Summary
Median nerve somatosensory evoked potentials were recorded in 21 patients undergoing
cardiac surgical procedures utilizing cardiopulmonary bypass, in order to establish
the effects of hypothermia, reductions in mean arterial pressure, and alterations
in cardiopulmonary bypass flows on evoked potential latency. Induction and maintenance
of anesthesia with fentanyl caused a significant prolongation of latency of the first
cortical peak. Temperature changes were linearly correlated with changes in latency
for peaks recorded from Erb's point (r = -0.843, p < 0.01) and the contralateral cortex
(r = 0.843, p < 0.01). There was no significant effect of mean arterial pressure or
cardiopulmonary bypass flow reductions on latencies under the conditions of this study.
Our results emphasize the importance of monitoring peripheral and first cortical peak
latencies in evaluating somatosensory evoked potentials. It is suggested that peak
latency prolongations beyond those predicted by temperature alterations may be indicative
of hypoperfusion.
Key words
Cardiopulmonary bypass - Fentanyl - Hypotension - Hypothermia - Somatosensory Evoked
potentials
