Perioperative glycemic control with a computerized algorithm versus conventional glycemic control

Introduction

In critically ill patients, both hypoglycemia and hyperglycemia seem to influence outcome. Since hypoglycemia can lead to organ dysfunction, hyperglycemia seems to boost surgical site infections (SSI) [1]. It was shown that intensive insulin therapy (IIT) reduced mortality in critically ill patients [2]. Unfortunately several studies could not reproduce the effects [3, 4]. In particular, IIT bears the risk of accidental hypoglycemia which could even have a negative effect on patient outcome [3, 4]. In cardiac surgery, the use of blood cardioplegia for cardiopulmonary bypass frequently leads to high blood glucose levels during surgery. In particular, a computer-based algorithm that guides the insulin therapy might be beneficial. We hypothesized that in patients undergoing major cardiac surgery with cardiopulmonary bypass and blood cardioplegia, the use of a computer-based algorithm for the application of insulin will lead to a tighter adherence of normoglycemia. Our primary study end-point was the duration, in which the patients fulfilled the predefined target range of 80 to 150 mg/dl blood glucose. Patients with conventional blood glucose therapy served as controls.

Methods

Seventy-five patients were enrolled and randomized into three groups. Start of therapy was determined as the beginning of cardiopulmonary bypass. Group 1: therapy with computer-based blood glucose control (TGC System; Braun, Melsungen, Germany) and measurement of blood glucose every 30 minutes. Group 2: same therapy as group 1 and measurement of blood glucose every 15 minutes. Group 3: conventional therapy using a fixed insulin dosing scheme. End of therapy was defined as discharge from the ICU. Statistical analysis was performed with using ANOVA and the LPS post hoc test. Data shown are mean ± standard deviation, n = number of patients.

Results

There were no statistical differences between the groups regarding age, height, weight, premedical history or intraoperative amount of glucose administration during cardioplegia (33 ± 15 g). Blood glucose levels in groups 1 and 2 stayed significantly longer in the target interval compared with group 3 (75 ± 19% vs. 72 ± 19%; vs. 50 ± 34%, P < 0.01, n = 25, respectively). There was no significant difference between the groups regarding ICU or hospital stay and SSI rates.

Conclusion

Early computer-based insulin therapy allows one to better warrant normoglycemia in patients undergoing major cardiac surgery with the use of blood cardioplegia.