Table 2.
Ventilator settings and gas-exchange parameters shortly after intubation and outcome in intubated patients
| Overall n = 897 | Oxygen mask n = 501 | High-flow oxygen therapy n = 307 | Non-invasive ventilation n = 89 | p | |
|---|---|---|---|---|---|
| Time from ICU admission to intubation [days] | 0 [0–1] | 0 [0—0] | 0 [0—1] | 0 [0—1] | < 0.001 |
| ARDS classification†, n (%) | |||||
| No ARDS | 73 (8) | 48 (9) | 18 (6) | 7 (8) | 0.264 |
| Mild | 253 (28) | 151 (30) | 84 (27) | 18 (20) | |
| Moderate | 451 (50) | 238 (48) | 159 (52) | 54 (61) | |
| Severe | 120 (14) | 64 (13) | 46 (15) | 10 (11) | |
| FiO2 (%) | 60 [50—80] | 60 [50—80] | 60 [50—70] | 60 [45—80] | 0.444 |
| PaO2 (mmHg) | 97 [79—126] | 98 [80—131] | 98 [78—122] | 91 [78—113] | 0.19 |
| PaO2/ FiO2 (mmHg) | 171 [126—229] | 173 [124–238] | 174 [127—228] | 157 [124—205] | 0.487 |
| PaCO2 (mmHg) | 46 [40–54] | 46 [40–54] | 47 [40–54] | 46 [38—57] | 0.993 |
| pH | 7.35 [7.29—7.4] | 7.35 [7.28—7.4] | 7.35 [7.29—7.41] | 7.35 [7.28—7.4] | 0.57 |
| Respiratory rate (1/min) | 22 [20–25] | 22 [20–25] | 22 [20–25] | 22 [20–26] | 0.555 |
| Tidal volume/ideal body weight [ml/kg] | 6.7 [6.0—7.5] | 6.7 [6.0—7.5] | 6.7 [6.1—7.6] | 6.7 [5.7—7.3] | 0.27 |
| PEEP (cmH2O) | 12 [10–14] | 12 [10–14] | 12 [10–14] | 14 [12–15] | < 0.001 |
| Plateau airway pressure (cmH2O) | 25 [23–28] | 25 [22–28] | 25 [23–28] | 26 [24–28] | 0.13 |
| Driving airway pressure (cmH2O) | 12 [10–15] | 12 [10–15] | 12 [10–15] | 12 [10–15] | 0.745 |
| Compliance rs (ml/cmH2O) | 35 [28–44] | 34 [28–42] | 35 [27–45] | 33 [27–43] | 0.591 |
| Ventilatory ratio * | 1.9 [1.5–2.3] | 1.9 [1.5–2.3] | 1.8 [1.5–2.3] | 1.8 [1.4–2.3] | 0.837 |
| Estimated physiological dead-space fraction (%) ** | 54 [42–64] | 54 [43–63] | 55 [39–64] | 51 [43–63] | 0.823 |
| Length of mechanical ventilation (days) | 14 [7–25] | 14 [7–24] | 16 [9–26] | 12 [7–22] | 0.031 |
| Length of ICU stay (days) | 17 [10–28] | 16 [9–27] | 19 [12–31] | 15 [9–26] | 0.004 |
| ICU mortality, n (%) | 297 (33) | 164 (33) | 96 (31) | 37 (41) | 0.275 |
Quantitative data are expressed as median [interquartile range]. P values are given for the difference between respiratory strategies. ARDS—acute respiratory distress syndrome; ICU—intensive care unit; PaO2—partial pressure of arterial oxygen; FiO2—fraction of inspired oxygen; PaCO2—partial pressure of arterial carbon dioxide; PEEP—positive end-expiratory pressure; Compliance rs—compliance of the respiratory system
†Mild: 200mHg < PaO2/FiO2 ≤ 300 mmHg; Moderate: 100mHg < PaO2/ FiO2 ≤ 200 mmHg; Severe: PaO2/ FiO2 ≤ 100 mmHg
*Calculated according to Sinha. (17), see formula in Additional file 1: Appendix 4
**Calculated according to Morales-Quinteros et al. (18), see formula in Additional file 1: Appendix 4