in the Video Laryngoscope Group and 20.9% of Patients in the Direct Laryngoscope Group Had a Severe Complication During Intubation (Absolute Risk Difference of 0.5 Percentage Points; 95% CI: -3.9 to 4.9)
  • Safety Outcomes (Including Esophageal Intubation, Injury to the Teeth, and Aspiration) were Similar in the Two Groups

Consensus Guideline Recommendations to Prevent Unrecognized Esophageal Intubation from the Project for Universal Management of Airways and International Airway Societies (Anaesthesia, 2022) [MEDLINE]

• Exhaled Carbon Dioxide Monitoring and Pulse Oximetry Should Be Available and Used for All Episodes of Airway Management
• Routine Use of Video Laryngoscopy is Recommended Whenever Feasible
• At Each Attempt at Laryngoscopy, the Airway Operator Should Verbalize the View Obtained
• The Airway Operator and Assistant Should Each Verbalize Whether Sustained Exhaled Carbon Dioxide and Adequate Oxygen Saturation are Present
• Inability to Detect Sustained Exhaled Carbon Dioxide Requires Esophageal intubation to Be Actively Excluded
• The Default Response to the Failure to Satisfy the Criteria for Sustained Exhaled Carbon Dioxide Should Be to Remove the Tube and Attempt Ventilation Using a Facemask or Supraglottic Airway
• If Immediate Tube Removal is Not Undertaken, Actively Exclude Esophageal Intubation
  • Repeat Laryngoscopy, Flexible Bronchoscopy, Ultrasound and Use of an Esophageal Detector Device are Valid Techniques
• Clinical Examination Should Not Be Used to Exclude Esophageal intubation
• Endotracheal Tube Removal Should Be Undertaken if Any of the Following are Present
  • Esophageal Placement Cannot Be Excluded
  • Sustained Exhaled Carbon Dioxide Cannot Be Restored
  • Oxygen Saturation Deteriorates at Any Point Before Restoring Sustained Exhaled Carbon Dioxide
• Actions Should Be Taken to Standardize and Improve the Distinctiveness of Variables on Monitor Displays
• Interprofessional Education Programs Addressing the Technical and Team Aspects of Task Performance Should Be Undertaken to Implement These Guidelines

Cormack-Lehane (C-L) View of Glottis

• Grade I: full view of glottis
• Grade II: partial glottic view
• Grade III: minimal glottic view
• Grade IV: no view of glottis

Lighted Stylet (Trachlight, etc)

• Lighted Stylet Can Be Used for Management of the Difficult Anterior Airway, Where Airway Anatomy is Not Distorted
  • Device Transilluminates the Glottis Through the Soft Tissues of the Neck
  • Device Requires Training to Become Proficient with its Use: typically 10-20 intubations are required before proficiency is attained
  • Hemodynamic Responses with Lighted Stylet are Similar to that with Direct/Video Laryngoscopy
• Advantages
  • Ability to Intubate When the Glottis Cannot Be Visualized Using Direct Laryngoscopy
  • Decreased Pharyngeal Trauma, as Compared to Direct Laryngoscopy
  • Produces Less Cervical Spinal Motion than Direct/Video Laryngoscopy: beneficial in patients with cervical spinal cord injury
• Disadvantages
  • Cannot Be Used with Any Airway Anatomic Distortion (Such as Trauma, Tumor, Airway Foreign Body, etc)

Optical Stylet (Clarus Video System, Shikani Optical Stylet, Bonfils Retromolar Intubation Fiberscope, Levitan FPS Scope)

• Optical Style Uses a Fiberoptic or Video Camera in the Distal End of a Metal Stylet
  • Stylet Can Be Rigid, Flexible, and/or Directable (Similar to a Bronchoscope)
• Disadvantages
  • Less Useful in the Presence of Any Obstructing Debris in the Airway (Such as Blood, Vomit, Secretions, etc)

Delayed Sequence Intubation (DSI)

Clinical Efficacy

• Prospective Trial of Delayed Sequence Intubation in Patients with Delirium (Ann Emerg Med, 2015) [MEDLINE]
  • Dissociative Dose of Ketamine, Allowing Preoxygenation with High-Flow Nonrebreather Mask or Noninvasive Positive-Pressure Ventilation (NIPPV), Followed by Rapid Sequence Intubation was Safe and Effective

“Awake” Direct Laryngoscopic Intubation

Definition

• Definition of Awake Intubation: use of topical anesthesia with light sedation (but without the use of a paralytic agent)

Relative Contraindications (J Emerg Med, 2017) [MEDLINE]

• Active Vomiting
• Hypercapnia
• Inability to Protect Airway
• Active Oral Hemorrhage/Hemoptysis/Hematemesis
• Refractory Hypoxemia
• Hemodynamic Instability

Advantages of Awake Endotracheal Intubation

• Maintains the Patient’s Spontaneous Ventilation and Airway Reflexes
  • Avoids the Apneic Period of Rapid Sequence Intubation (with its Attendant Physiologic Consequences)
  • Decreases the Loss of Upper Airway Tone (and Patency)

Disadvantages of Awake Endotracheal Intubation

• May Be Poorly Tolerated by the Patient
• Requires Topical Anesthesia (Which Takes Additional Time to Perform)
• Requires Secretion Control
• Requires Sedation (in Most Cases)
• Longer Time Required to Achieve Intubation

Clinical Efficacy

• Review of Awake Laryngoscopy in the Emergency Department ( J Emerg Med, 2017) [MEDLINE]

Technique

• Bronchoscope (see Bronchoscopy)

Clinical Efficacy

• Awake Fiberoptic Intubation is Successful in 88-100% of Difficult Airway Patients (Category B3-B Evidence) (American Society of Anesthesiologists Task Force on Management of the Difficult Airway; Anesthesiology, 2013) [MEDLINE]

Extension of Apnea Time During Endotracheal Intubation

• Clinical Efficacy
  • High-Flow Nasal Cannula May Be Used to Facilitate Oxygenation During Fiberoptic Intubation (Chest, 2015) [MEDLINE]

