Posted by Matt. on March 15, 1999 at 14:28:32 {MWb3SmLJcUBu2}:
Subject: Blood Transfusions Kill Patients, Say Doctors
Blood Transfusions Kill Patients, Say Doctors
LONDON (NYT Syndicate) -- Blood transfusions given routinely to tens
of thousands of critically ill patients may be killing
them, doctors
have found.
Canadian researchers have found that giving extra blood, despite its
essential role in maintaining life, can cause more harm than good in
those who have been thought in greatest need of it.
The
unexpected finding, from a study of more than 800 critically ill
patients, will deliver a serious blow to the idea of accident
victims being stretchered into a hospital with a bag of life-giving
blood suspended above
them.
Doctors had assumed that any means of boosting oxygen supply to the
body's tissues in those who were seriously ill would improve their
chances of survival.
But the Canadian research shows that critically ill patients
who
received more blood were up to twice as likely to die as those who
received less.
In Britain, an estimated 800,000 patients receive blood transfusions
each year, most after routine surgery, and demand for blood is
rising.
Using less blood would also save costs and conserve a scarce
resource.
The aim of a transfusion is to restore levels of hemoglobin, the
oxygen- carrying constituent of red blood cells. Normal levels of
hemoglobin range from 14
to 17 grams per deciliter.
In the Canadian study, half of the 838 seriously unwell patients
were given enough blood to raise their hemoglobin over 10 grams per
deciliter, while the other half were restricted to only 7-9
grams
per deciliter, half the normal level.
One third of the restricted group received no blood at all. On
average the restricted group received three units of blood (one and
a half liters) less than the unrestricted group _ but
more of them
survived.
Among patients under 55 and the less severely ill, those who
received less blood (or no blood at all) were half as likely to die
as those who received more.
The only exceptions were patients with heart
attacks and unstable
angina (chest pain).
Dr. Paul Hebert and his colleagues from the University of Ottawa say
in the New England Journal of Medicine: "Our findings indicate that
the use of a threshold...as low as 7 grams of
hemoglobin per
deciliter...was at least as effective as and possibly superior to a
liberal transfusion strategy...in critically ill patients."
It is well-known that giving too much blood or other infusions can
cause heart
attacks or water on the lungs because of the effort
required to pump the extra liquid around the body. But the
researchers found these factors could not explain the differences
they found.
In a commentary on the findings, Wesley
Ely and Gordon Bernard of
the Vanderbilt School of Medicine in Nashville, Tenn., say it is
difficult to explain the harm caused by liberal transfusion.
One possibility is that a transfusion, like a transplant, delivers a
shock
to the immune system. "Harmless" viruses in the blood may also
be implicated.
They say more trials are needed to determine the best treatment for
critically ill patients.
"With such knowledge, more physicians will be able to
adhere to the
dictum 'first do no harm,' and we will have a surplus of blood for
transfusion rather than a shortage."
Copyright 1999 The New York Times Syndicate. All rights reserved
March 9, 1999