Cardiopulmonary bypass increases postoperative glycemia and insulin consumption after coronary surgery

Abstract

Background: Perioperative hyperglycemia should be avoided in patients undergoing coronary surgery. The aim of our study was to find out what the influence of cardiopulmonary bypass is on postoperative glycemia and insulin consumption in patients with and without diabetes mellitus undergoing coronary artery surgery and whether a marked hyperglycemia in the early postoperative period is among the factors associated with early mortality and morbidity.

Methods: We retrospectively reviewed all patients who underwent first-time coronary artery surgery in our institution during the 11-month period. Among 814 patients, 239 patients (29.4%) had diabetes and 575 patients (70.6%) were nondiabetic. Blood glucose levels were registered every 2 hours in all patients during the first 24 postoperative hours. Outcomes were difficult glycemic control (postoperative blood glucose levels >11.0 mmol/L despite aggressive insulin treatment), hospital mortality, and morbidity (defined as any postoperative complication such as stroke, renal failure, wound infection, perioperative myocardial infarction, ventilation > 24 hours, sepsis, and multiorgan failure).

Results: Glycemic control was significantly worse in patients who underwent coronary artery bypass grafting, in comparison with off-pump coronary artery bypass grafting surgery, particularly in nondiabetic patients. Patients with difficult glycemic control had more serious postoperative complications resulting in higher mortality (2.5% versus 0.4%; p = 0.02). In the multivariate analysis, difficult glycemic control was significantly associated with a female sex (odds ratio [OR], 2.36), presence of diabetes (OR, 2.22), and the usage of cardiopulmonary bypass (OR, 1.81). Mortality was significantly associated with the left ventricular ejection fraction less than 0.35 (OR, 7.38), difficult glycemic control (OR, 7.06), and previous stroke (OR, 5.66). Difficult glycemic control was also significantly associated with postoperative morbidity (OR, 1.87).

Conclusions: Cardiopulmonary bypass increases postoperative glycemia and insulin consumption in both diabetic and nondiabetic patients. The use of cardiopulmonary bypass during coronary artery surgery in diabetic women is associated with a more difficult glycemic control in the early postoperative period. Difficult glycemic control is significantly associated with early mortality and morbidity in patients undergoing coronary artery surgery.