Table 1 Baseline characteristics of the intention-to-treat population according to obese status
|  | Obese patients with obesity (n = 91) | Non-obese patients without obesity (n = 222) | P value |
|---|---|---|---|
Characteristics of the patients | |||
 Age, year, mean ± SD | 66 ± 14 | 63 ± 14 | 0.13 |
 Male sex, n (%) | 64 (70) | 148 (67) | 0.53 |
 Body mass index,a kg·m−2, mean ± SD | 35 ± 5 | 24 ± 3 | < 0.0001 |
 SAPS IIb, point, mean ± SD | 49 ± 19 | 52 ± 19 | 0.20 |
Reason for ICU admission | 0.14 | ||
 Respiratory primary failure, n (%) | |||
  Respiratory infection | 28 (31) | 82 (37) |  |
  COPD exacerbation | 8 (9) | 8 (4) |  |
  Extra-pulmonary ARDS | 3 (3) | 3 (1) |  |
  Pulmonary atelectasis | 2 (2) | 2 (1) |  |
  Other | 6 (7) | 27 (12) |  |
 Non-respiratory primary failure, n (%) | |||
  Shock | 19 (21) | 47 (21) |  |
  Cardiogenic pulmonary edema | 4 (4) | 13 (6) |  |
  Neurologic | 7 (8) | 6 (3) |  |
  Other | 12 (13) | 24 (11) |  |
 Post-operative, n (%) | 2 (2) | 10 (4) |  |
Clinical characteristics | |||
 Oxygen device the last hour before inclusion, n (%) | 0.48 | ||
  Standard oxygen | 38 (42) | 98 (44) |  |
  High-flow nasal cannula oxygen | 28 (31) | 77 (35) |  |
  Non-invasive ventilation | 25 (27) | 47 (21) |  |
 Vasopressor support at inclusion, n (%) | 19 (21) | 43 (19) | 0.76 |
 Bilateral pulmonary infiltrates, n (%) | 54 (71) | 140 (73) | 0.71 |
 Respiratory variables | |||
  Respiratory rate, breaths·min, mean ± SD | 30 ± 7 | 31 ± 8 | 0.50 |
  PaO2/FIO2 ratio, mm Hg, mean ± SD | 152 ± 65 | 142 ± 68 | 0.26 |
 MACOCHA score,c n (%) | 0.003 | ||
  < 3 | 68 (75) | 195 (88) |  |
  ≥ 3 | 23 (25) | 26 (12) |  |
 Cormack III or IV,d n (%) | 15 (16) | 14 (6) | 0.005 |
Outcomes | |||
 SpO2 < 80% during intubation procedure, n (%) | 31 (34) | 49 (22) | 0.03 |
 Lowest SpO2 during intubation procedure, %, median (IQR) | 86 (77- 93) | 91 (81–96) | 0.002 |
 SpO2 at the beginning of preoxygenation, %, median (IQR) | 96 (92–98) | 95 (92–99) | 0.82 |
 SpO2 at the end of preoxygenation, %, median (IQR) | 99 (97–100) | 100 (98–100) | 0.04 |
 Intubation Difficulty Scale,e n (%) | 0.29 | ||
  ≤ 5 | 75 (85) | 196 (89) |  |
  > 5 | 13 (15) | 23 (11) |  |
Immediate complications, n (%) | |||
 Hypotension | 41 (45) | 115 (52) | 0.28 |
 Sustained cardiac arrhythmia | 0 | 6 (3) | 0.19 |
 Bradycardia or cardiac arrest during and after intubation | 5 (5) | 6 (3) | 0.22 |
 Esophageal intubation | 6 (7) | 8 (4) | 0.24 |
 Regurgitation | 0 | 2 (1) | 0.99 |
 Gastric distension | 3 (3) | 14 (6) | 0.26 |
 Dental injury | 0 (0) | 1 (0) | 0.99 |
 Agitation | 0 (0) | 1 (0) | 0.99 |
 New infiltrate on chest-ray after intubation | 14 (18) | 47 (25) | 0.20 |
Late outcomes | |||
 Ventilator-associated pneumonia during ICU stay, n (%) | 22 (24) | 44 (20) | 0.39 |
 Death at day 28 | 36 (40) | 75 (34) | 0.33 |
 SOFA score at Day 1, points, mean ± SD | 9 ± 4 | 8 ± 4 | 0.19 |
 SOFA score at Day 7, points, mean ± SD | 6 ± 4 | 5 ± 3 | 0.48 |
 Duration of mechanical ventilation, days, median (IQR) | 9 (5–17) | 7 (4–16) | 0.46 |
 Ventilator-free day at day 28, median (IQR) | 5 (0–19) | 8 (0–22) | 0.26 |
 ICU length of stay, days, median (IQR) | 11 (6–20) | 10 (6–17) | 0.27 |