Univariate comparison of patients ventilated within the first 24 h with those not ventilated within the first 24 h
| Mechanical ventilation in first 24 h | p Value | ||
|---|---|---|---|
| Yes (n = 685) | No (n = 1213) | ||
| ICU, intensive care unit; ABG, arterial blood gas; Pao2, Paco2, arterial oxygen and carbon dioxide tensions; Fio2, fraction of inspired oxygen. | |||
| All values reported as mean (SD) except length of stay reported as median (IQR). | |||
| All values recorded are the worst within the first 24 h. | |||
| *Chronic respiratory disease is defined as chronic restrictive, obstructive or vascular respiratory disease resulting in severe exercise restriction, ie, unable to climb stairs or perform household duties; or documented chronic hypoxia, hypercapnia, secondary polycythaemia, severe pulmonary hypertension (>40 mm Hg) or respiratory dependency. | |||
| Outcomes | |||
| Mortality, % (n) | 6.5% (43/660) | 1.3% (14/1165) | <0.001 |
| Duration of ICU stay (days) | 2.6 (1.4–5.9) | 1.2 (0.7–2.1) | <0.001 |
| Demographic data | |||
| Predicted mortality from APACHE II | 7.0% (95% CI 6.3% to 7.6%) | 2.4% (95% CI 2.3% to 2.7%) | <0.001 |
| Age (years) | 43.6 (18.3) | 37.5 (18.1) | <0.001 |
| Proportion ⩽16 years | 4.7% (32/681) | 9.7% (118/1211) | <0.001 |
| Proportion > 45 years | 45.5% (312/685) | 29.9% (363/1213) | <0.001 |
| Proportion with chronic respiratory disease* | 16.8% (129/685) | 16.8% (204/1213) | 0.998 |
| Proportion female | 64% (438/685) | 65% (791/1213) | 0.562 |
| Physiology | |||
| Pulse | 132 (24) | 132 (23) | 0.927 |
| Mean arterial blood pressure (mm Hg) | 86 (1.1) | 87 (0.6) | 0.253 |
| pH from ABG with lowest Pao2 | 7.18 (0.15) | 7.34 (0.11) | <0.001 |
| Paco2 from ABG with lowest pH (kPa) | 9.32 (4.36) | 6.07 (2.91) | <0.001 |
| Bicarbonate (mmol) | 24.0 (6.5) | 22.3 (5.9) | <0.001 |
| Lowest Pao2 (kPa) | 22.13 (15.87) | 15.73 (9.33) | <0.001 |
| Pao2/Fio2 ratio | 277 (171) | 275 (148) | 0.844 |
| Glasgow coma score | 12.2 (4.5) | 14.7 (1.5) | <0.001 |
| Urea (mmol/l) | 6.60 (0.22) | 6.28 (0.26) | 0.401 |
| Creatinine (μmol/l) | 94.3 (2.6) | 78.9 (0.9) | <0.001 |