Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1°- to 2°C-steps as body temperature was lowered from 36°C to 20°C to determine temperature-dependent changes. Hypothermia produced increased latencies of BAEP waves I, III, and V; the prolongation was more severe for the later components with the results that interpeak latencies I-III, III-V, and I-V were also prolonged. The temperature-latency relationship was nonlinear and best expressed by exponential curve. The latencies of waves I, III, V and the interpeak latency I-V increased roughly 7% for each 1°C drop; they doubled at a temperature around 26°C. The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28° or 27°C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23°C and absent below 20°C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.
ASJC Scopus subject areas
- Clinical Neurology