No effect of hyperoxia on outcome following major trauma

Oxygen supplementation has previously been considered beneficial when managing critically ill patients in order to avoid hypoxia. However, in recent years, studies have shown that hyperoxia may be harmful in critical care patients. The aim of the study was to investigate whether hyperoxia within the first 24 hours of admission following major trauma is associated with 30-day in-hospital mortality.

We conducted a retrospective database study of trauma patients admitted to the general intensive care unit at University Hospital Southampton from October 2008 to October 2014. Hyperoxia was defined as one arterial blood gas with a pO₂ ≥40.0 kPa during the first 24 hours of admission. Cox proportional hazards regression was used to compare 30-day in-hospital mortality between the two groups. HRs for death were calculated with 95% CIs and presented as both unadjusted and adjusted for age, sex, Acute Physiology and Chronic Health Evaluation II (APACHE II) score and number of arterial blood gases.

In total, 1,462 patients had trauma as the cause for admission. Of these, 343 patients met the study inclusion criteria, of which 265 were defined as normoxic and the remaining 78 patients as hyperoxic. The cumulative in-hospital risk of death within 30 days was 7.8% (95% CI: 4.9%-12.5%) for the normoxia group and 9.7% (95% CI: 4.4 %-20.4%) for the hyperoxia group. The crude HR for 30-day in-hospital mortality was 1.15 (95% CI: 0.45-2.90) for hyperoxia compared to normoxia. Adjusting for APACHE II, age, sex and number of arterial blood gases yielded an adjusted HR of 30-day in-hospital mortality of 0.65 (95% CI: 0.24-1.73) for the hyperoxia group compared to the normoxia group.

In our convenience sample of 343 patients, hyperoxia within the first 24 hours following admission to intensive care with major trauma had no impact on 30-day in-hospital mortality.