Comparison of the mode of ventilation, ventilator settings, use of sedatives and weaning by body mass index group
| Underweight (BMI < 18.5 kg/m2) | Normal (BMI 18.5–24.9 kg/m2) | Overweight (BMI 25–29.9 kg/m2) | Obese (BMI 30–39.9 kg/m2) | Severely obese (BMI >40 kg/m2) | p-Value | |
| N (% (95% CI)) | 184 (3.7% (3.2 to 4.3)) | 1995 (40.1% (38.8 to 41.5)) | 1781 (35.8% (34.5 to 37.2)) | 792 (15.9%; (14.9 to 16.9)) | 216 (4.3%; (3.8 to 4.9)) | |
| Non-invasive positive pressure ventilation, N (% (95% CI)) | 25 (13.6% (8.9 to 19.4)) | 183 (9.1% (7.9 to 10.5)) | 155 (8.7% (7.4 to 10.1)) | 84 (10.6% (8.5 to 12.9)) | 32 (14.8% (10.3 to 20.2)) | 0.010 |
| Successful, N (% (95% CI)) | 15 (60% (38.7 to 78.8)) | 118 (64.5% (57.1 to 71.4)) | 83 (53.5% (45.3 to 61.5)) | 51 (60.7% (49.4 to 71.2)) | 19 (59.4% (40.6 to 76.3)) | 0.377 |
| Ventilator settings | ||||||
| Day 1 of mechanical ventilation | ||||||
| Tidal volume | ||||||
| ml/kg actual body weight, mean (SD) | 11 (2.5) | 9 (1.8) | 7 (1.5) | 6.5 (1.4) | 5 (1.5) | <0.001 |
| ml/kg predicted body weight, mean (SD) | 8.2 (1.8) | 8.9 (1.9) | 9.1 (2.1) | 10.1(2.6) | 11.1 (3.9) | <0.001 |
| Positive end-expiratory pressure, cm of water, mean (SD) | 5 (3) | 5 (3) | 5.5 (3) | 5.5 (3) | 6 (4) | <0.001 |
| Peak pressure, cm of water, mean (SD) | 25 (8) | 26 (8) | 27 (8) | 28 (9) | 31 (10) | <0.001 |
| Plateau pressure, cm of water, mean (SD) | 21 (6) | 21 (6) | 21 (6) | 22 (6) | 25 (7) | <0.001 |
| Day 3 of mechanical ventilation | ||||||
| Tidal volume | ||||||
| ml/kg actual body weight, mean (SD) | 10.5 (2.6) | 8 (1.8) | 7 (1.5) | 6 (1.4) | 5 (1.2) | <0.001 |
| ml/kg predicted body weight, mean (SD) | 8.1 (1.8) | 8.7 (1.9) | 9 (2.1) | 9.8 (2.6) | 10.4 (3.8) | <0.001 |
| Positive end-expiratory pressure, cm of water, mean (SD) | 6 (4) | 6.5 (4) | 6.5 (4) | 7 (4.6) | 7 (5.4) | 0.004 |
| Peak pressure, cm of water, mean (SD) | 28 (9) | 26 (8) | 27 (7) | 28 (8) | 29 (9) | <0.001 |
| Plateau pressure, cm of water, mean (SD) | 23 (7) | 21 (6) | 22 (6) | 23 (6) | 25 (7) | <0.001 |
| Day 5 of mechanical ventilation | ||||||
| Tidal volume | ||||||
| ml/kg actual body weight, mean (SD) | 10.5 (2.6) | 8.5 (1.9) | 7 (1.5) | 6 (1.5) | 5 (1.3) | <0.001 |
| ml/kg predicted body weight, mean (SD) | 8.1 (1.8) | 8.8 (1.9) | 9 (1.9) | 10 (2.9) | 11 (3.7) | <0.001 |
