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 acute 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 from 2019 to 2021. Results: 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 vs control group: FFP 1.1 +/-1.6 vs 1.9 +/-2.3 (p=0.003), platelets 0.6 +/-0.8 vs 1.2 +/-1.3 (p=0.0008), and cryoprecipitate 0.3 +/-0.7 vs 0.7 +/-1.1 (p=0.008). Reduction in RBC 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 that ANH can improve coagulopathy after separation from CPB, and significantly reduce the number of transfused FFP, platelets and cryoprecipitate.

Effects of acute normovolemic hemodilution on allogeneic blood transfusion & coagulation in orthognathic surgery: A randomized study

“…Of note, some studies have also demonstrated a reduction in transfusion 20,21 . Indeed, some studies demonstrate that transfusion cannot be reduced 8,22 . In our study, the discrepancy might have occurred for the following reasons.…”

“…However, this technique is not considered a routine treatment. Besides, under diverse circumstances, the effect of this technique remains inconsistent 7–10 . Therefore, in this randomized, single‐blind study, we evaluated if ANH could reduce allogeneic red blood cell transfusion in orthognathic surgery.…”

“…Besides, under diverse circumstances, the effect of this technique remains inconsistent. [7][8][9][10] Therefore, in this randomized, single-blind study, we evaluated if ANH could reduce allogeneic red blood cell transfusion in orthognathic surgery. Additionally, the effect of ANH on coagulation function was also assessed.…”

Hemodilution in high‐risk cardiac surgery: Laboratory values, physiological parameters, and outcomes

“…3,4 However, recent studies showed ANH to be associated with reduced transfusions in complex thoracic aortic repairs. 8,16,17 Possible reasons for relative under-utilization of hemodilution in such surgeries are concerns for hemodynamic instability during and after removal of autologous blood, as well as decreased oxygen delivery during the hemodilution period. [18][19][20] Hence, rather than addressing transfusion-sparing benefits of ANH that have been studied before, we focused on assessing perturbations in laboratory, physiological parameters, and outcomes to assess safety of hemodilution in complex cardiac surgeries.…”

“…Importantly, this technique has been under‐studied in complex and higher‐risk cardiac surgeries, compared to less complex procedures such as CABG, single valve, or concomitant CABG and single valve procedures 3,4 . However, recent studies showed ANH to be associated with reduced transfusions in complex thoracic aortic repairs 8,16,17 . Possible reasons for relative under‐utilization of hemodilution in such surgeries are concerns for hemodynamic instability during and after removal of autologous blood, as well as decreased oxygen delivery during the hemodilution period 18–20 .…”