Effects of acute normovolemic hemodilution on post‐cardiopulmonary bypass coagulation tests and allogeneic blood transfusion in thoracic aortic repair surgery: An observational cohort study

Abstract

Background and Aim Perioperative blood transfusion is associated with increased morbidity and mortality. Acute normovolemic hemodilution (ANH) is a blood conservation strategy associated with variable success, and rarely studied in more complex cardiac procedures. The study aim was to evaluate whether ANH improves coagulopathy and reduces blood transfusions in thoracic aortic surgeries. Methods Single‐center observational cohort study comparing ANH and standard institutional practice in patients who underwent thoracic aortic repair with cardiopulmonary bypass (CPB) from 2019 to 2021. Results A total of 89 patients underwent ANH and 116 standard practice. There were no significant differences between the groups in terms of demographic or major perioperative characteristics. In the ANH group coagulation tests before and after transfusion of autologous blood showed decreased INR and increased platelets, fibrinogen, all with p < 0.0005. Coagulation results in the ANH and control groups were not statistically different. The average number of transfused allogeneic products per patient was lower in the ANH versus control group: FFP 1.1 ± 1.6 versus 1.9 ± 2.3 (p = 0.003), platelets 0.6 ± 0.8 versus 1.2 ± 1.3 (p = 0.0008), and cryoprecipitate 0.3 ± 0.7 versus 0.7 ± 1.1 (p = 0.008). Reduction in red blood cell transfusion was not statistically significant. The percentage of patients who received any transfusion was 53.9% in ANH and 59.5% in the control group (p = 0.42). There was no significant difference in major adverse outcomes. Conclusions ANH is a safe blood conservation strategy for surgical repairs of the thoracic aorta. Laboratory data suggests ANH can improve some coagulation values after separation from CPB, and significantly reduce the number of transfused FFP, platelets and cryoprecipitate.

Management of severe peri-operative bleeding: Guidelines from the European Society of Anaesthesiology and Intensive Care

“…The amount of blood removed depends on various factors such as baseline Hb concentration, expected blood loss and haemodynamic stability. The use of the technique of ANH has been shown to reduce transfusion of allogeneic blood products 399–403 . Benefits of ANH include decreasing Hb concentration during the period when most surgical blood loss is occurring, thereby minimising the effects of loss of RBCs; re-infusing the patient's own fresh whole blood containing RBCs, platelets and clotting factors when it is needed during or shortly after the surgical procedure.…”

“…The use of the technique of ANH has been shown to reduce transfusion of allogeneic blood products. [399][400][401][402][403] Benefits of ANH include decreasing Hb concentration during the period when most surgical blood loss is occurring, thereby minimising the effects of loss of RBCs; reinfusing the patient's own fresh whole blood containing RBCs, platelets and clotting factors when it is needed during or shortly after the surgical procedure. In cardiac surgical patients with normal to high initial Hb concentrations, a decreased blood viscosity because of ANH may have cardioprotective effects.…”

Management of Combined Cardiac Surgery Using Cardiopulmonary Bypass With Acute Normovolemic Hemodilution in a Jehovah’s Witness: A Case Report

“…For example, ANH reportedly improved the aPTT and fibrinogen levels slightly in cardiac surgery under CPB [ 3 ]. In thoracic aortic surgery, ANH improved the PT-INR, platelet count, and fibrinogen levels and reduced the transfusion of fresh frozen plasma and platelet concentrate [ 15 ]. Another study demonstrated the hemostatic effect of ANH on cardiac surgery under CPB [ 16 ].…”

Perioperative Management in Pulmonary Endarterectomy

“…This is an important part of the blood conservation strategy and clotting preservation. 92,93 The pump prime can be done with crystalloid or colloids (i.e., human albumin). While leading PEA centers differ in the priming methods, mortality outcomes are similar.…”