Intravenous loading of nitroglycerin during rewarming of cardiopulmonary bypass improves metabolic homeostasis in cardiac surgery: a retrospective analysis.

Abstract

The aim of the study was to evaluate the effects of high-dose nitroglycerine (NTG) on glucose metabolism, tissue oxygenation and postoperative recovery in cardiac surgical patients. Cardiac surgical patients in the retrospective survey were classified into two groups based on the NTG regimen. NTG group had intravenous loading of NTG (infusion rate 10-20mg/h with total dose of ≥0.5mg/kg) starting at rewarming of cardiopulmonary bypass (CPB) (n=101), and control group had no intravenous loading of NTG (n=151). Data for intraoperative plasma glucose and lactate levels, and regular insulin consumption were collected. Propensity score methodology was utilized to adjust for potential confounders. After adjustment for propensity score, the plasma glucose was significantly lower in the NTG group during (161±39 versus 179±45mg/dl, p=0.005) and after CPB (167±41 versus 184±48mg/dl, p=0.012). Total consumption of regular insulin was significantly lower in the NTG group, median 8 (range 0-50) versus 13 (0-90) international units, p=0.005. There was a trend towards statistical significance in a lower incidence of hyperlactatemia (>2.2mmol/l) in the NTG group during CPB, 21/100 (21%) versus 40/132 (30.3%), p=0.065. The mixed venous oxygen saturation in the intensive care unit was higher in the NTG group, 65±9 versus 62±11%, p=0.056. Intravenous loading of NTG during and after CPB is safe and effective for attenuating the hyperglycemic response and reduce the incidence of hyperlactatemia during cardiac surgery with CPB.