A cohort study of coagulation parameters and the use of blood products in surgery of the thoracic and thoracoabdominal aorta

OBJECTIVES: We sought to study the hemostatic profile and the use of blood products in patients undergoing thoracic and thoracoabdominal aortic aneurysm repair. METHODS: This is a cohort study comparing three groups of patients: 7 undergoing elective acute normovolemic hemodilution (ANH); 15 undergoing elective procedures without ANH (non-ANH); and 8 undergoing repair of ruptured thoracoabdominal aneurysms. A control group of 10 patients was used for comparison of preoperative hemostasis. The parameters studied were platelet concentration, partial thromboplastin time (PTT), and international normalized ratio (before and after surgery), packed red blood cells, fresh frozen plasma, platelets, cryoprecipitates, donor exposure, and use of desmopressin and epsilon-aminocaproic acid. Analysis of variance and multiple stepwise regression analysis were used. RESULTS: Before operation the patients with aneurysms had PTTs prolonged compared with control subjects (P <.05). After operation the ANH group had higher platelet counts than the ruptured group (P =.001) and higher platelet counts (P =.05) and lower PTTs (P =.001) than the non-ANH group. The ANH group was transfused fewer platelets than the non-ANH group (P =.001) and less of every blood product than the ruptured group (P =.05); statistically significant differences were not observed for packed red blood cells, fresh frozen plasma, or platelets. The ANH group was exposed to an average of 65 donors fewer than the ruptured group (P <.001) and 34 fewer than the non-ANH group (P <.05). These differences could not be explained by baseline coagulation status or by the intraoperative use of desmopressin or epsilon-aminocaproic acid. CONCLUSIONS: The coagulation abnormality identified before surgery is that of higher PTT values, suggesting a disturbance of the extrinsic coagulation pathway. Blood losses, donor exposure, and platelet use were highest in the ruptured group and lowest in the ANH group. After surgery the ruptured group exhibited the worst coagulation parameters, and the ANH group exhibited the best with higher platelet count and lower PTT values than the other groups. The ANH technique appears to be an useful adjunct in the anesthetic management of these patients.