Unstable Angina Classification

Class

I. New or worsened angina not at rest

II. Angina at rest, last occurred more than 48 hours ago

III. Angina at rest within last 48 hours and

Clinical circumstance

A. Secondary angina—-noncoronary precipitant (e.g., anemia, thyrotoxicosis, infection)

B. Primary angina—in the absence of an extracardiac condition

C. Postinfarction angina—within 2 weeks after a myocardial infarction, with those in class IIIC having the worst prognosis.

Source: Braunwald E. Unstable angina: A classification. Circulation 1989: 80:410-414.

(e.g.. Yersinia enterocolitica) causes fevers, sepsis, and even death during or soon after transfusion. Parasites (e.g.. malaria) are screened for by questioning a donor's medical and travel history.

There are also noninfectious concerns, both immune and nonimmune mediated. With respect to immune mechanisms, it is possible that a recipient has preformed natural antibodies that lyse foreign donor erythrocytes, which can be associated with the major A and/or B or O blood types or with other antigens (e.g.. D. Duffy. Kidd). Because hemolysis can ensue, a "type and cross" is first performed, in which blood samples are tested for compatibility prior to transfusion. The most common cause of this reaction actually is clerical (i.e.. mislabeling). Acute hemolytic reactions may present with hypotension, fever, chills, hemoglobinuria, and Hank pain. The transfusion must be halted immediately, and fluid and diuretics (or even dialysis) should be given to protect the kidney from failure via immune-complex deposits. Laboratory work for intravascular hemolysis should be checked (lactate dehydrogenase [LDH|, indirect bilirubin, haptoglobin), as well as coagulation tests for disseminated intravascular coagulopathy (DIC). Less predictably, milder, delayed hemolytic reactions involving amnestic responses from the recipient can occur. Febrile nonhemolytic transfusion reactions can occur and may be helped by antipyretics. Reactions range from urticaria treated with diphenhydramine and transfusion interruption to anaphylaxis, in which case the transfusion must be stopped, and epinephrine and steroids are needed. Sometimes seen is transfusion-related acute lung injury (TRAL1). in which the appearance of bilateral interstitial infiltrates in the lung represents noncardiogenic pulmonary edema.

Considering nonimmune consequences, the transfusion itself supplies 300 mL per unit of PRBC intravascularly. so patients can easily become volume overloaded. Adjusting the volume and rate and using diuretics will prevent this complication. Wach unit of blood also provides 250 mg of iron. Multiple and frequent transfusions can cause iron overload and deposition, leading to cirrhosis, cardiac problems (e.g.. arrhythmia, heart failure), or diabetes. Finally, a transfusion confers a mild immunosuppression to patients, which is potentially important in already compromised populations, such as patients with cancer or AIDS.

Alternatives to transfusion have shown a role for erythropoietin, a hormone that promotes red cell production. It is often used in the treatment of patients with renal failure-related anemia. It also can be used in patients who are banking a presurgical autologous transfusion to encourage quicker recovery of their hemoglobin levels prior to surgery. Cell savers salvage some intraoperative blood losses, which are then transfused back into the patient. A Jehovah's Witness often does not wish to have foreign blood products transfused based upon religious convictions. In some cases we can increase the baseline hemoglobin level by using erythropoietin and iron before planned surgery, minimize laboratory testing, and use cell savers. Ultimately, however, a competent patient's wishes are to be respected.

Thrombocytopenia can frequently be treated with platelet transfusion. When a patient has a platelet count <50,000/mm3 and is bleeding, or when a patient is at risk for spontaneous bleeding at a level <10,000/mm3, platelets can be transfused. Each unit increases the platelet count from 5000 to 10,000/mm3. In cases such as immune thrombocytopenic purpura (ITP), in which platelets are being destroyed, however, transfusion is generally not helpful unless active bleeding is occurring.

FFP replaces clotting factors and is often given to reverse warfarin (Coumadin) anticoagulation. Cryoprecipitate from FFP replaces fibrinogen and some clotting factors, making it useful in patients with hemophilia A and von Willebrand disease.

IVIg is administered in patients with immune thrombocytopenia to temporarily block the reticuloendothelial system and thus elevate platelets counts quickly, albeit temporarily. One caution is that IgA deficiency in a recipient can cause anaphylaxis when IVIg or FFP is administered.

Comprehension Questions

[57.1) A 32-year-old man is brought into the emergency room after a motor vehicle accident. He is noted to be in hypovolemic shock with a blood pressure of 60/40 mm Hg. He is actively bleeding from a femur fracture. The patient's hemoglobin level is 7 g/dL. His wife is positive that the patient's blood type is A-positive. Which of the following is the most appropriate type of blood to be transfused?

A. Give AB-positive blood, uncross-matched

B. Await cross-matched A-positive blood

C. Give type-specific A-positive blood, uncross-matched

D. Give O-negative blood, uncross-matched

[57.2J A 45-year-old woman is noted to have severe menorrhagia over 6 months and a hemoglobin level of 6 g/dL. She feels dizzy, weak, and fatigued. She receives 3 units of packed erythrocytes intravenously. Two hours into the transfusion, she develops fever to l()3°F and shaking chills. Which of the following laboratory tests would most likely confirm an acute transfusion reaction?

A. Lactate dehydrogenase (LDH) level

B. Leukocyte count

C. Direct bilirubin level

D. Glucose level

[57.3] A 57-year-old man has a prosthetic aortic valve for which he takes warfarin (Coumadin) 10 mg/d. He is noted to have an international normalized ratio (INR) of 7.0 and is actively bleeding large clots from his gums, rectum, and when urinating. Which of the following is the best management for this patient?

A. Administer vitamin D

B. Transfuse with fresh-frozen plasma

C. Administer intravenous immunoglobulin (IVIg)

D. Discontinue the warfarin (Coumadin) and observe

Answers

[57.11 D. This patient needs a blood transfusion immediately, as evidenced by his dangerously low blood pressure. He does not have the 45 minutes required for cross-matching his blood. Even though the patient's wife is "absolutely sure" about the blood type, history is not completely reliable, and in an emergent situation such that uncross-matched blood must be given, O-negative blood (universal donor) usually is administered.

[57.2] A. Elevated LDH and indirect bilirubin levels or decreased haptoglobin levels would be consistent with hemolysis.

157.31 B. When life-threatening acute bleeding occurs in the face of coagulopathy due to warfarin (Coumadin) use. the treatment is fresh-frozen plasma. The INR is extremely high, consistent with a severe coagulopathy. Sometimes vitamin K administration can be helpful if the bleeding is not severe.

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