Better Technologies Make Blood Transfusion Less Common, Safer
Maintaining Your
Health on Mackinac
By Yvan Silva, M.D.

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, quite 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 subtypes.

Whole blood, with all its components, is very rarely transfused in modern day medical practice. The more common transfusion is that 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 (RBC) 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. There is a great variety of conditions that lead to low levels of hemoglobin, ranging from acute blood loss or inadequate manufacture of red blood cells from disease processes. Clearly, individual circumstances vary widely, but anemia, when hemoglobin levels are seven grams or less, indicates the need for transfusion. Current medical research shows that levels of seven or less lead to significant decline in oxygen delivery to vital tissues, with potentially dangerous consequences.

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, aftereffects 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 crossmatching 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 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. 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 possibilities like syphilis and other known transmissible infectious agents. With modern testing methods, the risk of blood containing HIV is now less than 1 in 1.9 million, while the risk of exposure to the hepatitis C virus is less than 1 in 1 million.

Transfusion of blood and blood products can be lifesaving. Improved therapeutic support measures have diminished the need for transfusion, and research is developing several alternatives. Used under more stringent indications than before, and thus only when seriously indicated, blood transfusion is becoming safer than before, with risk of contamination and transmission of infection remarkably low. Blood transfusions occur more rarely than before 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.