Oxygen delivery and consumption in the perioperative period of coronary artery bypass grafting without blood transfusion

Abstract

The perioperative changes in relationship between oxygen delivery (D(O)(2)) and oxygen consumption (V(O)(2)) were examined in forty patients who underwent coronary artery bypass grafting (CABG) without blood transfusion. Hemodilution was performed to maintain hematocrit of 19.2 +/- 1.8% during cardiopulmonary bypass (CPB). Hemodynamic and metabolic parameters were measured in four stages; before CPB (stage I), after CPB (stage II), after ICU arrival (stage III), and the following day (stage IV). In each stage, there was a strong positive correlation between V(O)(2) and D(O)(2). In stage I, a decrease in D(O)(2) was met with low V(O)(2), and there was no imbalance between them (r = 0.67, P < 0.01). V(O)(2) increased significantly in stage II, and this increased V(O)(2) was compensated by an increase in D(O)(2) sufficiently to meet tissue oxygen demand (r = 0.59, P < 0.01). In stage III and IV, the increases in tissue oxygen requirements were met by increases in oxygen extraction ratio (r = 0.81, P < 0.01, r = 0.60, P < 0.01, respectively) reflected in lowered mixed venous oxygen tension and saturation. From these results, it is assumed that the adequate relationship between V(O)(2) and D(O)(2) can be maintained in the perioperative period of CABG without blood transfusion.