Hypothermia after CPR prolongs conduction times of somatosensory evoked potentials

Abstract

Background: To investigate the effect of mild hypothermia on conduction times and amplitudes of median nerve somatosensory evoked potentials (SEP) in patients after cardiopulmonary resuscitation (CPR).

Methods: Patients treated with hypothermia after CPR who underwent SEP recording during hypothermia and after rewarming were selected from a prospectively collected database. Latencies and amplitudes of N9 (peripheral conduction time, PCT), N13, and N20 were measured. The central conduction time (CCT) was defined as peak-peak latency N13-N20. Recordings of 25 patients were assessed by a second observer to determine the intraclass correlation coefficient (ICC).

Results: A total of 115 patients were included. The mean body temperature at SEP during hypothermia was 33.1 °C (SD 0.8) and after rewarming 37.1 °C (SD 0.8). Mean latencies of N9, N13, and N20 and mean CCT were longer during hypothermia. There were no consistent differences in amplitudes. There was an almost perfect ICC for assessment of latencies and amplitudes.

Conclusions: This study showed that PCT and CCT of median nerve SEP were prolonged during treatment with hypothermia after CPR compared with after rewarming. Amplitudes did not differ consistently.