Healthcare & Clinical Formulas
Berlin ARDS Severity (PaO2/FiO2) & Ventilator Oxygenation Index (OI)
Classify Acute Respiratory Distress Syndrome into Mild (200 < P/F <= 300), Moderate (100 < P/F <= 200), or Severe (P/F <= 100 on PEEP >= 5 cmH2O) per the 2012 Berlin Definition alongside Mean-Airway-Pressure Oxygenation Index OI = (100 * FiO2 * MAP) / PaO2.
Why pairing Berlin P/F with Oxygenation Index (OI) captures ventilator pressure cost!
The 2012 ESICM/ATS Berlin Definition eliminated the obsolete "Acute Lung Injury" term and stratified ARDS strictly on PEEP/CPAP >= 5 cmH_2O into Mild (200 < PaO_2/FiO_2 <= 300 mmHg, ~27% mortality), Moderate (100 < P/F <= 200 mmHg, ~32% mortality; <150 triggers prone positioning per PROSEVA!), and Severe (P/F <= 100 mmHg, ~45% mortality)!
Because cranking up PEEP and inspiratory pressure can artificially prop up PaO_2/FiO_2 while causing barotrauma, intensivists simultaneously compute the Mean-Airway-Pressure Oxygenation Index: OI = (100 * FiO_2 * MAP_aw) / PaO_2 (where FiO_2 is fractional 0.21–1.00, so 100 * FiO_2 is % O_2; OI >= 16 = Severe PARDS, OI >= 25–40 = refractory hypoxemia / ECMO consideration)! For PaO_2 = 85 mmHg on FiO_2 = 0.60, PEEP = 10 cmH_2O, and MAP_aw = 16 cmH_2O: P/F = 141.7 mmHg (Moderate ARDS, <150 prone-positioning candidate!) and OI = 11.3!
| Ventilated Arterial Blood Gas State (PEEP >= 5) | PaO2 / FiO2 Ratio | Berlin ARDS Tier | Oxygenation Index OI |
|---|---|---|---|
| PaO2 = 150, FiO2 = 0.60, MAP = 12 | 250.0 mmHg | Mild ARDS (200 < P/F <= 300) | 4.8 |
| PaO2 = 85, FiO2 = 0.60, MAP = 16 | 141.7 mmHg | Moderate ARDS (100 < P/F <= 200) | 11.3 |
| PaO2 = 55, FiO2 = 0.80, MAP = 22 | 68.8 mmHg | Severe ARDS (P/F <= 100) | 32.0 (ECMO Zone!) |
Berlin ARDS PaO2/FiO2 Severity Classification (Requiring PEEP >= 5 cmH2O)
Verifies FiO_2 in [0.21, 1.00] and PEEP >= 5 cmH_2O before classifying P/F = B2 / B3.
=IF(OR(B2 <= 0, B3 < 0.21, B3 > 1, B4 < 0), "Invalid Ventilator Inputs", IF(B4 < 5, "PEEP < 5 cmH2O (Berlin Requires PEEP >= 5)", IF(B2 / B3 <= 100, "Severe ARDS (P/F <= 100)", IF(B2 / B3 <= 200, "Moderate ARDS (100 < P/F <= 200)", IF(B2 / B3 <= 300, "Mild ARDS (200 < P/F <= 300)", "P/F > 300 (Above ARDS Hypoxemia Threshold)")))))Mean-Airway-Pressure Oxygenation Index OI = (100 * FiO2 * MAP_aw) / PaO2
Computes dimensionless OI accounting for mean airway pressure B5 (cmH_2O).
=IF(OR(B2 <= 0, B3 < 0.21, B3 > 1, B5 <= 0), "Invalid Ventilator Inputs", ROUND((100 * B3 * B5) / B2, 1))Try the example
Use the original values or change them to test your understanding.