The impact of a reduced dose of dexamethasone on glucose control after coronary artery bypass surgery

Abstract

Background: Intensive insulin therapy to maintain normoglycemia after cardiac surgery reduces morbidity and mortality. We investigated the magnitude and duration of hyperglycemia caused by dexamethasone administered after cardiopulmonary bypass.

Methods: A single-center before-after cohort study was performed. All consecutive patients undergoing coronary artery bypass grafting with cardiopulmonary bypass during a 6-month period were included. Insulin administration was guided by a sliding scale protocol. Halfway the observation period, the dexamethasone protocol was changed. The single dose (1D) group received a pre-operative dose of dexamethasone of 1 mg/kg. The double dose group (2D) received an additional dose of 0.5 mg/kg of dexamethasone post-operatively at ICU admission.

Results: We included 116 patients in the 1D group and 158 patients in the 2D group. There were no significant baseline differences between the groups. Median Euroscore was 5. In univariable analysis, the glucose level was different between groups 1D and 2D at 4, 6, 9, 12 and 24 hours after ICU admission (all p < 0.001). Insulin infusion was higher in the 1D group. Corrected for insulin dose in multivariable linear analysis, the difference in glucose between the 1D and 2D groups was 1.5 mmol/L (95% confidence interval 1.0-2.0, p < 0.001) 12 hours after ICU admission.

Conclusion: Dexamethasone exerts a hyperglycemic effect in cardiac surgery patients. Patients receiving high-dose corticosteroid therapy should be monitored and treated more intensively for hyperglycemic episodes.

Figure 1

Time course of glucose levels after ICU admission. Comparison of post-cardiac surgery hyperglycemia for the single dose group (1D group, triangles, 116 patients) and for the double dose group (2D group, circles, 158 patients). Data are medians and interquartile ranges. The glucose level was higher at 4, 6, 9, 12, and 24 hours in the 2D group (all p < 0.001, after Bonferroni correction for multiple testing). The difference was largest at 12 hours after ICU admission.

Figure 2

Glucose levels at 12 hours post ICU admission stratified for mean insulin dose before that time. White bars represent the 1D group, gray bars represent the 2D group.