Table 1.
Baseline characteristics, vital signs, laboratory test results, and organ support on the first day of ventilation according to BMI category.
| Normal (n = 244) |
Overweight (n = 531) |
Obese (n = 324) |
p Value | |
|---|---|---|---|---|
| Age, years | 67.0 (60.0–73.0) | 66.0 (59.0–73.0) | 61.0 (53.0–70.0) | <0.001 |
| Male gender—no (%) | 186 (76.2) | 407 (76.6) | 209 (64.5) | <0.001 |
| Body mass index, kg/m2 | 23.9 (22.9–24.6) | 27.3 (26.2–28.5) | 32.9 (31.2–35.9) | <0.001 |
| Transferred under invasive ventilation | 51 (20.9) | 82 (15.4) | 59 (18.2) | 0.160 |
| Days between intubation and admission | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) | 0.583 |
| Use of non-invasive ventilation—no (%) | 15 (6.8) | 45 (9.4) | 24 (8.1) | 0.517 |
| Duration of non-invasive ventilation, hours | 5.5 (2.0–48.0) | 8.0 (2.0–15.1) | 7.5 (2.0–14.8) | 0.803 |
| Chest CT scan performed—no (%) | 83/232 (35.8) | 169/509 (33.2) | 103/314 (32.8) | 0.738 |
| Lung parenchyma affected—no (%) | 0.839 | |||
| 0% | 3/84 (3.6) | 6/172 (3.5) | 5/103 (4.9) | |
| 25% | 32/84 (38.1) | 51/172 (29.7) | 33/103 (32.0) | |
| 50% | 26/84 (31.0) | 52/172 (30.2) | 28/103 (27.2) | |
| 75% | 20/84 (23.8) | 53/172 (30.8) | 29/103 (28.2) | |
| 100% | 3/84 (3.6) | 10/172 (5.8) | 8/103 (7.8) | |
| Chest X-ray performed—no (%) | 127/149 (85.2) | 289/334 (86.5) | 175/204 (85.8) | 0.907 |
| Quadrants affected—no (%) | 0.068 | |||
| 1 | 14/126 (11.1) | 21/291 (7.2) | 7/173 (4.0) | |
| 2 | 24/126 (19.0) | 67/291 (23.0) | 48/173 (27.7) | |
| 3 | 37/126 (29.4) | 72/291 (24.7) | 55/173 (31.8) | |
| 4 | 51/126 (40.5) | 131/291 (45.0) | 63/173 (36.4) | |
| Severity of ARDS—no (%) | 0.028 | |||
| Mild | 24/239 (10.0) | 51/523 (9.7) | 29/318 (9.1) | |
| Moderate | 157/239 (65.7) | 326/523 (62.3) | 171/318 (53.8) | |
| Severe | 58/239 (24.3) | 146/523 (27.9) | 118/318 (37.1) | |
| Co-existing disorders—no (%) | ||||
| Hypertension | 74 (30.3) | 186 (35.0) | 114 (35.2) | 0.383 |
| Heart failure | 9 (3.7) | 31 (5.8) | 8 (2.5) | 0.058 |
| Diabetes | 41 (16.8) | 115 (21.7) | 90 (27.8) | 0.007 |
| Chronic kidney disease | 8 (3.3) | 31 (5.8) | 8 (2.5) | 0.045 |
| Baseline creatinine, µmol/L * | 77.0 (61.0–98.0) | 78.0 (64.0–97.0) | 76.0 (62.8–97.0) | 0.767 |
| Liver cirrhosis | 0 (0.0) | 2 (0.4) | 1 (0.3) | 0.999 |
| Chronic obstructive pulmonary disease | 20 (8.2) | 41 (7.7) | 24 (7.4) | 0.934 |
| Active hematological neoplasia | 5 (2.0) | 10 (1.9) | 1 (0.3) | 0.091 |
| Active solid neoplasia | 6 (2.5) | 14 (2.6) | 7 (2.2) | 0.967 |
| Neuromuscular disease | 2 (0.8) | 3 (0.6) | 3 (0.9) | 0.728 |
| Immunosuppression | 9 (3.7) | 8 (1.5) | 7 (2.2) | 0.165 |
| Previous medication—no (%) | ||||
| Systemic steroids | 10 (4.1) | 17 (3.2) | 11 (3.4) | 0.786 |
| Inhalation steroids | 21 (8.6) | 58 (10.9) | 45 (13.9) | 0.137 |
| Angiotensin converting enzyme inhibitor | 33 (13.5) | 93 (17.5) | 60 (18.5) | 0.250 |
| Angiotensin II receptor blocker | 24 (9.8) | 57 (10.7) | 44 (13.6) | 0.318 |
| Beta-blockers | 40 (16.4) | 98 (18.5) | 71 (21.9) | 0.235 |
| Insulin | 14 (5.7) | 38 (7.2) | 26 (8.0) | 0.590 |
| Metformin | 29 (11.9) | 77 (14.5) | 65 (20.1) | 0.021 |
| Statins | 70 (28.7) | 155 (29.2) | 100 (30.9) | 0.826 |
| Calcium channel blockers | 47 (19.3) | 79 (14.9) | 67 (20.7) | 0.067 |
| Vital signs at the day of start of ventilation | ||||
