By Henrylito D. Tacio
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 a severe anemia or thrombocytopenia caused by a blood disease. People suffering from hemophilia or sickle-cell disease may require frequent blood transfusions.
The adult human has about six quarts of blood. And blood plays a part in every major bodily activity. Here is an information from The New American Desk Encyclopedia: “As the body’s main transport medium, blood carries a variety of materials: oxygen and nutrients (such as glucose) to the tissues for growth and repair; carbon dioxide and wastes from the tissues for excretion; hormones to various tissues and organs for chemical signaling; digested food from the gut to the liver; immune bodies for prevention of infection and clotting factors to help stop bleeding to all parts of the body.”
Blood also plays a major role in hemeostatis, as it contains buffer which keep the acidity of the body fluids constant and, by carrying heat from one part of the body to another, it tends to equalize body temperature.
Samuel Pepys recorded the first blood transfusion in his celebrated Diary. On Nov. 14, 1666, Pepys wrote that Richard Lower of the Royal Society made the first direct blood transfusion from the artery of one dog to the vein of another. Mr. Lower used quills to convey the blood.
This feat was dependent upon the discovery made by William Harvey earlier that century of the course of blood in the circulation. Harvey announced his discovery to the College of Physicians in 1616 and published his treatise on it, entitled Exercitato anatomica de motu cordis et sanguinis in animalibus, in 1628.
However, the science of modern blood transfusion dates to the first decade of the 19th century, with the discovery of distinct blood types leading to the practice of mixing some blood from the donor and the receiver before the transfusion (an early form of cross-matching).
In 1818, Dr. James Blundell, a British obstetrician, performed the first successful transfusion of human blood, for the treatment of postpartum hemorrhage. He used the patient’s husband as a donor, and extracted four ounces of blood from his arm to transfuse into his wife.
Twenty-two years later, at St. George’s Hospital Medical School in London, Samuel Armstrong Lane, aided by Dr. Blundell, performed the first successful whole blood transfusion to treat hemophilia.
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 had 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 are 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 kill 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’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.
In the same issue of the journal, Dr. Stamler’s colleague Timothy McMahon, confirmed this result (in fact, it showed that the initial drop of around 70 percent happens within three hours of collection) and showed that it was not caused by the way blood is processed, but merely by the passage of time. Dr McMahon also established that stored blood does indeed lose its ability to dilate blood vessels.
Dr. Stamler is in “little doubt” about the significance of these findings. In fact, he warns that putting blood lacking nitric oxide into the body does not merely dilute what gas is already present in the bloodstream. Blood that is poor in nitric oxide will scavenge the gas from other tissues, causing the vessels in those tissues to constrict. If the tissue in question is heart muscle, the result will be a heart attack.
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.
Meanwhile, the Geneva-based World Health Organization said that millions of lives are saved each year through blood transfusions. In many countries, however, people still die due to an inadequate supply of blood and blood products. — ###