Acute Normovolemic Hemodilution Significantly Reduces RBC Transfusion and Lactic Acidosis Following Cardiac Surgery-A Propensity-Matched Study.

Background: Bleeding represents a major complication in heart surgeries. However, even small amounts of allogeneic blood are associated with reduced long-term survival and short-term complications. Acute normovolemic hemodilution (ANH) serves as a viable alternative, but its effectiveness and safety remain controversial.

Objective: We aimed to clarify the effects of mild-volume ANH on blood transfusions and short-term complications following heart surgeries.

Methods: This was a quasi-experimental study in a referral center on 2271 patients. We performed an extensive propensity-score matching to mitigate the lack of random assignment and potential selection bias. This resulted in 778 patients with no significant differences in 28 variables, including clinical, paraclinical, and operative features.

Results: ANH significantly reduced the rate of RBC transfusion by 16% (50.9% vs. 60.9%; RR: 0.84; P = 0.006) and the number of transfused RBCs by 0.24 units (0.96 ± 1.32 vs. 1.20 ± 1.39; P = 0.013) but did not affect the transfusion of FFP or platelets. Furthermore, ANH significantly lowered the incidence of lactic acidosis by 53% (6.8 vs. 11.3%; RR: 0.47; P < 0.001) but had no notable impact on other short-term outcomes following heart surgery, including mortality, re-intubation, re-exploration, delayed sternal closure, length of ICU stay, or duration of mechanical ventilation.

Conclusion: Mild-volume ANH significantly reduced the rate and amount of perioperative RBC transfusions, as well as the incidence of lactic acidosis following heart surgery. ANH did not affect the incidence of other complications during hospitalization.

Implication: This suggests that ANH could be a safe and beneficial blood conservation technique. Further randomized clinical trials are needed to evaluate its effects.