Abstract 221: Value of Initial Middle Latency Auditory Evoked Potential Index for Cardiopulmonary Arrest Resuscitation

Abstract

Introduction: Non-invasive monitoring that can indicate cerebral resuscitation in cardiac arrest patients remains unknown. In an operative setting, middle latency auditory evoked potentials (MLAEP) provide a good discrimination of consciousness and cerebral function during anesthesia. Hypothesis: We seessed the hypothesis that initial MLAEP index (MLAEPi) can predict the return of spontaneous cardiac activity (ROSC) or survival on arrival at the emergency department (ED). Methods: This was a prospective study and included 50 patients with cardiac arrest who received BLS by prehospital paramedics. The patients were then administered ACLS by an emergency medical team member on arrival at ED. Initial MLAEPi was immediately measured using an aepEX monitor (1st version; Audiomex, Glasgow, UK) during the first cycle of ACLS in ED (Figure). Results: Seventeen (34%) patients who showed ROSC were admitted to our hospital (ROSC group); however, 33 patients did not show ROSC on resuscitation at the scene (non-ROSC group). Initial MLAEPi in the ROSC group was significantly higher than that in the non-ROSC groups (39±18 vs. 27±6, p<0.01). In the ROSC group, clinically significant correlations were identified between initial MLAEPi and the time to the beginning of ACLS (r=-0.57, p=0.02); time to ROSC from the beginning of BLS (r=-0.53, p=0.03); and lactate concentrations (r=-0.50, p=0.04). Eight patients were discharged from our hospital (survivors) and 4 of them had no disability as per Cerebral Performance Category 1. Initial MLAEPi of survivors was significantly higher than that of non-survivors (49±23 vs. 28±6, p<0.01). The ROC curve for initial MLAEPi demonstrated that area under the curve of 0.89 (95% CI=0.77-1.01, p<0.01), and MLAEPi cutoff point ≤ 33 predicted no survival with a likelihood ratio of 6.10 (sensitivity=76.2; specificity=87.5). Conclusions: In conclusion, although our sample size is small, it showed that initial MLAEPi is represented by simple numerical values for the initial evaluation of ROSC and survival in cardiac arrest patients. Alternatively, MLAEPi may help emergency medical teams as a clinical predictor for termination of resuscitative efforts in a clinical setting.