Prehospital ETCO 2 is predictive of death in intubated and non-intubated patients.

Background: Prehospital identification of shock in trauma patients lacks accurate markers. Low end tidal carbon dioxide (ETCO ₂ ) correlates with mortality in intubated patients. The predictive value of ETCO ₂ obtained by nasal capnography cannula (NCC) is unknown. We hypothesized that prehospital ETCO ₂ values obtained by NCC and in-line ventilator circuit (ILVC) would be predictive of mortality.
Methods: This was a prospective, observational, multicenter study. ETCO ₂ values were collected by a NCC or through ILVC. AUROCs were compared with prehospital systolic blood pressure (SBP) and shock index (SI). The Youden index defined optimal cutoffs.
Results: Of 550 enrolled patients, 487 (88.5%) had ETCO ₂ measured through an NCC. Median age was 37 (27-52) years; 76.5% were male; median ISS was 13 (5-22). Mortality was 10.4%. Minimum prehospital ETCO ₂ significantly predicted mortality with an AUROC of 0.76 (CI 0.69-0.84; Youden index ​= ​22 ​mmHg), outperforming SBP with an AUROC of 0.68; (CI 0.62-0.74, p ​= ​0.04) and shock index with an AUROC of 0.67 (CI 0.59-0.74, p ​= ​0.03).
Conclusion: Prehospital ETCO ₂ measured by non-invasive NCC or ILVC may be predictive of mortality in injured patients.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper
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