Hematology and oncology

1. A Trauma is the leading cause of death in the 1- to 15-year-old population. Neoplastic disease is second. The other responses are true. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp.

1433-1434.)

2. D Infection is higher in patients with central lines than those without. Recent retrospective data suggests that there are no differences in infection rates between subcutaneously implanted versus externalized catheters. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1438.)

3. E Fifty-five to seventy percent of febrile episodes in oncology patients are of infectious origin. Blood cultures are positive in less than 50% of cases of serious disseminated fungal infections. C. albicans and Aspergillus species are the most common fungal organisms. Neu-tropenia is closely correlated with morbidity and mortality. Pneumocystis is unlikely in this clinical scenario; however, pneumocystis is responsible for up to 50% of nonbacterial pneumonitis in oncology patients. Chest radiographs demonstrate bilateral infiltrates radiating from the hilum. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1438-1445; table 42.6.)

4. D The half-life of transfused platelets is 7 days; with significant alloimmunization, it can be hours. All of the other statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1442,1443.)

5. D, E, C, B, F, A Chemotherapy may promote the development of a coagulopathy associated with an increased risk of hemorrhage or thrombosis. Actino-mycin D and other antibiotics decrease the vitamin K-dependent clotting factors. Anthracycline increases fibrinolysis. L-Asparaginase may cause hypofibrino-genemia. Methotrexate can cause an antithrombin III deficiency. Vincristine may cause chronic hepatic dysfunction. Glucocorticoids increase the levels of factors II, VII, VIII, and X. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1442-1457.)

6. A Primary pulmonary parenchymal involvement with leukemia is very rare. Parenchymal involvement is occasionally seen with histiocytosis X and metastatic disease (e.g., osteogenic and Ewings sarcoma, and Wilms tumor). All other statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1445-1447, table 42.8.)

7. T, T, F, T, T, F A variety of chemotherapeu-tics, as well as radiotherapy, can cause cardiomyopathy. Effects appear to be dose related. Radiotherapy may cause pericarditis with a chronic effusion. Histologi-cally, interstitial fibrosis with vascular narrowing is seen. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1447-1448.) The onset of Pneumocystis carinii infection typically occurs 3-6 months after bone marrow transplantation. Bacterial or fungal infection can occur within the first 2 weeks. Cytomegalovirus (CMV) infection occurs 6-12 weeks after bone marrow transplantation. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1454,1455.)

8. B, D, A, C The child with neoplastic disease may acquire a variety of neurological deficits related to the neoplasm, the therapy, or a combination of both. Methotrexate is associated with aseptic meningitis, arachnoiditis, demyelinization, somnolence, and chronic leukoencephalopathy. Cisplatin may cause ototoxicity, cerebral edema, and seizures. Vincristine is associated with SIADH. 5-FU may cause acute cerebellar ataxia.

(Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1449-1452; table 42.17.)

9. B, D, A Chemotherapy is commonly associated with renal injury. High-dose methotrexate is associated with renal tubular injury. Cisplatin may cause tubular necrosis; cyclophosphamide and ifosfamide are both associated with hemorrhagic cystitis. L-Asparagi-nase is not associated with renal injury. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1452,1453; table 42.18.)

10. D CMV infection occurs most commonly 6-12 weeks after bone marrow transplantation. All of the other statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1454,1455.)

11. A, D, B, C, E Chemotherapeutic agents form the mainstay of treatment for childhood neoplasms. All agents act by disrupting some aspect of normal cell growth or division. Antimetabolites interact with various cell enzymes (e.g., methotrexate inhibits the activity of dihydrofolate reductase). Vincristine, a vinca alkaloid, inhibits microtubule function within the cell. This prevents the formation of the spindle apparatus during metaphase, thus inhibiting cell division. The anthracycline (daunorubicin and doxorubicin) and acti-nomycin D inhibit the synthesis of DNA in tumor cells. Alkylating agents like cyclophosphamide cause breaks in the DNA strands. The glucocorticoids are directly lymphocytotoxic to lymphoid leukemia and lymphoma cells. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1456-1458; tables 42.23, 42.24, 42.26, and 42.27.)

