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. 2022 Mar 31;2022:4579030. doi: 10.1155/2022/4579030

Table 2.

Changes in arterial blood gas and Crs.

  PP (n = 136) Control (n = 128) Difference (95% CI) P value
When enrolled in the study
 pH 7.44 ± 0.05 7.44 ± 0.04 0.00 (−0.11, 0.01) 0.559
 PaCO2, mmHg 38.4 ± 1.7 39.1 ± 1.9 0.7 (0.3, 1.2) 0.163
 P/F, mmHg 125.8 ± 15.6＃ 121.9 ± 18.1 −3.9 (−8.0, 0.2) 0.061
 FiO2 0.99 ± 0.04＃ 0.98 ± 0.06 −0.008 (−0.020, 0.004) 0.198
 Crs, mL/cmH2O 64.7 ± 4.8＃ 63.7 ± 5.0 −1.0 (−2.2, 0.2) 0.109
1 day after enrollment
 pH 7.43 ± 0.05 7.44 ± 0.05 0.01 (−0.00, 0.01) 0.199
 PaCO2, mmHg 39.3 ± 1.4 39.2 ± 1.4 −0.1 (−0.4, 0.3) 0.959
 P/F, mmHg 208.9 ± 23.1 125.0 ± 19.2 −80.87 (−89.04, −78.71) <0.001∗
 FiO2 0.78 ± 0.08 0.98 ± 0.05 0.195 (0.179, 0.212) <0.001∗
 Crs, mL/cmH2O 75.8 ± 5.4 63.4 ± 5.5 −12.5 (−13.8, −11.1) <0.001∗
2 days after enrollment
 pH 7.43 ± 0.05 7.45 ± 0.04 0.02 (0.01, 0.03) 0.377
 PaCO2, mmHg 39.4 ± 1.4 39.2 ± 1.5 −0.2 (−0.6, 0.2) 0.394
 P/F, mmHg 222.6 ± 30.8 136.7 ± 24.1 −85.9 (−92.6, −79.2) <0.001∗
 FiO2 0.58 ± 0.09 0.95 ± 0.09 0.367 (0.346, 0.389) <0.001∗
 Crs, mL/cmH2O 77.6 ± 5.3 64.2 ± 7.8 −13.4 (−14.9, −11.9) <0.001∗
3 days after enrollment
 pH 7.43 ± 0.05 7.45 ± 0.04 0.02 (0.01, 0.03) 0.684
 PaCO2, mmHg 39.3 ± 1.3 39.5 ± 1.4 0.02 (−0.31, 0.35) 0.282
 P/F, mmHg 245.4 ± 30.9 152.2 ± 28.6 −93.3 (−100.5, −86.1) <0.001∗
 FiO2 0.51 ± 0.1 0.79 ± 0.17 0.284 (0.250, 0.317) <0.001∗
 Crs, mL/cmH2O 78.1 ± 5.3 66.1 ± 7.6 −11.99 (−13.6, −10.4) <0.001∗

Crs, compliance of the respiratory system; CI, confidence interval; FiO2, inspiratory oxygen fraction; PaCO2, arterial partial pressure of carbon dioxide; P/F, partial pressure of oxygen in arterial blood/fraction of inspired oxygen; PP, prone position. #P  <  0.05 for comparisons between enrollment and after 1 day of enrollment. ∗P  <  0.05 for patients with versus without PP. 1 cmH2O = 0.098 kPa.