| Control | ARDS | Pneumonia | Cardiogenic pulmonary oedema | p–value | |
| Subjects n | 52 | 42 | 3 | 4 | |
| Age years | 60 (46–70) | 67 (48–75) | 57 (39–68) | 69 (66–71) | 0.42 |
| Males | 31 (70) | 35 (67) | 1 (33) | 1 (25) | 0.16 |
| APACHE II | 20 (14–26) | 23 (18–29) | 28 (19–31) | 26 (24–30) | 0.12 |
| SAPS II | 44 (35–64) | 46 (39–62) | 55 (41–66) | 63 (59–71) | 0.079 |
| Admission type | |||||
| Medical | 34 (65) | 31 (74) | 2 (67) | 2 (50) | 0.89 |
| Elective surgery | 10 (19) | 8 (19) | 1 (33) | 2 (50) | |
| Emergency surgery | 3 (6) | 3 (7) | 0 (0) | 0 (0) | |
| Comorbidities | |||||
| Asthma | 0 (0) | 1 (2) | 0 (0) | 0 (0) | 0.49 |
| COPD | 1 (2) | 2 (5) | 1 (33) | 0 (0) | 0.24 |
| Other respiratory | 1 (2) | 2 (5) | 0 (0) | 0 (0) | 0.68 |
| Malignancy | 4 (8) | 7 (16) | 1 (33) | 2 (50) | 0.09 |
| DM | 6 (12) | 9 (20) | 0 (0) | 0 (0) | 0.34 |
| PImax cmH2O | 16 (13–18) | 23.5 (18–29) | 15 (13–19) | 20 (18–22) | <0.001 |
| Pplateau cmH2O | 14.0 (12–18) | 22.5 (18–28) | 14.0 (12–18) | 18.5 (17–21) | <0.001 |
| PEEP cmH2O | 5 (5–5) | 10 (5–10) | 5 (5–5) | 7.5 (5–10) | <0.001 |
| VT mL | 450 (391–510) | 486 (397–569) | 670 (547–992) | 458 (387–540) | 0.28 |
| VT/IBW mL·kg−1 | 6.5 (5.6–7.5) | 6.8 (6.1–7.6) | 11.6 (9.7–14.6) | 7.3 (7.0–8.3) | 0.057 |
| Minute volume L·min−1 | 8.9 (7.5–10.9) | 10.9 (8.7–13.6) | 11.1 (10.6–12.0) | 9.9 (9.2–10.9) | 0.014 |
| PaCO2 kPa | 5.1 (4.5–5.5) | 5.4 (4.7–6.0) | 4.6 (4.3–5.0) | 5.2 (5.0–5.5) | 0.15 |
| PaO2 kPa | 14.7 (13.0–22.2) | 12.7 (11.0–15.5) | 15.7 (15.2–18.9) | 13.7 (13.4–15.0) | 0.019 |
| FIO2 % | 35 (30–40) | 40 (40–56) | 40 (35–45) | 40 (39–43) | <0.001 |
| PaO2/FIO2 | 360 (281–454) | 233 (174–297) | 294 (257–423) | 270 (251–286) | <0.001 |
| LIPS | 2.5 (1.5–4.0) | 5.0 (3.5–5.0) | 5.0 (3.5–5.0) | 3.0 (2.5–4.0) | <0.001 |
| ICU mortality | 5 (10) | 12 (29) | 1 (33) | 1 (25) | 0.17 |
Data are presented as median (interquartile range) or n (%), unless otherwise stated. Differences between groups were tested using Kruskal–Wallis one-way ANOVA or Chi-square test (with Yates’ correction if necessary). ARDS: acute respiratory distress syndrome; APACHE: Acute Physiology and Chronic Health Evaluation; SAPS: Simplified Acute Physiology Score; COPD: chronic obstructive pulmonary disease; DM: diabetes mellitus; PImax: maximal inspiratory pressure; Pplateau: plateau pressure; PEEP: positive end-expiratory pressure; VT: tidal volume; IBW: ideal body weight derived from height and sex; PaCO2: arterial carbon dioxide tension; PaO2: arterial oxygen tension; FIO2: inspiratory oxygen fraction; LIPS: Lung Injury Prediction Score; ICU: intensive care unit.