Table 3.
Respiratory mechanics, gas exchange and outcome of the patients divided according to lower or higher airway driving pressure at PEEP 15 cmH2O
| Variable | Overall population (N = 150) | Lower airway driving pressure (<15 cmH2O) (N = 97) | Higher airway driving pressure (≥15 cmH2O) (N = 53) | p value |
|---|---|---|---|---|
| Airway driving pressure (cmH2O) | 13.2 [11.2–16.9] | 11.9 [10.2–13.0] | 18.0 [16.6–19.9] | <0.001 |
| Transpulmonary driving pressure (cmH2O) | 9.5 [7.8–12.2] | 8.4 [6.6–9.7] | 13.1 [10.4–15.5] | <0.001 |
| End-inspiratory airway plateau pressure (cmH2O) | 28.4 [25.8–31.3] | 26.7 [24.8–28.2] | 32.9 [30.8–35.1] | <0.001 |
| Lung stress (cmH2O) | 20.7 [17.9–23.1] | 19.3 [16.8–21.7] | 23.9 [20.8–26.2] | <0.001 |
| Respiratory system elastance (cmH2O/L) | 26.3 [21.2–32.2] | 22.8 [19.5–26.6] | 34.2 [29.6–41.9] | <0.001 |
| Lung elastance (cmH2O/L) | 18.7 [14.5–24.2] | 16.7 [13.1–19.7] | 24.6 [19.5–31.3] | <0.001 |
| Chest wall elastance (cmH2O/L) | 7.0 [4.8–10.3] | 6.2 [4.6–8.2] | 10.2 [5.9–12.3] | <0.001 |
| PaCO2 (mmHg)a | 45 [40.2–50.4] | 43.8 [39.0–49] | 46.8 [41.9–53.2] | 0.039 |
| PaO2/FiO2 ratioa | 178 [137–237] | 175 [136–230] | 187 [146–257] | 0.314 |
| ICU mortality N (%) | 48 (32.0) | 28 (28.9) | 20 (37.7) | 0.352 |
Lung mechanics and gas exchange variables were determined at PEEP 15 cmH2O. Statistical analysis: Mann-Whitney rank sum test, chi-square, as appropriate
Abbreviations: PEEP positive end-expiratory pressure, PaCO 2 arterial partial pressure of carbon dioxide, PaO 2 arterial partial pressure of oxygen, FiO 2 inspired fraction of oxygen, ICU intensive care unit
aData available in 91 patients (64 in the “lower airway driving pressure” group and 27 in the “higher airway driving pressure” group)