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Table 1  Respiratory mechanics according to BMI group and PEEP level

From: Transpulmonary pressures in obese and non-obese COVID-19 ARDS

VPariable BMI group PEEP (cm H2O)
6 8 10 12 14 16 18 20
Pplat (cm H2O) Non-obese$ 15 [13.6–17.7] 16.3 [16.2–18.4] 18 [17.7–21.1] 21.8 [21.1–22.6] 25.8 [23.8–25.9] 29.9 [28.6–30.7] 34 [32.6–35.4] 38 [35.4–40.9]
Obese$ 16.5 [15.1–17.3] 17.5 [16.5–18.5] 20.5 [19–21] 22.5 [21–23.3] 24.5 [23.8–26.3] 27 [25.8–28.5] 29.5 [27–30.5]* 31.5 [28.8–32.8]*
Total PEEP (cm H2O) Non-obese$ 6.8 [6.8–6.9] 9 [8.4–9.5] 10.9 [10.9–11] 12.2 [12.2–13.3] 15 [15–15] 16.3 [16.3–16.7] 19 [19–19] 20.4 [20.4–21.4]
Obese$ 6.9 [6.7–6.9] 8.7 [8.3–8.9] 10.5 [10–11] 13 [12.2–13] 15 [14–15] 16.7 [16–17] 18.5 [18–19] 20 [20–20.6]
PRS (cm H2O) Non-obese$ 8.2 [6.8–10.2] 6.8 [6.8–8.9] 7 [6.8–9.6] 8.2 [8.2–10.5] 10.8 [8.8–11.4] 13.6 [11.6–14.5] 15 [13.6–16.9] 18 [14.3–20.2]
Obese 9.6 [7.6–10.5] 8.15 [7.7–9.9] 10 [8–11] 9 [8–12] 10 [8.8–12.3] 11 [8.8–12.3] 10.5 [8.1–12.5]* 11.5 [8–13.3]*
Pes. insp (cm H2O) Non-obese$ 8.6 [6.9–10.2] 9.4 [7.6–10.9] 10 [7.6–11.6] 10.9 [8.8–11.6] 10.9 [8.8–12.8] 10.9 [9.3–12.8] 12 [9.5–12.9] 13 [10.9–14.3]
Obese$ 11.5 [9.1–14.5] 11.5 [9.5–15.3] 11.5 [9.5–16.3] 12 [9.5–16] 12.5 [10.5–16.3] 12.5 [10.6–16.5] 13 [11.4–17.3] 13.5 [12.8–17.5]
Pes. exp (cm H2O) Non-obese$ 7.1 [5.2–8.9] 7.5 [5.9–8.9] 7.8 [6.4–10.2] 8.3 [7.1–10.2] 9.1 [7.1–10.9] 9.5 [7.6–11] 10 [8.1–11.6] 11 [8.8–12.2]
Obese$ 9.9 [8.1–12.3] 10.5 [8.2–13] 10.5 [8.5–13.3] 11 [8.7–14] 11 [8.7–15] 11.5 [9.3–14.5] 11.5 [10.3–15.3] 12.5 [11–16]
PL. insp (cm H2O) Non-obese$ 6.8 [6.4–9.3] 8.2 [6.8–10.3] 9.6 [9.5–11.5] 10.9 [10.9–15] 14.9 [12.9–16.4] 20.4 [17.7–20.7] 24.5 [21.1–24.8] 28 [23.1–28.3]
Obese$ 5.5 [2.8–9] 7 [4.3–9.3] 9 [6.5–11.3] 10 [8.5–12.4] 12.6 [9.5–15] 14.8 [12.3–17] 16.2 [13–18.5]* 17.15 [14.8–19]*
PL, ER (cm H2O) Non-obese$ 10.8 [9.4–15.4] 11.9 [10.6–14.3] 15.4 [14.1–17.3] 17.6 [15.9–19.2] 20.5 [18.5–22.1] 25.7 [23.3–27.7] 31.1 [26–32.4] 33.8 [28.6–37.4]
Obese$ 13 [11.8–14.2] 13.8 [12.8–15.7] 17.2 [14.5–19.1] 18.4 [15.7–20.9] 21.7 [18.3–22.8] 24 [20.3–25.9] 25.3 [21.3–27.4] 27.8 [23.8–29.4]
PL. exp (cm H2O) Non-obese$ 0 [− 1.9 to 1.7] 1.4 [− 0.2 to 3.4] 3.2 [1.4–4.6] 4.1 [2.7–5.4] 5.9 [4.2–7.4] 7.3 [5.5–8.6] 9 [7.5–10.4] 10 [8.9–11.5]
