Effect of norepinephrine and phenylephrine on lactate levels during cardiopulmonary bypass in diabetic patients

Abstract

Objective: To determine the effect of norepinephrine and phenylephrine on lactate levels in diabetic patients during on-pump coronary artery bypass grafting procedure.

Method: The quasi-experimental study was conducted at the Armed Forces Institute of Cardiology, National Institute of Heart Diseases, Rawalpindi, Pakistan, from June 2023 to January 2024, and comprised type-2 diabetic patients of either gender aged 18-65 years undergoing on-pump coronary artery bypass grafting. The patients were non-randomly allocated into groups I and II. To maintain mean arterial pressure 65-90mmHg during the procedure, Group I was given phenylephrine 0.2-0.3mg diluted in 50ml normal saline, while Group II was given norepinephrine 0.05-0.1mg diluted in 50ml normal saline. Serum lactate levels were measured before anaesthesia induction, before cardiopulmonary bypass, at cooling, at rewarming. and before shifting to the intensive care unit. The effect of vasopressor type on serum lactate levels was evaluated. Data was analysed using SPSS 25.

Result: Of the 140 patients, 70(50%) were in Group I; 47(67.1%) male and 23(32.9%) female with mean age 55.50±7.336 years. There were 70(50%) patients in Group II; 50(71.4%) male and 20(28.6%) female with mean age 55.36±6.785 years (p>0.05). Overall, 45(32.1%) patients had controlled diabetes, while 95(67.9%) had uncontrolled diabetes. Group II patients demonstrated higher lactate levels during cooling, rewarming and prior to intensive care unit transfer (p<0.001).

Conclusion: Phenylephrine demonstrated better metabolic control, suggesting it may be a preferable vasopressor in diabetic patients during cardiac surgery.

Key Words: Cardiopulmonary bypass, Coronary artery bypass Grafting procedure, Diabetes, Lactate, Norepinephrine, Phenylephrine.