Relation of cytokines to vasodilation after coronary artery bypass grafting

Abstract

Hemodynamic instability is frequent after coronary surgery. The present study tested the hypothesis that inflammation, as determined by circulating cytokine levels, may contribute to the difficulty of controlling arterial blood pressure after coronary artery bypass grafting. A group of 44 male patients undergoing elective coronary artery bypass grafting with cardiopulmonary bypass were studied. Plasma levels of tumor necrosis factor-alpha, interleukin-6 (IL-6), IL-8, and IL-10 were measured before anesthesia induction, 5 minutes and 1 hour after reperfusion to the myocardium, and 2 and 18 hours after arriving in the intensive care unit (ICU). The 29 patients who did not need a vasopressor (norepinephrine) during their ICU stay were designated group I. They were compared to group II, which consisted of 15 patients who required a pressor agent in the ICU. Although no significant differences between groups were found regarding their hemodynamic variables, IL-6 and IL-8 levels were higher in the patients who used a pressor agent in the ICU. The norepinephrine dosage used in the ICU correlated with plasma IL-8 levels 2 hours after arriving in the ICU (r = 0.56, p = 0.031). Circulating IL-6 levels in group II were significantly higher than those in group I 2 hours after arriving in the ICU (126.5 +/- 90.5 vs. 66.5 +/- 48.2 pg/ml; p < 0.05). The mean IL-8 levels were higher in group II at 5 minutes (34.9 +/- 25.7 vs. 17.3 +/- 11.3 pg/ml) and 1 hour (38.6 +/- 30.5 vs. 22.4 +/- 16.7 pg/ml) after reperfusion, and 2 hours (33.0 +/- 21.6 vs. 22.8 +/- 16.7 pg/ml) after arriving in the ICU (p = 0.036). Postoperative vasodilation was associated with increased circulating IL-8 levels. Strategies that modulate cytokine responses may improve hemodynamic stability after coronary artery bypass grafting.