Extracorporeal Hemolysis of Blood in a Microwave Blood Warmer

Abstract

Marked hemoglobinemia and hemoglobinuria developed in a 13-year-old girl during an operative repair for scoliosis. Residual blood from 1 of 5 U of whole blood, preheated in a microwave blood warmer and administered during the procedure, was found to be hemolyzed. The blood warmer was studied in an effort to reproduce extracorporeal hemolysis. Faulty placement of the blood container in the heating unit was found to produce improper heating through nonrotation of the container. No change in plasma hemoglobin or red-cell filterability was found when normally heated samples were compared with unheated control samples. Improperly heated blood revealed a marked increase in plasma hemoglobin (maximum, 949 mg per 100 ml) and a reduction in filterability of residual cells (maximum, 19 per cent). Morphologic changes (e.g., budding) were identified in improperly but not properly heated red cells. These studies indicate the production of extracorporeal hemolysis and reduced viability of a population of nonhemolyzed cells through improper heating of blood in a microwave blood warmer.