MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 4. BLOOD SYSTEM

BLOOD TRANSFUSION

1. GENERAL PRINCIPLES OF BLOOD TRANSFUSION

People who donate Blood are called Donors, while those who receive it are known as recipients. During a blood transfusion, it is essential that the donor's erythrocyte agglutinogens are not agglutinated by the recipient's plasma agglutinins, as this leads to hemolysis, capillary blockage, Circulatory Disorders, and even death. Consequently, when transfusing small volumes of blood, it was traditionally believed that type I blood, which lacks agglutinogens, could be safely transfused to individuals with any blood type: I, II, III, or IV. Therefore, individuals with blood type I were referred to as universal donors. Type II blood can only be transfused to individuals with type II or IV blood. Type III blood can be given to those with type III or IV blood. Type IV blood, which contains both agglutinogens, can only be transfused to individuals with type IV blood. For this reason, individuals with blood type IV were designated as universal recipients.

In modern clinical practice, where indications for blood transfusion are strictly limited and substantial volumes of blood are typically administered (such as during surgeries or trauma), only blood of the exact same group must be transfused.

To meet the demands of practical medicine for blood supply, donation is widely utilized. Blood donation involves THE CONTRIBUTION OF a small amount of blood by individuals for therapeutic use. This does not harm the donor's health; on the contrary, it stimulates hematopoiesis.

In medical practice, blood substitutes are used for partial blood replacement or to restore hemodynamic parameters. Only isotonic and iso-oncotic solutions (solutions with the same osmotic and oncotic pressure as Blood Plasma) are employed for this purpose.

The simplest blood substitute is normal saline, which is a 0,9 % sodium chloride solution. It is isotonic. Ringer-Locke solution is even closer in composition to blood plasma because it contains 15 % glucose. There are also blood substitutes containing not only salts and glucose, but Proteins as well. Such solutions are transfused to normalize blood pressure. Serum is produced from blood plasma. Serum is defibrinated plasma (i.e., lacking fibrin), which is why it does not clot.