Minimized cardiopulmonary bypass reduces retinal microembolization: a randomized clinical study using fluorescein angiography.

BACKGROUND: The use of minimized cardiopulmonary bypass (MCPB) circuits has recently increased in an attempt to reduce the adverse effects of CPB. This prospective randomized study aimed to determine the effects of MCPB on retinal microembolization and related inflammatory, coagulation, and endothelial markers compared with conventional extracorporeal circulation (CCPB) among patients undergoing coronary artery bypass graft surgery. METHODS: Forty patients entered, and 37 patients completed the study. After the induction of anesthesia and immediately after the termination of CPB, standardized retinal fluorescein angiographs and digital images were obtained on both eyes and analyzed in a blinded fashion in terms of the CPB circuit. Blood samples for inflammatory, coagulation, and endothelial markers were collected at eight time points until the third postoperative day. RESULTS: Postperfusion retinal fluorescein angiographs revealed microembolic perfusion defects in 2 of 18 in the MCPB group and in 9 of 18 in the CCPB group (p=0.027 [11% vs. 50%, difference 39%, confidence interval: 0.087 to 0.613, p=0.029]). Activation of polymorphonuclear leukocytes as measured with polymorphonuclear elastase was significantly decreased in the MCPB group. Other markers of inflammation, coagulation, and endothelial dysfunction increased comparably in both groups during CPB. CONCLUSIONS: Retinal microembolization was found to be decreased after the use of minimized CPB compared with CCPB, suggesting a decreased embolic load to the brain after MCPB.

Leukocyte filter enhances neutrophil activation during combined aortic valve and coronary artery bypass surgery.

OBJECTIVE: Cardiopulmonary bypass-induced systemic inflammatory reaction involving the expression of neutrophil surface adhesion molecules is the main mechanism leading to myocardial ischemia-reperfusion injury as well as multiorgan dysfunction. Patients undergoing prolonged cardiopulmonary bypass are especially at risk in this regard. The aim of this prospective, randomized study was to evaluate the impact of continuous leukocyte filtration on the perioperative expression of neutrophil adhesion molecules along with the markers of systemic inflammation during combined coronary artery revascularization and aortic valve surgery due to aortic stenosis. PATIENT AND METHODS: Twenty patients scheduled for combined coronary artery revascularization and aortic valve surgery due to aortic stenosis were randomized to undergo cardiopulmonary bypass with or without a leukocyte filter (LeukoGuard LG6). The expression of neutrophil adhesion molecules and proinflammatory cytokine response were measured. RESULTS: The use of the leukocyte filter significantly increased neutrophil CD11b expression (Pg = .003) compared to the control group, which was followed by a faster rise in interleukin-6 levels 5 minutes (median, 125 versus 34 pg/mL) and 2 hours after cardiopulmonary bypass (median, 158 versus 92 pg/mL, Pt x g < .001), respectively. No marked differences in terms of levels of CD11a, CD62L, cardiac troponin-I, or oxyhemodynamics were observed. CONCLUSIONS: The observed increased neutrophil activation and enhanced inflammatory response do not support the use of continuous leukofiltration in patients undergoing prolonged cardiopulmonary bypass.

Metabolic and hemodynamic effects of high-dose insulin treatment in aortic valve and coronary surgery.

BACKGROUND: Glucose and insulin have been used as an adjuvant therapy in cardiac surgery because of their potentially beneficial effects on myocardial metabolism and contractile function. This study evaluated the effects of high-dose insulin on systemic metabolism and hemodynamics after combined heart surgery. METHODS: Forty elective patients scheduled for combined aortic valve replacement and coronary artery bypass surgery were randomly assigned to receive either high-dose insulin treatment (short-acting insulin 1 IU.kg(-1).h(-1) with 30% glucose 1.5 mL.kg(-1).h(-1) administered separately) or control treatment (saline). The blood glucose levels were maintained within a targeted range by adjusting the rate of glucose infusion in the treatment group and by short-acting insulin bolus doses in the control group. RESULTS: The lactate clearance was faster (p = 0.046), and the lactate levels (p = 0.016), blood glucose levels (p < 0.001), and free fatty acid levels (p < 0.001) were lower in the insulin group postoperatively. Besides, there was lesser need for dobutamine support (p = 0.013) and a trend toward better cardiac indices. Insulin treatment increased the respiratory quotient (p < 0.001), but there were no differences between the groups with regard to systemic oxygen consumption or energy expenditure measured by indirect calorimetry. The average glucose uptake in the insulin group was 7.1 g/kg in 24 hours (28 kcal.kg(-1).day(-1)). CONCLUSIONS: The high-dose insulin treatment was associated with lower blood glucose levels, better preserved myocardial contractile function, and less need for inotropic support, and hence led to lower lactate levels postoperatively. The protocol is safe, but requires strict control of blood glucose level.