Airway Management

Indications for Intubation and Invasive Mechanical Ventilation

Respiratory Failure (see Respiratory Failure, [[Respiratory Failure]])

  • Excessive Work of Breathing
  • Inability to Protect Airway
  • Type I Hypoxemic Respiratory Failure (see Respiratory Failure, [[Respiratory Failure]])
    • Acute Hypoxemic Respiratory Failure
    • Chronic Hypoxemic Respiratory Failure
  • Type II Hypoxemic, Hypercapnic Respiratory Failure (see Respiratory Failure, [[Respiratory Failure]])
    • Acute Hypoxemic, Hypercapnic Respiratory Failure (Acute Hypoventilation, Acute Ventilatory Failure)
    • Chronic Hypoxemic, Hypercapnic Respiratory Failure (Chronic Hypoventilation, Chronic Ventilatory Failure)
  • Pulmonary Toilet
    • Inability to Manage Secretions
    • Massive Hemoptysis (see Hemoptysis, [[Hemoptysis]])

Measures to Decrease Altered Mental Status/Sedation-Related Upper Airway Obstruction

  • Jaw Thrust
  • Oral Airway
  • Nasal Airway
  • Positive-Pressure Ventilation with Bag/Valve/Mask
  • Endotracheal Intubation (see Mechanical Ventilation-General, [[Mechanical Ventilation-General]])

Pre-Intubation Airway Assessment

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

LEMON Mnemonic

  • Look
    • Dentition: assess for dentures, prominent maxillary incisors, broken/loose teeth, and crowns
    • Incisor Size
    • Scars
    • Tongue Size
  • Evaluate Using the 3-3-2 Rule
    • At Least 3 Fingers Between the Incisors
    • At Least 3 Fingers for the Thyromental Distance: distance from thyroid prominence to the point of chin (mentum) with the neck 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
    • At Least 2 Fingers for the Hyomental Distance: distance between hyoid bone (just above thyroid cartilage) and point of chin (mentum)
  • Mallampati Airway Class/Score: 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

MALLAMPATI

  • Obstruction of Airway
  • Neck Mobility: assess for next extension
    • Neck Extension May Be Limited with History of C-Spine Surgery
    • Neck Extension May Be limited Due to Rheumatoid Arthritis (RA) (see Rheumatoid Arthritis, [[Rheumatoid Arthritis]]): neck extension during intubation in some patients with RA may result in atlanto-axial subluxation, resulting in spinal cord injury

Bag-Valve-Mask Ventilation

Difficult Mask Ventilation

General Comments

  • Difficult Intubation is More Likely with Difficult Mask Ventilation
    • 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 (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

Body Positioning for Intubation

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

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, Maintenance of 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)

Structure of the Endotracheal Tube

Anatomic Relationships of the Endotracheal Tube


Induction and Paralysis for Intubation

Sedatives

  • Etomidate (Amidate) (see Etomidate, [[Etomidate]])
    • Dose: 0.3 mg/kg IVP (Usual Dose: 20 mg)
    • Onset: xxx
    • Duration: 3-5 min
  • Midazolam (Versed) (see Midazolam, [[Midazolam]])
    • Dose: 2-10 mg IVP
    • Onset: xxx
    • Duration: xxx
  • Propofol (Diprivan) (see Propofol, [[Propofol]])
    • Dose: xxx
    • Onset: xxx
    • Duration: xxx

Paralytics

  • Vecuronium (Norcuron) (see Vecuronium, [[Vecuronium]])
    • Dose: 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, [[Rocuronium]])
    • Dose: 0.6-1.2 mg/kg IVP (Usual Dose: 100 mg)
    • Onset: 75 sec
    • Duration: 33 min
  • Succinylcholine (see Succinylcholine, [[Succinylcholine]])
    • Dose: 1-1.5 mg/kg IVP
    • Onset: xxxx
    • Duration: 7-10 min
    • Contraindications to Use of Succinylcholine

Direct Laryngoscopic Intubation

Cricoid Pressure (Sellick Maneuver)

  • Definition: cricothyroid pressure applied throughout the entire rapid sequence intubation procedure to prevent vomiting -> maintain until ETT cuff is inflated
    • 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

Direct Laryngoscopy Blades

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

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

Techniques to Improve Laryngeal View During Direct Laryngoscopy

  • Backward-Upward-Rightward (BURP) Maneuver: backward-upward-rightward movement of larynx by manipulating the thyroid cartilage
  • Mandibular Advancement: improves view