Technique

• Disadvantages
  • Higher Incidence of Maxillary Sinusitis

Auscultation

• Technique
  • Auscultation Over Bilateral Lung Fields and Auscultation Over the Epigastric Area: note that auscultation over the lung field alone is inadequate to confirm endotracheal tube placement (epigastric auscultation is additionally required to confirm a lack of breath sounds in that location)
• Clinical Efficacy
  • Auscultation Alone Mistakenly Identifies Location of the Endotracheal Tube in 16% of Cases (Anesth Analg, 1986) [MEDLINE]

Bronchoscopy (see Bronchoscopy)

• Technique
  • Bronchoscopy May Be Used to Confirm ETT Placement

Chest Wall Movement/Excursion

• Clinical Efficacy
  • Observation of Chest Wall Movement is an Unreliable Means of Confirming Endotracheal Tube Placement, as Chest Wall Movement May Occur in Esophageal Intubation (Anaesth Intensive Care, 1980) [MEDLINE]

Chest X-Ray (CXR) (see Chest X-Ray)

• Clinical Efficacy
  • Single-View (Antero-Posterior) CXR Cannot Reliably Confirm Endotracheal Intubation: although it is usually obtained to determine the location of the distal tip of the endotracheal tube

Condensation in Endotracheal Tube (“Fogging”)

• Clinical Efficacy
  • Observation of Condensation (Fogging) in the Endotracheal Tube is an Unreliable Means of Confirming Endotracheal Tube Placement, as Condensation Occurs in the Endotracheal Tube in 83% of Esophageal Intubations (Ann Emerg Med, 1998) [MEDLINE]

Endotracheal Introducer (Eschmann Introducer or Gum Elastic Bougie)

• Technique
  • Bougie is Inserted and Advanced, Feeling the “Clicks” of the Tracheal Rings
• Clinical Efficacy
  • Cadaveric Trial of Eschmann Tracheal Tube Introducer (Gum Elastic Bougie) to Confirm Endotracheal Tube Placement (Am J Emerg Med, 2005) [MEDLINE]
    • Sensitivity of Ring Clicks in the Detection of Endotracheal Intubation: 95%

End-Tidal Carbon Dioxide Detection

General Comments

• End-Tidal Carbon Dioxide Detection is Most Accurate Means of Confirming Endotracheal Tube Placement in the Non-Cardiac Arrest Patient: end-tidal carbon dioxide detection is a standard of care practice to confirm appropriate endotracheal intubation
  • In the Setting of Cardiac Arrest (without a Detectable Pulse), Gas Exchange in the Lungs is Markedly Decreased and Carbon Dioxide May Not Be Detectable Despite Appropriate Endotracheal Tube Positioning in the Trachea (Crit Care Med, 1985) [MEDLINE]
  • However, the Detection of Carbon Dioxide Which Persists for 6 Breaths in the Cardiac Arrest Patient Indicates Appropriate Endotracheal Tube Positioning in the Trachea

Colorimetric Carbon Dioxide Indicator

• Principle/Technique: colorimetric carbon dioxide indicators use use sulfonephthalein-impregnated pH-sensitive (litmus) filter paper as an indicator which tidally changes (breath by breath) from purple to yellow in the presence of exhaled carbon dioxide
  • Easy CAP II (Medtronic)
    • A Range Corresponds to ETCO2 <0.5%: dark tan-purple
    • B Range Corresponds to ETCO2 0.5-2%: dark tan-light tan
    • C Range Corresponds to ETCO2 2-5%: light tan-yellow
• False-Positive Results: yellow color change without successful endotracheal intubation
  • Difficult Intubation with Prolonged Bag Ventilation: air previously pushed into the stomach during bag ventilation may cause yellow color change during the first few breaths
    • However, if Color Remains Yellow After >4-5 breaths, this Indicates Endotracheal Intubation (Anesth Analg, 1989) [MEDLINE]
  • Epinephrine (see Epinephrine): acidic medication which can cause (non-tidal) yellow color change
  • Lidocaine (see Lidocaine): acidic medication which can cause (non-tidal) yellow color change
  • Regurgitation of Gastric Contents During Intubation: gastric acid can cause (non-tidal) yellow color change
• False-Negative Results: lack of yellow color change even with successful endotracheal intubation
  • Acute Pulmonary Embolism (PE) (see Acute Pulmonary Embolism): due to decreased pulmonary blood flow and decreased delivery of carbon dioxide to the lungs
  • Airway Obstruction: indicator may not turn yellow, due to poor carbon dioxide exchange across the obstructed airway (Emerg Med J, 2003) [MEDLINE]
  • Cardiac Arrest (see Cardiac Arrest): due to decreased pulmonary blood flow and decreased delivery of carbon dioxide to the lungs
    • If Chest Compressions are Adequate (with Adequate Blood Flow to the Lungs), Indicator Will Likely Turn Yellow
    • Indicator Has Only 69% Sensitivity for Endotracheal Intubation When Used During Cardiopulmonary Resuscitation (Ann Emerg Med, 1992) [MEDLINE]
  • Endotracheal Tube Cuff Leak
    • When Using Colorimetric Carbon Dioxide Indicator: cuff leak (with endotracheal tube still properly positioned in the trachea) will typically produce a weak yellow color change (due to loss of carbon dioxide around the endotracheal tube)
    • When Using Waveform Capnography: cuff leak (with endotracheal tube still properly positioned in the trachea) results in decreased amplitude of the plateau (due to loss of carbon dioxide around the endotracheal tube)
• Clinical Efficacy
  • Sensitivity of End-Tidal Carbon Dioxide Detection Approaches 100% in Non-Cardiac Arrest Patients
  • Sensitivity of End-Tidal Carbon Dioxide Detection is Variable in Cardiac Arrest Patients: ranges from 62-100% in various studies (depending on the modality used and the duration of cardiac arrest)
  • In Non-Cardiac Arrest, Infrared Capnometry and Infrared Capnography Have a 100% Sensitivity/100% Specificity in Detecting Endotracheal Intubation (Intensive Care Med. 2002) [MEDLINE]
  • In Cardiac Arrest, Infrared Capnometry Has a 88% Sensitivity/100% Specificity in Detecting Endotracheal Intubation (Intensive Care Med. 2002) [MEDLINE]

Waveform Capnography (see Capnography)

