Implementing tight glucose control after coronary artery bypass surgery

Abstract

Background: The clinical benefit of tight glucose control has been demonstrated in diabetic patients. In adopting an approach of tight glucose control for all cardiac surgery patients at Beth Israel Deaconess Medical Center, we encountered several challenges, including defining good glucose control, meaningfully measuring control, and assessing the impact of variables that may affect control.

Methods: An interdisciplinary team used an insulin protocol to achieve tight glucose control of cardiac surgery patients in the operating room and intensive care unit as part of an effort to reduce sternal wound infections. Good control was defined as glucose less than 130 mg/dL for more than 50% of measured time.

Results: Eight hundred eighteen patients underwent coronary artery bypass grafting between November 2002 and August 2004. Seven hundred thirty-seven (90%) received insulin. Fifty-seven percent did not have a preoperative diagnosis of diabetes. The trigger for insulin initiation was decreased sequentially from 150 mg/dL to 110 mg/dL, but the measure of good control remained the same: glucose less than 130 mg/dL. The factor most highly predictive of glucose being well controlled was the protocol with the 110 mg/dL trigger for insulin (p < 0.001). Patient factors such as age, ejection fraction, preoperative angiotensin-converting enzyme inhibitor or beta-blocker use, or time on cardiopulmonary bypass were not significantly associated with glucose control. During the course of the protocols, the rate of mediastinitis decreased from 1.6% to 0%.

Conclusions: Key elements to implementing tight glucose control include having a standard protocol and metrics to track protocol performance. This practice improved control and was associated with a marked reduction in mediastinitis.