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Table 2 Baseline respiratory mechanics and clinical outcomes

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

Variables COVID-19 ARDS Non-COVID ARDS
Entire group N = 23 Entire group N = 145 P valuea PaO2/FiO2-matched N = 23 P valuea Compliance-matched N = 23 P valuea
Arterial blood gas analysis
 pH 7.37 (7.34–7.39) 7.34 (7.28–7.40) 0.173 7.36 (7.26–7.40) 0.291 7.34 (7.28–7.41) 0.568
 PaCO2, mmHg 44 (40–49) 49 (40–55) 0.139 48 (45–54) 0.071 46 (37–54) 0.860
 PaO2, mmHg 75 (66–80) 71 (62–85) 0.467 79 (65–93) 0.391 69 (55–78) 0.097
 HCO3, mEq/L 24.9 (24.1–28.4) 24.2 (21.5–27.3) 0.161 23.3 (21–28.6) 0.191 23.3 (18.6–28.6) 0.240
Ventilator FiO2 0.7 (0.6–0.8) 0.8 (0.65–1.0) 0.047 0.75 (0.6–0.9) 0.537 0.75 (0.7–1.0) 0.221
PaO2/FiO2 ratio, mmHg 107 (92–132) 96 (74–120) 0.037 107 (92–131) 1.000 90 (72–104) 0.007
PEEP, cmH2O 12 (9–13) 10 (8–11) 0.016 10 (7–10) 0.063 10 (8–11) 0.135
Driving pressure, cmH2O 13 (12–16) 18 (15–21) < 0.001 18 (15–22) 0.001 15 (13–18) 0.096
Respiratory rate, breaths/min 21 (19–27) 27 (24–30) 0.002 26 (25–30) 0.012 24 (21–30) 0.116
Tidal volume per PBW, mL/kg 6.3 (5.6–7.0) 6.6 (6.0–7.3) 0.126 6.4 (5.9–7.2) 0.734 6.5 (5.9–9.0) 0.177
Minute ventilation per PBW, mL/kg/min 140 (123–171) 177 (145–200) < 0.001 167 (133–193) 0.044 173 (141–194) 0.003
Static respiratory system compliance, mL/cmH2O 27.2 (21.9–32.7) 21.9 (18.2–26.5) 0.005 20.0 (15.6–27.2) 0.008 27.2 (21.9–32.7) 0.983
Ventilatory ratio 1.7 (1.4–2.0) 2.2 (1.7–2.7)  < 0.001 2.1 (1.7–2.5) 0.015 2.2 (1.7–2.6) 0.002
Laboratory results
 White blood cell, 103/μL 10.46 (6.53–16.04) 13.36 (5.73–17.77) 0.717 15.73 (13.14–23.71) 0.008 10.01 (5.73–16.86) 0.904
 Segmented neutrophil, 103/μL 9.66 (5.88–14.57) 11.42 (4.93–15.06) 0.906 14.40 (11.53–19.56) 0.014 9.56 (4.53–14.43) 0.684
 Lymphocyte, 103/μL 0.69 (0.48–0.86) 0.43 (0.18–0.84) 0.047 0.70 (0.27–0.98) 0.895 0.51 (0.16–0.88) 0.249
 C-reactive protein, mg/dL 10.9 (6.3–19.8) 13.5 (6.6–21.5) 0.234 13.8 (7.6–21.5) 0.449 19.2 (9.1–25.7) 0.037
 RT-PCR for SARS-CoV-2
  Ct value for env gene 23.01 ± 4.99       
  Ct value for RdRp gene 22.60 ± 5.22       
Adjunctive therapies
 Inhaled nitric oxide 8 (34.8%) 56 (38.6%) 0.725 4 (17.4%) 0.179 8 (34.8%) 1.000
 Renal replacement therapy 4 (17.4%) 29 (20.0%) 1.000 2 (8.7%) 0.665 7 (30.4%) 0.491
 ECMO or ECCO2R 3 (13.0%) 7 (4.8%) 0.141 0 (0.0%) 0.233 2 (8.7%) 1.000
 Tracheostomy 12 (52.2%) 59 (40.7%) 0.300 15 (65.2%) 0.369 6 (26.1%) 0.070
90-days clinical outcome
 Successful discontinuation of mechanical ventilation 16 (69.6%) 27 (18.6%) < 0.001 5 (21.7%) 0.005 4 (17.4%) 0.001
 Dependent on mechanical ventilation 2 (8.7%) 11 (7.6%)   5 (21.7%)   1 (4.3%)  
 Death 5 (21.7%) 107 (73.8%)   13 (56.6%)   18 (78.3%)  
 Ventilator free days 45 (0–82) 0 (0–0) < 0.001 0 (0–0) 0.002 0 (0–0) 0.002
  1. ARDS acute respiratory distress syndrome, Ct value cycle threshold value, ECCO2R extracorporeal carbon dioxide removal, ECMO extracorporeal membrane oxygenation, FiO2 fraction of inspired oxygen, PaCO2 partial pressure of carbon dioxide, PaO2 partial pressure of oxygen, PBW predicted body weight, PEEP positive end expiratory pressure, RT-PCR reverse transcription polymerase chain reaction
  2. aP values are for comparison between patients with COVID-19 ARDS and patients with non-COVID ARDS