• Principle/Technique: end-tidal carbon dioxide monitor attached to the end of the endotracheal tube uses infrared absorption to detect carbon dioxide
  • Displays Either Waveform Capnography or Digital Readout
• Clinical Efficacy
  • Sensitivity of End-Tidal Carbon Dioxide Detection Approaches 100% in Non-Cardiac Arrest Patients
  • Sensitivity of End-Tidal Carbon Dioxide Detection is Variable in Cardiac Arrest Patients: ranges from 62-100% in various studies (depending on the modality used and the duration of cardiac arrest)
  • In Non-Cardiac Arrest, Infrared Capnometry and Infrared Capnography Have a 100% Sensitivity/100% Specificity in Detecting Endotracheal Intubation (Intensive Care Med. 2002) [MEDLINE]
  • In Cardiac Arrest, Infrared Capnometry Has a 88% Sensitivity/100% Specificity in Detecting Endotracheal Intubation (Intensive Care Med. 2002) [MEDLINE]

Esophageal Detector Device

• Technique
  • Uses Suction Applied with Syringes (or Bulb Suction Device) to Distinguish the Trachea from Esophagus
    • Trachea is Rigid and Allows Free Flow of Air into the Device
    • Esophagus is Collapsible and Does Not Allow Free Flow of Air When Suction is Applied

Transtracheal Ultrasound

• Technique
  • Advantages
    • Technique Can Be Performed Quickly and Offers Real-Time Information
    • Technique is Independent of Pulmonary Blood Flow and Does Not Require Lung Ventilation
• Clinical Efficacy
  • Systematic Review/Meta-Analysis of Transtracheal Ultrasound for Confirmation of Endotracheal Tube Placement (Can J Anaesth, 2015) [MEDLINE]: n = 11 studies
    • Transtracheal Ultrasound is a Useful Tool to Confirm Endotracheal Tube Placement with Acceptable Sensitivity/Specificity: it can be used as a preliminary test in emergency situations before final confirmation by capnography
      • Sensitivity: 98%
      • Specificity: 98%
  • Systematic Review/Meta-Analysis of Transtracheal Ultrasound for Confirmation of Endotracheal Tube Placement (Resuscitation, 2015) [MEDLINE]
    • Transtracheal Ultrasound is a Useful Tool to Confirm Endotracheal Tube Placement
      • Sensitivity: 93%
      • Specificity: 97%
  • Combination of Tracheal (to Determine Endotracheal Tube Position) and Pleural Ultrasound (to Detect Lung Sliding) is Superior to Auscultation in Determining Endotracheal Tube Location (Anesthesiology, 2016) [MEDLINE]: small, randomized trial

Recommendation (2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway) (Anesthesiology, 2022) [MEDLINE]

Recommendations for Confirmation of Tracheal Intubation

• Confirm Endotracheal Intubation Using Capnography or End-Tidal Carbon Dioxide Monitoring
• When Uncertain About the Location of the Endotracheal Tube, Determine Whether to Either Remove it and Attempt Ventilation or Use Additional Techniques to Confirm Endotracheal Rube Positioning

General Comments

• Complications of Unrecognized Mainstem Bronchial Intubation (Ann Emerg Med, 1989) [MEDLINE]
  • Hypoxemia/Hypercapnia (see Hypoxemia and Hypercapnia)
  • Pneumothorax (see Pneumothorax)
• Mainstem Bronchial Endotracheal Tube Placement is More Common in Females Who Have Undergone Emergency Intubation (Crit Care Med, 1994) [MEDLINE]

Auscultation

• Technique
  • Auscultation to Determine Equality of Bilateral Breath Sounds May Reveal Louder Breath Sounds Unilaterally, Indicating Mainstem Bronchial Intubation

Bronchoscopy (see Bronchoscopy)

• Technique
  • Bronchoscopy May Be Used to Confirm Endotracheal Tube Placement

Chest X-Ray (CXR) (see Chest X-Ray)

• Technique
  • CXR May Be Used to Confirm Endotracheal Tube Placement

Depth of Endotracheal Tube Insertion

• Technique
  • Depth of Endotracheal Tube Insertion May Be Used to Confirm Endotracheal Tube Placement
    • Measurement at Teeth/Gums is Preferred, Since These are Fixed Landmarks
• Clinical Efficacy
  • Endotracheal Tube is Usually Inserted to a Depth of 20-21 cm in Females and 22-23 cm in Males (BMJ, 2010) [MEDLINE]

Transtracheal Ultrasound

• Clinical Efficacy
  • Transtracheal Ultrasound May Be Used to Confirm Ventilation Via Detection of Lung Sliding (Acta Anaesthesiol Scand, 2011) [MEDLINE]: lung sliding observed in only one lung indicates mainstem bronchial intubation
  • Combination of Tracheal (to Determine Endotracheal Tube Position) and Pleural Ultrasound (to Detect Lung Sliding) is Superior to Auscultation in Determining Endotracheal Tube Location (Anesthesiology, 2016) [MEDLINE]: small, randomized trial

Reasons for Exchange of Endotracheal Tube

• Endotracheal Tube Cuff Leak
  • Discrepancy Between Endotracheal Tube Size and Tracheal Diameter (Especially in a Patient with Tracheomalacia)
  • Pilot Balloon Line or Cuff Leak: some cases of severed pilot balloon lines can be remedied with a pilot balloon line repair kit (assuming the leak is at/near the pilot balloon itself, allowing the pilot balloon line to be cut and repaired)
• Obstruction of Endotracheal Tube
  • Airway Foreign Body (see Airway Foreign Body)
  • Mucous Plugging Due to Inadequate Saline Lavage and Suctioning of the Endotracheal Tube
    • Example: in postoperative patients with tracheal resection, suctioning is frequently discouraged to avoid disruption of the anastomosis -> these patients can rapidly develop concretions within the endotracheal tube within a matter of days, leading to life-threatening endotracheal tube obstruction with inability to ventilate
      • Gradual Development of Endotracheal Tube Obstruction is Manifested by an Increasing Peak Airway Pressure-Plateau Pressure Difference

Risks of Endotracheal Tube Exchange

• Airway Trauma: since intubation itself contributes to at least some degree of laryngeal and tracheal mucosal injury (even in the best of circumstances), reintubations can be expected to increase the risk of this trauma to some extent
• Increased Risk of Ventilator-Associated Pneumonia (VAP) (se eHospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)
• Inability to Reintubate Patient

