Female Plasma May Not Be As Harmful As Once Thought
As the national blood banking community considers limiting the use of plasma from female donors because of a rare but potentially catastrophic lung condition, researchers from Duke University Medical Center have shown that this policy change might be premature.
In their analysis of 8,300 heart surgery patients, the researchers found no association between transfused female plasma and any adverse outcome. In fact, they found a significant decrease in complications in patients receiving only female plasma.
Plasma, which makes up about 55 percent of blood's total volume, is the liquid portion of blood that is separated from oxygen-carrying red blood cells after donation. It is pale yellow in color and is usually given to patients after surgery to help restore their blood's normal clotting ability.
Transfused plasma from female donors has been implicated as a cause of a rare condition known as transfusion-related acute lung injury (TRALI), in which the lungs fill with fluid. The incidence of TRALI is hard to determine, and it is estimated that it occurs at a rate of 1 in 1,300 transfusions to 1 in 5,000 transfusions. It is the leading cause of transfusion-related death in the United States.
"Our data showed no deleterious effect associated with female plasma transfusion, and even pointed toward the possibility of a protective effect," said Duke anesthesiologist Ian Welsby, M.D. Collaborator and co-author Marla Brumit, M.D., from the Carolinas Region of the American Red Cross, presented the results of the Duke study at the annual meeting of the American Association of Blood Bankers in Anaheim, Calif.
While red blood cells can easily be separated from whole blood, antibodies from immune cells remain in plasma products, which is the root of the problem. Pregnant women develop a specific kind of antibody in response to carrying a baby, which is genetically half mother and half father. The more children a woman has, the more of these antibodies are produced. It is thought that some recipients of transfused plasma from women react negatively to these antibodies in the plasma.
Because of this apparent risk, the United Kingdom has used only plasma from male donors since 2004.
"TRALI is important and effective preventative steps should be taken to prevent it; however, we believe that more prospective data needs to be evaluated prior to enacting a policy such as the one in the United Kingdom," Welsby continued. "By focusing on a single rare event, they may be missing the forest for the trees. The bottom line is that female donor plasma may not be as harmful as it has been made out to be and antibodies from female plasma are only one source of TRALI."
The Duke researchers scoured their extensive database of patients who underwent cardiac surgery over a ten-year period beginning in 1993, looking for any possible negative effects in patients who received female plasma. These patients were chosen because surgery and the use of the heart-lung machine during a procedure are both important risk factors for developing TRALI.
Of the sampled patients, 25.6 percent received plasma transfusions, of which 44.8 percent came from female donors.
"We found that the volume of plasma a patient received was associated with higher mortality, which makes sense, since if you can stop the bleeding sooner, the patient will do better," Welsby said. "However, there was no association between female plasma and death, respiratory complications or even delayed recovery. These results raise questions concerning the overall benefit of a broad policy that completely excludes the transfusion of female plasma."
The researchers were also intrigued by the finding that female plasma may actually reduce complications after heart surgery. They are planning future prospective studies to better understand this phenomenon.
"Theoretically, there are some plausible reasons supporting the idea that female plasma may help patients," Welsby said. "Female plasma contains estrogen and other hormones that are known to promote blood clotting and have anti-inflammatory effects."