Pupillary signs during cardiac surgery. Their use in the prediction of major cerebral deficit following cardiopulmonary bypass.
Pupil sizes and reactions to light were studied in 100 patients who had cardiopulmonary bypass. Behaviour of the pupils was observed at six stages during the operation. Most patients (71) had pupils of equal size and similar reaction to light at all times. Twenty-three patients developed unequal pupils at some stage, while six had equal pupils throughout but exhibited differing reaction to light. Major cerebral deficit was significantly more common after operation in patients who developed inequality in pupil size than those who did not (p less than 0.05). No relationship was seen between dissimilar pupil reaction to light and the development of neurological complications. The clinical estimation of pupil size may help to identify those patients who may exhibit postoperative major neurological dysfunction.