Effects of hypothermia on brainstem auditory evoked potentials in humans.
Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1 degree- to 2 degrees C-steps as body temperature was lowered from 36 degrees C to 20 degrees 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 result 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 degree C drop; they doubled at a temperature around 26 degrees C. The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28 degrees or 27 degrees C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23 degrees C and absent below 20 degrees C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.
Markand
O N
ON
Indiana University School of Medicine, Department of Neurology, Indianapolis 46223.
Lee
B I
BI
Warren
C
C
Stoelting
R K
RK
King
R D
RD
Brown
J W
JW
Mahomed
Y
Y
D000161:Acoustic Stimulation; D000328:Adult; D001831:Body Temperature; D001933:Brain Stem / Q000502:physiology*; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology