Alterations in 2-3 Diphosphoglycerate and O ₂ Hemoglobin Affinity in Patients Undergoing Open-Heart Surgery

Alterations in red blood cell (RBC) 2-3 diphosphoglycerate (2-3 DPG) and hemoglobin affinity for oxygen were studied in 14 patients undergoing heart-lung bypass. RBC 2-3 DPG decreased with institution of bypass and continued to decrease during bypass. The day following heart-lung bypass RBC 2-3 DPG levels returned to normal, but were lower than preoperative control values. In vitro studies demonstrated that a portion of the RBC 2-3 DPG loss is due to circulation of blood through the oxygenator itself. Other factors appear to be involved. Hemoglobin affinity for oxygen increased during heart-lung bypass in most patients It was found that the increased affinity was less than would be expected relative to the demonstrated RBC 2-3 DPG decrease, and that a progressive decrease in RBC pH partially corrected the alteration in O 2 affinity. Our data suggest that other factors are involved in the demonstrated alteration in hemoglobin affinity for O 2 , and these factors are discussed.