Aspirin and Coronary Artery Surgery: A Systematic Review and Meta-analysis

R esearchers evaluated the differential effects of both colloid and crystalloid fluid retention on renal oxygen delivery, glomerular filtration, renal oxygen consumption, and the renal oxygen supply-demand relationship after cardiopulmonary bypass surgery. Subjects included 30 patients with normal preoperative renal function who underwent uncomplicated cardiac surgery. The patients were studied in the early postoperative period while admitted to the intensive care unit. Patients were randomized to receive a bolus of either crystalloid or colloid fluids. Despite an increase in cardiac index and renal blood flow identified with the administration of each, neither type of fluid improved renal oxygen delivery, owing to hemodilution. Crystalloid fluids increased glomerular filtration, but colloid fluids did not. Furthermore, an increase in filtration fraction and renal oxygen extraction in the crystalloid group indicates that the increase in glomerular filtration was not matched by a proportional increase in renal oxygen delivery.