Incidence of hyperoxia in combat wounded in iraq and Afghanistan: A potential opportunity for oxygen conservation

Abstract

Introduction: Oxygen supplementation is frequently used in critically injured trauma casualties in thecombat setting. Oxygen supplies in the deployed setting are limited so excessive use of oxygen may unnecessarily consume this limited resource. We describe the incidence of supraphysiologic oxygenation (hyperoxia) within casualties inthe Department of Defense Trauma Registry (DoDTR). Methods: This is a subanalysis of previously published datafrom the DoDTR-we isolated casualties with a documented arterial blood gas (ABG) and categorized hyperoxia asan arterial oxygen >100 mmHg and extreme hyperoxia > 300 mmHg (a subset of hyperoxia). We defined serious injuries as those with an Abbreviated Injury Score (AIS) of 3 or greater. We defined a probable moderate traumatic braininjury of those with an AIS of 3 or greater for the head region and at least one Glasgow Coma Scale at 8 or less.Results: Our initial search yielded 28,222 casualties, of which 10,969 had at least one ABG available. Within the10,969, the proportion of casualties experiencing hyperoxia in this population was 20.6% (2,269) with a subset of4.1% (452) meeting criteria for extreme hyperoxia. Among those with hyperoxia, the median age was 25 years (IQR21-30), most were male (96.8%), most frequently US forces (41.4%), injured in Afghanistan (68.3%), injured byexplosive (61.1%), with moderate injury scores (median 17, IQR 10-26), and most (93.8%) survived to hospital discharge. A total of 17.8% (1,954) of the casualties underwent endotracheal intubation: 27.5% (538 of 1,954) prior toemergency department (ED) arrival and 72.5% (1,416 of 1,954) within the ED. Among those intubated in the prehospital setting, upon ED arrival 35.1% (189) were hyperoxic, and a subset of 5.6% (30) that were extremely hyperoxic.Among those intubated in the ED, 35.4% (502) were hyperoxic, 7.9% (112) were extremely hyperoxic. Within the 1,277with a probable TBI, 44.2% (565) experienced hyperoxia and 9.5% (122) met criteria for extreme hyperoxia.Conclusions: In our dataset, more than 1 in 5 casualties overall had documented hyperoxia on ABG measurement, 1 in 3intubated casualties, and almost 1 in 2 TBI casualties. With limited oxygen supplies in theater and logistical challengeswith oxygen resupply, efforts to avoid unnecessary oxygen supplementation may have material impact on preservingthis scarce resource and avoid potential detrimental clinical effects from supraphysiologic oxygen concentrations.