| Positive end-expiratory pressure, cm of water, mean (SD) | 6 (4) | 6 (4) | 6 (4) | 6.5 (4) | 7 (5.5) | <0.001 |
| Peak pressure, cm of water, mean (SD) | 27 (8) | 26 (8) | 27 (8) | 29 (8) | 30 (9) | <0.001 |
| Plateau pressure, cm of water, mean (SD) | 22 (7) | 22 (6) | 22 (6) | 23 (7) | 26 (6) | <0.001 |
| Pharmacology | ||||||
| Use of neuromuscular blockers, N (% (95% CI)) | 22 (11.9% (7.6 to 17.5)) | 197 (9.8% (8.6 to 11.2)) | 184 (10.3% (8.9 to 11.8)) | 97 (12.2% (10.0 to 14.7)) | 24 (11.1% (7.2 to 16.8)) | 0.415 |
| Use of sedatives, N (% (95% CI)) | 127 (69.0% (61.8 to 75.6)) | 1382 (69.3% (67.2 to 71.3)) | 1263 (70.9% (68.7 to 73.0)) | 562 (70.9% (67.6 to 74.1)) | 152 (70.3% (63.8 to 76.4)) | 0.810 |
| Weaning | ||||||
| Simple weaning, N (% (95% CI)) | 55 (57.3% (46.8 to 67.3)) | 599 (56.0% (52.9 to 59.0)) | 548 (55.3% (52.1 to 58.4)) | 245 (55.9% (51.1 to 60.6)) | 55 (45.8% (36.7 to 55.1)) | 0.307 |
| Difficult weaning, N (% (95% CI)) | 36 (37.5% (27.8 to 47.9)) | 407 (38.1% (35.1 to 41.1)) | 397 (40.1% (36.9 to 43.2)) | 164 (37.4% (32.9 to 42.2)) | 54 (45.0% (35.9 to 54.3)) | 0.523 |
| Prolonged weaning, N (% (95% CI)) | 5 (5.2% (1.7 to 11.7)) | 63 (5.8% (4.5 to 7.4)) | 46 (4.6% (3.4 to 6.1)) | 29 (6.6% (4.5 to 9.4)) | 11 (9.2% (4.7 to 15.8)) | 0.236 |
| Reintubation, N/Extubated patients (% (95% CI)) | 11/96 (11.4% (5.9 to 19.6)) | 121/1069 (11.3% (9.5 to 13.4)) | 91/991 (9.2% (7.4 to 11.1)) | 45/438 (10.3% (7.6 to 13.5)) | 11/120 (9.2% (4.7 to 15.8)) | 0.583 |
| Accidental extubation, N/Patient at risk* (% (95% CI)) | 4/160 (2.5% (0.7 to 6.3)) | 58/1824 (3.2% (2.4 to 4.1)) | 45/1661 (2.7% (1.9 to 3.6)) | 23/724 (3.2% (2.0 to 4.7)) | 5/190 (2.6% (0.78 to 6.0)) | 0.913 |
| Reintubation, N (% (95% CI)) | 1 (25% (0.6 to 80.6)) | 15 (25.9% (15.2 to 39.0)) | 8 (17.7% (8.0 to 32.0)) | 14 (60.9% (38.5 to 80.3)) | 3 (60.0% (14.7 to 94.7)) | 0.003 |
| Tracheostomy, N/Patients at risk* (% (95% CI)) | 26/160 (16.2% (10.9 to 22.9)) | 257/1824 (14.1% (12.5 to 15.8)) | 234/1661 (14.1%(12.4 to 15.8)) | 119/724 (16.4% (13.8 to 19.3)) | 28/190 (14.7% (10.0 to 20.6)) | 0.550 |
| Timing, days, median (IQR) | 10 (5, 14) | 9 (6, 14) | 10 (6, 16) | 8 (6, 13) | 11 (4, 16) | 0.339 |
↵* Excluding patients with tracheostomy at admission to intensive care unit and patients who were ventilated successfully with non-invasive positive pressure ventilation.