| | Premeasurement | Postmeasurement |
P value |
|---|
Ventilator settings |
VT/PBW, ml/kg | 6.5 [6.2–7.0] | 6.4 [6.2–6.7] | 0.006 |
PEEP, cmH2O | 12 [10–14] | 12 [10–14] | 0.077 |
FiO2
| 0.60 [0.50–0.70] | 0.60 [0.50–0.70] | 0.325 |
Physiological variables |
PaCO2, mmHg | 41 [38–50] | 42 [38–50] | 0.553 |
PaO2/FiO2, mmHg | 146 ± 60 | 162 ± 69 | 0.020 |
Pplat
a, cmH2O | 30 ± 5 | 28 ± 5 | 0.004 |
∆Pa, cmH2O | 18 [14–20] | 15 [12–19] | 0.023 |
OIb, cmH2O/mmHg | 15.2 ± 7.4 | 13.8 ± 8.3 | 0.021 |
O/SIa, mmHg/cmH2O | 7.5 [5.4–11.5] | 8.2 [5.9–14.7] | 0.029 |
VD/VT, est
| 0.63 ± 0.10 | 0.62 ± 0.12 | 0.494 |
VE, corr, L/minute | 13.0 ± 3.2 | 12.8 ± 3.3 | 0.421 |
-
Abbreviations: Vt/PBW Tidal volume per predicted body weight, PEEP Positive end-expiratory pressure, FiO
2
Fraction of inspired oxygen, PaCO
2
Partial pressure of carbon dioxide, PaO
2
/FiO
2
Ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, Pplat Plateau pressure, ∆P Driving pressure, OI Oxygenation index, O/SI Oxygenation/Stretch Index, indicating a benefit-to-cost ratio, V
D
/V
T
,
esti
Estimated physiological dead-space fraction, V
E,corr
Corrected expired volume per minute
- Continuous variables were described as mean ± SD and compared using paired t tests or described as median [IQR] and compared using Wilcoxon matched-pairs signed-rank sum tests, as appropriate. Bonferroni adjustment was not used. (Refer to main text for explanations.)
-
a
N = 45; 6 patients who were ventilated in volume control mode without documented Pplat were excluded. ∆P was calculated as the difference between Pplat and PEEP
-
b
N = 59; 2 patients who were ventilated in pressure support mode either before or after the measurements were excluded from analysis
