British Journal of Anaesthesia, Vol 76, Issue 1 20-22, Copyright © 1996 by The Board of Management and Trustees of the British Journal of Anaesthesia
G. C. Fletcher, A. J. Asbury and J. H. Brown
Pupil diameter is used during anaesthesia to assess depth of anaesthesia
and indicate cerebral hypoxia. This is especially so during cardiac bypass
when other autonomic signs cannot be monitored. We have used a pupillometer
to determine the effect of cardiopulmonary bypass on the pupil. We have
also investigated if any effect was caused by washout of opioid from the
central nervous system by allocating patients to one of two groups: in one
the bypass pump was preloaded with fentanyl, in the other with 0.9% saline.
Cardiopulmonary bypass caused pupil dilatation of between 17% and 53%,
which was unaffected by preloading the bypass pump with fentanyl. This
effect lasted for the duration of the study, which ended 30 min after the
start of cardiopulmonary bypass. Sympathetic nervous system reflexes and
hypothermia may account for this observation, but further research is
necessary to exclude other contributory factors.
CLINICAL INVESTIGATIONS
Pupil changes during cardiopulmonary bypass
Clinical Shock Study Group, Department of Anaesthetics, Western Infirmary, Glasgow G11 6NT; Anaesthetic Department, Western Infirmary, Glasgow G11 6NT
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