August 1999
Volume 63 |
Number 8
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| FDA Alert: Hypotension
and Bedside Leukocyte Reduction Filters |
Larry G. Kessler, Sc.D., Director, Office
of Surveillance and Biometrics
Center for Devices and Radiological Health
U.S. Food and Drug Administration
This is to alert you to the possibility that patients who receive
blood products transfused through a bedside leukocyte reduction
filter may develop a precipitous drop in blood pressure. These
reactions have a rapid onset. In some cases, patients also develop
respiratory distress and shock. In most situations, the reactions
resolve when the transfusion is discontinued and when appropriate
medical intervention is performed.
Reports
Since 1994, FDA has received more than 80 reports of patients
developing significant hypotensive events while receiving blood
products transfused through a bedside leukocyte reduction filter.
It is estimated that approximately 20 million bedside leukocyte
reduction filters were used during this period. Although some
sources have attributed several of these events to the use of
angiotensin converting enzyme (ACE) inhibitors and the use of
negatively charged filter surfaces, FDA's analysis of these reports
indicated that neither ACE inhibitor therapy nor exposure to negatively
charged filter surfaces were consistently associated with these
events. The reactions occurred with a variety of blood products,
although the majority of events occurred during platelet transfusions.
The common variable in almost all of the hypotensive events appeared
to be bedside leukocyte reduction filtration.
It was also noted that there are almost no adverse event
reports associated with the use of in-process, leukocyte-reduced
blood products, i.e., blood products that are leukocyte-reduced
by blood collection centers or laboratories at the time of collection
or after the product was stored. This may be because the longer
storage time allows more time for bradykinin to break down before
the product is transfused.
Cause of Problem
A review of the literature indicates that many authors
believe these reactions occur more frequently in patients receiving
ACE inhibitor therapy. It is hypothesized that these reactions
are due to the ACE inhibitors' tendency to retard degradation
of bradykinin, a potent vasodilator. Some authors have shown evidence
that bradykinin may be generated as a result of filtration at
room temperature or when the storage period for filtered blood
is insufficient to inactivate bradykinin. Others have discussed
the possibility that these reactions occur when the negative charged
membranes in these filters activate Factor XII, one of the blood
clotting factors, which triggers a production of bradykinin. However,
there have also been adverse events reported with the use of positively
charged filters.
Recommendations
Based on the current scientific knowledge, FDA recommends
the following:
Watch for a precipitous drop in blood pressure.
The primary clinical manifestation of the reaction is the sudden
onset of a severe hypotensive episode within one hour of transfusing
blood or blood components through a bedside leukocyte reduction
filter. The hypotension may be associated with respiratory distress,
facial flushing, abdominal pain and nausea, and loss of consciousness.
Immediately stop the transfusion. Should the patient
develop signs of a leukocyte reduction blood filter reaction,
immediately stop the transfusion. A rapid resolution of the symptoms
is usually seen once the transfusion is discontinued. Follow your
institution's protocol for treatment of transfusion reactions.
Use blood products leukocyte-reduced at the time of
collection or during laboratory storage if available. Whenever
feasible, should the patient's condition require such products,
use blood products leukocyte-reduced during the time it was collected
or during its laboratory storage period.
Reporting Adverse Events to FDA
FDA is interested in additional data on adverse events
involving the use of leukocyte reduction filters. Health care
providers employed by health care facilities that are subject
to FDA's user facility reporting requirements should follow the
reporting procedures established by their facility. All other
providers may submit their reports to MedWatch, FDA's voluntary
reporting program. The reports can be submitted by telephone at
(800) FDA-1088, fax (800) FDA-0178, the MedWatch Web site <www.fda.gov/medwatch>
or by mail to MedWatch, FDA, HF-2, 5600 Fishers Lane, Rockville,
MD 20852-9787.
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