Effect of temperature and cardiopulmonary bypass on the auditory evoked response

• Published in: British journal of anaesthesia : BJA Vol. 75; no. 3; pp. 293 - 296
• Main Authors: Hett, D A, Smith, D C, Pilkington, S N, Abbott, T R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.1995; Oxford University Press
• Subjects: Aged; Biological and medical sciences; Body Temperature; Cardiopulmonary Bypass; Child; Evoked Potentials, Auditory; Evoked Potentials, Auditory, Brain Stem; Female; Humans; Hypothermia, Induced; Male; Medical sciences; Middle Aged; Reaction Time; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the heart; Time Factors; Cardiopulmonary bypass; Heart; Human; Electrodiagnosis; Moderate induced hypothermia; Surgery; Auditory evoked potential; General anesthesia; Monitoring
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/75.3.293

We have recorded auditory evoked potentials before and during cardiopulmonary bypass in 10 adult patients undergoing cardiac surgery under moderate hypothermia to 27-28 degrees C. The immediate effect of bypass was a small decrease in latency and increase in amplitude of the early cortical response. We also studied two adults and two children during profound hypothermia with circulatory arrest during cardiopulmonary bypass. Reduction in core temperature to 25 degrees C resulted in an increase in latency and amplitude of the brain stem responses; below this temperature the amplitude decreased but latency continued to increase until the auditory evoked response trace became completely flat between 21 and 19 degrees C. These changes were reversible on rewarming.