title: Postoperative bypass bleeding: a bypass-associated dilutional (BAD) coagulopathy?
abstract: A number of associations with post-bypass bleeding have been described in the accompanying paper. Herein we hypothesize that dilution is an underlying cause through a malign series of bypass-associated events. Heparinized blood behaves anomalously when diluted. Clotting times first shorten somewhat, then--as the dilution of whole blood approaches 50%--rapidly lengthen to unclottability. During cardiopulmonary bypass, low blood volume patients are at a significant risk of clotting factor dilution which will always be more severe than the level of whole blood dilution. If severe enough, this dilution may lower plasma clotting factors to a critical level and may result in excess protamine administration, secondary to overestimation of heparin. The presence of un-neutralized protamine combined with critically lowered clotting factors leads to marked coagulopathy.
authors.affiliation: School of Medicine, Department of Pathology and Human Anatomy, Loma Linda University, Loma Linda, CA 92350, USA. bbull@llu.edu
authors.forename: Brian S
authors.initials: BS
authors.lastname: Bull
authors.forename: Karen L
authors.initials: KL
authors.lastname: Hay
authors.forename: Paul C
authors.initials: PC
authors.lastname: Herrmann
mesh_terms: D001778:Blood Coagulation Disorders / Q000209:etiology*; D001779:Blood Coagulation Factors / Q000032:analysis / Q000378:metabolism*; D002315:Cardiopulmonary Bypass; D006493:Heparin / Q000097:blood; D006801:Humans; D019106:Postoperative Hemorrhage / Q000209:etiology*; D011479:Protamines / Q000097:blood; D012737:Sex Factors; D065227:Transfusion Reaction
chemical_list: D001779:Blood Coagulation Factors; D011479:Protamines; D006493:Heparin