Abstract 140: Near-Infrared Spectroscopy, Pupillometry and End-Tidal Co2 as Predictive Factors of Survival for Patients With Out-of-Hospital Cardiac Arrest

Abstract

Background: During out-of-hospital cardiac arrest (OHCA), early prognostication of patient’s outcomes at the early phase is difficult and based on a combination of factors. EtCO2 is one of the validated parameters associated with survival. Near-infrared spectroscopy (rSO2) and infrared automated pupillometry measurements could in addition be of value in the prehospital setting. Hypothesis: To assess the prognostic value of rSO2, pupillometry and EtCO 2 alone or in association with other prognostic factors for patients with OHCA. Methods: We conducted a prospective cohort analysis in 3 French prehospital intensive care units. Adult patients with a presumed medical OHCA were included. Measurements were made at medical team arrival every 5 minutes for 15 minutes by the ambulance driver in order to ensure blindness for the medical team. The primary outcome was the prognostic value of rSO2, pupillometry, bystander CPR and initial cardiac rhythm alone or in association for survival at hospital admission. The secondary outcome was the prognostic value of capnography (EtCO2) alone or in association with primary outcomes parameters for survival at hospital admission. Results: 112 patients were included and analyzed. Bystander CPR was initiated for 72 (65.5%) patients, 19 (17.3%) survived to hospital admission. For survival at hospital admission, rSO2 alone had an AUC of 0.74 (IC95% 0.59-0.88) and the optimal threshold was 29% with a negative predictive value of 90.8% (IC95% 81-96.5). All patients with rSO2 ≥ 45% survived at hospital admission. Pupillometry alone had an AUC of 0.65 (IC95% 0.51-0.79) and no optimal threshold was found. The association of rSO2 and pupillometry adjusted on bystander CPR and initial rhythm provided an AUC of 0.77 (IC95% 0.61-0.92). EtCO2 alone had an AUC of 0.77 (IC 95% 0.64-0.89) and the optimal threshold was 25 mmHg with a negative predictive value of 97.7% (IC95% 87.7-99.9). In association, EtCO2 and rSO2 provided an AUC of 0.85 (IC 95% 0.73-0.96). Conclusion: During OHCA, near-infrared spectroscopy alone and in association with EtCO2 could be a major prognostic factor of survival at hospital admission. Pupillometry alone failed to be a prognostic factor of survival at hospital admission.