Acute Normovolemic Hemodilution (ANH) impacts postoperative coagulation profile and bleeding in Adult Cardiac Surgery

Introduction: The coagulation profile of cardiac surgery patients is impacted by pro-inflammatory effects caused by procedures involving cardiopulmonary bypass. In order to counteract these effects, pharmacological therapies and allogeneic blood transfusions are required. The strategy of Acute normovolemic hemodilution also known as “intraoperative autologous donation” is also a viable option to address these negative effects. The theoretical basis for ANH is that the removed blood of a patient’s own self is shielded from the inflammatory response of blood cells to the bypass circuit. ANH is an infrequently practiced strategy at various cardiac surgery institutes within Pakistan to enhance coagulation profile, decrease the need for blood transfusions despite being an established approach abroad. Aims and Objectives: The objective of our study is to compare the effect of ANH on patients undergoing adult cardiac surgery in a sample group versus a control group with the primary endpoint of postoperative drain output as a measure of effectiveness of blood coagulation profile. Blood coagulation profiles were also compared between the two groups as secondary variables. Place and Duration of study: The study was conducted at the Faisalabad Institute of Cardiology from December 21st, 2023 to February 13th, 2024. Material and Methods: A randomized controlled trial involving 60 patients over the age of 12 years who were to undergo adult cardiac surgery was conducted. An online research randomizer software randomly selected them into two equal groups, sample and control (n=30). The ANH volume retrieved from the patient's central vein in the sample group was used to fill the CPD blood transfusion bags after administering anesthesia. After the patients in both groups were weaned off CPB and protamine administered to neutralize heparin, ANH blood was infused back into the patients in the sample group whereas the control group received allogenic blood only. Chi square test was applied to all qualitative variables and Independent Samples t-test for all quantitative variables. The results were analyzed using SPSS version 25, and a p-value ? 0.05 was considered statistically significant. Results: Hemoglobin (12.9±0.90 g/dL in ANH and 11.8±1.00 g/dL in non-ANH) and aPTT levels (34.2±6.06 seconds in ANH and 54.2±10.95 seconds in non-ANH) were statistically significant (p-value <0.01). In the ANH group, the mean value (623.3±86.28 mL) of postoperative drain output significantly decreased by approximately 220mL compared to the non-ANH group (842.3±99.26 mL) (p-value <0.01). Conclusion: ANH positively conserves most of the coagulation profile parameters. It assists in reducing postoperative bleeding and the volume of allogeneic blood required perioperatively in cardiac surgery.