Abstract 136: Does End-Tidal Carbon Dioxide Measured at the Facial Mask Predict Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest?

Abstract

Introduction: High value of end-tidal carbon dioxide (EtCO2), measured at the end of a tracheal tube, is closely associated with return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) resuscitation. The aim of this study was to evaluate whether EtCO2 measured at the face mask (FM) before an intubation procedure, may also predict ROSC in OHCA. Material and Methods: This was a prospective non-interventional study. Between May 1 st 2022 and January 30 th 2023, all patients ≥ 18 years with an OHCA on EMS arrival and for whom a laryngoscopy for tracheal intubation was considered, were included. An EtCO2 sensor was directly placed between the valve of the bag-valve-mask and the FM while cardiopulmonary resuscitation was continued. Age, gender, initial rhythm, ROSC on scene and last EtCO2 at the FM (FM-EtCO2) value before laryngoscopy were collected. Patients were assigned to 3 groups: FM-EtCO2 < 10 mmHg ; 10 mmHg < FM-EtCO2 < 30 mmHg and FM-EtCO2 > 30 mmHg. Results: Twenty-three patients were included. Mean age was 64.9 ± 12.2 years and sex ratio was 3.6. Initial rhythm was asystole for 16 (69.6 %) patients, ventricular fibrillation for 5 (21.7 %) and pulseless rhythm for 2 (8.7%). Eight (34.8 %) patients had a ROSC on scene. Five (21,8 %) patients had a FM-EtCO2 < 10 mmHg ; 7 (30,4%) a 10 mmHg < FM-EtCO2 < 30 mmHg and 11 (47,8 %) a FM-EtCO2 > 30 mmHg. Among those with a ROSC, 2 had a FM-EtCO2 < 10 mmHg and 6 a FM-EtCO2 > 30 mmHg (p=0,038). Conclusion: A high value of EtCO2 measured at the face mask (above 30mmHg) was significantly associated with ROSC. This survey proposes a method that would facilitate the knowledge of an EtCO2 value, well known to predict ROSC in OHCA, earlier than with the reference method. Further studies are needed to validate these results.