Middle latency auditory evoked potential index for prediction of post-resuscitation survival in elderly populations with out-of-hospital cardiac arrest

Background. Out-of-hospital cardiac ar-rest (OHCA) is associated with a high mortality rate in the elderly. Although most reports have investigated among el-derly patients with OHCA until 1990s, non-invasive monitorings cannot pres-ently predicted cerebral resuscitation dur-ing cardiopulmonary resuscitation (CPR). Findings of a previous study suggest that monitoring of middle latency auditory evoked potentials (MLAEP) during CPR could provide an indicator of effective post-resuscitation survival.Objectives. We speculated that the MLAEP index (MLAEPi), measured in an emer-gency room, can predict post-resuscita-tion survival among elderly patients with OHCA. Methods. This prospective study included 31 elderly patients aged ≥65 years with OHCA who received basic life support (BLS) and did not achieve restoration of spontaneous circulation (ROSC) until ar-rival at the emergency center between December 2010 and December 2011. All patients were administered advanced car-diac life support (ACLS) in the emergency room. Initial MLAEPi was measured using an MLAEP monitor (aepEX plus®, Audi-omex, UK) during the first cycle of ACLS. Prediction of the post-resuscitation sur-vival was investigated. Results. Eight patients who achieved ROSC were admitted to our hospital and 23 did not achieve ROSC in the emergency room. Initial MLAEPi was significantly higher in patients with than without ROSC (median, 33 vs. 26, p = 0.02). Three survivors, among patients with ROSC, were discharged from our hospital (survivors) and 5 died dur-ing hospitalization (non-survivors). Initial MLAEPi was significantly higher in sur-vivors than in non-survivors (median, 35 vs. 28, p = 0.03) or patients without ROSC (median, 35 vs. 26, p < 0.01). Conclusions. MLAEPi satisfactorily de-notes cerebral function and predicts post-resuscitation survival in elderly popula-tions.