Obese$ − 3.1 [− 5.4 to − 1.3] − 1.9 [− 4.2 to 0.5] 0 [− 3 to 1.8] 1 [− 1 to 3.8] 3.9 [− 0.3 to 5.8] 5 [1.8–7] 7 [3.5–7.6] 7 [4.8–9]*
PL Non-obese$ 5.5 [4.8–8.9] 5.4 [4.6–6.8] 6 [5.4–7.8] 6.9 [6.2–8.8] 9.1 [6.8–9.4] 12 [9.5–13] 13.7 [10.9–15.5] 16 [11.5–18.5]
Obese 7.6 [5.9–8.7] 6.7 [5.9–8.2] 8 [6.5–10] 7.5 [5.8–10.3] 9 [6.8–10.4] 9.4 [7.5–11.3] 9 [6.6–11.3] 10.5 [6.8–11.3]*
ELRS (cm H2O.L−1) Non-obese$ 20 [17.4–23.8] 18.3 [15.6–23.2] 18.3 [17–23.3] 24.1 [18.4–26.4] 24 [22.7–28.9] 33.3 [27.4–38.3] 39.3 [32–43] 47.1 [33.5–54.1]
Obese 27.3 [18.5–38.1] 26.3 [18–38.3] 25.1 [17.6–53.7] 26.7 [18–49.1] 30.1 [18.6–48.5] 31.4 [19.9–53.4] 29.2 [23.3–45.9] 31.4 [22.9–45.9]
ELCW (cm H2O.L−1) Non-obese 4.6 [3.8–5.7] 5.8 [4.7–6.2] 3.2 [3.1–5.2] 5.2 [3.5–6.3] 5.2 [3.6–6.3] 5.2 [3.6–6.3] 3.8 [3.2–6.2] 6.2 [4.7–6.3]
Obese 4.2 [4–5.7] 4.2 [3.5–7.1] 4.8 [2.7–7.8] 4.9 [2.7–8.2] 4.8 [4.2–8.4] 5.7 [2.7–8.2] 4.2 [3.5–6.7] 3.9 [2.7–6.7]
ELL(cm H2O.L−1) Non-obese$ 15.9 [11.6–20.7] 13.1 [10.9–17.8] 15.7 [13.7–19.6] 20.3 [13.8–22.2] 20.9 [17.7–24.6] 30.2 [22.5–33.8] 36.4 [25.7–39.8] 41.9 [27.2–48.7]
Obese 23.3 [14.6–32.4] 22.3 [15.3–30.7] 22.6 [14.9–42] 23.2 [12.8–39.8] 26.4 [14.2–42.5] 28.9 [16.1–43.6] 25.2 [19.9–36.6] 28.9 [20.3–38.8]
EL ratio Non-obese$ 0.79 [0.67–0.87] 0.75 [0.66–0.80] 0.8 [0.79–0.84] 0.81 [0.74–0.84] 0.83 [0.74–0.85] 0.86 [0.8–0.9] 0.9 [0.79–0.92] 0.89 [0.81–0.9]
Obese$ 0.8 [0.77–0.85] 0.80 [0.78– 0.85] 0.84 [0.74–0.89] 0.82 [0.72–0.89] 0.85 [0.77–0.86] 0.87 [0.79–0.9] 0.85 [0.8–0.9] 0.88 [0.79–0.91]
  1. Variables are reported as medians [interquartile range]
  2. BMI body mass index, PEEP positive end-expiratory pressure, Pplat plateau pressure, ∆PRS respiratory system driving pressure, Pes. insp esophageal inspiratory pressure, Pes. exp esophageal expiratory pressure, PL. insp inspiratory transpulmonary pressure, PL, ER transpulmonary pressure calculated with the elastance ratio, EL ratio, PL. exp expiratory transpulmonary pressure, ∆PL driving transpulmonary pressure, ELRS respiratory system elastance, ELCW chest wall elastance, ELL lung elastance, EL ratio, ratio of lung elastance to elastance of the respiratory system.
  3. *p < 0.05 between obese and non-obese group for a given PEEP by Mann–Whitney U test; $p < 0.05 for PEEP effect by Friedman test. Computed for each group