End-tidal carbon dioxide and occult injury in trauma patients: ETCO2 does not rule out severe injury

Abstract

ObjectiveTo determine if early measurement of end-tidal carbon dioxide (ETCO2) in nonintubated patients triaged to a level 1 trauma center has utility in ruling out severe injury. MethodsWe performed a prospective cohort study of adult patients triaged to our urban, academic, level 1 trauma center. Included patients had ETCO2 measured within 30 minutes of arrival. Chart review was performed on enrolled patients to identify severe injury defined by: admission to an intensive care unit, need for an invasive procedure, blood product transfusion, acute blood loss anemia, and acute clinically significant finding on computed tomographic scan. ResultsOf 170 patients enrolled, 115 met the outcome of no severe injury. Mean ETCO2 for patients without and with severe injury was 33.1 mm Hg (SD, 5.8) and 30.3 mm Hg (SD, 6.7), respectively. This difference reached statistical significance (P=.05), but did not demonstrate added clinical utility when combined with Glasgow Coma Scale, systolic blood pressure, and age in predicting the primary outcome (area under curve, 0.70 with ETCO2 vs area under curve, 0.68 without ETCO2, P=.5). Patients with ETCO2 ≤30 mm Hg were found to be older, more likely to require intensive care unit admission or emergency operative intervention, develop acute blood loss anemia, and have an acute finding on computed tomography than patients with a higher ETCO2. ConclusionEnd-tidal carbon dioxide cannot be used to rule out severe injury in patients meeting criteria for trauma center care. The ETCO2 ≤30 mm Hg may be associated with increased risk of traumatic severe injury.