Technique

• Gum Elastic Bougie (Plastic Stylet): a plastic intubating stylet is the most commonly used method to change a dysfunctional endotracheal tube in a patient whose airway is not anticipated to be difficult
  • While Endotracheal Tube Change Can Be Performed Blindly (without Concomitant Airway Visualization) in Many Cases, Use of a Direct Laryngoscope/Video Laryngoscope is Highly Recommended in Case the Operator is Unable to Pass the New Endotracheal Tube Through the Vocal Cords
• Endotracheal Tube Changer: a plastic hollow-bore tube changer (with adapters to allow either supplemental oxygen therapy or bag ventilation) is preferred in a patient whose airway is anticipated to be difficult
  • While Endotracheal Tube Change Can Be Performed Blindly (without Concomitant Airway Visualization) in Many Cases, Use of a Direct Laryngoscope/Video Laryngoscope is Highly Recommended in Case the Operator is Unable to Pass the New Endotracheal Tube Through the Vocal Cords
• Removal of the Endotracheal Tube with Reintubation by Any of the Methods Described Above: this method can be used by experienced operators in a patient whose airway is not anticipated ot be difficult

General Comments

• Supraglottic Airways Can Be Placed into the Pharynx and Utilized to Provide Oxygenation, Ventilation, and Anesthetic Gas Administration without the Need for Endotracheal Intubation
  • Use for Respiratory Failure in the Prehospital Setting
  • Use in Operating Room with/without General Anesthesia
    • Use of General Airway Management
    • Use for Emergency Airway Management When Endotracheal Intubation is Unsuccessful
    • Use as a Conduit for Endotracheal Intubation
  • Use in the Hospital Setting s Part of the Emergency Airway Algorithm
    • Use for Emergency Airway Management When Endotracheal Intubation is Unsuccessful
    • Use as a Conduit for Endotracheal Intubation

Types of Supraglottic Airways

• Laryngeal Mask Airway (LMA)
• Other Supraglottic Devices
  • Combitube
  • Laryngeal Tube
  • Pharyngeal Tube

Laryngeal Mask Airway (LMA)

Rationale

• Laryngeal Mask Airway Rests in the Hypopharynx (Facing the Glottis) Forming a Seal Over the Laryngeal Inlet to Allow Mask Ventilation
  • Laryngeal Mask Airway is Generally Less Stimulating than Endotracheal Intubation
  • Laryngeal Mask Airway Does Not Fully Protect Against Aspiration
  • Laryngeal Mask Airway Does Not Prevent Laryngospasm

Indications

• Temporary Ventilation During a Surgical Procedure
• During Emergency Airway Management When an Endotracheal Tube is Not Initially Desired or Cannot Be Successfully Placed by Laryngoscopy (Can J Anaesth, 2005) [MEDLINE]
  • Clinical Efficacy
    • Laryngeal Mask Airway Can Be Placed by Emergency Medical Response Personnel in the Field with Subsequent Exchange for an Endotracheal Tube During Transport or in the Emergency Department (Prehosp Emerg Care, 2007) [MEDLINE]
    • Laryngeal Mask Airway Placement During Out-of-Hospital Cardiac Arrest was Safer than Bag-Valve-Mask Ventilation (Am J Emerg Med, 2015) [MEDLINE]
    • Laryngeal Mask Airway Placed During Out-of-Hospital Cardiac Arrest Resulted in Improved 72 hr Survival, as Compared to Endotracheal Intubation (JAMA, 2018) [MEDLINE]
    • In the AIRWAYS-2 Trial, Laryngeal Mask Airway Placed During Out-of-Hospital Cardiac Arrest Did Not Impact the 30-Day Mortality Rate (JAMA, 2018) [MEDLINE]

Contraindications to Use of Laryngeal Mask Airway

• Esophageal Varices (see Esophageal Varices): due to risk of hemorrhage or perforation
• Gag Reflex (Due to Risk of Emesis/Aspiration)
  • Gag Reflex Can Be Removed by Using Pharmacologic Paralysis
• Gastroesophageal Reflux Disease (GERD) (see Gastroesophageal Reflux Disease): since LMA’s do not offer the same degree of protection against aspiration as endotracheal intubation, they generally should not be used in patients with significant gastroesophageal reflux (except in emergency situations)
  • However, LMA with a Gastric Decompression Port May Be Preferred in this Population
  • Mild GERD is Probably Not a Contraindication to LMA Use
• Obesity with BMI >35 kg/m2, Limited Access to Airway During Surgery, Surgery Expected to Last >90 min, and/or Use of Lithotomy Position During Surgery
  • When Used for Airway Management During Surgery, Obesity Increases the Amount of Time Required for LMA Insertion (Cochrane Database Syst Rev, 2013) [MEDLINE]: probably not clinically important (although the failure rate of LMA’s is approximately 3-5%)
  • When Used for Airway Management During Surgery, Obesity Increases the Risk of Gastric Insufflation
  • When Used for Airway Management During Surgery, Obesity Increases the Peak Inspiratory Pressure (PIP)
  • When Used for Airway Management During Surgery, Obesity Increases the Risk of Mask Leak, Although it Does Not Appear to Affer Ventilation (Cochrane Database Syst Rev, 2013) [MEDLINE]
  • When Used for Airway Management During Surgery in Obese Patients, LMA Significantly Improves Oxygenation During and After Surgery: suggests improved pulmonary performance
• Oropharyngeal Trauma with Risk of Perforation
• Proximal Esophageal Trauma with Risk of Perforation
• Upper Airway Foreign Body (see Airway Foreign Body): since foreign body can be inadvertently moved into the trachea, resulting in tracheal obstruction

