Blood transfusions after heart surgery may do more harm than good
Publication Date:29/11/2007
Many heart surgery patients are given blood transfusions while they are recovering from their operation. Doctors have thought this might help prevent serious complications after surgery, such as a heart attack or a stroke. But a new study suggests that, for these patients, blood transfusions may do more harm than good.
What do we know already?
About half of patients having open heart surgery (such as a heart bypass, also called a coronary artery bypass graft) are given blood afterwards. Doctors usually do this if the patient has a low level of red blood cells during the days following the operation. Red blood cells carry oxygen around the body.
Doctors worry that if the level of red blood cells gets too low, organs like the heart, brain and kidneys won't get enough oxygen. They think that might cause a heart attack, stroke or kidney failure.
Doctors do know that having a blood transfusion increases your chances of getting an infection. But they thought that the benefits would outweigh this risk.
What does the new study say?
The new study showed that blood transfusions don't help people avoid having a heart attack, stroke or kidney failure after heart surgery. In fact, having a blood transfusion seems to increase your chances of these problems, as well as your chances of getting an infection.
Also, people who'd had a blood transfusion were much more likely to die, especially in the first month after the operation. People who'd had a transfusion spent longer in intensive care and longer in hospital.
Tell me more about the study's findings
The researchers looked at the records of all the adults who had heart surgery at Bristol Royal Infirmary between 1996 and 2003. More than half of these patients had a transfusion after surgery.
Overall, 9 in 100 people had an infection and 10 in 100 people had a heart attack, stroke or kidney problems. Chest infections and kidney problems were most common.
People who had blood transfusions were three times as likely to have an infection, or to have a heart attack, stroke or kidney problems. They were six times more likely to die in the first 30 days after the operation, and twice as likely to die in the first year after the operation.
The more units of blood that people were given, the higher their chances of having problems.
Where does the study come from?
The research was done by doctors at the Bristol Heart Institute at the University of Bristol. It was published in the medical journal Circulation, which is published by the American Heart Association.
How reliable are the findings?
This was a large, carefully done study, looking at over 8,500 patients.
There is one main problem with this type of research. Doctors tend to give blood transfusions to the people who are most ill after surgery, such as people who lost more blood, or who are old or frail. These people are more likely to have problems after surgery. So, the findings might just show that people who are more ill are more likely to have problems.
However, the researchers were careful to take things like age and other illnesses into account as much as possible. Even making adjustments for these things, they still found that blood transfusions did more harm than good. Even people with quite low levels of red blood cells, who we might think were most in need of a transfusion, did no better with a transfusion.
What does this mean for me?
These findings don't apply to people who need emergency blood transfusions because they have lost a lot of blood, either during an operation or because of injuries. Blood transfusions still save lives in those circumstances. The study's findings only apply to routine blood transfusions after planned heart surgery.
If you are planning to have heart surgery, it's important to keep the risks in perspective. Less than 1 in 10 people having heart surgery in this study had major problems afterwards. Most people having an operation like a heart bypass do well and get a lot of benefit from it.
Different hospitals have different guidelines for when to give people a transfusion. In one survey of hospitals, the number of people having transfusions after heart surgery varied from 25 percent to 95 percent.
What should I do now?
If you are concerned about the risks of a planned heart operation, the best person to talk to is your surgeon. He or she will be able to tell you all about the risks and the benefits.
You could ask your surgeon if you are likely to need a blood transfusion afterwards, and how many people having your operation have transfusions at your hospital.
From:
Murphy GJ, Reeves BC, Rogers CA, et al. Increased mortality, postoperative morbidity, and cost after red blood cell transfusion in patients having cardiac surgery. Circulation. 2007; 116: 2544-2552.
To find out more about heart surgery, see our information on coronary artery bypass and coronary angioplasty.
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© BMJ Publishing Group Limited ("BMJ Group") 2007. All rights reserved
This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
