Posts Tagged 'blood transfusion'

Blood – The Doctor Giveth and the Doctor Taketh: Myths, Beliefs and Evidence

This Country Doctor learned something interesting at Grand Rounds the other day. One of the Cityside hematologists gave a talk about blood transfusions that made me think about how slow the medical profession is to change its beliefs and its practice, even when faced with overwhelming evidence that we are doing the wrong thing.

It turns out our profession has been wrong about the benefits of transfusing anemic patients, just like our predecessors were wrong in their belief that bloodletting was helpful.

For thousands of years medical practitioners used bloodletting, drawing off sometimes very large quantities of blood, as a treatment for various illnesses. After this treatment was proven useless and dangerous in 1628 by Harvey, the practice continued for more than 200 years. It is said to have brought on George Washington’s death in 1799 after 9 pints of his blood was withdrawn. Samuel Hahnemann, the physician who founded Homeopathy, looking for kinder, gentler treatments for his patients, wrote in 1809:

“The more refined humoralists, in addition to the impurities in the blood, alleged, besides, the existence of a pretended, almost universal, plethora, as an excuse for their frightful, merciless bloodlettings.”

Analyzing why it took so long to eliminate this type of treatment, Kerridge and Lowe wrote in 1995:

“That bloodletting survived for so long is not an intellectual anomaly—it resulted from the dynamic interaction of social, economic, and intellectual pressures, a process that continues to determine medical practice.”

Legend has it that early adopters of non-bloodletting didn’t dare to withhold this “treatment” for their sickest patients. They, like modern day physicians, were afraid of “doing nothing”.

Today, bloodletting is only used for a handful of conditions where the patient actually has too many red blood cells or too much iron in the blood. But we have gone too far in the opposite direction, thinking that most anemic patients could benefit from a couple of extra units of blood.

In 1999 The New England Journal of Medicine wrote authoritatively about several negative effects from transfusions. Since then the evidence has continued to mount against transfusion in medical patients with anemia. Bleeding surgical patients are in a different category.

But for many years we transfused our sickest patients in hope of helping them do better. When they didn’t, we usually didn’t blame the transfusion, but thought they were just too sick to fully benefit from transfusion. This is exactly what happened in the days of bloodletting.

The new findings about the negative effects of transfusion were ignored, perhaps even swept under the carpet. After all, giving blood seemed like such an obvious thing to do.

Even though we know that anemic patients are more likely to suffer for example heart attacks due to low oxygen delivery to their tissues, it turns out that blood transfusion to correct anemia actually further decreases oxygen delivery to heart muscle tissue. Transfused patients have a greater risk for illness and death than non-transfused patients, all the way down to degrees of anemia that usually raise the hair on every physician’s back. Even our own (autologous) blood donation has this effect due to changes in blood cells and plasma caused by handling and storage. Transfused blood cells have a tendency to be less flexible and slippery than normal blood cells and have been proven to block tiny blood vessels and thereby keeping patients’ own, healthy, blood cells from getting through.

A chilling fact is that even though blood between 30 and 42 days old carries a dramatically greater risk of negative effects than blood less than 30 days old, we still continue to offer it to patients without informing them of the additional risk we subject them to.

The increased risk for illness and death extends well beyond the immediate period after transfusion: We are now seeing an increased cancer risk in people who have received blood transfusions several years ago.

The International Consensus Conference on Transfusion and Outcomes issued this statement in 2009:

“There is little evidence to support a beneficial effect from the greatest number of transfusions currently being given to patients. The vast majority of studies show an association between red blood cell transfusions and higher rates of complications such as heart attack, stroke, lung injury, infection and kidney failure and death.”

At Cityside and many other hospitals, the threshold for transfusion in medical patients has been lowered, and surgical patients sometimes have their operations postponed in order to manage anemia with iron infusions and erythropoietin injections to allow the patient to build up their own blood supply before surgery. And if transfusions are given, they are kept to a minimum.

Such changes in practice are likely to happen in other areas of medicine if we are willing to really practice evidence based medicine and not just do what sounds like a good idea. Too many things have sounded good and turned out bad to make that a defensible strategy.

I can’t help thinking about how uncomfortable many doctors have been over the years when treating Jehovah’s Witnesses, whose religion forbids them to accept blood transfusions. That belief may actually have saved many lives.

Medicine is an ever-changing practice, and it is humbling to realize how doctors sometimes harm their patients by doing what seems to be the right thing to do.

Dr. Martin H. Fischer said it well:

”It is not hard to learn more.  What is hard is to unlearn when you discover yourself wrong.”  

Osler said “Listen to your patient, he is telling you the diagnosis”. Duvefelt says “Listen to your patient, he is telling you what kind of doctor he needs you to be”.



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