Summary

Prehospital ETCO2: Predictor of hemorrhagic shock, massive transfusion, and mortality in trauma patients

Lorena Pérez Martos¹, Leire Zaraín Obrador², Francisco de Paula Delgado Moya³, María Bringas Bollada⁴, Iván Huercio Martínez⁵, Ervigio Corral Torres¹

Affiliation of the authors

¹SAMUR-Protección Civil, Madrid, Spain. ²Servicio de Cirugía General y del Aparato Digestivo, Hospital Universitario Gregorio Marañón, Madrid, Spain. ³Servicio de Medicina Intensiva, Hospital Universitario 12 de Octubre, Madrid, Spain. ⁴Servicio de Medicina Intensiva, Hospital Universitario Clínico San Carlos, Madrid, Spain. ⁵Servicio de Anestesiología y Reanimación, Hospital Universitario La Paz, Madrid, Spain.

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Pérez Martos L, Zaraín Obrador L, Delgado Moya FP, Bringas Bollada M, Huercio Martínez I, Corral Torres E. Prehospital ETCO2: Predictor of hemorrhagic shock, massive transfusion, and mortality in trauma patients. Rev Esp Urg Emerg. 2025;4:95–100

Summary

OBJECTIVE. To analyze the early predictive capacity of prehospital end-tidal carbon dioxide (ETCO2) in intubated trauma patients to determine the presence or absence of hemorrhagic shock (HS). Additionally, to assess whether low ETCO2 values are associated with the need for red blood cell (RBC) transfusion and mortality.
MATERIALS AND METHODS. We conducted a retrospective observational study using a prospective database and went on to analyze a cohort of intubated trauma patients attended by an out-of-hospital emergency service from 2021 through 2024. Patients were categorized into 2 groups: those with HS and those without it (NHS). Prehospital and hospital criteria were established for HS diagnosis. A univariate analysis was performed using the Student’s t test for all independent variables. Binary logistic regression was conducted on variables with statistical significance.
RESULTS. A total of 108 patients were studied (mean age of 40.34 years; 74.1% men). A total of 48 patients were categorized as NHS, and 60 as HS. A significant association was observed between ETCO2 and HS: initial ETCO2 was 43.50 mmHg in NHS vs 33.42 mmHg in HS (P < .001, OR, 0.79 [0.70-0.88]). The Youden index was calculated, identifying a cut-off point for HS at an ETCO2 of 37.5 mmHg. Additionally, a significant association was found between ETCO2 and mortality: ETCO2 was 39.63 mmHg in survivors vs 29.79 mmHg in non-survivors (P < .001). A significant negative correlation was identified between ETCO2 and RBC transfusion requirements (Pearson correlation: -0.35; P < .001).
CONCLUSIONS. Patients with HS have significantly lower prehospital ETCO2 values. Low ETCO2 values are associated with RBC transfusion needs and increased mortality.