9. Effect of steady-state hypothermic cardiopulmonary bypass on somatosensory evoked potentials

Neurophysiological techniques are used to assess cerebral functioning in operating room and intensive care unit, but the introduction of hypothermia as a means of intraoperative neuroprotection has brought their reliability into question. The present study aimed to evaluate the effect of mild/moderate hypothermia on somatosensory evoked potentials (SSEPs)’ amplitude and latency in a cohort of cardiopulmonary bypass (CPB) patients as the temperature reached the steady-state. The amplitude and latency of four different SSEP signals – N9, N13, P14/N18, and N20/P25 – were evaluated retrospectively in 84 patients undergoing CPB during normothermic (36 ± 0.43 °C) and mild/moderate hypothermic (32 ± 1.38 °C) conditions. A paired-samples t -test was performed for each SSEP to test the differences in latencies and amplitudes between normothermic and hypothermic conditions. Compared to normothermia, hypothermia not only significantly increased the latency of all SSEPs, N9 ( P P P P P P