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Table 3 PaO2/FiO2 ratio and static respiratory system compliance responses after the first prone positioning session

From: Effect of prone positioning on oxygenation and static respiratory system compliance in COVID-19 ARDS vs. non-COVID ARDS

  Entire group PaO2/FiO2-matched Compliance-matched
N = 168 P value N = 46 P value N = 46 P value
PaO2/FiO2 ratio
 Change at the end of the first prone positioning session, mmHg
  COVID-19 ARDS, median (IQR) 89.8 (35.3–135.2) 0.003 89.8 (35.3–135.2) 0.091 89.8 (35.3–135.2) < 0.001
  Non-COVID ARDS, median (IQR) 40.1 (7.0–77.5) 48.7 (5.0–87.0) 21.1 (0.0–43.8)
 Regression coefficient (COVID vs. non-COVID)
  Unadjusted (95% CI) 46.7 (17.8–75.6) 0.002 32.5 (− 14.7–79.8) 0.172 69.7 (31.2–108.2) 0.001
  Adjusted (95% CI)a 39.3 (5.2–73.5) 0.024 4.0 (− 62.9–71.0) 0.903 58.4 (− 13.5–130.2) 0.108
Static respiratory system compliance
 Change at the end of the first prone positioning session, mL/cmH2O
  COVID-19 ARDS, median (IQR) 3.7 (− 1.0–7.3) < 0.001 3.7 (− 1.0–7.3) 0.044 3.7 (− 1.0–7.3) < 0.001
  Non-COVID ARDS, median (IQR) − 0.3 (− 4.0–1.9) 0.4 (− 1.2–2.3) − 2.3 (− 7.2–0.0)
 Regression coefficient (COVID vs. non-COVID)
  Unadjusted (95% CI) 4.2 (2.3–6.2) < 0.001 2.7 (0.0–5.5) 0.047 6.6 (3.8–9.3) < 0.001
  Adjusted (95% CI)a 3.4 (1.1–5.6) 0.003 0.3 (− 3.3–3.8) 0.883 2.2 (− 2.4–6.7) 0.340
  1. CI confidence interval, FiO2 fraction of inspired oxygen, IQR interquartile range, PaO2 partial pressure of oxygen
  2. aFor multivariable linear regression, the following variables were adjusted: age, sex, body mass index, duration of mechanical ventilation before initiation of prone positioning, sequential organ failure assessment (SOFA) score, Charlson comorbidity index (CCI), baseline setting of mechanical ventilator (positive end-expiratory pressure and tidal volume), and baseline respiratory mechanics before initiation of prone positioning (PaO2/FiO2, static compliance, and ventilatory ratio)