Table 2.
Variations between early and persistent ARDS
| Study variables | Early ARDS, n = 33 | P | Persistent ARDS, n = 24 | P | ||
|---|---|---|---|---|---|---|
| Supine | Prone | Supine | Prone | |||
| Ventilator setting | ||||||
| FIO2 | 0.4 [0.4, 0.6] | 0.4 [0.4, 0.5] | 0.01 | 0.5 [0.4, 0.65] | 0.5 [0.4, 0.55] | 0.05 |
| Respiratory rate, /min | 20 [17, 22] | 20 [18, 22] | 0.76 | 27 [20, 30] | 26 [20, 30] | 0.35 |
| Positive end-expiratory pressure, cmH2O | 8 [8, 10] | 8 [8, 10] | 0.26 | 8 [6, 10] | 8 [6, 10] | 0.98 |
| Tidal volume, mL/kg predicted body weight | 7 [6, 8.1] | 7 [6, 8.1] | 0.59 | 6.1 [5.1, 7.0] | 6.1 [5.1, 7.0] | 0.96 |
| Respiratory mechanics | ||||||
| Plateau pressure, cmH2O | 20.5 [18.6, 21.7] | 19.6 [18.8, 21.0] | 0.84 | 19.3 [16.7, 23.6] | 20.6 [17.8, 23.4] | 0.26 |
| Driving pressure, cmH2O | 11.0 [10.3, 12.6] | 11.9 [9.4, 13.5] | 0.62 | 12.3 [9.6, 13.6] | 12.2 [11.4, 13.4] | 0.24 |
| Respiratory system compliance, ml/cmH2O | 36.0 [31.2, 41.8] | 35.9 [29.3, 44.0] | 0.30 | 30.8 [26.8, 38.7] | 29. 8 [23.6, 37.0] | 0.04 |
| Arterial blood gases | ||||||
| pH | 7.40 [7.38, 7.45] | 7.41 [7.38, 7.45] | 0.54 | 7.39 [7.37, 7.45] | 7.39 [7.35, 7.42] | 0.98 |
| PaCO2, mmHg | 40.1 [37.8, 42.1] | 38.3 [35.6, 40.5] | 0.02 | 42.6 [39.7, 44.6] | 42.3 [38.2, 52.6] | 0.94 |
| PaO2, mmHg | 72.4 [66.8, 78.4] | 82.6 [73.1, 97.8] | < 0.001 | 84.7 [73.9, 101.8] | 84.8 [77.3, 102.9] | 0.55 |
| PaO2/FIO2 | 157 [121, 191] | 190 [164, 245] | < 0.001 | 168 [136, 232] | 177 [155, 232] | 0.10 |
| Ventilatory ratio | 1.42 [1.24, 1.87] | 1.30 [1.21, 1.60] | 0.01 | 1.84 [1.43, 2.11] | 1.72 [1.5, 2.06] | 0.48 |
| Electrical impedance tomography | ||||||
| VT distribution dorsal, % | 36.5 [29.5, 42.6] | 60.4 [47.9, 73.8] | < 0.001 | 36.9 [29.6, 45.7] | 57.2 [44.9, 66.0] | 0.002 |
| Perfusion distribution dorsal, % | 47.9 [42.5, 52.2] | 59.1 [54.0, 65.7] | 0.001 | 45.3 [41.1, 50.5] | 56.6 [49.5, 64.2] | 0.001 |
| COV index | 44.8 [41.6, 46.8] | 54.6 [49.7, 58.6] | < 0.001 | 44.3 [40.9, 47.5] | 54.6 [49.1, 57.1] | < 0.001 |
| RVD index | 6 [4, 8] | 4 [4, 5] | < 0.001 | 6 [4, 7] | 5 [4, 6.5] | 0.38 |
| Shunt, % | 11.4 [7.1, 18.5] | 12.7 [6.9, 17.8] | 0.21 | 12.3 [7.4, 20.6] | 19.4 [12.6, 24.6] | 0.002 |
| Shunt, dorsal, % | 8.2 [4.8, 13.8] | 3.8 [1.5, 9.6] | 0.005 | 7.7 [3.9, 12.6] | 10.7 [6.2, 16.4] | 0.04 |
| Shunt, ventral, % | 2.0 [0.6, 5.5] | 5.7 [2.9, 9.9] | 0.02 | 3.6 [1.4, 8.0] | 5.5 [2.9, 11.9] | 0.02 |
| Dead space, % | 14.2 [7.7, 21.9] | 9.1 [5.3, 13.4] | 0.004 | 11.9 [9.4, 16.5] | 11.3 [5.9, 15.6] | 0.15 |
| Dead space, dorsal, % | 3.3 [0.9, 5.5] | 3.1 [1.3, 5.2] | 0.64 | 3.7 [1.3, 6.6] | 2.9 [0.9, 6.4] | 0.16 |
| Dead space, ventral, % | 10.0 [5.2, 17.6] | 5.9 [2.0, 8.8] | 0.001 | 8.5 [6.5, 10.1] | 6.9 [4.9, 10.2] | 0.36 |
| Dead space/shunt ratio | 1.1 [0.5, 2.9] | 0.7 [0.4, 1.7] | 0.48 | 1.2 [0.4, 2.1] | 0.6 [0.3, 1.1] | 0.009 |
| Dead space/shunt ratio, dorsal | 0.4 [0.1, 0.9] | 0.7 [0.2, 2.2] | 0.22 | 0.3 [0.1, 1.4] | 0.2 [0.1, 0.8] | 0.14 |
| Dead space/shunt ratio, ventral | 2.0 [0.8, 6.0] | 0.3 [0.1, 0.8] | < 0.001 | 2.0 [0.8, 4.2] | 1.1 [0.5, 2.7] | 0.07 |
| Total unmatched units, % | 28.7 [24.6, 35.4] | 22.8 [20.0, 26.8] | < 0.001 | 26.9 [20.1, 31.4] | 31.2 [24.5, 36.4] | 0.02 |
| Unmatched units, dorsal, % | 13.0 [9.2, 20.6] | 9.0 [5.5, 13.2] | < 0.001 | 12.8 [10.0, 16.3] | 17.3 [11.2, 20.2] | 0.095 |
| Unmatched units, ventral, % | 14.8 [11.3, 18.4] | 13.4 [9.4, 14.9] | 0.094 | 12.4 [9.2, 16.9] | 14.8 [11.2, 20.2] | 0.179 |
| Hemodynamic variables | ||||||
| Heart rate (beats per minute) | 80 [69, 90] | 81 [72, 95] | 0.50 | 85 [69, 93] | 85 [75, 93] | 0.54 |
| MAP (mmHg) | 82 [74, 88] | 82 [75, 90] | 0.28 | 83 [68, 87] | 74 [69, 87] | 0.80 |
ARDS acute respiratory distress syndrome, COV center of ventilation, RVD regional ventilation delay index, SBP systolic blood pressure, MAP mean arterial pressure
Values are represented as median (interquartile range)
p indicates Wilcoxon signed-rank tests between paired supine position and prone position values