Acute Respiratory Distress Syndrome (ARDS)-Part 1


In 1967, Ashbaugh Introduced the Term “Respiratory Distress Syndrome” to Describe a Clinical Syndrome with the Following Clinical Features (Lancet, 1967) [MEDLINE]

  • Acute Onset of Tachypnea (see Tachypnea)
  • Decreased Lung Compliance
  • Diffuse Pulmonary Infiltrates
  • High Short-Term Adult Mortality Rates
  • Hypoxemia (see Hypoxemia)



  • LUNG SAFE Global Observational Study of Acute Respiratory Distress Syndrome (ARDS) in 50 Countries (JAMA, 2016) [MEDLINE]
    • Epidemiology
      • Approximately 10.4% of ICU Admissions Met ARDS Criteria
      • Approximately 23.4% of Mechanically Ventilated Patients Met ARDS Criteria
    • Clinical
      • Clinical Recognition of ARDS Ranged from 51.3% in Mild ARDS to 78.5% in Severe ARDS
    • Therapy
      • Less Than 66% of the Patients Received Tidal Volume <8 mL/kg
      • Proning was Used in Only 16.3% of Patients with Severe ARDS
    • Hospital Mortality Rates
      • Mild ARDS: 34.9%
      • Moderate ARDS: 40.3%
      • Severe ARDS: 46.1%
    • Conclusions
      • ARDS Recognition and Management Has Room for Potential Clinical Improvement


  • Systematic Review of the Costs of Acute Respiratory Distress Syndrome (ARDS) (Chest, 2021) [MEDLINE]: n = 49,483 (from 22 studies)
    • Mean Inpatient Costs Ranged from $8,476 (2021 US Dollars) to $547,974 (2021 US Dollars) and were Highest in Publications of Lower Quality and in American Health Systems and were Associated with Trauma Cohorts
    • Mean Outpatient Costs were Highest in Publications with Higher Readmission Rates, Longer Durations of Follow-Up, and in American Health Systems

Risk Factors

Prediction of Acute Respiratory Distress Syndrome (ARDS) Using Clinical Factors

  • Lung Injury Prediction Score (LIPS) Study (Am J Respir Crit Care Med, 2011) [MEDLINE]: multicenter observational cohort study (n = 5,584 patients at risk)
    • Acute Lung Injury Occurred at a Median of 2 Days in 6.8% of Patients
    • Acute Lung Injury Can Be Predicted Early in the Course of Illness Using Clinical Parameters
      • Aspiration: LIPS points +2 pts
      • High-Risk Surgery (add 1.5 pts if emergency surgery)
        • Aortic/Vascular: +3.5 pts
        • Cardiac: +2.5 pts
        • Acute Abdomen: +2 pts
        • Orthopedic Spine: +1 pt
      • High-Risk Trauma
        • Traumatic Brain Injury: +2 pts
        • Smoke Inhalation: +2 pts
        • Near Drowning: +2 pts
        • Lung Contusion: +1.5 pts
        • Multiple Fractures: +1.5 pts
      • Pneumonia: +1.5 pts
      • Shock: +2 pts
      • Sepsis: +1 pt
      • Negative Risk Modifiers (Decrease the Risk of Acute Lung Injury)
        • Diabetes Mellitus: -1 pt (only if sepsis)
        • Note: Diabetes Mellitus is the Only Risk factor Which Decreases the Risk of Developing ARDS
      • Positive Risk Modifiers (Increase the Risk of Acute Lung Injury)
        • FIO2 >35%: +2 pts
        • pH <7.35: +1.5 pts
        • Tachypnea with RR >30: +1.5 pts
        • Alcohol Abuse: +1 pts
        • Obesity with BMI >30: +1 pt
        • Hypoalbuminemia: +1 pt
        • Chemotherapy: +1 pt
        • SpO2 <95%: +1 pt
    • Scoring
      • Over 4 points (Optimal Cutoff Point in the Study Based on the Area Under the Curve Analysis): 69% sensitivity and 78% specificity for the prediction of development of ARDS

