Prognostication of out-of-hospital cardiac arrest patients by 3-min end-tidal capnometry level in emergency department

ObjectiveTo evaluate the role of initial ETCO2 value in prognostication of OHCA patients in an Asian-Chinese cohort.DesignProspective cohort study.SettingEmergency departments of two regional hospitals in a cluster of Hong Kong.Patients: Patients were recruited prospectively from the local cardiac arrest registry from July 2012 to June 2013. Patients of non traumatic OHCA aged ≥18 years old were included. Patients of OHCA presented with postmortem changes, those who decided for Do Not Resuscitate (DNR), regained pulse before arrival, or those without proper documentation of ETCO2 would be excluded.OutcomePrimary outcome was return of spontaneous circulation (ROSC).ResultsA 3-min ETCO2 >10 mmHg was a predictor of ROSC with OR 18.16 (95% CI 4.79–51.32, p < 0.001). The diagnostic accuracy of 3-min ETCO2 >10 mmHg to predict ROSC: sensitivity was 0.95 (95% CI 0.89–0.98) while the specificity was 0.27 (95% CI 0.21–0.33). Positive predictive value was 0.40 (95% CI 0.34–0.46) while negative predictive value (NPV) was 0.92 (95% CI 0.82–0.97). Area under ROC curve of 3-min ETCO2 predicting ROSC was 0.80 (95% CI 0.71–0.91).ConclusionsA 3-min ETCO2 ≤10 mmHg was associated with poor prognosis and low chance of ROSC. Low ETCO2 level may have a role to reduce prolonged medically futile resuscitation.