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Table 3 Changes in respiratory mechanics and gas exchange at 5 and 15 cmH2O of PEEP between high and low PaO2/FiO2 group

From: Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

Variables

Low

PaO2/FiO2 < 81.8

31 patients

High

PaO2/FiO2 ≥ 81.8

30 patients

p

Δ15-5 Plateau pressure, cmH2O

8 [10–11]

11 [10–13]

0.147

Δ15-5 Driving pressure, cmH2O

0 [− 2 to 1]

1 [0–3]

0.147

Δ15-5 Respiratory system elastance, cmH2O/L

0 [− 3 to 3]

3 [0–6]

0.126

Δ15-5 Lung elastance, cmH2O/L

2 [− 2 to 4]

3 [1–7]

0.257

Δ15-5 Chest wall elastance, cmH2O/L

0 [− 2 to 1]

0 [− 2 to 2]

0.373

Δ15-5 Lung stress, cmH2O

9 [7–11]

9 [8–13]

0.534

Δ15-5 Mechanical power, J/min

9 [8–11]

10 [9–11]

0.351

Δ15-5 Mechanical Power_Compliancers, J/min/(mL/cmH2O)

0.21 [0.12–0.34]

0.30 [0.17–0.37]

0.436

Δ15-5 PaO2, mmHg

26 [16–38]

16 [4–23]

0.012

Δ15-5 PaO2/FiO2, mmHg

31 [16–55]

28 [9–42]

0.212

Δ15-5 Right-to-left shunt, %

− 16 [− 26 to − 10]

0 [− 11 to 0]

 < 0.001

Δ15-5 PvO2, mmHg

3 [2–11]

1 [0–2]

 < 0.001

Δ15-5 ScvO2, %

8.5 [4.4–13.4]

0.6 [− 1 to 3]

 < 0.001

Δ15-5 Ca-vO2, mL

1.3 [0.9–1.8]

0.4 [0.0–0.6]

 < 0.001

Δ15-5 PaCO2, mmHg

1 [− 2 to 3]

2 [1–5]

0.110

Δ15-5 Ventilatory ratio

0.04 [− 0.09 to 0.10]

0.08 [− 0.02 to 0.19]

0.065

Δ15-5 Estimated physiological dead space

0.01 [− 0.02 to 0.03]

0.02 [0.01–0.05]

0.070

  1. T-test or Wilcoxon–Mann–Whitney test were performed, as appropriate. Δ15-5: difference between 15 and 5 cmH2O of PEEP; Ca-vO2: arterial–venous oxygen content difference; Compliancers: respiratory system compliance; ScvO2 central oxygen venous saturation; PvO2 mixed venous oxygen tension