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.

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.

Background: Acute normovolemic hemodilution (ANH) is a blood conservation strategy in cardiac surgery, predominantly used in coronary artery bypass graft (CABG) and/or valve procedures. Although higher complexity cardiac procedures may benefit from ANH, concerns for hemodynamic instability, and organ injury during hemodilution hinder its wider acceptance. Laboratory and physiological parameters during hemodilution in complex cardiac surgeries have not been described. Study design and methods:This observational cohort (2019-2021) study included 169 patients who underwent thoracic aortic repair, multiple valve procedure, concomitant CABG with the aforementioned procedure, and/or redo sternotomies. Patients who received allogeneic blood were excluded. Statistical comparisons were performed between ANH (N = 66) and non-ANH controls (N = 103). ANH consisted of removal of blood at the beginning of surgery and its return after cardiopulmonary bypass.Results: Intraoperatively, the ANH group received more albumin (p = .04) and vasopressor medications (p = .01), while urine output was no different between ANH and controls. Bilateral cerebral oximetry (rSO 2 ) values were similar before and after hemodilution. During bypass, rSO 2 were discretely lower in the ANH versus control group (right rSO 2 p = .03, left rSO 2 p = .05).No differences in lactic acid values were detected across the procedural continuum. Postoperatively, no differences in extubation times, intensive care unit length of stay, kidney injury, stroke, or infection were demonstrated.Discussion: This study suggests hemodilution to be a safe and comparable blood conservation technique, even without accounting for potential benefits of reduced allogenic blood administration. The study may contribute to better

Background: Acute normovolemic hemodilution (ANH) is a blood conservation strategy in cardiac surgery, predominantly used in coronary artery bypass graft (CABG) and/or valve procedures. Although higher complexity cardiac procedures may benefit from ANH, concerns for hemodynamic instability and organ injury during hemodilution hinder its wider acceptance. Laboratory and physiological parameters during hemodilution in complex cardiac surgeries have not been described. Study Design and Methods: This observational cohort (2019-2021) study included 169 patients who underwent thoracic aortic repair, multiple valve procedure, concomitant CABG with the aforementioned procedure, and/or redo sternotomies. Patients who received allogeneic blood were excluded. Statistical comparisons were performed between ANH (N=66) and non ANH controls (N=103). ANH consisted of removal of blood at the beginning of surgery and its return after cardiopulmonary bypass (CPB). Results: Intraoperatively, the ANH group received more albumin (p=0.04) and vasopressor medications (p=0.01); while urine output was no different between ANH and controls. Bilateral cerebral oximetry (rSO2) values were similar before and after hemodilution. During bypass rSO2 were discretely lower in the ANH vs. control group (right rSO2 p=0.03, left rSO2 (p=0.05). No differences in lactic acid values were detected across the procedural continuum. Postoperatively, no differences in extubation times, ICU length of stay, kidney injury, stroke or infection were demonstrated. Discussion: This study suggests hemodilution to be a safe and comparable blood conservation technique, even without accounting for potential benefits of reduced allogenic blood administration. The study may contribute to better understanding and wider acceptance of ANH protocols in high risk cardiac surgeries.