Prediction of Acute Respiratory Distress Syndrome (ARDS) Using Clinical Factors Present in the Emergency Department

  • Emergency Department Lung Injury Prediction Score Study (EDLIPS)/LIPS-1 Study (Int J Emerg Med, 2012) [MEDLINE]
    • Incidence of Acute Lung Injury was 7%
    • EDLIPS (Obtained Early in ED Course) Discriminated Patients Who Developed Acute Lung Injury Better than APACHE II Scoring and Similar to Original LIPS Score

Protective Factors

Older Age

  • Clinical Efficacy
    • Prospective Multicenter Observational Cohort Study of Hospitalized Patients at Risk of Developing Acute Respiratory Distress Syndrome (ARDS) (from 3/09-8/09) (J Intensive Care Med, 2019) [MEDLINE]: n = 5,584 (22 hospitals)
      • Approximately 6.8% of the Patients Developed ARDS
      • After Adjusting for Severity of Illness and the Risk of ARDS Development Attributable to Other Factors, Older Adult Patients Had a Lower Incidence of ARDS, as Compared to Younger Patients (Odds Ratio: 0.28, 95% Confidence Interval: 0.18-0.42)

Corticosteroid Treatment (see Corticosteroids)

  • Clinical Efficacy
    • Retrospective Study Examining the Effect of Preadmission Oral Corticosteroid on the Risk of Development of Acute Respiratory Distress Syndrome in Intensive Care Unit Patients with Sepsis (Crit Care Med, 2017) [MEDLINE]: n = 1080
      • Preadmission Oral Corticosteroid Use Decreases the Risk of Early Acute Respiratory Distress Syndrome (Within 96 hrs of ICU Admission) in ICU Patients with Sepsis (35%), as Compared to Patients Who Had Not Received Preadmission Corticosteroids (42%)
      • Higher Corticosteroid Doses (Prednisone 30 qday) were Associated with Lower Risk of ARDS (Odds Ratio 0.53) than were Lower Corticosteroid Doses (Prednisone 5 mg qday)
      • Preadmission Oral Corticosteroid Use Did Not Impact the In-Hospital Mortality Rate, ICU Length of Stay, or Ventilator-Free Days

Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors Treatment in the Setting of Diabetes Mellitus (see Sodium-Glucose Cotransporter-2 Inhibitors)

  • Clinical Efficacy
    • South Korean Nationwide Cohort Study (2015-2020) of Sodium-Glucose Cotransporter-2 Inhibitors in Adult Patients with Type 2 Diabetes Mellitus (BMC Med, 2023) [MEDLINE]
      • Methods
        • 205,534 Patient Pairs (Mean Age: 53.8 y/o, 59% Male, Median F/U 0.66 yrs)
        • Primary Outcome was Respiratory Events Composite Endpoint
        • Secondary Outcomes were the Individual Components of the Primary Outcome and In-Hospital Death
        • Cox Models were Used to Estimate Hazard Ratios 95% Confidence Intervals
      • Incidence Rates for Overall Respiratory Events were 4.54 and 7.54 Per 1000 Person-Years Among Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors and Dipeptidyl Peptidase-4 (DPP-4) Inhibitors Users, Respectively, Corresponding to a Rate Difference of 3 Less Events Per 1000 Person-Years (95% CI – 3.44 to – 2.55)
      • Hazard Ratios (95% CIs)
        • 0.60 (0.55 to 0.64) for the Composite Respiratory Endpoint (Acute Pulmonary Edema, Acute Respiratory Distress Syndrome, Pneumonia, and Respiratory Failure
        • 0.35 (0.23 to 0.55) for Acute Pulmonary Edema
        • 0.44 (0.18 to 1.05) for Acute Respiratory Syndrome (ARDS)
        • 0.61 (0.56 to 0.66) for Pneumonia
        • 0.49 (0.31 to 0.76) for Respiratory Failure
        • 0.46 (0.41 to 0.51) for In-Hospital Death
      • Similar Trends were Found Across Individual Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors, Subgroup Analyses of Age, Sex, History of Comorbidities, and a Range of Sensitivity Analyses




