Table 2.
Ventilatory parameters on the first day of ventilation. Values given as median (interquartile range) if not stated otherwise. All ventilation and arterial blood gas parameters were collected at the same time point (e.g. 08.00 am if the patient was stable for at least 1 h, otherwise 1 h earlier or later)
| All | With inhalation trauma | Without inhalation trauma | P value | |
|---|---|---|---|---|
| N = 160 | N = 84 | N = 75 | ||
| V T (mL/kg PBWa), n | 7.3 (6.2–8.3), 130 | 7.3 (6.2–8.5), 71 | 7.3 (6.2–7.8), 59 | 0.58 |
| ≤8, n | 96 | 50 | 46 | |
| >8, n | 34 | 21 | 13 | |
| Absolute VT (mL), n/N | 500 (430–584), 137/160 | 500 (440–600), 73/84 | 480 (420–560), 63/75 | 0.33 |
| Controlled mode, n | 7 (6.1–8), 107 | 7.1 (6.1–8.2), 59 | 7 (6.1–7.8), 48 | 0.58 |
| Spontaneous mode, n | 8 (7.3–9.5), 22 | 8.3 (7.5–9.2), 12 | 7.6 (7–9.5), 10 | 0.82 |
| PEEP (cmH2O), n/N | 6 (5–8), 135 | 8 (5–10), 74 | 5 (5–8), 62 | 0.004 |
| 5, n | 66 | 30 | 37 | |
| 6–10, n | 64 | 40 | 24 | |
| >10, n | 5 | 4 | 1 | |
| FiO2, n | 0.35 (0.3–0.4), 155 | 0.39 (0.3–0.5), 82 | 0.35 (0.3–0.4), 73 | 0.36 |
| Peak pressure (cmH2O), n | 23 (19–31), 67 | 31 (23–35), 29 | 20 (17–25), 38 | <0.001 |
| P plat (cmH2O), n | 18 (16–23), 40 | 21 (18–24), 20 | 17 (15–23), 20 | 0.12 |
| P max (cmH2O), n | 20 (17–24), 59 | 20 (17–25), 37 | 20 (17–22), 22 | 0.46 |
| Maximum airway pressureb, n | 21 (18–30), 121 | 24 (19–31), 64 | 20 (17–24), 58 | 0.007 |
| Driving pressurec (cmH2O), n | 13 (11–17), 118 | 14 (11–18), 62 | 13 (10–16), 56 | 0.55 |
| Other parameters | ||||
| PaO2/FiO2 (mmHg) | 288 (186–402) | 275 (172–358) | 320 (229–415) | 0.05 |
| n (%) | 154 (96) | 73 (90) | 6(85) | |
| Respiratory rate (breaths per minute), n | 18 (15–21), 138 | 18 (15–22), 74 | 18 (15–20), 63 | 0.71 |
| Compliance (mL/cm H2O)d, n | 35.6 (21.2–50), 92 | 34.3 (20.4–48.8), 61 | 36.2 (21.7–51.8), 31 | 0.59 |
| Minute ventilation (L/min), n | 8.8 (7.6–10.8), 130 | 8.8 (7.5–11), 71 | 8.8 (7.6–10), 59 | 0.42 |
| PaCO2 (mmHg), n | 41 (36–45), 142 | 41 (36–47), 73 | 41 (36–44), 68 | 0.46 |
| Arterial blood pH, n | 7.39 (7.32–7.43), 142 | 7.38 (7.31–7.43), 73 | 7.40 (7.34–7.43), 68 | 0.31 |
| HCO2 (mEq/L), n | 23 (21–26), 142 | 23 (12–25), 73 | 24 (22–26), 68 | 0.10 |
N number, VT tidal volume, mL/kg PBW milliliters per kilogram predicted body weight, PEEP positive end-expiratory pressure, Ppeak peak airway pressure, Pplat plateau pressure, Pmax maximum airway pressure, PaO2 partial pressure of oxygen in arterial blood, FiO2 fraction of inspired oxygen
aCalculated for males as follows: 50 + 0.91 (cm of height−152.4) and for females as 45.5 + 0.91 (cm of height−152.4). Patients for which PBW could not be calculated were omitted from the analysis.
bMaximum airway pressure: Ppeak pressure, Pmax or Pplat depending on ventilator mode.
cCalculated as Pplat (or equivalent)−PEEP.
dCompliance = VT/(Pplat (or equivalent)−PEEP)