Approach To Symptomatic Anemia

Symptoms attributable to anemia are manifold and depend primarily on the patient's underlying cardiopulmonary status and the chronicity with which the anemia developed. For a slowly developing, chronic anemia in patients with good cardiopulmonary reserve, symptoms may not be noted until the hemoglobin level falls very low, for example, to 3-4 g/dL. For patients with serious underlying cardiopulmonary disease who depend upon adequate oxygen-carrying capacity, falls in hemoglobin level can be devastating. Such is the case with the man in this clinical scenario, who is suffering a cardiac complication as a consequence of his anemia, in this case, unstable angina. Unstable angina is defined as ischemic chest pain at rest, of new onset or occurring at a lower level of activity. Unstable angina does not cause elevated levels of cardiac markers or a myocardial infarction tracing on ECG. The Braunwald classification defines patients into both class and clinical circumstance (Table 57-1).

In this case of secondary angina, the anemia must be corrected, which requires an understanding of transfusion medicine. Anemia is generally considered to be a hemoglobin level <12 g/dL in women or <13 g/dL in men. Although lower values often can be tolerated or underlying etiologies treated, blood transfusions have been both necessary and lifesaving at times. In addition to PRBCs, there are other components of whole blood, including platelets, FFP, cryoprecipitate. and intravenous immunoglobulin (IVIg).

The indications for transfusion of PRBCs are acute surgical or nonsurgical blood loss, anemia with end-organ effects (e.g., syncope, angina pectoris) or hemodynamic compromise, and in critical illness to improve oxygen-carrying capacity or delivery to tissues. However, there are no absolute guidelines or thresholds for transfusion. Many believe that a hemoglobin level of 7 g/dL is adequate in the absence of a clearly defined increased need, such as cardiac ischemia, for which a hematocrit level of at least 30 may be desired. In the absence of ongoing bleeding or destruction of red cells, we typically expect that each unit of PRBC will result in an increase of 1 g/dL in the hemoglobin level or 3% in the hematocrit level.

Transfusion carries a small but definite risk, including transmission of infection, reactions, and consequences. Viruses that are screened for but which can be passed include hepatitis C virus (I in 103,000 units), human T-cell lymphocyte virus types I and II. human immunodeficiency virus (1 in 700,000), hepatitis B virus (1 in 66.000), and parvovirus B19. Rarely, bacterial contamination

Table 57-1

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