  • Sepsis (see Sepsis)
    • Epidemiology
      • Sepsis is the Most Common Etiology of ARDS
    • Risk Factors for the Development of Sepsis-Associated ARDS
      • Acute Abdomen (Ann Intensive Care, 2017) [MEDLINE]
      • Acute Pancreatitis (Ann Intensive Care, 2017) [MEDLINE]
      • Alcohol Abuse (Crit Care Med, 2003) [MEDLINE] and (Crit Care Med, 2008) [MEDLINE]
        • Ethanol May Decrease Glutathione Concentrations in the Epithelial Lining Fluid, Increasing the Risk of Oxidative iInjury to the Lung
      • Delayed Antibiotics (Crit Care Med, 2008) [MEDLINE]
      • Delayed Goal-Directed Resuscitation (Crit Care Med, 2008) [MEDLINE]
      • Diabetes Mellitus (Crit Care Med, 2008) [MEDLINE]
      • Higher APACHE II Score (Ann Intensive Care, 2017) [MEDLINE]
      • Higher Intravenous Fluid Resuscitation within the First 6 hrs (Ann Intensive Care, 2017) [MEDLINE]
        • In Stratified Analysis, the Total Fluid Infused within the First 6 hrs was a Risk Factor in the Non-Shock Group, But Not in the Shock Group
      • Increased Baseline Respiratory Rate (Crit Care Med, 2008) [MEDLINE]
      • Older Age (Ann Intensive Care, 2017) [MEDLINE]
      • Pneumonia as the Site of Infection (Ann Intensive Care, 2017) [MEDLINE]
      • Recent Chemotherapy (Crit Care Med, 2008) [MEDLINE]
      • Shock (Ann Intensive Care, 2017) [MEDLINE]
      • Transfusion (Crit Care Med, 2008) [MEDLINE]

Viral Pneumonia

Bacterial Pneumonia

Fungal Pneumonia

Parasitic Pneumonia


Dermatologic Disorder

  • Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) (see Drug Rash with Eosinophilia and Systemic Symptoms)
    • Epidemiology (from Systematic Review) (Biomed Res Int, 2019) [MEDLINE]
      • Dyspnea Occurs in 81% of Cases (see Dyspnea)
      • Interstitial Infiltrates/Interstitial Pneumonia Occur in 50% of Cases (see Interstitial Lung Disease)
      • Acute Respiratory Distress Syndrome (ARDS) Occurs in 31% of Cases
      • Cough Occurs in 19% of Cases (see Cough)
  • Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) (see Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis)
    • Epidemiology
      • Respiratory Complications (Including Sloughing of the Bronchial Epithelium, Pneumonia, Atelectasis, and Acute Respiratory Distress Syndrome) are Common During the Acute Phase of Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)
      • Approximately 25% of Patients with Pulmonary Involvement Develop Acute Respiratory Failure Requiring Mechanical Ventilation (Crit Care Med, 2014) [MEDLINE]


