A standard medical practice at some of the nation's largest children's hospitals – using whole, recently donated blood for certain infant open heart surgeries – may do more harm than good. Researchers from Wake Forest University Baptist Medical Center and the University of Texas, Southwestern Medical School reported the findings in this week's New England Journal of Medicine.
"A long-time accepted practice has now been tested, and our results show it could actually be worse for infants," said Steven Mou, M.D., principal investigator and assistant professor of anesthesiology at Wake Forest Baptist. "Abandoning this practice could help reduce hospital stays for infants who have surgery for heart defects and help reduce some of the inventory problems that blood banks grapple with."
The study involved 200 children under age 1 who required heart surgery using the heart-lung bypass machine, which adds oxygen to blood and maintains circulation while the heart is stopped for surgery. The research team compared two different blood products used to fill, or "prime" the equipment: whole blood donated within the previous 48 hours and "reconstituted" blood formed by combining red blood cells and plasma. Plasma can be stored up to a year and red cells for 42 days after donation.
The results showed that patients who got the whole blood did no better in terms of bleeding, transfusion requirements, after-surgery complications and mortality than patients who got the reconstituted blood. In fact, infants who received the reconstituted blood had a shorter stay in the intensive care unit (70 hours versus 97 hours) and spent less time on respirator (36 hours versus 53 hours) – which could also dramatically affect health care costs.
The researchers believe the differences were because the patients receiving reconstituted blood were observed to accumulate less fluid. Fluid accumulation is a marker for inflammation.
The research was conducted between January 1999 and January 2003 at the University of Texas, Southwestern Medical School, Children's Medical Center of Dallas during Mou's fellowship training. He is now in Wake Forest Baptist's Department of Anesthesia, section of pediatric critical care.
Mou said that some surgeons insist on using whole blood that has been donated within 48 hours, believing that it may reduce potential complications from the heart-lung bypass machine, including bleeding and inflammation. Inflammation is the body's response to exposure to a foreign object – the plastic tubing through which the blood circulates.
Research in children has shown that blood loss after heart surgery can be minimized if fresh whole blood is used for transfusions. However, until the research by Mou and colleagues, no study had addressed whether this benefit also applies to using fresh, whole blood for priming the heart-lung bypass equipment.
"The notion that fresh, whole blood is critical for optimal outcomes from congenital heart surgery has long been accepted, but had never been tested," says Mou. "Our data indicate that this practice is not superior to standard priming, but more importantly, we have shown that it is detrimental to patients, leading to increased intensive care length of stay and more time on the respirator."
Each year in the United States, about 19,000 infants undergo heart surgery, with the majority requiring cardiopulmonary bypass. While the reconstituted blood may be more expensive (about $110 per operation), the cost associated with a longer intensive care stay is about $5,750, and greatly outweighs the extra cost of the reconstituted blood, the authors said.
"The potential aggregate cost savings from the use of reconstituted blood for bypass priming could be substantial," said Mou.
Before beginning the research, the authors surveyed several children's hospitals, including prominent cardiac centers such as Children's Hospital of Philadelphia and Texas Children's in Houston and found that in these centers the use of fresh whole blood for circuit priming was standard practice in infants. At Brenner Children's Hospital, part of Wake Forest Baptist, pediatric heart surgeons prime the equipment with stored red blood cells.