Extension of Apnea Time During Endotracheal Intubation

  • Clinical Efficacy
    • Pre-Oxygenation with Supplemental Oxygen Bag-Mask Ventilation: removes nitrogen from the lungs and creates an alveolar oxygen reservoir (this reservoir remains fixed at the end of pre-oxygenation and does not get replenished once depleted)
      • Mechanisms to Increase the Reservoir Size
        • Head-Up Patient Positioning: reduces dependent atelectasis
        • Increasing Mean Airway Pressure
    • Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) Increases Apnea Time During Endotracheal Intubation (Anaesthesia, 2015) [MEDLINE]: high-flow nasal supplemental oxygen (during pre-oxygenation 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
    • Trial of High-Flow Nasal Cannula During Endotracheal Intubation (Crit Care Med, 2015) [MEDLINE]: high-flow nasal cannula oxygen significantly improved preoxygenation and reduced the prevalence of severe hypoxemia compared with non-rebreathing bag reservoir facemask
    • 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%

Video Laryngoscopic Intubation

Technique

  • Glidescope

Clinical Efficacy

  • Systematic Review/Meta-Analysis of Video Laryngoscopic vs Direct Laryngoscopic Endotracheal Intubation (Intensive Care Med, 2014) [MEDLINE]: 9 trials (n = 2133) comparing direct laryngoscopic vs video laryngoscopic intubaton in the ICU
    • 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

Fiberoptic Intubation

Technique

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]

Nasotracheal Intubation

  • Disadvantages
    • Higher Incidence of Maxillary Sinusitis

Cricothyroidotomy (Cricothyrotomy)

  • Indications
    • Inability to Intubate Patient

LARYNX

CRIC KIT


Confirmation of Endotracheal Tube (ETT) Placement

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 ETT 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, [[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, [[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 ETT

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 ETT 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 (Easy Cap II, etc) use litmus paper that tidally changes (breath by breath) from purple to yellow in the presence of exhaled carbon dioxide
    • ETCO2 <0.5%: purple
    • ETCO2 0.5-2%: tan
    • ETCO2 >2%: 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
    • Epinephrine (see Epinephrine, [[Epinephrine]]): acidic medication which can cause (non-tidal) yellow color change
    • Lidocaine (see Lidocaine, [[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, [[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, [[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]
  • 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, [[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

Exclusion of Mainstem Bronchial Endotracheal Tube Placement

General Comments

  • Complications of Unrecognized Mainstem Bronchial Intubation (Ann Emerg Med, 1989) [MEDLINE]
  • 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, [[Bronchoscopy]])

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

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

Endotracheal Tube (ETT) Movement with Head Positioning

  • ETT Tip Movement Follows Direction of Chin Movement
    • Neck Flexion (Chin Downward): ETT tip moves downward
    • Neck Extension (Chin Upward): ETT tip moves upward

References

General

  • Safe intrahospital transport of critically ill ventilator-dependent patients. Chest 1989; 96:631-635 [MEDLINE]
  • Unplanned extubations in the adult intensive care unit. Am J Respir Crit Care Med 1998; 157:1131-1137 [MEDLINE]
  • Death and other complications of emergency airway management in critically ill adults. Anesthesiology 1995; 82:367-376 [MEDLINE]
  • Bedside procedures: solutions to the pitfalls of intrahospital transport. Crit Care Clin 2000; 16:1-6 [MEDLINE]
  • Prediction of difficult mask ventilation.  Anesthesiology 2000;92:1229–1236 [MEDLINE]
  • Difficult airway management in the emergency department. J Emerg Med. 2002 Jan;22(1):31-48 [MEDLINE]
  • Clinical practice guidelines for sustained neuromuscular blockade in the adult critically ill patient. Crit Care Med. 2002 Jan;30(1):142-56 [MEDLINE]
  • Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Colourimetric CO(2) detector compared with capnography for confirming ET tube placement. Emerg Med J 2003: 20: 265-266 [MEDLINE]
  • The assessment of three methods to verify tracheal tube placement in the emergency setting. Resuscitation 2003; 56:153-157 [MEDLINE]
  • The effectiveness of out-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services system. Ann Emerg Med 2005; 45:497-503 [MEDLINE]
  • Clinical review: management of difficult airways.  Crit Care 2006;10:243.  doi: 10.1186/cc5112 [MEDLINE]
  • Incidence and predictors of difficult or impossible mask ventilation.  Anesthesiology 2006;105:885–891 [MEDLINE]
  • Caution when using colorimetry to confirm endotracheal intubation. Anesth Analg 2007;104:738 [MEDLINE]
  • 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 8: adult advanced cardiovascular life support. Circulation 2010; 122(18 Suppl 3):S729-S767 [MEDLINE]
  • Airway management in critically ill patients.  Lung  2011; 189:181-192 [MEDLINE]
  • Emergency airway management: the difficult airway.  Emerg Med Clin North Am  2012; 30:401-420 [MEDLINE]
  • Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2013;118:251–270 [MEDLINE]
  • Video laryngoscopy versus direct laryngoscopy for orotracheal intubation in the intensive care unit: a systematic review and meta-analysis. Intensive Care Med. 2014 May;40(5):629-39. doi: 10.1007/s00134-014-3236-5. Epub 2014 Feb 21 [MEDLINE]
  • Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia 2015;70:323-9 [MEDLINE]
  • Use of high-flow nasal cannula oxygen therapy to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia. Crit Care Med. 2015;43:574–583 [MEDLINE]
  • Heated humidified high-flow nasal oxygen in adults: mechanisms of action and clinical implications. Chest. 2015;148(1):253–261 [MEDLINE]
  • First Pass Success Without Hypoxemia Is Increased With the Use of Apneic Oxygenation During Rapid Sequence Intubation in the Emergency Department. Acad Emerg Med. 2016 Jun;23(6):703-10. Epub 2016 May 13 [MEDLINE]