  • Burns (see Burns)
  • Blast Injury
    • Explosion
    • Lightning
  • Fat Embolism (see Fat Embolism)
  • Head Trauma/Traumatic Brain Injury (TBI) (see Traumatic Brain Injury)
  • Pulmonary Contusion (see Pulmonary Contusion)
  • Surgery
    • Systematic Review/Meta-Analysis of Morbidity/Mortality in Post-Operative Acute Lung Injury (Lancet Respir Med, 2014) [MEDLINE]
      • Incidence of Acute Lung Injury was Similar Following Both Thoracic and Abdominal Surgery
      • Risk Factors for Post-Operative Acute Lung Injury
        • Higher American Society of Anesthesiology (ASA) Score
        • Higher Prevalence of Pre-Existing Sepsis or Pneumonia
        • Older Age
        • Receipt of Blood Transfusions
        • Receipt of High Tidal Volume Ventilation and/or Low PEEP During Surgery
      • Post-Operative Acute Lung Injury Increased ICU Length of Stay and Hospital Length of Stay
      • Overall Attributable Mortality Rate for Post-Operative Acute Lung Injury: 19%
        • Attributable Mortality Rate for Post-Operative Acute Lung Injury Following Thoracic Surgery: 26.5%
        • Attributable Mortality Rate for Post-Operative Acute Lung Injury Following Abdominal Surgery: 12.2%
      • Risk of In-Hospital Mortality was Independent of the Ventilation Strategy
  • Other Trauma

Mechanical Pulmonary Edema

Hemodynamic Disturbance

Hematologic Disorder

Neurogenic Pulmonary Edema (see Neurogenic Pulmonary Edema)

Rheumatologic Disease

Lung Transplant Rejection/Dysfunction (see Lung Transplant Rejection)



