OKLAHOMA CITY – A University of Oklahoma study published Sept. 3 in JAMA Surgery reports that acute normovolemic hemodilution (ANH) – a blood-saving method in which a patient's blood is collected before going on heart-lung bypass and reinfused near the end of cardiac surgery – remains underused in the United States at 14.7%. Yet the study found that ANH lowered the likelihood of a transfusion by 27%, a decrease in blood use that could cut costs substantially while still protecting patient safety and outcomes.
Global demand for cardiac surgery is increasing, with more than 1 million procedures performed annually worldwide. In high-income countries like the United States, cardiac surgery remains the largest consumer of blood products, with 30% to 50% of patients receiving red blood cell transfusions.
The lead author of the study, Kenichi Tanaka, M.D., professor and chair of the Department of Anesthesiology at the University of Oklahoma College of Medicine, said he hopes the study jump-starts a new conversation about the validity of ANH in the United States. An international study published earlier this summer in the New England Journal of Medicine showed that ANH does not reduce the need for red blood cell transfusions. However, less than 5% of participants were from the United States, and U.S. patients differ in several important ways.
"We know that patients receiving ANH have survival rates and duration of hospitalization similar to those who receive transfusions, but I believe we are improving resource utilization by performing ANH," Tanaka said. "That is especially true when we take a bleeding patient to the ICU, where we tend to use more resources, therefore leading to higher costs.
"Blood may look reasonably inexpensive compared to some of the medications we use every day, but when you think about how blood is administered, there are multiple steps involved, including testing and typing the blood, before we even purchase it," he added. "Our study estimates that these costs associated with blood processing are almost three times higher than just the cost of acquiring the blood."
In addition to a 27% lower chance of a blood transfusion among those receiving ANH, the study showed that platelet usage was lower in the ANH group. This is clinically significant, as platelets begin to lose functionality if stored in a blood bank for more than a few days.
"Most heart surgery patients are on aspirin prior to their procedures," Tanaka said, "but with ANH, we can preserve the patient's own platelets and protect them from damage caused by the heart-lung machine, allowing them to function more effectively at the end of surgery."
The retrospective study analyzed 16,795 patients from 52 sites in the United States. ANH was performed at 28 sites, representing 2,463 cases, or 14.7%. A limitation of the study is that there is no standardized protocol for ANH, so the study team did not know how much blood was removed nor how much solution was given to maintain a normal volume while the patient was on bypass, Tanaka said.
Tanaka said he plans to continue performing ANH and hopes other centers start using it as well. Future research could combine ANH with clotting factor concentrates, which has been shown to reduce the need for transfusions.
"Even a small reduction in blood usage could significantly impact overall demand, particularly given the rising cost of blood components and the more than 300,000 adult cardiac surgical cases performed annually in the U.S.," he said. "Blood donations are also declining, making an effort to reduce transfusions even more important."
