Thoracic Epidural Anesthesia and Blood Glucose Levels in Diabetic Patients Undergoing Cardiopulmonary Bypass Under Insulin Infusion According to the Portland Protocol

Abstract

We investigated the effect of thoracic epidural anesthesia on perioperative blood glucose levels in diabetic patients undergoing cardiopulmonary bypass by continuous insulin infusion according to the Portland Protocol. Diabetic patients undergoing surgery with cardiopulmonary bypass were assigned to receive either general anesthesia alone (n=40) or general anesthesia with thoracic epidural anesthesia (n=18). Patient data were retrospectively reviewed from prospective chart records used in our anesthesia clinic. In all study patients, insulin infusion with the Portland Protocol was used to maintain stable blood glucose levels. We evaluated blood glucose levels in both groups at 6 time points including before surgery, before cardiopulmonary bypass, during cardiopulmonary bypass, immediately following cardiopulmonary bypass, and on the first and second postoperative days. The amounts of insulin required at the intraoperative period and during two postoperative days were compared between two groups. Groups were similar with respect to the duration of cardiopulmonary bypass, aortic cross-clamping, surgery, and blood glucose levels at any of the 6 time points, mean insulin requirements during intraoperative period and mean insulin requirements and blood glucose levels during the first 2 postoperative days (General anesthesia alone, 189+/-29 mg/dl vs. General anesthesia with thoracic epidural anesthesia, 191+/-19 mg/dl; p=0.782). In diabetic patients undergoing cardiopulmonary bypass receiving insulin infusion by the Portland Protocol for glycemic control, thoracic epidural anesthesia provides no additional benefit for maintaining blood glucose levels during surgery.