Scope: applies not just to the Berlin definition of ARDS, but also to Acute Hypoxemic Respiratory Failure (AHRF) often seen in severe sepsis, pancreatitis, etc which is phenotypically similar but lacks the positive PEEP requirement in Berlin definition ARDS.

Definition of ARDS

Criterion Notes
Imaging - bilateral pulmonary opacities perhaps allowing CT/US diagnosis?
Minimum timeframe must be present after time period (not specified) of initial stabilization
P/F ratio Consider using S/F ratio (uncertain accuracy particularly in darker skinner patients)
Intubation/PEEP Consider including patients on HFNC/NIV

HFNC

  1. Strongly recommended in non-intubated patients with AHRF not due to cardiogenic pulmonary edema or AECOPD in order to reduce intubation rates.
  2. Unclear effect on mortality however - therefore no recommendations for this benefit.
  3. No clear recommendation with regards to HFNC vs NIV for non-Chronic obstructive pulmonary disease (COPD) or cardiogenic pulmonary edema. NIV may reduce the risk of intubation slightly.

CPAP/NIV

  1. CPAP/NIV does not clearly reduce intubation or mortality when compared to conventional O2 therapy for non-Chronic obstructive pulmonary disease (COPD)/ADHF presentations
  2. CPAP recommended over COT for risk of intubation in COVID-19, but may not decrease mortality
  3. Helmet CPAP/NIV - not enough evidence yet

Low tidal Volume Ventilation

  1. Low tidal volume ventulation (4-8 mL/kg PBW) recommended over larger Vt the reduce mortality in ARDS
  2. Pplat < 30

PEEP and LRM

  1. Routine PEEP/FiO2 titration using a higher strategy compared to a lower strategy: no recommendation due to high level of evidence of no effect
  2. PEEP/FiO2 table vs mechanics-titrated strategy (transpulmonary pressure): high level of evidence of no effect
  3. Prolonged LRM: recommended against due to moderate level of evidence against
  4. Brief LRM (less than 1 minute): suggested against. High level of evidence of no effeect

Prone Positioning

  1. Recommended for moderate to severe ARDS (PF < 150 and PEEP > 5). High level of evidence in favour of mortality.
  2. Start early after intubation, after a period of initial stabilization and titration. Prolonged sessions (16+ hours) should be the target as well.
  3. Awake proning is suggested for nonintubated patients with COVID-19 related AHRF

Neuromuscular Blockade

  1. Routine use of continuous infusion NMB is recommended against in moderate to severe ARDS