| Heart rate, bpm ** | 84.0 (71.5–97.0) | 84.0 (73.0–97.1) | 86.0 (76.9–98.0) | 0.130 |
| Mean arterial pressure, mmHg ** | 78.7 (73.0–86.0) | 80.0 (73.5–87.5) | 82.0 (75.7–89.5) | 0.002 |
| Laboratory tests at the day of start of ventilation | ||||
| pH ** | 7.36 (7.30–7.41) | 7.37 (7.32–7.41) | 7.36 (7.31–7.41) | 0.700 |
| Worst PaO2/FiO2, mmHg *** | 130.0 (101.0–166.9) | 125.0 (98.5–162.4) | 114.6 (87.6–146.0) | 0.001 |
| PaCO2, mmHg ** | 44.5 (39.5–51.3) | 44.3 (38.8–49.6) | 44.6 (39.8–51.0) | 0.356 |
| Lactate mmol/L ** | 1.2 (0.9–1.5) | 1.2 (1.0–1.4) | 1.1 (0.9–1.4) | 0.132 |
| Organ support at the day of start of ventilation—no (%) | ||||
| Continuous sedation | 231/243 (95.1) | 506/530 (95.5) | 316 (97.5) | 0.213 |
| Inotropic or vasopressor | 192/243 (79.0) | 412/530 (77.7) | 241 (74.4) | 0.377 |
| Vasopressor | 192/243 (79.0) | 412/530 (77.7) | 240 (74.1) | 0.328 |
| Inotropic | 18/243 (7.4) | 17/530 (3.2) | 10 (3.1) | 0.022 |
| Fluid balance, mL | 696.7 (29.0–1441.0) | 515.8 (7.3–1239.3) | 449.0 (-15.0–1299.9) | 0.171 |
| Urine output, mL | 692.5 (333.8–1116.2) | 647.5 (350.0–1145.0) | 705.0 (395.0–1115.0) | 0.500 |
| Ventilation support at the day of start of ventilation | ||||
| Assisted ventilation—no (%) | 73/243 (30.0) | 161/527 (30.6) | 84 (25.9) | 0.328 |
| Tidal volume, mL/kg PBW ** | 6.4 (5.9–6.9) | 6.4 (5.9–7.0) | 6.6 (5.9–7.5) | < 0.001 |
| PEEP, cmH2O ** | 12.0 (10.0–14.0) | 12.7 (11.0–14.5) | 14.0 (12.0–15.0) | < 0.001 |
| Peak pressure, cmH2O ** | 25.2 (22.8–28.9) | 26.6 (23.5–29.3) | 28.0 (25.3–31.0) | < 0.001 |
| Driving pressure, cmH2O ** | 13.0 (11.2–15.3) | 13.7 (12.0–16.0) | 14.5 (12.5–17.0) | < 0.001 |
| Mechanical power, J/min ** | 18.1 (14.7–21.6) | 18.2 (15.3–21.9) | 19.4 (15.8–23.5) | 0.014 |
| Compliance, mL/cmH2O ** | 36.2 (28.7–45.1) | 33.4 (26.8–41.1) | 31.9 (26.0–38.1) | < 0.001 |
| Total respiratory rate, mpm ** | 21.7 (19.3–24.0) | 21.7 (19.8–24.0) | 22.0 (19.2–24.0) | 0.921 |
| Minute ventilation, L/min | 9.8 (8.5–11.4) | 9.6 (8.4–11.2) | 9.7 (8.3–11.2) | 0.556 |
| Minute ventilation corrected, mL/kg/min PBW | 137.2 (122.3–157.5) | 138.3 (122.4–157.3) | 141.3 (125.7–164.1) | 0.053 |
| FiO2 ** | 0.54 (0.45–0.65) | 0.57 (0.47–0.66) | 0.60 (0.52–0.71) | <0.001 |
| etCO2, mmHg ** | 35.7 (32.0–40.7) | 36.5 (32.4–41.6) | 38.4 (34.6–43.8) | <0.001 |
| Rescue therapy at the day of start of ventilation—no (%) | ||||
| Prone positioning | 61/241 (25.3) | 161/522 (30.8) | 104/317 (32.8) | 0.142 |
| Duration, hours | 9.0 (6.0–14.0) | 8.0 (4.0–13.5) | 8.0 (3.1–13.0) | 0.138 |
| Recruitment maneuver | 3/197 (1.5) | 12/434 (2.8) | 5/268 (1.9) | 0.641 |
| ECMO | 1/241 (0.4) | 0/523 (0.0) | 3/318 (0.9) | 0.066 |
| Use of NMBA | 54/243 (22.2) | 154/529 (29.1) | 89 (27.5) | 0.128 |
| Duration, hours | 0.0 (0.0–0.0) | 0.0 (0.0–8.0) | 0.0 (0.0–8.0) | 0.182 |
Data are median (first quartile–third quartile) or No (%). Percentages may not total 100 because of rounding. CT: computed tomography; PEEP: positive end expiratory pressure; ECMO: extracorporeal membrane oxygenation; FiO2: inspired fraction of oxygen; PEEP: positive end-expiratory pressure; NMBA: neuromuscular blocking agent. * Most recent measurement in 24 h before intubation or at ICU admission under invasive ventilation. ** Aggregate as the mean of all values available at the first day of ventilation. *** Worst value of four available.