Intravascular and extravascular hemolysis accompanying extracorporeal circulation. A clinical study

Eleven patients undergoing open heart surgery were studied by means of a technic previously developed by us to quantitate intravascular and extravascular hemolysis. Endogenous production of carbon monoxide, which correlates quantitatively with red blood cell and hemoglobin catabolism, was measured preoperatively, 5 hr postoperatively, and 24 hr postoperatively. Rates of plasma hemoglobin catabolism and intravascular hemolysis were calculated from serial plasma hemoglobin determinations. Extravascular hemolysis results from catabolism of erythrocytes damaged during perfusion and subsequently sequestered in the reticuloendothelial system. Intravascular hemolysis occurred only during perfusion and averaged 252.22 ± se 49.64 µmoles heme. Extravascular hemolysis measured for the first 5 hr after perfusion averaged 462.48 ± se 68.70 µmoles heme, or 64% of the total calculated red blood cell destruction. In all but one of the eight patients studied 24 hr after perfusion, heme catabolism remained elevated (mean, 46.76 ± se 13.05 µmoles heme/hr compared to a normal value of ≦22 µmoles heme/hr), indicating that extravascular hemolysis was still occurring. This extravascular destruction probably resulted from alterations in the cell membrane induced during the pumping procedure.