Table 2.
Oxygenation parameters
| Parameter | Overall N = 202 |
Non-Survivors N = 63 |
Survivors N = 139 |
p-value |
|---|---|---|---|---|
|
Highest PaO2 (kPa) {mmHg} |
17.40 [14.8, 21.9] {130.5 [111.0, 164.3]} |
16.5 [14.3, 21.8] {123.8 [107.3, 163.5]} |
18.2 [15.0, 21.8] {136.5 [112.5, 163.5]} |
0.22 |
| Highest FiO2 (%) | 0.7 [0.5, 0.8] | 0.7 [0.6, 0.9] | 0.7 [0.5, 0.8] | 0.17 |
|
Highest P/F ratio (kPa) {mmHg} |
41.0 [32.7, 48.6] {307.5 {245.3, 364.5]} |
38.2 [26.4, 44.6] {286.5 [198.0, 334.5]} |
41.7 [35.1, 49.5] {312.8 [263.3, 371.3]} |
0.004 |
| Average time-weighted PaO2 (kPa) {mmHg} | ||||
| First 24 h of ARDS |
11.5 [10.4, 13.1] {86.3 [78.0, 98.3]} |
11.4 [10.1, 12.9] {85.5 [75.8, 96.8]} |
11.6 [10.5, 13.1] {87.0 [78.8, 98.3]} |
0.37 |
| First 7 days of ARDS |
11.8 [10.7, 12.6] {88.5 [80.3, 94.5]} |
11.3 [10.2, 12.5] {84.8 [76.5, 93.8]} |
11.9 [10.9, 12.6] {89.3 [81.8, 94.5]} |
0.08 |
| Number of hyperoxaemia episodes (First 7 days of ARDS) | 3.0 [1.0, 6.0] | 2.0 [0.5, 4.0] | 3.0 [1.0, 6.0] | 0.04 |
| Any hyperoxaemia episode–N (%) | 166 (82) | 47 (75) | 119 (86) | 0.09 |
| Ever exposed to excess oxygen–N (%) | 111 (55) | 36 (57) | 75 (54) | 0.79 |
| Excess oxygen exposure | ||||
| First 24 h of ARDS | 0.0 [0.0, 0.2] | 0.0 [0.0, 0.2] | 0.0 [0.0, 0.1] | 0.75 |
| First 7 days of ARDS | 0.1 [0.0, 0.2] | 0.1 [0.0, 0.2] | 0.1 [0.0, 0.3] | 0.84 |
Data are presented as median [IQR] unless otherwise stated
Values of oxygenation are presented in kPa, and the corresponding values in mmHg is presented in italics
Average time-weighted PaO2 was obtained by calculating the value between consecutive time points prior to multiplying this value by the period of time between these points. The sum of these time-weighted values was then divided by the total time of mechanical ventilation within the timepoints of interest. Hyperoxaemia was defined as a PaO2 > 14 kPa (105 mmHg). Excess oxygen exposure was defined as any FiO2 value above an FiO2 > 0.5 in patients with a PaO2 > 10.7 kPa (80.3 mmHg), and was calculated at 24-h intervals with a cumulative value obtained
PaO2, partial pressure of arterial oxygen; FiO2, Fraction of inspired oxygen; P/F ratio, partial pressure of arterial oxygen to fraction of inspired oxygen ratio