'Old' Blood Raises Heart Surgery Risk
Patients Who Received Newer Blood Fared Better
March 19, 2008 -- Heart surgery patients who get transfusions with blood
stored for longer than two weeks have a higher risk of complications and death
than patients who get newer blood, a new study finds.
The risk of death following heart surgery was 30% higher among patients
transfused with blood stored for longer than 14 days, researchers from the
Cleveland Clinic reported.
These patients were also more likely to suffer surgical complications,
including longer airway intubation, kidney failure, and infection.
The study, which appears in tomorrow's New England Journal of
Medicine, is not the first to suggest a link between stored blood age and
surgical outcomes. But it is among the largest and most rigorously designed
investigations ever to address the question.
"We know that from the time blood is donated changes start
occurring," Cleveland Clinic anesthesiologist and study researcher Colleen
Gorman Koch, MD, tells WebMD.
New Blood, Old Blood
More than 14 million units of blood are transfused each year in the United
States, according to government figures.
Transfusions save lives, but there is also extensive evidence linking them
to an increased risk for complications and death in critically ill
Studies examining the impact of blood age on surgical outcomes have been
more equivocal, with some finding older blood to be associated with poorer
outcomes and others finding no link.
The FDA allows red blood cells to be stored for up to 42 days. The
average time of storage is estimated to be 15 days in a 2005 government
In an effort to shed light on the issue, Koch and colleagues reviewed
outcomes among 6,002 patients who had coronary artery bypass surgery,
heart-valve surgery, or both at the Cleveland Clinic between the summer of 1998
and January 2006.
About half of the patients had transfusions from blood that had been stored
for 14 days or less, and half had transfusion from blood stored longer. The
average length of storage was 11 days in the "new blood" group and 20
days in the "older blood" group.
After controlling for a long list of factors that could affect outcomes and
survival, the researchers reported statistically significant increases in death
and complications among the patients treated with the older blood.
These patients had higher rates of death prior to leaving the hospital
following surgery (2.8% vs. 1.7%), intubation lasting more than 72 hours (9.7%
vs. 5.6%), kidney failure (2.7% vs. 1.6%), and potentially life-threatening
blood infections (4% vs. 2.8%).
The death rate a year after surgery among patients infused with older blood
was also significantly higher (11% vs. 7.4%).
Is That Transfusion Needed?
Koch says the research linking transfusions to poorer outcomes should make
cardiac surgeons stop and think before they give patients transfusions they may
"Most [cardiac surgery] transfusions involve one to two units," she
says. "A one-unit transfusion isn't done because a patient is bleeding to
But she adds that it is too soon to call for policy changes shortening the
time that stored blood can be kept.
The researchers will conduct a randomized, controlled trial that may provide
definitive answers within two-and-a-half years, she says.
In an editorial published with the study, John W. Anderson, MD, of the VA
San Diego Healthcare System, wrote that the findings should "arm those who
believe that the transfusion of older red-cell units carries risk and should be
But he added that the study will not end the debate, because it included a
relatively homogeneous group of patients.
"The study simply adds an important piece to the discussion of the risks
of transfusion but does not settle the issue of best practices," he