Table 2.
Ventilation characteristics in the first day of mechanical ventilation
| All patients (n = 1,315) | LIPS < 4 (n = 389) | LIPS ≥ 4 (n = 837) | Acute respiratory distress syndrome (n = 89) | P-value LIPS < 4 vs. LIPS ≥ 4 | P-value* | |
|---|---|---|---|---|---|---|
| Absolute VT (mL) | 450 [400, 500] | 450 [400, 500] | 450 [400, 500] | 400 [360, 470] | 0.642 | 0.0001 |
| Absolute VT (mL) mode | 500 | 500 | 500 | 400 | – | – |
| VT PBW (mL/kg PBW) | 7.9 [6.8, 9.1] | 7.9 [6.8, 8.9] | 8.0 [6.8, 9.2] | 7.0 [5.8, 8.4] | 0.621 | 0.0001 |
| Controlled mode | 7.9 [6.8, 9.1] | 7.9 [6.8, 8.9] | 8.0 [6.8, 9.2] | 7.0 [5.8, 8.5] | 0.765 | 0.0002 |
| Spontaneous mode | 8.1 [7.0, 9.2] | 7.8 [6.5, 9.5] | 8.3 [7.4, 9.3] | 7.7 [7.1, 8.0] | 0.372 | 0.4113 |
| ≤ 7.0 | 396 (30.5) | 111 (28.8) | 240 (29.2) | 45 (50.6) | 0.0715 | 0.0002 |
| 7.1–8.9 | 561 (43.2) | 181 (46.9) | 350 (42.5) | 30 (33.7) | – | – |
| 9.0–10.0 | 143 (11.0) | 31 (8.0) | 107 (13.0) | 5 (5.6) | – | – |
| > 10.0 | 198 (15.3) | 63 (16.3) | 126 (15.3) | 9 (10.1) | – | – |
| VT actual body weight (mL/kg) | 7.0 [6.0, 8.2] | 7.1 [6.2, 8.3] | 7.0 [6.0, 8.1] | 6.4 [5.6, 7.3] | 0.016 | 0.0001 |
| Positive end-expiratory pressure (cmH2O) | 5.0 [5.0, 8.0] | 5.0 [5.0, 7.0] | 5.0 [5.0, 7.5] | 10.0 [5.0, 12.0] | 0.123 | < 0.0001 |
| ≤ 5 | 804 (61.1) | 261 (67.1) | 520 (62.1) | 23 (25.8) | 0.232 | < 0.0001 |
| 6–8 | 335 (25.5) | 94 (24.2) | 220 (26.3) | 21 (23.6) | – | – |
| 8–10 | 112 (8.5) | 27 (6.9) | 69 (8.2) | 16 (18.0) | – | – |
| > 10 | 64 (4.9) | 7 (1.8) | 28 (3.3) | 29 (32.6) | – | – |
| Ventilation mode, n (%) | 0.0077 | 0.0001 | ||||
| Volume controlled | 483 (36.7) | 171 (44.0) | 288 (34.4) | 24 (27.0) | – | – |
| Pressure controlled | 327 (24.9) | 80 (20.6) | 218 (26.0) | 29 (32.6) | – | – |
| Pressure support ventilation | 40 (3.0) | 16 (4.1) | 22 (2.6) | 2 (2.2) | – | – |
| Synchronized intermittent mandatory ventilation | 389 (29.6) | 108 (27.8) | 255 (30.5) | 26 (29.2) | – | – |
| Airway pressure release ventilation | 3 (0.2) | 0 (0.0) | 1 (0.1) | 2 (2.2) | – | – |
| Pressure regulated volume-controlled ventilation | 68 (5.2) | 14 (3.6) | 48 (5.7) | 6 (6.7) | – | – |
| Other | 5 (0.4) | 0 (0.0) | 5 (0.6) | 0 (0.0) | – | – |
| Ppeak (cmH2O) | 22 [18, 28] | 21.0 [18, 25] | 22 [18, 28] | 28 [23, 36] | 0.0009 | < 0.0001 |
| Pplat (cmH2O)† | 18 [15, 21] | 16 [14, 18] | 18 [16, 21] | 28 [22, 30] | < 0.0001 | < 0.0001 |
| Driving pressure (cmH2O) | 14 [11, 18] | 13 [10, 17] | 15 [11, 18] | 16 [14, 20] | 0.0705 | 0.0037 |
| Set RR (bpm) | 14 [12, 16] | 14 [12, 16] | 14 [14, 16] | 17 [14, 22] | 0.0011 | < 0.0001 |
| Measured RR (bpm) | 18 [15, 22] | 16 [14, 20] | 18 [15, 22] | 20 [16, 25] | < 0.0001 | < 0.0001 |
| FiO2 (%) | 50 [40, 60] | 40 [40, 50] | 50 [40, 60] | 80 [60, 100] | < 0.0001 | < 0.0001 |
| Oxygen partial pressure/FiO2 (mmHg) | 258 [157, 378] | 311 [229, 419] | 253 [151, 375] | 112 [76, 211] | < 0.0001 | < 0.0001 |
| Pulse oxymetric saturation of haemoglobin/FiO2 | 200 [155, 250] | 245 [194, 250] | 200 [150, 245] | 119 [95, 167] | < 0.0001 | < 0.0001 |
| Arterial pH level | 7.3 [7.3, 7.4] | 7.4 [7.3, 7.4] | 7.3 [7.2, 7.4] | 7.3 [7.2, 7.4] | < 0.0001 | < 0.0001 |
| Carbon dioxide partial pressure (mmHg) | 36 [31, 43] | 35 [29, 40] | 37 [31, 44] | 41 [34, 52] | 0.0020 | < 0.0001 |
| Use of neuromuscular blockers (%) | 225/1,306 (17.2) | 74/385 (19.2) | 117/382 (14.1) | 34 (38.2) | 0.0267 | < 0.0001 |
| Use of prone positioning (%) | 6 (0.5) | 0 (0.0) | 0 (0.0) | 6 (6.7) | – | < 0.0001 |
| Use of recruitment maneuvers (%) | 24 (1.8) | 0 (0.0) | 8 (1.0) | 16 (18.0) | 0.120 | < 0.0001 |
| Tracheostomy | 95 (7.2) | 34 (8.7) | 49 (5.9) | 12 (13.5) | 0.080 | 0.0118 |
Data are number of patients/total number of patients (%) or median [IQR]. FiO2 = fraction of inspired oxygen; PBW = predicted body weight; Ppeak = peak inspiratory airway pressure; Pplat = plateau airway pressure; RR = respiratory rate; VT = tidal volume.
*
P-value represents comparisons across the three study groups for each variable.
†
Plateau pressure values are restricted to patients in whom this value was reported and in whom either an assist control mode was used or in whom a mode permitting spontaneous ventilation was used.