BETHESDA, Md. - Experimental blood substitutes should be tested only in patients at high risk of death, doctors and researchers said at a workshop reviewing the products.
Previous studies were too broad, putting participants at unnecessary risk, participants in the Food and Drug Administration meeting said yesterday.
Artificial blood raised death risks by 30 percent and almost tripled the odds of heart attacks in 16 clinical trials analyzed by researchers, according to the Journal of the American Medical Association. Lead study author Charles Natanson said he feels the products should be tried only on patients sure to die.
"There have been no meaningful beneficial effects reported in any trial" of these products, said Natanson, who is a National Institutes of Health researcher. "The only population where a justification could be made is that with an expectation of 100 percent mortality."
Though the goal of developing blood substitutes is important, more studies should be done in animals, Natanson said during the meeting in Bethesda.
The blood substitutes in Natanson's analysis were made by Baxter International Inc., Cambridge, Mass.-based Biopure Corp., Hemosol BioPharma Inc., Northfield Laboratories Inc., and Sangart Inc. They contain hemoglobin, the carrier of oxygen in the blood.
Researchers have long tried to find an alternative to human blood for cases of severe blood loss, which accounts for a third of trauma deaths. Paramedics in emergencies usually substitute saline solution for blood, which must be matched by type and kept cold.
The military services have pressed for blood substitutes that could be used on the battlefield, and representatives objected yesterday to Natanson's proposal to test the products only in those who are expected to die.
A good study could be conducted in young people who were seriously wounded, of whom 62 percent were likely to die anyway, said Commander Daniel Freilich, head of the hematomimetics program at the Naval Medical Research Center.
Demetrios Demetriades, a trauma surgeon at the University of Southern California, suggested the FDA make the products available for so-called compassionate use, when no other treatments are available, and in patients such as Jehovah's Witnesses, for whom blood transfusions are unacceptable.