Prehospital end-tidal CO2 as an early marker for transfusion requirement in trauma patients

Below normal end-tidal carbon dioxide measurement (ETCO2) is associated with worse outcomes in sepsis and trauma patients as compared to patients with normal ETCO2. We sought to determine if ETCO2 can be used in the prehospital setting to predict transfusion requirement, operative hemorrhage control, or mortality in the first 24 h after admission for trauma.

This is a retrospective cohort study at a suburban, academic Level 1 Trauma Center. Patients were sequentially identified as prehospital trauma alerts from a single EMS system which requires, per policy, ETCO2 for all traumas. One year of prehospital data was collected and paired with hospital trauma registry data. Comparisons were made between ETCO2 values for patients who required transfusion, operative blood loss control, or who died, and those who did not.

Two hundred thirty-five trauma patients were transported via the study EMS system, of which 105 (44.7%) had documented ETCO2 values. Patient mean age was 60 (SD24) years with 59 (56.2%) male. Three patients were intubated prehospital and seven were intubated in the trauma bay. Mean prehospital ETCO2 for those who needed transfusion, surgery, or died (n = 11) was 25.7 (9.1) compared to 30.6 (7.8) for those who did not (p = 0.049). Optimal cutoff for our population was EtCO2 ≤ 27 with a sensitivity of 72.7% (95% CI 32-93) and specificity of 72.2% (62-81).

Below normal ETCO2 values were associated with increase need for transfusion, operative intervention, and death. Further study is warranted to determine if ETCO2 outperforms other predictors of severe trauma.