Effects of Shed Mediastinal Blood on Cardiovascular and Pulmonary Function: A Randomized, Double-Blind Study

Abstract

Shed mediastinal blood during cardiopulmonary bypass (cardiotomy blood) contains fat, particulate matter, and vasoactive mediators that can adversely affect the pulmonary and systemic vasculature, as well as impair gas exchange. Our aim was to evaluate the effects of processing cardiotomy blood on cardiovascular and pulmonary function after cardiac surgery. Patients undergoing coronary artery bypass or aortic valve surgery, or both, using cardiopulmonary bypass were randomly allocated to receiving processed (treated, n = 132) or unprocessed shed blood (control, n = 134) In the treated group, shed blood was processed by centrifugation, washing, and additional filtration. Pulmonary function, arterial and venous blood gases, and hemodynamics were measured before, immediately after, and 2 hours after cardiopulmonary bypass in a consecutive subset of patients (n = 154). Patients and treating physicians were blinded to treatment assignment. Preoperative characteristics were similar between groups. There were no significant differences between groups in indexes of pulmonary mechanical function at any of the measured time points. Patients in the treated group demonstrated reduced pulmonary and systemic vascular resistance (both p < 0.01) as well as increased cardiac index in the perioperative period (2.6 +/- 0.07 versus 2.3 +/- 0.06 L . min(-1) . m(-2) at 2 hours after CPB, p = 0.004). Larger volumes of cardiotomy blood were associated with greater changes in systemic and pulmonary vascular resistance. Indicators of pulmonary gas exchange were similar between groups at all measured time points. Treated patients demonstrated a trend toward reduced length of ventilation (11.0 +/- 1.9 versus 13.9 +/- 2.4 hours, p = 0.12). Processing of shed mediastinal blood improves cardiopulmonary hemodynamics and may reduce ventilatory requirements after cardiac surgery.