Tight perioperative glucose control is associated with a reduction in renal impairment and renal failure in non-diabetic cardiac surgical patients

Abstract

Introduction: Acute renal failure after cardiac surgery increases in-hospital mortality. We evaluated the effect of intra- and postoperative tight control of blood glucose levels on renal function after cardiac surgery based on the Risk, Injury, Failure, Loss, and End-stage kidney failure (RIFLE) criteria, and on the need for acute postoperative dialysis.

Methods: We retrospectively analyzed two groups of consecutive patients undergoing cardiac surgery with cardiopulmonary bypass between August 2004 and June 2006. In the first group, no tight glycemic control was implemented (Control, n = 305). Insulin therapy was initiated at blood glucose levels > 150 mg/dL. In the group with tight glycemic control (Insulin, n = 745), intra- and postoperative blood glucose levels were targeted between 80 to 110 mg/dL, using the Aalst Glycemia Insulin Protocol. Postoperative renal impairment or failure was evaluated with the RIFLE score, based on serum creatinine, glomerular filtration rate and/or urinary output. We used the Cleveland Clinic Severity Score to compare the predicted vs observed incidence of acute postoperative dialysis between groups.

Results: Mean blood glucose levels in the Insulin group were lower compared to the Control group from rewarming on cardiopulmonary bypass onwards until ICU discharge (p < 0.0001). Median ICU stay was 2 days in both groups. In non-diabetics, strict perioperative blood glucose control was associated with a reduced incidence of renal impairment (p = 0.01) and failure (p = 0.02) scoring according to RIFLE criteria, as well as a reduced incidence of acute postoperative dialysis (from 3.9% in Control to 0.7% in Insulin; p < 0.01). The 30-day mortality was lower in the Insulin than in the Control group (1.2% vs 3.6%; p = 0.02), representing a 70% decrease in non-diabetics (p < 0.05) and 56.1% in diabetics (not significant). The observed overall incidence of acute postoperative dialysis was adequately predicted by the Cleveland Clinic Severity Score in the Control group (p = 0.6), but was lower than predicted in the Insulin group (1.2% vs 3%, p = 0.03).

Conclusions: In non-diabetic patients, tight perioperative blood glucose control is associated with a significant reduction in postoperative renal impairment and failure after cardiac surgery according to the RIFLE criteria. In non-diabetics, tight blood glucose control was associated with a decreased need for postoperative dialysis, as well as 30-day mortality, despite of a relatively short ICU stay.

Figure 1

Overview of enrolment process. CPB, cardiopulmonary bypass; DHCA, deep hypothermic circulatory arrest; ESRF, end-stage renal failure.

Figure 2

Mean blood glucose levels ± standard deviation (SD) (mg/dL) during surgery and during ICU stay between groups. Induction, startCPB, rewarming, stopCPB, arrival ICU, ICU12, ...24, ...36, ...48 = blood glucose level at induction of anesthesia, on the initiation of cardiopulmonary bypass, at rewarming to normothermia on CPB, at separating from bypass, at admission in the ICU and after 12, 24, 36 and 48 h after arrival in the ICU, respectively. Control, control group; CPB, cardiopulmonary bypass; ICU, Intensive Care Unit; Insulin, group with tight glycemic control.

Figure 3

Percentage of patients with R, I or F (according to the RIFLE score) and postoperative dialysis throughout hospital stay, both in non-diabetic and diabetic patients. Control, control group; F, renal failure; I, impairment of renal function; Insulin, group with tight glycemic control; R, risk for renal failure.

Figure 4

Comparison of the predicted vs the observed incidence of acute renal failure with the need for dialysis in non-diabetics between groups. 0 to 2, 3 to 5, ... represent the different risk classes for acute renal failure with dialysis, as defined by the Cleveland Clinic Severity Score: 0 to 2 representing a predicted incidence of ARF with dialysis of 0.4%, 3 to 5 representing a predicted incidence of ARF with dialysis of 1.8%, 6 to 8 representing a predicted incidence of ARF with dialysis of 9.5%, 9 to 13 representing a predicted incidence of ARF with dialysis of 21.3%. Control, control group; Insulin, group with tight glycemic control; predicted, the predicted risk for postoperative dialysis based on the Cleveland Clinic Severity Score.

Figure 5

Comparison of 30-day mortality between groups. 0-RIF, patients without R, I or F score; RIF-D = patients scoring R(isk), I(mpairment) or F(ailure) (accoding to the RIFLE score) but without the need for haemodialysis; RIF+D, patients requiring hemodialysis. Control, control group; Insulin, group with tight glycemic control.