AIPGMEE 2014- 2015

Question 1

Each of the following treatments might be useful in restoring a prolonged prothrombin time (PT) to the normal range EXCEPT

• Recombinant factor VIII
• Vitamin K
• Fresh frozen plasma
• Stopping warfarin (Coumadin)
• Cryoprecipitate

The PT and the activated partial thromboplastin time (aPTT) are common tests used to evaluate coagulation factors. The PT primarily tests for factor VII in the extrinsic pathway, as well as factors I, II, V, and X of the common pathway. The aPTT primarily tests for factors VIII and IX of the intrinsic pathway, as well as factors I, II, V, and X of the common pathway. Although the PT is prolonged with deficient function of factors I, II, V, VII, or X, it is more sensitive to deficiencies of factor VII and less so with deficiencies of factor I or II. In fact, the PT is not prolonged until the level of fibrinogen (factor I) is less than 100 mg/dL and may only be prolonged 2 seconds when the level of factor II (prothrombin) is 10% of normal. Factors II, VII, IX, and X are vitamin-K-dependent factors and their formation is blocked with Coumadin therapy. Administering factor VIII will not help a prolonged PT (Barash: Clinical Anesthesia, ed 5, pp 222-224, 228).

Question 2

Proper processing of platelet concentrates (to avoid future hemolytic transfusion reactions) before administration involves

• Type and crossmatch
• ABO and Rh matching
• Rh matching only
• ABO matching only
• Platelets can be administered without regard to any antigen system

Platelet concentrates contain a fair amount of plasma and white blood cells (WBCs) but relatively few RBCs. Although ABO-compatible platelet transfusions are preferred (platelets survive better and crossmatching for subsequent RBCs is easier), in emergencies it has been noted that platelets often give adequate hemostasis without regard to ABO compatibility. Even though there are only small quantities of RBCs in platelets, the RBCs present can cause Rh immunization if Rh-positive platelet concentrates are injected into Rh-negative patients. Thus, until childbirth is no longer possible, Rh-negative females should only receive Rh-negative platelets (Miller: Anesthesia, ed 6, pp 1822-1823; Stoelting: Pharmacology and Physiology in Anesthetic Practice, ed 4, p 625).

Question 3

The most common inherited coagulopathy is

• Hemophilia A
• Hemophilia B
• von Willebrand disease
• Factor V deficiency
• Factor II deficiency

Coagulopathies can be inherited or acquired. Of the inherited coagulopathies, von Willebrand’s disease is the most common, affecting 1 in 100 to 500 people. Both hemophilia A (Factor VIII) deficiency and hemophilia B (Factor IX or Christmas disease) are X-linked recessive disorders. Hemophilia A occurs in 1 to 2 per 10,000 males and hemophilia B occurs in 1 per 100,000 males. Factor V, Factor VII, Factor X, and prothrombin (Factor II) are exceedingly rare autosomal recessive disorders. (Kasper: Harrison’s Principles of Internal Medicine, ed 16, pp 680-682; Stoelting: Anesthesia and Co-Existing Disease, ed 4, pp 490-493).

Question 4

In a 70-kg patient, 1 unit of platelet concentrate should increase the platelet count by

• 2000 to 5000/mm³
• 5000 to 10,000/mm³
• 15,000 to 20,000/mm³
• 20,000 to 25,000/mm³
• Greater than 25,000/mm³

Platelet count is increased about 5000 to 10,000/mm³ per unit of platelet concentrate in the typical 70-kg patient. Each unit contains greater than 5.5 × 1010 platelets (Barash: Clinical Anesthesia, ed 5, p 216; Harmening: Modern Blood Banking and Transfusion Practices, ed 5, pp 14-15; Miller: Anesthesia, ed 6, pp 1822-1823).

Question 5

A 68-year-old patient receives a one unit transfusion of packed red blood cells (RBCs) in the recovery room after a laparoscopic prostatectomy. As the blood is slowly dripping into his peripheral IV, the patient complains of itching on his chest and arms, but his vital signs remain stable. The antibody most likely responsible for this is directed against

• Rh
• ABO
• MN, P & Lewis
• Kell, Duffy & Kidd
• None of the above

This is an example of a typical allergic reaction. All of the other choices in this question may be involved in hemolytic reactions. Allergic reactions are a form of nonhemolytic transfusion reactions, which are thought to be caused by foreign proteins in the transfused blood. The reactions occur in about 3% of all transfusions and present with urticaria, erythema, pruritus, fever and sometimes respiratory symptoms. When it occurs, the transfusion is stopped and supportive therapy including antihistamines is administered. If the symptoms resolve and there are no signs of a hemolytic reaction (no free hemoglobin in the plasma or urine) or a severe anaphylactic reaction, the transfusion can be resumed (Lobato: Complications in Anesthesiology, p 512; Miller: Anesthesia, ed 6, p 1817; Stoelting: Basics of Anesthesia, ed 5, p 361).