Types of Laryngeal Mask Airways

• LMA Classic: standard multiple-use LMA
  • Orogastric Tube Capability: none
  • Blind Intubation Capability: variable success rate
• LMA Fastrach
  • Orogastric Tube Capability: none
  • Blind Intubation Capability: good success rate (can also be used for bronchoscopically-guided intubation)
  • Design Contains an Epiglottic Elevating Bar, Which Prevents the Epiglottis from Entering the Mask/Shaft
  • Allows Endotracheal Intubation Through the LMA
  • Most Commonly-Used LMA for Emergency Intubation
• Air-Q Intubating Laryngeal Airway (ILA)
  • Orogastric Tube Capability: yes
  • Blind Intubation Capability: good success rate (can also be used for bronchoscopically-guided intubation)
• LMA ProSeal: similar to LMA Classic, but with a built-in bite block and orogastric tube port
  • Orogastric Tube Capability: yes
  • Intubation Capability: none
• LMA Protector: similar to LMA Supreme, but with intubation capabilities
• LMA Supreme: single-use LMA with stiffer cuff, integrated bite block, and orogastric tube port
  • Orogastric Tube Capability: yes
  • Blind Intubation Capability: none
• LMA Unique: single-use version of LMA Classic
• Air-Q
  • Orogastric Tube Capability: yes (with blocker version)
  • Blind Intubation Capability: good success rate (can also be used for bronchoscopically-guided intubation)
• Aura-Gain
  • Orogastric Tube Capability: yes
  • Blind Intubation Capability: limited data available
• Aura-i
  • Orogastric Tube Capability: none
  • Blind Intubation Capability: limited data available
• i-Gel
  • Orogastric Tube Capability: yes
  • Blind Intubation Capability: variable success rate

Laryngeal Mask Airway Sizing

• Determinants of Proper Laryngeal Mask Airway Sizing
  • Patient Anatomy
  • Laryngeal Mask Airway Size: the usual adult LMA sizes are 3/4/5/6 (most LMA’s are available in full sizes, some are available in half sizes too)
  • Cuff Inflation
• General Sizing
  • Adult Female (Up to 100 kg): usually size 4
  • Adult Male (Up to 100 kg): usually size 5
• Cuff Volume: appropriate cuff volume is usually provided by the manufacturer (note: cuff overinflation should be avoided to prevent worsening mask seal and/or injury the oropharyngeal mucosa)
  • Size 4 LMA: approximate cuff volume 30 mL (if larger cuff volume is required to maintain an adequate seal, a larger LMA should be placed or the patient should be endotracheally intubated)
  • Size 5 LMA: approximate cuff volume 40 mL (if larger cuff volume is required to maintain an adequate seal, a larger LMA should be placed or the patient should be endotracheally intubated)

Laryngeal Mask Airway Insertion

• Anesthesia
  • Adequate Anesthesia (General Anesthesia, Intravenous Sedation) is Required Prior to LMA Inseriton to Avoid Gagging, Coughing, Laryngospasm, Breath Holding, and Straining
    • However, Some Patients Can Tolerate Placement with Topical Anesthesia Alone
  • Pharmacologic Neuromuscular Blockade Can Be Utilized to Facilitate LMA Placement: decreases the incidence of gagging, laryngospasm, and coughing
• Use of Bronchoscopy for Laryngeal Mask Airway Placement
  • Bronchoscope Can Be Utilized to Verify Correct Placement of the LMA
• Features Which Indicate Correct Laryngeal Mask Airway Placement
  • Ability to Ventilate without Difficulty: as determined by tidal volume, peak airway pressure <20 cm H20, and chest rise
  • Normal Capnography
  • No Leak (with Peak Airway Pressure <20 cm H2O)
• Other Aspects
  • With Correct LMA Positioning, Cuff Inflation May Result in Outward Movement of the LMA and Slight Swelling in the Neck
• Technique for LMA Fastrach Insertion
  • Deflate the LMA Cuff Completely and Lubricate Both Sides with Water-Soluble Lubricant
  • Standing at the Head of the Bed, with LMA in Dominant Hand, Place Mask on the Palate and Advance Along Palate Until Resistance is Felt
    • In Proper Position, the Handle Will Have a Slight Upward Angle (and Will Not Be Horizontal)
  • Inflate LMA Fastrach Cuff to Maintain Seal (Pressure <40 cm H2O)
  • Check for Proper Ventilation with Bag-Valve and Capnography
• Technique for Air-Q Insertion
  • Similar to Placement of the LMA Classic, Except that the Air-Q Does Not Need to Ride Against the Palate During Insertion: cuff is stiff, so that it does not need to touch the pharyngeal structures during insertion
  • Inflate Air-Q Cuff to Maintain Seal (Pressure <40 cm H2O)

Difficulties Associated with Laryngeal Mask Airway Placement and Function

• Epiglottis Entrapment (Tip of Epiglottis Flipped Over by the Laryngeal Mask)
  • Management
    • “Up-Down” Technique: withdraw LMA 2-4 cm without deflating the cuff and then reinsert
    • Head Extension
    • Replacement of the LMA
• Inadequate Anesthesia
  • Clinical Manifestations
    • Bronchospasm (see Obstructive Lung Disease)
    • Laryngospasm (see Laryngospasm)
    • Straining
    • Breath Holding
    • Patient Maintaining Upper Airway Tone (Which Prevents Proper Seating of the Mask in the Larynx)
  • Management
    • Increase Anesthesia/Sedation
• Inadequate Laryngeal Mask Seal
  • Etiology
    • Folded Over LMA Cuff
    • Improper LMA Size
      • Since Larger Size LMA’s Generally Provide a Better Seal with Lower Cuff Inflation Volumes and Pressures, as Compared to Smaller Size LMA’s, Replacing with a Larger LMA May Remedy the Problem
    • Inadequate Air in the LMA Cuff
    • High Peak Airway Pressure
  • Management
    • Add Air to Cuff (If Necessary)
    • Replace with Same or Larger LMA
    • Transition to Endotracheal Intubation: if unable to maintain adequate seal
• Poor Patient Anatomy Contributing to Difficult LMA Placement
  • Management
    • Rotational Placement of LMA (with Partially-Inflated Cuff) May Facilitate Placement in Difficult Cases
    • Placement with the Aid of Ultrasound or Bronchoscopy

