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Table 2 Ventilator settings and physiological variables before and after measurements (N = 61)

From: Implementing a bedside assessment of respiratory mechanics in patients with acute respiratory distress syndrome

  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
  1. 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
  2. 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.)
  3. 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
  4. b N = 59; 2 patients who were ventilated in pressure support mode either before or after the measurements were excluded from analysis