3-15. INTRODUCTION

 

Transfusions of blood or blood products are normally initiated at the direction of the physician during surgery. These transfusions differ from the infusion of other fluids in many ways. The products used are generally prepared in a laboratory. Many products need to be matched to the patient by using laboratory analysis. The rate of transfusion is often slower, and a greater variety of complications is possible. The venipuncture site

may be different. Even the equipment differs from other administration sets. Most blood products have special refrigeration requirements to prevent spoilage. The most common reasons for transfusions are replacement of red blood cells for oxygen-carrying capacity or restoration of blood volume. Transfusion should not be initiated too hastily. Most patients in good general health can sustain a loss of about 1,000 milliliters and need replacement by colloid or crystalloid solutions infusion alone. Transfusion should be used as a last resort. It may lower the production of erythrocytes by the patient's own body. The normal red cell has a life span of about 80 to 120 days. Each unit of blood contains red blood cells of all ages between 1 and 120 days. As a unit of blood is stored, the red blood cells continue to age. A unit of blood is stored for no more than 35 days. These aged blood cells are removed from the patient's circulation by his own body within 24 hours after transfusion of the unit of blood. About 70 to 79 percent of the red blood cells survive 24 hours after transfusion and begin to age normally. Many surgeons believe that surgical blood loss can usually be replaced with packed red blood cells and saline.