Intubating Via the Laryngeal Mask Airway

• General Comments
  • While Intubation Through an Intubating Laryngeal Mask Airway Can Be Achieved Blindly, May Providers Utilize a Bronchoscope to Intubate by this Technique
    • Endotracheal Tube is Loaded Onto the Bronchoscope and the Bronchoscope/Tube are Passed Through the LMA Channel
• Technique for Intubation Via Laryngeal Mask Airway Fastrach
  • General Comments
    • LMA Fastrach Contains a Bar Which Elevates the Epiglottis as the Endotracheal Tube Passes Through the Aperture
    • LMA Fastrach Has a Ramp in the Intubating Channel Which Directs the Endotracheal Tube Anteriorly and Centrally to Facilitate Movement into the Trachea (and Minimize Damage to Glottis)
  • LMA Fastrach May Use Either a Standard Endotracheal Tube or a Proprietary Non-Kinking Endotracheal Tube
    • If Standard Endotracheal Tube is Used, Warm it Beforehand (to Increase Flexibility) and Insert it onto a Bronchoscope, then Insert the Bronchoscope/Endotracheal Tube Asssembly into the LMA with the Curvature Reversed (To Facilitate the Tip Exiting the LMA at a Shallow Angle and Entering the Trachea)
    • At 15 cm Depth, an Endotracheal Tube Emerges from the LMA and Lifts the Epiglottis Elevating Bar
    • Proprietary Endotracheal Tube
      • Vertical Black Line Should Face the Operator (This Aligns the Bevel with the Vocal Cords)
      • Horizontal Black Line Marks the 15 cm Insertion Depth (at Which the Tube Exits the LMA)
  • Perform a “Skillet Lift” Using the LMA Fastrach Handle to Align the Cuff with the Glottic Opening
  • Gently Advance the Endotracheal Tube: if resistance is encountered, glottic alignment is not correct
  • When Endotracheal Placement is Confirmed, Deflate the LMA Fastrach Cuff to Relieve the Mucosal Pressure
  • After Intubation, Carefully Remove the LMA Fastrach
    • LMA Fastrach May Remain in Place for Several Hours Prior to Removal
• Technique for Intubation Via the Air-Q
  • General Comments
    • Large Adult Size Air-Q Can Accomodate a 8.5 Endotracheal Tube
    • Air-Q Has a Mild Curvature and is Designed to Utilize a Standard Endotracheal Tube: it does not require a specialized non-kinking endotracheal tube
  • Lubricate the Endotracheal Tube with Water-Soluble Lubricant
  • Remove the 15 mm Bag Connector and Insert the Endotracheal Tube into the Lumen
  • Move Endotracheal Tube Up and Down in the Lumen to Lubricate the Channel
  • Advance the Endotracheal Tube into the Trachea
    • May Need to Gently Insert/Withdraw the Air-Q to Facilitate Endotracheal Tube Passage
  • Inflate the Endotracheal Tube Cuff
  • When Endotracheal Placement is Confirmed, Deflate the Air-Q Cuff to Relieve the Mucosal Pressure
  • After Confirmation of Endotracheal Tube Placement, Remove the Air-Q Using the Removal Stylet: this decreases the risk of damage to the pilot balloon
    • Air-Q May Remain in Place for Several Hours Prior to Removal

Ventilation Technique

• Spontaneous Ventilation
  • Advantages
    • Better Tolerance of LMA Malpositioning
    • Decreases Air Leak Around the LMA
    • Limits the Development of Gastric Insufflation
• Positive-Pressure Ventilation
  • Pressure-Limited Ventilation (Pressure Support, Pressure Control) is Used More Commonly than Volume-Limited Ventilation, Since the LMA Does Not Seal the Pharynx and There is Leak Around the Device (with Resulting Gastric Insufflation and/or Inadequate Ventilation)
  • LMA’s are Generally Designed for Use with Peak Airway Pressure <20 cm H2O: higher peak airway pressure may result in LMA leak and/or gastric insufflation
    • LMA ProSeal was Designed for Use with Somewhat Higher Peak Airway Pressures (<25 cm H2O): cuff has a posterior extension which provides a “double seal”
  • Advantages
    • Allows Control of Respiratory Rate and Tidal Volume
    • Ventilation is Assured During Deeper Levels of Sedation

Adverse Effects/Complications

• General Comments
  • Laryngeal Mask Airway-Associated Complications are Low: occur in approximately 0.15% of cases (Anesth Analg, 1996) [MEDLINE]
  • High Laryngeal Mask Airway Cuff Pressure May Increase the Risk of Airway Complications (Anesthesiology, 2010) [MEDLINE] (Can J Anaesth, 2013) [MEDLINE]
• Arytenoid Cartilage Dislocation (see Arytenoid Cartilage Dislocation)
• Aspiration (see Aspiration Pneumonia)
  • Epidemiology
    • When Laryngeal Mask Airways are Used in the Anesthesia Setting, Aspiration is the Most Common Cause of Death (Br J Anaesth, 2011) [MEDLINE]
    • Risk of Aspiration is with LMA is Low: meta-analysis indicated a risk of approximately 1/5000 cases ( J Clin Anesth, 1995) [MEDLINE]
      • This Risk is Similar to the Risk of Aspiration with Bag-Valve-Mask Ventilation and Endotracheal Intubation (Anesthesiology, 1993) [MEDLINE]
    • Risk Factors for Aspiration with Laryngeal Mask Airway (Br J Anaesth, 2004) [MEDLINE]
      • Full Stomach
      • Inadequate Depth of Anesthesia
      • Intra-Abdominal Surgery
      • Laryngeal Mask Airway Cuff Deflation
      • Lithotomy Position During Surgery
      • Multiple Trauma
      • Obesity (wee Obesity)
      • Upper Gastrointestinal Tract Disease
  • Physiology
    • Laryngeal Mask Airway May Function to Some Extent to Seal Off the Trachea from Aspiration of Regurgitated Gastric Contents
      • However, Vomiting or Increase in Intragastric Pressure Can Overcome this Protection, Resulting in Aspiration (Br J Anaesth, 2002) [MEDLINE]
    • Laryngeal Mask Airway Decreases Lower Esophageal Sphincter Tone Via a Reflex Mechanism (Br J Anaesth, 1992) [MEDLINE]: this is similar to the reflex which occurs while swallowing a bolus of food
      • This Results in Increased Acid Reflux into the Esophagus During Lithotomy and Trendelenburg Positioning (Can J Anaesth, 1999) [MEDLINE]
  • Prevention
    • Patient Selection
      • Assess Risk Factors for Aspiration
      • Assess Lung/Chest Wall Compliance for Factors that Might Increase Peak Airway Pressure
    • Procedure Selection (Accounting for Expected Patient Positioning Which Might Contribute to Aspiration)
    • Maintenance of Adequate Depth of Anesthesia During Laryngeal Mask Airway Insertion and During Surgery
    • Minimization of Peak Airway Pressure During Mechanical Ventilation to Avoid Gastric Insufflation
    • Ensure Adequate Reversal of Neuromuscular Blockade Prior to Emergence from General Anesthesia
    • Use of Laryngeal Mask Airway with Gastric Decompression Port (Anaesthesia, 2011) [MEDLINE]
• Dental/Lingual/Labial Injury During Insertion
• Epiglottic Injury
• Laryngospasm (see Laryngospasm)
  • Laryngospasm is Less Common During Extubation with LMA’s, as Compared to Endotracheal Tubes
  • However, in Contrast to Endotracheal Tubes, LMA’s Do Not Protect Against Intraoperative Laryngospasm
• Lingual/Hypoglossal/Recurrent Laryngeal/Alveolar Nerve Injury
  • Epidemiology: rare
• Negative Pressure Pulmonary Edema (see Mechanical Pulmonary Edema)
  • Physiology: biting of LMA shaft during emergence from anesthesia, resulting in airway obstruction
• Oropharyngeal Mucosal Injury
  • Physiology: may be related to excessively high laryngeal mask airway cuff pressure
• Pharyngolaryngeal Rupture/Pneumomediastinum (see Pneumomediastinum)
  • Epidemiology: rare

