Clinical Skills Muse #24: Transfusions Part 1

Patients with acute blood loss or symptomatic anemia frequently require blood replacement therapy. SO TODAY'S QUESTIONS ARE 1) CAN YOU DESCRIBE THE PATHOPHYSIOLOGY OF 5 DIFFERENT TRANSFUSION REACTIONS 2) WHICH IS THE MOST COMMON?

As a clerk, one of the things you will be called to assess (or were called to assess!) are adverse blood transfusions reactions . . . if you suspect a reaction, the first treatment is to stop the transfusion. So what are some of the adverse effects of a blood transfusion?

1) Hemolytic transfusion reactions are the result of antibodies in the recipient's plasma directed against antigens on the donor's erythrocytes. This results in rapid intravascular hemolysis of the donor red blood cells. ABO incompatibility due to clerical error is the most frequent cause. This results in hemoglobinemia, hemoglobinuria, disseminated intravascular coagulation (DIC), renal failure, and complement-mediated cardiovascular collapse.

2) Nonhemolytic febrile reactions are thought to stem from the formation of cytokines during the storage of the blood. These reactions seldom proceed to hypotension or respiratory distress.

3) Infectious diseases also may be transmitted through transfusion. (Hep B and Hep C, bacteria, viruses etc)

4) Transfusion-related acute lung injury may be caused by transfusing any plasma-containing blood product. It is caused by the interaction between the recipient's leukocytes and preexisting donor antileukocyte antibodies. This results in complement activation and increased pulmonary vascular permeability. In addition, mediators of inflammation that form while the blood is in storage are also felt to be contributory.

5) Massive transfusion is defined as the replacement of more than one-half of the blood volume within a 24-hour period or the replacement of 10 units of blood over the course of a few hours. Complications of massive transfusion include the following: -Coagulopathy is caused by a dilutional effect on the host's clotting factors and platelets, as well as the lack of platelets and clotting factors in packed red blood cells.
-Volume overload
-Hypothermia
-Hyperkalemia may be caused by lysis of stored red cells and is increased in irradiated red blood cells.
-Metabolic alkalosis and hypokalemia may be caused by the transfusion of a large amount of citrated cells.
-Hypocalcemia due to citrate toxicity may occur in those with hepatic failure, congestive heart failure (CHF), or other low-output states.

Frequency
1) Hemolytic transfusion reactions occur in 1 per 40,000 transfused units of packed RBCs.
2) (MOST COMMON) Nonhemolytic febrile reactions and minor allergic reactions are the most common transfusion reactions, each occurring in 3-4% of all transfusions.
3) Nonhemolytic febrile reactions and extravascular hemolysis are observed more commonly in patients who have developed antibodies from prior transfusions.
4) Anaphylactic reactions occur in 1 per 20,000 transfused units.
5) Due to improved preventative measures, the incidence of GVH disease is less than 0.15%.
6) Transfusion-related acute lung injury complicates 0.1-0.2% of all transfusions.
7) Risk of transfusion-related hepatitis B is 1 per 50,000 units transfused. Risk for hepatitis C is 1 per 3000-4000 units transfused. Risk of transfusion-related HIV infection is 1 per 150,000 units transfused.

Posted on behalf of M. Luterman