Table 3. Respiratory parameters at baseline, 24 hours and 48 hours

Parameters	Baseline	24 hours	48 hours	p-value
PaO2/FiO2	135.8 [100.5–169.8]	167.5 [140.8–232.7]	203.6 [149.0–267.9]	<0.0011)2)
Set PEEP (cm H2O)	10.0 [8.0–10.0]	10.0 [10.0–12.0]	10.0 [9.0–10.0]	<0.0011)3)
Tidal volume (mL/kg PBW)	6.7 [6.3–7.4]	6.7 [6.1–7.3]	6.8 [6.2–7.3]	0.614
Respiratory rate (rate/min)	22.0 [20.0–25.0]	22.0 [20.0–26.0]	23.0 [20.0–26.0]	0.769
Plateau pressure (cmH2O)	27.0 [24.0–29.0]	26.0 [23.0–27.8]	25.0 [22.0–27.0]	<0.0011)2)3)
Airway driving pressure (cmH2O)	17.0 [14.0–20.0]	15.0 [13.0–16.0]	15.2 [12.0–17.6]	0.0011)2)
Crs (mL/cmH2O)	23.8 [19.7–27.7]	26.6 [24.6–30.8]	26.7 [22.2–33.2]	<0.0012)
Esophageal end-inspiratory pressure (cmH2O)	18.2 [16.7–19.4]	17.6 [16.0–18.7]	16.5 [14.7–18.7]	0.297
Transpulmonary end-inspiratory pressure (cmH2O)	8.3 [6.4–9.7]	7.9 [6.4–10.3]	7.6 [5.1–9.8]	0.294
Esophageal end-expiratory pressure (cmH2O)	9.7 [8.7–11.2]	9.1 [8.7–10.8]	8.7 [7.8–9.7]	<0.0011)2)
Transpulmonary end-expiratory pressure (cmH2O)	–0.8 [–1.4–0.78]	1.2 [0.9–1.8]	1.3 [0.7–1.7]	<0.0011)2)
Heart rate (beat/min)	114 [110.5–128]	109 [90.5–120]	104 [90–116.5]	0.152
Mean arterial pressure (mmHg)	86.7 [76.7–93.8]	86.7 [80.2–95.3]	86.7 [76.7–97.0]	0.950
VIS (score)	5.6 [0–13.5]	0 [0–14.5]	0 [0–4.35]	<0.0011)2)

Variables with non-parametric distribution are presented using the median and interquartile range. The Friedman test was used for the statistical analysis, followed by post-hoc comparisons using the Wilcoxon test with Bonferroni adjustment for p-values.
A p-value<0.05 for the comparison baseline vs 24 hours.
A p-value<0.05 for the comparison baseline vs 48 hours.
A p-value<0.05 for the comparison 24 hours vs 48 hours.
PaO₂, partial pressure of arterial oxygen; FiO₂, fraction of inspired oxygen; PEEP, positive end-expiratory pressure; PBW, predicted body weight; Crs, compliance respiratory system; VIS, vasopressor index score.