Body Position

  • Analysis of the forces and position required for direct laryngoscopic exposure of the anterior vocal folds. Ann Otol Rhinol Laryngol. 1999;108(8):715 [MEDLINE]
  • Head and neck elevation beyond the sniffing position improves laryngeal view in cases of difficult direct laryngoscopy. J Clin Anesth. 2002;14(5):335 [MEDLINE]
  • Head-elevated laryngoscopy position: improving laryngeal exposure during laryngoscopy by increasing head elevation. Ann Emerg Med. 2003;41(3):322 [MEDLINE]
  • Laryngoscopy and morbid obesity: a comparison of the “sniff” and “ramped” positions. Obes Surg. 2004;14(9):1171 [MEDLINE]
  • Head-Elevated Patient Positioning Decreases Complications of Emergent Tracheal Intubation in the Ward and Intensive Care Unit. Anesth Analg. 2016 Apr;122(4):1101-7 [MEDLINE]

Cricoid Pressure (Sellick Maneuver)

  • Best evidence topic report. Cricoid pressure in emergency rapid sequence induction. Emerg Med J. 2005;22(11):815 [MEDLINE]

Confirmation of Endotracheal Tube Placement

  • Accidental intubation of the oesophagus. Anaesth Intensive Care. 1980;8(2):183 [MEDLINE]
  • End-tidal CO2 as a guide to successful cardiopulmonary resuscitation: a preliminary report. Crit Care Med. 1985;13(11):910 [MEDLINE]
  • Esophageal intubation: a review of detection techniques. Anesth Analg. 1986;65(8):886 [MEDLINE]
  • Unrecognized endobronchial intubation of emergency patients. Ann Emerg Med. 1989;18(8):853 [MEDLINE]
  • A comparative study of methods of detection of esophageal intubation. Anesth Analg. 1989;69(5):627 [MEDLINE]
  • Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device. Ann Emerg Med. 1992 May;21(5):518-23 [MEDLINE]
  • Women are at greater risk than men for malpositioning of the endotracheal tube after emergent intubation. Crit Care Med. 1994;22(7):1127 [MEDLINE]
  • Proper depth placement of oral endotracheal tubes in adults prior to radiographic confirmation. Acad Emerg Med. 1995;2(1):20 [MEDLINE]
  • Use of tube condensation as an indicator of endotracheal tube placement. Ann Emerg Med. 1998;31(5):575 [MEDLINE]
  • Comparison of three different methods to confirm tracheal tube placement in emergency intubation. Intensive Care Med. 2002;28(6):701 [MEDLINE]
  • Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Colourimetric CO(2) detector compared with capnography for confirming ET tube placement. Emerg Med J. 2003 May;20(3):265-6 [MEDLINE]
  • An assessment of a tracheal tube introducer as an endotracheal tube placement confirmation device. Am J Emerg Med. 2005;23(6):754 [MEDLINE]
  • Endobronchial intubation detected by insertion depth of endotracheal tube, bilateral auscultation, or observation of chest movements: randomised trial. BMJ. 2010;341:c5943 [MEDLINE]
  • Ultrasonography in the management of the airway. Acta Anaesthesiol Scand. 2011 Nov;55(10):1155-73. Epub 2011 Sep 7 [MEDLINE]
  • Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation. Resuscitation. 2011 Oct;82(10):1279-84. Epub 2011 Jun 1 [MEDLINE]
  • Transtracheal ultrasound for verification of endotracheal tube placement: a systematic review and meta-analysis. Can J Anaesth. 2015 Apr;62(4):413-23. Epub 2014 Dec 24 [MEDLINE]
  • Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis. Resuscitation. 2015;90:97 [MEDLINE]
  • Auscultation versus Point-of-care Ultrasound to Determine Endotracheal versus Bronchial Intubation: A Diagnostic Accuracy Study. Anesthesiology. 2016 May;124(5):1012-20 [MEDLINE]