ARDS Guidelines 2024–2026

Sources Referenced

ATS 2024Am J Respir Crit Care Med

ESICM 2023Intensive Care Med

Global Def 2024PMC12784126

EMA 2025 Rev.2European Medicines Agency

Nature 2025Signal Transduct Target Ther

ATS 2017MV Guidelines

▲ Key Paradigm Shift

The 2024 Global ARDS Definition is the first major revision since Berlin 2012. It introduces three diagnostic categories (non-intubated, intubated, resource-limited), formally accepts lung ultrasound and SpO₂/FiO₂ ratio, and enables ARDS diagnosis without intubation — transforming both clinical practice and research inclusion criteria.

§ 1

Berlin 2012 → Global Definition 2024: Key Changes

Feature	Berlin Definition (2012)	Global ARDS Definition (2024)
Patient population	Intubated, mechanically ventilated only	Intubated + non-intubated + resource-limited settings
Imaging	Chest X-ray or CT only	Lung ultrasound added as accepted modality
Oxygenation	PaO₂/FiO₂ ratio with PEEP ≥5 cmH₂O	SpO₂/FiO₂ (SF) ratio accepted if SpO₂ ≤97%
HFNO/NIV patients	Excluded from diagnosis	Included — non-intubated ARDS category
HFNO criteria	N/A	≥30 L/min flow rate required
NIV/CPAP criteria	CPAP ≥5 cmH₂O (implicit)	CPAP/NIV with PEEP ≥5 cmH₂O (clarified)
Resource-limited	Not addressed	Kigali modification adopted — no PEEP requirement
Severity categories	Mild / Moderate / Severe (PF only)	Three categories with separate PF and SF cutoffs
PaCO₂ / dead space	Not addressed	Identified as important future direction

§ 2

Severity Classification — Intubated ARDS

Severity	PaO₂/FiO₂ (PF ratio)	SpO₂/FiO₂ (SF ratio)	Mortality implication
Mild	200 < PF ≤ 300 mmHg	235 < SF ≤ 315	~27%
Moderate	100 < PF ≤ 200 mmHg	148 < SF ≤ 235	~32–45%
Severe	PF ≤ 100 mmHg	SF ≤ 148	~45–60%

§ 3

Clinical Recommendations — At a Glance

Strong Rec

Lung-Protective Ventilation

Tidal volume 4–8 mL/kg PBW (start 6), plateau pressure <30 cmH₂O. Cornerstone of ARDS management. Unchanged since 2017.

Strong Rec

Prone Positioning

>12–16 h/day for severe ARDS (ATS 2024: >12h; ESICM 2023: ≥16h). Reduces mortality ~50% in severe ARDS (PROSEVA).

Against

Routine HFOV

Routine high-frequency oscillatory ventilation not recommended for moderate-to-severe ARDS. (ATS 2017 & 2024 maintained)

Against

Prolonged Recruitment Maneuvers

PEEP ≥35 cmH₂O for >60 sec strongly discouraged in moderate-to-severe ARDS — associated with higher mortality. (ATS 2024)

Conditional · New

Higher PEEP (no RM)

Conditional for higher PEEP without recruitment maneuvers in moderate-to-severe ARDS. ESICM 2023: insufficient data for specific PEEP recommendation.

Conditional · New

VV-ECMO

Venovenous ECMO may be considered in selected patients with severe refractory ARDS (PF <80, pH <7.25). Prefer high-volume centers. (ATS 2024)

Conditional · New

Corticosteroids

Dexamethasone 6 mg IV/day × 10 days conditionally recommended. Alternative: methylprednisolone 1 mg/kg/day. Evidence most robust in COVID-19 ARDS.

Conditional · New

Early NMBA (48h)

Neuromuscular blocking agents first 48 hours in severe ARDS (ATS 2024). ESICM 2023: not for non-COVID. Risk: ICU-acquired weakness.

Strong Rec

HFNO for AHRF

High-flow nasal oxygen strongly recommended for acute hypoxemic respiratory failure (non-cardiogenic, non-COPD). FLORALI trial basis. (ESICM 2023)

Conditional · New

Awake Prone Positioning

Recommended for non-intubated patients with AHRF (COVID and non-COVID). Reduces intubation rates; adherence is the key practical challenge.

§ 4

ARDS Subphenotypes — Precision Medicine Approach

Inflammation High IL-6, IFN-γ, TNF-α

Biomarkers ↑ Angiopoietin-2/1, ↑ PAI-1

Clinical More sepsis, vasopressors, metabolic acidosis

Lung morphology Non-focal / diffuse infiltrates

Recruitability High

90-day mortality Significantly higher

PEEP response May benefit more from higher PEEP

Fluid strategy Conservative fluid management beneficial

Inflammation Lower systemic inflammatory markers

Biomarkers Lower inflammatory mediators

Clinical Fewer comorbidities, less vasopressor use

Lung morphology Focal infiltrates

Recruitability Lower

90-day mortality Lower

PEEP response May not benefit from higher PEEP

Limitation Real-time biomarker testing unavailable at bedside

Subphenotypes identified by latent class analysis (Calfee et al., Lancet Respir Med 2014). Clinical implementation requires prospective validation.

§ 5

10 Take-Home Points

01 2024 Global ARDS Definition introduces three categories (non-intubated, intubated, resource-limited) and accepts lung ultrasound and SF ratio — the first major revision in 12 years.
02 HFNO (≥30 L/min) and NIV/CPAP (≥5 cmH₂O PEEP) patients now qualify for ARDS diagnosis — a paradigm shift from Berlin's intubation-only approach.
03 Lung-protective ventilation (tidal volume 4–8 mL/kg PBW, plateau <30 cmH₂O) remains the cornerstone — unchanged since 2017.
04 Higher PEEP without recruitment maneuvers is conditionally recommended for moderate-to-severe ARDS (ATS 2024); prolonged recruitment maneuvers are strongly discouraged.
05 Prone positioning ≥12–16 hours/day reduces mortality in severe ARDS; awake prone positioning is recommended for non-intubated AHRF patients.
06 VV-ECMO should be considered in selected patients with severe refractory ARDS (PF <80, pH <7.25), preferentially at high-volume centers.
07 Corticosteroids (dexamethasone 6 mg/day × 10 days) are conditionally recommended for ARDS. No other pharmacotherapy has demonstrated survival benefit in large trials.
08 ARDS subphenotypes (hyperinflammatory vs. hypo-inflammatory) demonstrate differential treatment responses — precision medicine is the future, but bedside phenotyping is not yet ready for routine clinical use.
09 Under-recognition of ARDS remains critical — ~20% of severe ARDS cases are missed, leading to suboptimal lung-protective ventilation and worse outcomes.
10 EMA 2025 (Rev.2) provides the regulatory framework for future ARDS drug trials; standard of care in trials must include conservative fluids, prone positioning, and lung-protective ventilation.