Kat Piper
Mounting evidence that routinely giving blood transfusions to patients could actually increase their risk of death or other complications has prompted calls for medical staff to be more cautious about who they administer transfusions to.
Jehovah's Witnesses refuse blood transfusions based on a passage from the Bible, which forbids them to "eat blood," but many still successfully undergo operations including open-heart surgery. This, say some surgeons and anaesthetists, should be the way most operations are performed.
Higher death rates
The danger is not from infections such as HIV but from something to do with the blood itself. Many studies over the past ten years have shown that transfusions, particularly of those involving red blood cells, are linked to higher death rates in patients who have had a heart attack, heart surgery, or who are in critical care.
Although the exact nature of the link is not yet known, it seems likely that chemical changes in ageing blood, their impact on the immune system, and the blood's ability to deliver oxygen are key. "Probably 40 to 60 percent of blood transfusions are not good for the patients," said Bruce Spiess, a cardiac anaesthesiologist at Virginia Commonwealth University in Richmond, to New Scientist.
Transfusions first became part of medical procedure during World War One when they were used as a last resort to treat soldiers who had lost a lot of blood. Its usage is now no longer confined to cases of catastrophic bleeding, but is often employed as a routine treatment for patients undergoing surgery or intensive care.
Background
The rationale behind giving transfusions is that by giving patients red blood cells, oxygen is better transported around the body thereby increasing the chances of survival. A healthy person has 120 to 170 grams per liter of haemoglobin—the oxygen-carrying protein in red cells—in their blood, usually with 35 to 50 percent of their blood volume being composed of red cells. Doctors commonly decide to give patients a transfusion if the haemoglobin levels fall to between 70 and 100 grams per litre.
Less effective blood
A 1999 Canadian study of 838 critical care patients found that significantly fewer patients (22 versus 28 percent) died in hospital when treatment with transfusion was limited to patients with haemoglobin levels of less than 70 grams per litre. In 2004, a study published in the Journal of the American Medical Association showed that heart attack patients with red blood cell levels of over 25 percent were three times more likely to die or have another heart attack within 30 days of having a transfusion.
A U.K. study of almost 9,000 heart surgery patients between 1996 and 2003 supports this finding, and indicates a six-fold increase in the risk of death after 30 days with a three-fold increase in the risk within one year following surgery. Transfusions were also associated with more infections and higher incidences of stroke, heart attack, and kidney failure. These complications were usually linked to a lack of oxygen to body tissues.
Little benefit
"There is virtually no high-quality study in surgery, or in intensive or acute care—outside of when you are bleeding to death—that shows that blood transfusion is beneficial and many that show it is bad for you," said Gavin Murphy, a cardiac surgeon at the Bristol Heart Institute and leader of the U.K. study.
Recommendations ignored
Many experts are now worried that guidelines are being ignored. They suggest that transfusions should only be given as a last resort and that preventing blood loss in the first place whilst ensuring patients are not anaemic before they undergo surgery should be prioritised.
"Usually when there is any clinical uncertainty about a treatment you don't give it, but with transfusions we do," said James Isbister of the Royal North Shore Hospital in Sydney, Australia, who is an adviser to the Australian Red Cross Blood Service. But Mr. Isbister still encourages people to donate blood as it is used to treat other conditions as well as extreme blood loss.
The specific reasons why blood transfusions appear to be harmful to some patients are not yet fully understood and further research is being strongly encouraged by health authorities, including the U.S. National Institutes of Health.
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Mounting evidence that routinely giving blood transfusions to patients could actually increase their risk of death or other complications has prompted calls for medical staff to be more cautious about who they administer transfusions to.
Jehovah's Witnesses refuse blood transfusions based on a passage from the Bible, which forbids them to "eat blood," but many still successfully undergo operations including open-heart surgery. This, say some surgeons and anaesthetists, should be the way most operations are performed.
Higher death rates
The danger is not from infections such as HIV but from something to do with the blood itself. Many studies over the past ten years have shown that transfusions, particularly of those involving red blood cells, are linked to higher death rates in patients who have had a heart attack, heart surgery, or who are in critical care.
Although the exact nature of the link is not yet known, it seems likely that chemical changes in ageing blood, their impact on the immune system, and the blood's ability to deliver oxygen are key. "Probably 40 to 60 percent of blood transfusions are not good for the patients," said Bruce Spiess, a cardiac anaesthesiologist at Virginia Commonwealth University in Richmond, to New Scientist.
Transfusions first became part of medical procedure during World War One when they were used as a last resort to treat soldiers who had lost a lot of blood. Its usage is now no longer confined to cases of catastrophic bleeding, but is often employed as a routine treatment for patients undergoing surgery or intensive care.
Background
The rationale behind giving transfusions is that by giving patients red blood cells, oxygen is better transported around the body thereby increasing the chances of survival. A healthy person has 120 to 170 grams per liter of haemoglobin—the oxygen-carrying protein in red cells—in their blood, usually with 35 to 50 percent of their blood volume being composed of red cells. Doctors commonly decide to give patients a transfusion if the haemoglobin levels fall to between 70 and 100 grams per litre.
Less effective blood
A 1999 Canadian study of 838 critical care patients found that significantly fewer patients (22 versus 28 percent) died in hospital when treatment with transfusion was limited to patients with haemoglobin levels of less than 70 grams per litre. In 2004, a study published in the Journal of the American Medical Association showed that heart attack patients with red blood cell levels of over 25 percent were three times more likely to die or have another heart attack within 30 days of having a transfusion.
A U.K. study of almost 9,000 heart surgery patients between 1996 and 2003 supports this finding, and indicates a six-fold increase in the risk of death after 30 days with a three-fold increase in the risk within one year following surgery. Transfusions were also associated with more infections and higher incidences of stroke, heart attack, and kidney failure. These complications were usually linked to a lack of oxygen to body tissues.
Little benefit
"There is virtually no high-quality study in surgery, or in intensive or acute care—outside of when you are bleeding to death—that shows that blood transfusion is beneficial and many that show it is bad for you," said Gavin Murphy, a cardiac surgeon at the Bristol Heart Institute and leader of the U.K. study.
Recommendations ignored
Many experts are now worried that guidelines are being ignored. They suggest that transfusions should only be given as a last resort and that preventing blood loss in the first place whilst ensuring patients are not anaemic before they undergo surgery should be prioritised.
"Usually when there is any clinical uncertainty about a treatment you don't give it, but with transfusions we do," said James Isbister of the Royal North Shore Hospital in Sydney, Australia, who is an adviser to the Australian Red Cross Blood Service. But Mr. Isbister still encourages people to donate blood as it is used to treat other conditions as well as extreme blood loss.
The specific reasons why blood transfusions appear to be harmful to some patients are not yet fully understood and further research is being strongly encouraged by health authorities, including the U.S. National Institutes of Health.
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