New Concerns Regarding Lifesaving Blood Transfusions
Maintaining Your Health on Mackinac
By Yvan Silva, M.D.

About five million Americans receive blood transfusions every year, and the guidelines for donation from volunteers, and the screening for safety of blood and blood products, have been stringently updated, according to continuing oversight and research. The health care system carefully safeguards the testing, to prevent transmission of infectious diseases and minimizes incompatibility and allergic reactions.

Blood transfusion is one of the most important lifesaving treatments available. Whole blood is comprised of several components - plasma, the fluid component that contains several biological elements and clotting factors and cellular components - red blood cells that carry oxygen, white blood cells that work to fight infection and platelets - cells that participate in the formation of blood clots. Human blood, very much like all other organs, reflects the complex pattern of each individual, genetic identity, and hereditary and familial information. Humans are identified by their blood type - in the ABO blood groups and the presence or absence of the Rh factor - Rh positive or negative. Occasionally, some individuals carry rare blood sub-types.

Whole blood, with all its components, is rarely used for transfusion in modern day medical practice. The more common transfusion, when the oxygen carrying capacity of blood is needed, is transfusion of packed red blood cells. The red cells are separated out under sterile conditions and suspended in a fluid vehicle for transfusion. Red blood cells primarily contain hemoglobin, a protein that carries oxygen vital to cells and tissues of the body. Thus packed red blood cell (PRBC) transfusions are given to raise the level of hemoglobin circulating in the blood stream of patients when the levels are significantly low - the clinical condition termed anemia.

Normal hemoglobin levels are about 14 to 17 grams per 100 milliliters of blood for men, and 12 to 15 for women. Several conditions can lead to low levels of hemoglobin, ranging from acute blood loss or inadequate manufacture of red blood cells because of disease processes. Clearly, individual circumstances vary widely, but anemia, when hemoglobin levels are 7 grams percent or less, indicates the need for urgent transfusion. Current medical research shows that levels of 7 grams percent or less lead to significant decline in oxygen delivery to vital tissues with potentially dangerous consequences. Using another parameter, the hematocrit (the percentage volume of red blood cells in whole circulating blood) "trigger" for transfusing blood has been reduced to 30% from a previous 45% to 55%.

There are many reasons that transfusions may be needed. Blood loss, from internal bleeding or injuries, is commonly seen in emergency situations; blood loss during or after major surgery, treatment for leukemia and other types of cancer, after effects of chemotherapy and other cancer treatments, chronic anemia resulting from chronic illness, bleeding disorders and other causes like malnutrition and deficiency syndromes.

Testing for compatibility is essential for safe blood transfusion. Typing and cross-matching are the techniques used to identify commonality between the recipient and blood donor - matching for ABO compatibility, Rh factor, and other possible rare blood subtypes. Several other safety procedures are employed for preservation, shelf life, and infection control. The ideal transfusion is done to bring hemoglobin levels to normal, without the undesirable side effects of a transfusion reaction. When these occur, they can range from mild - fever or chills, to severe - in the case of ABO incompatibility, they can be fatal.

An important imperative in the field of blood and blood products is the control of infection risk. Blood donors give voluntarily. Every blood donor is carefully screened; unhealthy individuals and carriers of chronic disease are excluded. Each unit of blood is tested for the presence of viruses, including hepatitis, the virus that causes AIDS - the human immunodeficiency virus (HIV), cytomegalus virus, and West Nile virus. There is also testing for other diseases like syphilis and other known transmissible infectious agents. With modern testing methods, the chances of risk of blood containing the HIV is now less than 1 in 1.9 million, the risk of exposure to the hepatitis C virus is less than 1 in 1 million.

Recent studies in the area of deleterious effects of transfusions have shown a disturbing spike in the number of heart attacks, close to 25%, and even in deaths in patients who have received blood within a month or so after receiving it. This research has carefully controlled comparison data, since many such patients are critically ill, victims of multiple trauma, or in the intensive care with many comorbidities. In spite of keeping transfusion criteria to a minimum, physicians are concerned with these findings. Samples of freshly-drawn blood from healthy donors, and donated blood from blood banks, were subjected to 26 different types of analyses. This showed dramatic differences in the levels of nitric oxide (NO), a normally occurring blood gas that keeps tiny vessels opened and facilitates the transference of oxygen from red blood cells to the tissues. Meticulous examination showed that freshly-donated blood loses 70% of the gas within an hour and that, 42 days later at the time of the expiration date, "for use," NO is almost non-existent. The conclusions include the observa- tion that blood transfusions fail to deliver oxygen to tissues optimally. The revised standards for transfusing blood, mentioned above, are in use and less controversial than when first instituted.

Studies in dogs have shown that the heart attack rate in dogs, depleted by bleeding, is lowered when they're transfused with blood enriched with nitric oxide. The American Red Cross oversees about 14 million units of stored blood, and will await results of further studies with nitric oxide enrichment of blood before it might change its practices of processing and storage. Premature

babies in neonatal intensive units with underdeveloped lungs are already being treated with gaseous NO to fulfill their needs for oxygen.

Transfusion of blood and blood products can be lifesaving. Transfusion of components of blood - plasma and other cellular components are also of tremendous importance when required. These are used to correct clotting abnormalities and improve some cellular deficits when desirable. Improved therapeutic support measures have diminished the need for transfusion, and research is developing several alternatives. Used under more stringent indications than before, and therefore only when clinically indicated, blood transfusion is becoming safer than before, with risk of contamination and transmission of infection remarkably low. Blood transfusions are used more rarely than before, under carefully-controlled guidelines, and safety is, as always, an important consideration.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.