  • Acetic Acid Inhalation (see Acetic Acid)
    • Inhalational Exposure
  • Acetic Anhydride Inhalation (see Acetic Anhydride)
    • Inhalational Exposure
  • Acrolein Inhalation (see Acrolein)
    • Inhalational Exposure
  • Acute Beryllium Exposure (see Beryllium)
    • Inhalational Exposure
  • Amitrole Inhalation (see Amitrole)
    • Inhalational Exposure
  • Ammonia Inhalation (see Ammonia)
    • Inhalational Exposure
  • Bromine/Methyl Bromide Inhalation (see Bromine-Methyl Bromide)
    • Inhalational Exposures
      • Bromine Liquid (Readily Vaporizes): used in chemical synthesis and water purification
      • Methyl Bromide Gas (Bromomethane): used as industrial fumigant
  • Carboxyhemoglobinemia (see Carboxyhemoglobinemia)
    • Inhalational Exposure
  • Chlorine Inhalation (see Chlorine)
    • Inhalational Exposure
  • Chloropicrin Gas Inhalation (see Chloropicrin Gas)
    • Inhalational Exposures
      • Chemical Manufacturing
      • Fumigant
      • World War I Wartime Exposure
  • Chromic Acid Inhalation (see Chromic Acid)
    • Inhalational Exposures: used in electroplating
  • Contaminated Rapeseed Oil (see Contaminated Rapeseed Oil)
  • Copper Dust/Fume Inhalation (see Copper)
    • Inhalational Exposure
  • Cyanide Intoxication (see Cyanide)
    • Fire/Smoke Inhalation (see Smoke Inhalation)
      • Smoke Inhalation is the Most Common Etiology of Cyanide Intoxication in Industrialized Countries
    • Industrial Exposure (to Cyanide Salts or Nitriles)
      • Dermal
      • Inhalational
      • Ingestion
    • Medical Administration
    • Dietary Ingestion of Amygdalin (see Amygdalin)
      • Contained in Rosaceae Family Fruit/Nuts, Bamboo Shoots, Cassava Root, Flaxseed, and Soy
    • Other
      • Illicit Synthesis of Phencyclidine
      • Terrorist Attack
      • Tobacco Abuse (see Tobacco)
  • Diazomethane Inhalation (see Diazomethane)
    • Inhalational Exposure
  • Diborane Gas Inhalation (see Diborane Gas)
    • Inhalational Exposure During Microelectronics Manufacturing
  • Dinitrogen Tetroxide Inhalation (see Dinitrogen Tetroxide)
    • Inhalational Exposure to Rocket Propellant
  • Ethylene Oxide Gas Inhalation (see Ethylene Oxide Gas)
    • Inhalational Exposure During Medical Disinfection and Sterilization
  • Formic Acid Inhalation (see Formic Acid)
    • Inhalational (Aerosol, Vapor) Exposures
      • Leather Tanning
      • Limescale Remover
      • Rubber Manufacturing
      • Textile Industry
      • Toilet Bowl Cleaner
      • Treatment of Livestock Feed: due to to its antibacterial properties
  • Glyphosate Ingestion (see Glyphosate
    • Ingestion Exposure to Herbicide (Roundup, etc)
  • Heavy Metal Fume Inhalation
  • Hydrocarbons (see Hydrocarbons)
    • Ingestion/Aspiration Exposure
  • Hydrofluoric Acid Inhalation (see Hydrofluoric Acid)
    • Inhalational Exposure
  • Hydrogen Sulfide Gas Inhalation (see Hydrogen Sulfide Gas)
    • Inhalational Exposure
  • Isopropanol Intoxication (see Isopropanol)
  • Lycoperdonosis (see Lycoperdonosis)
    • Inhalational Exposure to Puffball Mushroom (Lycoperdon) Spore, Resulting in Allergic Bronchioloalveolitis
  • Methamphetamine Intoxication (see Methamphetamine)
  • Methyl Isocyanate Inhalation (see Methyl Isocyanate)
    • Inhalational Exposure
  • Methyl Isothiocyanate Inhalation (see Methyl Isothiocyanate)
    • Inhalational Exposure
  • Nickel Carbonyl Inhalation (see Nickel Carbonyl)
    • Inhalational Exposure
  • Nitric Acid Inhalation (see Nitric Acid)
    • Inhalational Exposure
  • Nitrogen Dioxide Inhalation (see Nitrogen Dioxide)
    • Inhalational Exposure
  • Nitrogen Mustard Gas Inhalation (see Nitrogen Mustard Gas)
    • Inhalational Exposure
  • Osmium Tetroxide Inhalation (see Osmium Tetroxide)
    • Inhalational Exposure
  • Ozone Inhalation (see Ozone)
    • Inhalational Exposure (Welding/Water Treatment/Pulp Paper Bleaching)
  • Palytoxin (see Palytoxin)
    • Epidemiology
      • Palytoxin Rarely is Associated with ARDS
    • Inhalational Exposure to Microalgae (Ostreopsis Ovate, Ostreopsis Siamensis), Corals, and Sea Anemones
  • Paraquat Intoxication (see Paraquat)
    • Ingestion Exposure
  • Phosgene Gas Inhalation (see Phosgene Gas)
    • Inhalational Exposure
  • Phosphine Gas Inhalation (see Phosphine Gas)
    • Inhalational Exposure
  • Polytetrafluoroethylene (PTFE, Teflon) Inhalation (see Polytetrafluoroethylene)
    • Inhalational Exposure
  • Rattlesnake Bite (see Rattlesnake Bite)
  • Smoke Inhalation (see Smoke Inhalation)
    • Inhalational Exposure to Fire (Especially in an Enclosed Space)
  • Sodium Azide Inhalation (see Sodium Azide)
    • Inhalational Exposure (Automobile Airbag Deployment)
  • Sulfur Dioxide Inhalation (see Sulfur Dioxide
    • Inhalational Exposure
  • Sulfuric Acid Inhalation (see Sulfuric Acid)
    • Inhalational Exposure
  • Sulfur Mustard Gas Inhalation (see Sulfur Mustard Gas)
    • Inhalational Exposure
  • Tear Gas Inhalation (see Tear Gas)
    • Inhalational Exposure to Tear Gas Used by Police/Military for Crowd Control
  • White Phosphorus Inhalation (see White Phosphorus)
    • Inhalational Exposure to Firework/Incendiary Explosion
  • Zinc Chloride Gas Inhalation (see Zinc Chloride Gas)
    • Inhalational Exposure to Smoke Bomb







Hematologic Disorder