Insulin resistance after cardiopulmonary bypass in the elderly patient

Preoperative carbohydrate administration attenuates insulin resistance. We studied effects of preoperative oral carbohydrate loading in elderly patients undergoing coronary artery bypass grafting.

Eighteen patients were assigned either to get a carbohydrate drink or to be controls. Perioperatively, glucose was administered. A gastric emptying test was performed. Glucose and insulin concentrations were measured. Levels of glucose, insulin and stress hormones were studied pre-, per- and postoperatively.

Preoperative carbohydrate loading did not affect stress hormones. Gastric residual after the carbohydrate drink was 11+/-3% (mean+/-SEM). Glucose concentration was lower before anaesthesia induction in the carbohydrate group, possibly due to increased insulin release. Insulin levels differed at baseline, induction and day six. All patients returned to baseline on day six.

The study group was insulin resistant on postoperative day one and two. The effects were explainable by the traumatic stress response. No adverse effect was noted from the carbohydrate drink. If glucose is administered intravenously during surgery, there is no obvious advantage of preoperative carbohydrate loading on insulin resistance or stress hormone response.