What are the Berlin Criteria for ARDS?

The Berlin Definition of ARDS requires acute onset within one week of a known clinical insult, bilateral opacities on chest imaging, respiratory failure not fully explained by cardiac failure or fluid overload, and oxygenation impairment measured by PaO₂/FiO₂ ratio with PEEP or CPAP of at least 5 cm H₂O.

How is ARDS severity classified by the Berlin Definition?

ARDS severity is classified by PaO₂/FiO₂ ratio when PEEP or CPAP is at least 5 cm H₂O: mild ARDS is P/F 201–300, moderate ARDS is P/F 101–200, and severe ARDS is P/F 100 or less.

Does a low P/F ratio alone diagnose ARDS?

No. A low PaO₂/FiO₂ ratio supports oxygenation severity, but ARDS diagnosis also requires acute timing, bilateral opacities, PEEP or CPAP support, and respiratory failure not fully explained by cardiac failure or fluid overload.

Can cardiogenic pulmonary edema be classified as ARDS?

Respiratory failure should not be fully explained by cardiac failure or fluid overload before applying the Berlin ARDS classification. Cardiogenic pulmonary edema can mimic ARDS and should be evaluated clinically.

What PEEP is required for Berlin ARDS severity classification?

The Berlin Definition uses oxygenation severity measured with PEEP or CPAP of at least 5 cm H₂O. If PEEP or CPAP is below 5, the Berlin severity category should not be applied from oxygenation data alone.

When should severe ARDS prompt ECMO consideration?

Severe ARDS may warrant early ECMO center discussion when hypoxemia or hypercapnic acidosis remains refractory despite lung-protective ventilation, appropriate PEEP strategy, prone positioning when feasible, and other ICU rescue strategies.

Berlin Definition ARDS Workflow

ARDS diagnosis and severity decision support

Berlin ARDS Criteria Calculator for severity classification

Confirm Berlin Definition ARDS criteria using acute timing, bilateral opacities, non-cardiogenic origin, PEEP/CPAP support, and P/F ratio severity.

Use this workflow before escalation tools like the ARDSNet calculator, P/F Ratio calculator, ROX Index calculator, and VV ECMO Referral Criteria.

Step 01

Confirm timing, imaging, and edema origin

Step 02

Calculate P/F ratio on PEEP/CPAP/EPAP ≥5

Output

No ARDS, possible ARDS, or mild/moderate/severe ARDS

Step 01

Core Berlin ARDS criteria

ARDS is not just hypoxemia. Confirm timing, imaging, origin of edema, and PEEP/CPAP support.

Acute timing within 1 week

New or worsening respiratory symptoms within 1 week of a known clinical insult.

Timing not yet confirmed

Bilateral opacities on chest imaging

Chest X-ray, CT, or ultrasound findings not fully explained by effusions, lobar collapse, or nodules.

Imaging unclear or pending

Respiratory failure not fully explained by cardiac failure or fluid overload

Use clinical context, echo, hemodynamics, volume status, and response to diuresis as needed.

Origin of edema still uncertain

Berlin-compatible positive-pressure support

For mild ARDS (P/F 201–300), confirm PEEP or noninvasive CPAP ≥5 cm H₂O. For moderate or severe ARDS (P/F ≤200), confirm invasive ventilation with PEEP ≥5 cm H₂O.

Support mode or pressure is not yet confirmed

Step 02

Oxygenation severity

Calculate PaO₂/FiO₂ and apply the support requirement for the resulting Berlin severity range.

Current P/F

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FiO₂Enter 1.0 or 100 for 100% oxygen.PaO₂Use most recent ABG PaO₂ in mmHg.P/F ratio overrideOptional if you already calculated it.PEEP / CPAP / EPAPOptional numeric level. Berlin oxygenation severity requires applied positive pressure ≥5 cm H₂O.

How Berlin ARDS criteria work

The Berlin Definition combines timing, chest imaging, origin of edema, oxygenation impairment, and minimum applied positive pressure support. A low P/F ratio alone is not enough to diagnose ARDS.

Severity is classified by PaO₂/FiO₂ ratio: mild 201–300, moderate 101–200, and severe 100 or less. Mild Berlin ARDS may use noninvasive CPAP ≥5 cm H₂O; moderate and severe Berlin categories require invasive ventilation with PEEP ≥5 cm H₂O.

Clinical caution

Cardiogenic pulmonary edema, fluid overload, atelectasis, pleural effusions, lobar collapse, and non-ARDS hypoxemia can mimic parts of the Berlin workflow.

Use this calculator as a structured bedside checklist, not a replacement for imaging review, echocardiography, hemodynamic assessment, or clinician judgment.

Related PulmTools

P/F Ratio Calculator ARDSNet Calculator VV ECMO Referral Criteria Oxygenation Index Calculator ABG Analyzer Causes of Hypoxemia