Cricothyroidotomy (Cricothyrotomy) (see Cricothyroidotomy)

Background

• Definition
  • Incision of the Cricothyroid Membrane with Insertion of a Tube to Establish an Artificial Airway
• History
  • Cricothyroidotomy (Initially Referred to as “High Tracheostomy”) was First Performed by Dr. Chevalier Jackson in 1909: cases were often performed due to upper airway obstruction related to diphtheria
    • Due to Complications of Tracheal Stenosis, He Later Criticize the Use of Cricothyroidotomy
• Epidemiology
  • The Historical Rate of Cricothyroidotomies Has Been Demonstrated to Decrease Over Time, Attributable to Several Factors (Acad Emerg Med, 1998) [MEDLINE]
    • Adoption of Rapid Sequence Intubation (RSI)
    • Decreased Concern Related to the Perfomance of Endotracheal Intubation in Trauma Patients Without Initial Evaluation to Rule Out Cervical Spinal Cord Injury
    • Establishment of Emergency Medicine Residencies with the Presence of 24 hr Supervising Emergency Medicine Faculty
  • Rates of Cricothyroidotomy Might Be Expected to Continue to Decline with the Increased Use of Video Laryngoscopy and the Advancement of Other Airway Management Techniques
  • In a Single-Center Retrospective Study, Cricothyroidotomy Comprised 1% of All Emergency Department Intubations (and 10.9% of All Prehospital Intubations) (J Emerg Med. 2003) [MEDLINE]

Indications

• General Indications for Cricothyroidotomy
  • Inability to Intubate Patient
  • Contraindication to Intubation
  • Upper Airway Obstruction: note that cricothyroidotomy will only be effective if the airway obstruction is proximal to the site of the cricothyroidotomy
• Specific Etiologies Requiring Cricothyroidotomy (Acad Emerg Med, 1998) [MEDLINE]
  • Facial Fracture: 32% of cases
  • Emesis in the Airway: 32% of cases
  • Failure of Intubation (in the Absence of Clinical Issues): 11% of cases
  • Traumatic Upper Airway Obstruction: 7% of cases

Relative Contraindications

• Childhood (<5-12 y/o): since the childhood airway is funnel-shaped with the narrowest aspect at the cricoid ring rather than at the vocal cords (with an increased risk of developing subglottic stenosis) and procedure can damage the relatively soft cricoid cartilage in children
• Coagulopathy (Uncontrolled) (see Coagulopathy)
• Laryngeal Fracture (see Laryngeal Fracture)
• Laryngotracheal Disruption with Retraction of the Distal Trachea into the Mediastinum
• Tracheal Fracture (see Tracheal Fracture)

Etiology of Difficult Cricothyroidotomy

• SMART Mnemonic
  • Surgery (of Neck/Upper Airway)
    • Remote/Recent Surgery Which May Alter the Upper Airway Anatomy
  • Mass Lesion (Extrinsic)
    • Abscess
    • Hematoma
    • Tumor
  • Access/Anatomy
    • Obesity (see Obesity)
    • Poor Landmarks
  • Radiation Therapy
    • Remote Radiation Therapy (or Other Deformity/Scarring) Which May Alter the Upper Airway Anatomy
  • Tumor
    • Intrinsic Airway Tumor

Technique

• Cricothyroid Membrane Lies Below the Thyroid Cartilage and Above the Cricoid Cartilage
  • Laterally on Both Sides of the Cricothyroid Membrane are the Cricothyroideus Muscles
  • Location of the Cricothyroid Membrane by Palpation Can Be Difficult Even for Experienced Providers with Surgical Airway Experience (Success Rates ≤50%) (Can J Anaesth, 2016) [MEDLINE]: this is especially true in obese patients (Anaesthesia, 2015) [MEDLINE]
  • Location of the Cricothyroid Membrane by Ultrasound: may be useful, but studies are lacking

• Cook Melker Kit Procedure
  • Components: 6 mL syringe, 18 gauge needle with overlying catheter, a guide wire, a tissue dilator, cuffed cricothyroidotomy tube, and tracheostomy tape
  • Time Required: 1-4 min (Anaesthesist, 2003) [MEDLINE]
  • Steps
    • Stand at the Patient’s Right Side
    • Immobilize the Larynx by Holding the Thyroid Cartilage with the Left Hand
    • With Right Hand, Insert Needle (Pointed at a Downward 45 Degree Angle) into the Cricothyroid Membrane with Syringe Filled with Saline, Aspirating as You Go: watch for air bubbles into the syringe, indicating that you are in the trachea
    • Remove Syringe and Pass Wire Through the Needle
    • Remove Needle
    • Make a 1-2 cm Horizontal Incision Through the Skin and Cricothyroid Membrane: take care to not incise too deep (which may injury the posterior tracheal wall) or with the blade oriented superiorly (which may injure the vocal cords)
    • Thread the Dilator/Tube Assembly Over the Wire into the Airway
    • Remove the Dilator and Wire
    • Secure Airway Tube with Tracheostomy Tape and Attach to Either Bag Ventilation or Mechanical Ventilator

