ANH Does Not Appear to Reduce Need for RBC Transfusion in Cardiac Surgery

Acute normovolemic hemodilution (ANH) does not appear to reduce the need for red blood cell transfusion among patients undergoing cardiac surgery with cardiopulmonary bypass, according to findings published in the New England Journal of Medicine.

In the multinational, phase 3 trial, investigators randomized 2,010 adult patients to receive either usual care (1,000 patients) or ANH (1,010 patients), a blood conservation technique that involves removing a patient’s blood before bypass and reinfusing it after surgery.

At hospital discharge, 27.3% of patients in the ANH group and 29.2% in the usual care group received at least one unit of allogeneic red blood cells (relative risk, 0.93; 95% CI, 0.81–1.07; P=0.34). The median number of units transfused was two in both groups.

Thirty-day mortality rates were similar between groups: 1.4% in the ANH group and 1.6% in the usual care group. Median blood loss at 12 hours post-surgery was similar (290 mL in the ANH group versus 300 mL in the usual care group), though a higher proportion of ANH patients required reoperation for bleeding (3.8% versus 2.6%).

While ANH did not reduce the proportion of patients receiving allogeneic RBC transfusion, study co-author Kenichi Tanaka, MD, professor and chair of anesthesiology at the University of Oklahoma College of Medicine, noted that the findings may not be fully generalizable to U.S. practice. He cited the small proportion of U.S. participants, differences in patient size and clinical protocols, and the trial’s lack of a standardized transfusion protocol.

Tanaka emphasized that ANH may still be beneficial in select patient populations, particularly those for whom transfusion is not an option.

“I plan to continue practicing ANH,” he said. “It is also an option for Jehovah’s Witness patients whose beliefs stipulate they cannot receive blood transfusions. At the least, the study proved that there is no downside for ANH. I believe ANH can be part of a multi-pronged blood conservation strategy in the U.S., where blood product costs are very high.”