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Table 1 Patient characteristics, ventilator settings, arterial blood gas results, and outcomes

From: P/FP ratio: incorporation of PEEP into the PaO2/FiO2 ratio for prognostication and classification of acute respiratory distress syndrome

  All patients (N = 3442)
Demographics
 Age, median (IQR), years 51 (39 – 63)
 Gender, male (%) 1888 (54.9)
Cause of ARDS, N (%)
 Pneumonia 1699 (49.4)
 Sepsis 748 (21.7)
 Aspiration 429 (12.5)
 Trauma 239 (6.9)
 Transfusion 71 (2.1)
 Others 256 (7.4)
Severity Severe (≤ 100) Moderate (101–200) Mild (201–300)
Categorization P/F P/FP P Value P/F P/FP P Value P/F P/FP P Value
N (%) 640 (19) 794 (30)  < 0.001 1928 (57) 1252 (47)  < 0.001 839 (25) 640 (24) 0.368
Ventilator settings, mean ± SD
 FiO2 0.82 ± 0.14 0.79 ± 0.16  < 0.001 0.55 ± 0.14 0.56 ± 0.14 0.049 0.43 ± 0.12 0.49 ± 0.13  < 0.001
 PEEP, cmH2O 12.6 ± 4.4 14.2 ± 3.6  < 0.001 9.32 ± 3.5 10.2 ± 2.6  < 0.001 8.0 ± 3.6 8.1 ± 2.4 0.544
 PaO2, mmHg          
Arterial blood gases 65.0 ± 11.4 71.7 ± 19.7  < 0.001 80.0 ± 19.8 81.9 ± 24.9 0.017 104.5 ± 31.2 96.1 ± 38.2  < 0.001
 SaO2, % 91.2 ± 5.7 92.2 ± 5.4  < 0.001 94.6 ± 3.2 94.5 ± 3.7 0.419 96.9 ± 2.3 95.8 ± 3.0  < 0.001
 PaCO2, mmHg 43.7 ± 12.9 44.4 ± 13.0 0.309 40.1 ± 9.9 40.3 ± 9.3 0.569 37.8 ± 8.5 38.5 ± 9.0 0.126
 pH 7.33 ± 0.10 7.33 ± 0.10 1.000 7.38 ± 0.08 7.38 ± 0.07 1.000 7.39 ± 0.07 7.38 ± 0.07 0.006
  1. P values refer to comparisons between patients classified according to the P/F ratio versus patients classified according to the P/FP ratio in each severity category. Definition of abbreviations: ARDS  acute respiratory distress syndrome, FiO2  fraction of inspired oxygen, IQR  interquartile range PaCO2  partial pressure of arterial carbon dioxide, PaO2  partial pressure of arterial oxygen, PEEP positive end-expiratory pressure, P/F =ratio of the PaO2 to FiO2; P/FP = (PaO2 * 10)/(FiO2 * PEEP); SaO2  arterial oxygen saturation; SD standard deviation