Complications

• Early Adverse Effects/Complications
  • Bleeding: usually occurs and can be controlled with direct pressure/packing
  • Cricoid Cartilage Fracture
  • Infection
  • Passage of Tube into Extratracheal Location
  • Posterior Tracheal Wall Perforation
  • Thyroid Cartilage Fracture
  • Tracheal Ring Fracture
  • Unintentional Tracheostomy
• Late Adverse Effects/Complications
  • Subglottic Stenosis
  • Voice Changes

Patient Awareness of Paralysis During Endotracheal Intubation

• Study of Awareness of Paralysis in Emergency Department Patients Undergoing Endotracheal Intubation (Chest, 2023) [MEDLINE]: n = 886
  • Approximately 7.4% of Patients Recalled Awareness of Paralysis During Endotracheal Intubation (95% CI: 5.8-9.4)
  • Logistic Regression Model Demonstrated that Decreased Level of Consciousness Prior to Intubation was Associated with Lower Odds of Awareness (Adjusted Odds Ratio 0.39; 95% CI: 0.22-0.69)
  • The Class of Neuromuscular Blocking Agent Used, Sedative Used, Preintubation Shock Index, and Postintubation Sedation were Not Significantly Associated with Recall of Paralysis During Endotracheal Intubation

Impact on Medical Malpractice Claims

• Significant Morbidity/Mortality (as Well as Medical Malpractice) is Related to Adverse Events/Complications of Airway Management and Endotracheal Intubation
  • Inadequate Ventilation, Esophageal Intubation, and Difficult Endotracheal Intubation are the Most Common Mechanisms of Respiratory Adverse Events/Complications Associated with Endotracheal Intubation/Mechanical Ventilation by Anesthesiologists (Anesthesiology, 1991) [MEDLINE]
  • US Review of Airway Complications in Patients Undergoing General Anesthesia (Anesthesiology, 2009) [MEDLINE]: mortality rate of 1.1 per million
  • British National Health Service Review of Major Airway Complications in Patients Undergoing General Anesthesia (Br J Anaesth. 2011) [MEDLINE]: 46 events per million (associated mortality of 5.6 per million)
  • British National Health Service Review of Major Airway Complications Noted that 25% of Reported Airway Events Occurred in the Intensive Care Unit or Emergency Department (and 61% of Those Events Resulted in Permanent Patient Harm or Death) (Br J Anaesth, 2011) [MEDLINE]
  • Closed Claims Analysis of Difficult Endotracheal Intubation by Anesthesiologists (Comparison of 2000-2012 to 1993-1999 Time Periods) (Anesthesiology, 2019) [MEDLINE]
    • Patients in 2000-2012 Difficult Intubation Claims were Sicker (78% American Society of Anesthesiologists, ASA, Physical Status III-V) and Had More Emergency Procedures (37%) as Compared to Patients in 1993-1999 Claims (47% ASA Physical Status III-V; P < 0.001 and 22% Emergency; P = 0.025)
    • More Difficult Endotracheal Intubation Events Occurred in Nonperioperative Locations in 2000-2012 than 1993-1999 (23% vs 10%; P = 0.035)
    • Outcomes Differed Between Time Periods (P < 0.001), with a Higher Proportion of Death in 2000-2012 claims (73% vs 42% in 1993-1999 Claims; P < 0.001 Adjusted for Multiple Testing)
    • In 2000-2012 Claims, Preoperative Predictors of Difficult Endotracheal Intubation were Present in 76% of Cases
    • In the 97 Claims with Sufficient Information for Assessment, Inappropriate Airway Management Occurred in 73% of Cases (κ = 0.44-0.66)
    • A “Can’t Intubate, Can’t Oxygenate” Emergency Occurred in 80 Claims with Delayed Surgical Airway in 39% of Cases

Multiple Intubation Attempts

• Multiple Intubation Attempts is a Risk Factor for Adverse Events/Complications of Airway Management and Endotracheal Intubation
  • In Emergency Endotracheal Intubations Performed in Critically Ill Patients Suffering Deterioration, As Compared to ≤2 Attempts, Repeated Attempts (≥3) were Significantly Associated with Increased Incidence of Hypoxemia (11.8% vs 70%), Regurgitation of Gastric Contents (1.9% vs 22%), Aspiration of Gastric Contents (0.8% vs 13%), Bradycardia (1.6% vs 21%), and Cardiac Arrest (0.7% vs 11%; P<0.001) (Anesth Analg, 2004) [MEDLINE]
  • In Emergency Department Intubations, ≥3 Intubation Attempts were Associated with a Significantly Increased Rate of Adverse Events (35% vs 9%) (Ann Emerg Med, 2012) [MEDLINE]
  • Patients Requiring 1 Intubation Attempts Had a 14.2% Adverse Event Rate, Patients Requiring 2 Intubation Attempts Had a 47.2% Adverse Event Rate, and Patients Requiring 3 Intubation Attempts in the Emergency Department Had a 63.6% Adverse Event Rate (Acad Emerg Med, 2013) [MEDLINE]

Intubation Bundles

• Intubation Bundles Can Decrease the Incidence of Post-Intubation Adverse Effects/Complications in the Intensive Care Unit (Intensive Care Med, 2010) [MEDLINE]: n = 244
  • Bundle Components
    • Capnography
    • Cricoid Pressure
    • Intravenous Fluid Loading
    • Preoxygenation with Noninvasive Positive-Pressure Ventilation
    • Preparation and Early Administration of Sedation
    • Presence of Two Operators
    • Protective Ventilation
    • Rapid Sequence Induction
    • Vasopressor Use (If Required)

Specific Adverse Effects and Complications of Endotracheal Intubation and Invasive Mechanical Ventilation

• See Invasive Mechanical Ventilation-Adverse Effects and Complications