Table 1 Demographic data and clinical characteristics
|  | Total population (n = 191) | Responders (n = 96) | Non responders (n = 95) | P |
|---|---|---|---|---|
Age—yr | 66 [59–72] | 65 [59–72] | 68 [59–72] | 0.25 |
Sex—male—no (%) | 152 (79.6) | 75 (78) | 77 (81) | 0.72 |
BMI | 28 [26–31] | 28 [25–31] | 28 [26–31] | 0.35 |
SAPS II score | 38 [30–45] | 38[30–46] | 38[30–44] | 0.81 |
SOFA score | 5 [3–7] | 4 [3–6] | 5 [3–7] | 0.31 |
Hypertension—no (%) | 104 (54.5) | 50 (52) | 54 (57) | 0.56 |
Chronic ischemic heart disease—no (%) | 20 (10.5) | 8 (8) | 12 (13) | 0.36 |
Chronic kidney disease—no (%) | 12 (6.3) | 5 (5.2) | 7 (7.4) | 0.57 |
Diabetes—no (%) | 46 (24.1) | 22 (22.9) | 24 (25.3) | 0.74 |
Chronic liver disease (MELD > 10)—n (%) | 3 (1.6) | 1 (1) | 2 (2.1) | 0.62 |
COPD—no (%) | 14 (7.3) | 8 (8.3) | 6 (6.3) | 0.39 |
HFNO before intubation—no (%)—183 | 20 (10.9) | 13 (13.5) | 7 (7.4) | 0.24 |
CPAP/NIV before intubation—no (%) | 127 (70.4) | 60 (62.5) | 67 (70.5) | 0.20 |
PaO2/FiO2 before intubation—mmHg | 94 [76–112] | 90 [70–113] | 96 [80–110] | 0.50 |
Tidal volume set—ml/kg IBW | 7.2 [6.6–7.8] | 7.3[6.5–8.1] | 7.1[6.6–7.6] | 0.48 |
PEEP set—cmH2O | 12 [10–14] | 12 [10–15] | 12 [10–14] | 0.80 |
Highest Pplata—cmH2O | 25 [23–28] | 25 [22–28] | 26 [24–29] | 0.04 |
Lowest CRS supinea—ml/cmH2O | 35 [29–41] | 37 [30–43] | 33 [27–40] | 0.005 |
Lowest PaO2/FiO2a—mmHg | 90 [69—113] | 89 [67—114] | 90 [70—110] | 0.87 |
 Class 3—P/F200—300 (%) | 0 (0) | 0 (0) | 0 (0) |  |
 Class 2—P/F 100—200 (%) | 72 (38.8) | 40 (41.7) | 32 (33.7) |  |
 Class 1—P/F < 100 (%) | 119 (62.3) | 56 (58.3) | 63 (66.3) |  |
Duration of CPAP/NIV trial before intubation | (n = 127) | (n = 60) | (n = 67) | 0.23 |
  < 12 h—no (%) | 26 (20.5) | 8 (13.3) | 18 (26.9) |  |
 12—24 h—no (%) | 31 (24.4) | 16 (26.7) | 15 (22.4) |  |
 24—48 h—no (%) | 22 (17.3) | 13 (21.7) | 9 (13.4) |  |
  > 48 h—no (%) | 48 (37.8) | 23 (38.3) | 25 (37.3) |  |