Tuesday, July 22, 2008 Is blood transfusion necessary? By Henrylito D. Tacio Health 101
BLOOD transfusion saves lives. Is this true or false? Even though deaths caused in the 1980s by accidental HIV infection mean that donated blood is now screened meticulously to keep it free of infectious agents, there is still a nagging feeling that something is wrong.
Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. Wikipedia, the free encyclopedia, informs: "Blood transfusions can be life-saving in some situations, such as massive blood loss due to trauma, or can be used to replace blood lost during surgery."
In some instances, blood transfusions may also be resorted to treat severe anemia or thrombocytopenia caused by a blood disease. People suffering from hemophilia or sickle cell disease may require frequent blood transfusions.
In recent years, nagging questions about the capability of blood transfusions have been asked. A 2004 study of people suffering from acute coronary syndrome (a specific type of heart attack) concluded that unnecessary blood transfusions "might be causing tens of thousands of deaths in America alone."
Dr. Sunil Rao, of Duke University Medical Centre in North Carolina, found that patients who have had a transfusion because of a low red blood cell count had an 8 percent chance of dying within 30 days. Without a transfusion, only 3 percent died.
However, those figures need to be treated with caution. As Dr. Rao points out, the patients who underwent transfusion were, on average, sicker and older than those who did not. "Nevertheless, his study is not the only indication of something amiss," to quote the words of "The Economist," which carried a special report on the subject.
Some researches have also shown that blood transfusion is not necessarily a good thing for patients suffering from serious injuries, for those who have undergone surgery, and even for those who are anemic. Another study carried out earlier this year found that critically ill children whose red blood cell counts had dropped by half fared no better after a transfusion than those who did not receive one.
If blood transfusion saves, why do some people died as a result? Two reports, which were published in the "Proceedings of the National of Academy Sciences," traced the problem to the lack of an essential component found in the blood used in transfusion.
The main reason for giving a patient blood is that it carries oxygen. And this lack of oxygen is the one that kills a person quickest. Dr. Jonathan Stampler, a colleague of Dr. Rao, explains that what determines whether transfused blood works as a treatment is not merely how much oxygen it is carrying, but whether that oxygen can reach the tissues that need it.
This is where nitric oxide comes in. "Nitric oxide increases the flow of blood to tissues by dilating the arteries that penetrate those tissues," The Economist's report explains. The best-known example is the erectile tissue of man's sexual organ (Viagra works by sustaining the signal that the gas gives).
"However, it is not just penile blood vessels that nitric oxide relaxes," explains The Economist. "When a red blood cell reaches any tissue in need of oxygen it releases nitric oxide in order to dilate the capillaries. Only then can it deliver its cargo. And that is doubly true of the cells in stored blood since red blood cells become less flexible with age, and thus less able to squish into capillaries."
Is this lack of nitric oxide, then, causing the problems associated with blood transfusions? Indeed, their study has shown that the amount of nitric oxide in stored blood does indeed decrease and does so rapidly. Within a day of storage, blood loses 70 percent of its nitric oxide. After a few days, up to 90 percent has been lost.
The good news from this study is that the problem should be easy to correct. As Dr. Stamler points out: If nitric oxide is what is needed, it can be added to banked blood just before transfusion.
In addition, blood boosted with nitric oxide might be used as a therapy for people who have had heart attacks by providing extra oxygen in the crucial minutes after an attack, before the affected heart muscle has died. At that point, blood transfusions would no longer be part of the problem: they would be part of the cure.
