Study shows blood transfusions during heart surgery appear to increase death risk

Patients who received blood platelet transfusions during coronary bypass surgery were more likely to have prolonged hospital stays, longer surgeries, more bleeding and higher risk of infection, stroke and death, according to an international study led by the Virginia Commonwealth University Medical Center.

The findings, published in the August issue of Transfusion, the official journal of the American Association of Blood Banks, contribute to increasingly scientific evidence that blood transfusions do not always improve outcomes from surgery.

"Although this analysis cannot prove that platelet infusions caused the increases in adverse events examined, the data are sobering and should be taken into account when determining the risk-benefit ratio of platelet transfusion therapy," says Dr. Bruce D. Spiess, professor of anesthesiology and lead author on the article. "Prophylactic platelet transfusion appears from this study to increase the risk for serious adverse outcomes in coronary artery bypass graft patients."

The study examined data collected during six randomized, double-blinded Phase III clinical trials conducted from January 1990 through May 1995 at 37 medical centers in the United States, Denmark and Israel for licensure by the Food and Drug Administration of aprotinin, a drug sold by Bayer Corp. under the trade name Trasylol to control bleeding during surgery and avoid the need for transfusions. Data from patients in a pilot study also were included.

Of the 1,720 adult patients analyzed, 284 patients (14.4 percent of the total) received blood platelet transfusions during coronary artery bypass graft surgery, which is a common procedure used to improve blood flow and alleviate chest pains. In coronary artery surgery, doctors remove a clear vein or artery from a leg, arm or the chest and use it to detour blood flow around a blocked artery. Because about 20 percent of coronary bypass patients suffer abnormal bleeding, blood platelets often are given after surgery to prevent or treat bleeding.

The retrospective analysis showed that death was greater than five times more likely to occur in patients receiving platelet transfusions, and stroke was at least three times more likely to occur compared with patients who did not receive transfusions.  In addition:

  • The operation was almost one hour longer for patients receiving a platelet transfusion than for those not receiving one.
  • Almost 20 percent of patients who received platelet transfusions returned to surgery for re-exploration compared with a 2 percent re-operation rate for those who did not receive platelets.
  • The amount of bleeding and length of time in the hospital were greater in the group who received transfusions.

"Blood transfusions may do more harm than good in virtually every instance except trauma," says Spiess. "Blood transfusions increase the risk of pneumonia, infections, heart attacks and strokes. Patients who don't have transfusions often do better."

Platelets are blood cells that strengthen blood vessel walls, help blood to clot and help stop bleeding from cuts. Since the early 1980s, concentrates of platelets increasingly have been used in transfusions, surpassing use of such other blood products as red blood cells and whole blood.

At the same time, however, questions have been raised about the risks of transmission of infectious diseases by blood platelet transfusions. Platelet products also contain a high concentration of donor white blood cells, which can suppress the immune system and increase the risk of infections. A European study of 3,500 patients in intensive care units published in 2002 found that the death rate for critically ill patients who received transfusions was twice as high as those who did not get blood.

As a result of these concerns and the high cost of blood platelets, scientists have been working to develop alternatives to blood platelet transfusion, such as drugs to control bleeding and mechanical devices that can collect a patient's own whole blood during surgery for transfusion, if necessary.  Some patients also store several units of their own blood before surgery.

Spiess says he is working with his colleagues to reduce the use of transfusions during surgeries at the VCU Medical Center by 30 percent or more.

In addition to Spiess, researchers from Harvard Medical School, Emory University, the University of Oklahoma, Harefield Hospital in London, Munich Heart Institute in Germany and the University of Western Ontario, as well as Bayer Corp., participated in the analysis.

http://www.vcu.edu

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