ACUTE INTRAVASCULAR HEMOLYSIS
Acute Hemolytic Transfusion Reaction
Acute transfusion reactions usually occur within minutes. The most common cause of an acute hemolytic transfusion reaction (AHTR) is a transfusion of incompatible red cells. The recipient must have antibodies to an antigen on the transfused cells. Most often the reaction is due to ABO-incompatible blood; however, other antibodies may also be responsible.
During these reactions, the lysis of erythrocytes results in hemoglobinemia and hemoglobinuria. Other laboratory findings with AHTR are decreased hematocrit, increased lactate dehydrogenase (LDH), increased serum bilirubin, and decreased haptoglobin.
Clinical symptoms of AHTR include abdominal, chest, flank, or back pain, hypotension, bronchospasm, pulmonary edema, shock, renal failure, and disseminated intravascular coagulation (DIC). There are several important steps in its management (Table 198-1).
TABLE 198-1Management of Acute Intravascular Hemolysis ||Download (.pdf) TABLE 198-1 Management of Acute Intravascular Hemolysis
If a transfusion reaction is expected, a transfusion reaction workup includes the following:
Stop transfusion immediately.
IV fluids to maintain urine output, blood pressure, and CVP.
Maintain urine output—urine output should be > 1.5 cc/kg/h. Use diuretics such as mannitol, if necessary. It may also be beneficial to alkalinize the urine with bicarbonate to prevent the precipitation of hematin in the kidneys.
Bronchodilators if indicated for bronchospasm.
Clerical check: review the records for patient identification, blood component labels, type, and crossmatch data.
Hemolysis check—visually check the urine for signs of free hemoglobin—pink or red colored plasma.
Direct antiglobulin test (DAT)—The DAT is used to demonstrate the presence of antibodies or complements bound to red blood cells.
Acute Hemolysis Induced by Cell Trauma
There are multiple causes of trauma to red blood cells that can result in hemolysis. Common causes of trauma include severe cardiac valve disease, prosthetic cardiac valves, vascular grafts, intra-aortic balloon pumps, ventricular assist devices. In addition, the mixing of packed red blood cells with hypotonic solution or excessive warming of packed red blood cells can result in hemolysis. Severe burns can also cause hemolysis to exposed red blood cells.
Glucose-6-Phosphate Dehydrogenase Deficiency
A glucose-6-phosphate dehydrogenase (G6PD)-deficient patient lacks the ability to protect red blood cells against oxidation. Numerous drugs, infections, and metabolic conditions have been shown to cause acute hemolysis of red blood cells in the G6PD-deficient patient (Table 198-2). Management of this reaction involves blood transfusions for hemolysis. Occasionally, dialysis is needed for acute renal failure. When a blood transfusion is given, the transfused red cells are generally not G6PD-deficient and will live a normal lifespan in the recipient’s circulation. Most commonly there is spontaneous recovery from a hemolytic episode due to G6PD.
TABLE 198-2Drugs, Food, and Conditions that Cause Hemolysis in G6PD