Glycemic Control to Prevent Cardiac Morbidity in Vascular Surgery

This is a randomized, prospective controlled trial in both diabetic and non diabetic patients undergoing vascular surgery such as abdominal aortic, infra inguinal vascular bypass procedures and amputations, comparing tight versus standard blood glucose control regimens in the operating room, post anesthesia care unit and in the postoperative vascular intensive care unit up to 48 hours and its impact on the cardiovascular, infectious and other morbidity and mortality during the hospital admission and up to 30 days from surgery.

After obtaining informed consent, the study subjects will be randomized to tight versus standard blood glucose control regimens. These regimens will be started in the operating room and continued for the first 48 hours or until their discharge, whichever is earlier. All the patients will be inpatients. Day surgery patients will be excluded.

The anesthesiologist providing patient care will be given either the tight glucose control protocol or the standard sliding scale insulin protocol. In the tight control regimen, target blood glucose is 100-150 mg/dl. If 3 consecutive blood glucose (BG) level >150 mg/dL or 1 BG level >200 mg/dL, then the insulin infusion will be initiated in the tight control group. The insulin infusion rate adjustments will be made based on the blood sugar results. In post anesthetic care unit (PACU) and vascular intensive care unit (VICU), these protocols will be nurse driven. The adjustments will be made based on the current blood sugar levels as well as the insulin infusion rates. They are adjusted in such a way to account for the rate of change of blood sugars and the presence of steroid therapy in the patients. The frequency of blood glucose testing in this group will be every 1-hour until stable (when frequent changes in insulin dosage are no longer necessary, and glucose is in the range of 100 to 150 for 3 consecutive blood sugar checks); then test every 2 hours for 3 consecutive target values and then every 4 hours thereafter. If there is a change in the infusion rates, then blood sugar checks will be done every hour and the cycle followed thereafter.

In the standard sliding scale insulin group, blood sugars will be treated with insulin boluses if the blood sugars go more than 150 mg/dL and blood glucose will be monitored every 4 hours.

These regimens will be initiated after 2 weeks of in-service training for anesthesiologists, post anesthetic care unit (PACU) and vascular intensive care unit (VICU) nurses. The study investigators will provide this training. Insulin infusion in the tight control regimen will be started through pump piggyback to maintenance intravenous infusion as follows. Insulin infusion bags will be made by the pharmacy (100 units in a 100 ml bag). The anesthesiologists in the operating room and PACU, and VICU nurses will perform blood glucose monitoring, bolus insulin administration, and infusion initiation and rate adjustments as specified by the protocol. Blood glucose levels will be tested by finger stick method or arterial line drop sample.