12. E Von Willebrand's disease is the most common inherited bleeding disorder. One percent of the population has detectable abnormalities in the von Willebrand's disease protein. All of the statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1414-1416; figure 41.2.)

13. T, F, T, T, T, F The preferred source for factors II, VII, X, and antithrombin III is fresh frozen plasma (FFP). Vitamin K is not a stored vitamin. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1415,1416.)

14. D Antithrombin III, protein C, and protein S are the main components of the antithrombotic system. Thrombomodulin and heparin cofactor II, among others, are also included as endogenous anticoagulants. Protein B is not included among these components. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1421; figure 41.3.)

15. E When the liver itself is diseased, abnormal coagulation results. The liver synthesizes fibrino-gen, prothrombin, protein C, protein S, antithrombin III, plasminogen, and factors V, VII, IX, X, XI, and XII. All of the above statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1408,1409, 1415,1416.)

16. B e-Aminocaproic acid prevents the breakdown of the fibrin clot by complexing with plasmin to prevent its fibrinolytic activity. Protamine is used to reverse the effects of heparin. Vitamin K deficiency generally occurs within 2-3 days following cardiopul-monary bypass. D-dimers are rarely elevated. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1405,1406; table 41.11; Chang, AC, et al. Pediatric Cardiac Intensive Care; pp. 397-399.)

17. D Massive transfusion is defined as the replacement of at least one blood volume; estimated as 75 mL/kg for children less than 1 year of age and burn victims, and 70 mL/kg for all others. All of the other statements are true. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1403-1408.)

18. C A variety of metabolic abnormalities can be induced by massive transfusion. 2,3-Diphosphoglyc-erate is decreased in transfused red cells, which increases red cell affinity for oxygen. Thus, oxygen unloading to tissues may be impaired. All other statements are correct. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1421,1422; Gilman, AG, et al. Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th Edition; pp. 1316.)

19. E Antithrombin III primarily inhibits the vitamin K dependent procoagulant factors (II, VII, IX, and X). Deficiency will lead to recurrent thrombosis. Heparin induced antiplatelet antibodies occur in approximately 5% of patients receiving heparin ther apy. Most cases are mild with platelet counts higher than 100,000/^L. All of the other statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1406,1407.)

20. D Two forms of acute, heparin-induced thrombocytopenia occur. The mild form occurs in approximately 5% of patients, 4-15 days after initiation of full-dose heparin therapy (platelet counts higher than 100,000/^L). Severe thrombocytopenia occurs less frequently. The more severe form is associated with thrombotic complications. All of the other statements are correct. (Gilman, AG, et al. Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th Edition; pp. 1316.)

21. E Protein C activation is controlled by several different mechanisms, including by thrombomodulin. Protein C activation and thrombin generation are tightly coupled. Acquired and hereditary deficiencies are the primary cause of thrombophilia. (Nathan, DG, et al. Nathan and Oski's Hematology of Infancy and Childhood, 5th Edition; pp. 1545-1547.)

22. E In contrast to heparin, which acts as a cofactor with antithrombin III to prevent coagulation, the plasminogen activators, urokinase, streptokinase, and tissue plasminogen activator increase fibrinolysis, thereby lysing the clot. Plasminogen is cleaved into plasmin by these activators. Plasmin lyses clot directly. All of the other statements are correct. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1415,1416, 1423,1424.)

23. E Both heparin and plasminogen activators (streptokinase, tissue plasminogen activator) may be used to treat arterial thrombosis. The partial thromboplastin time should be kept 1.5-2.0 times normal during heparin therapy. Note: younger neonates may be resistant to thrombolytic therapy, possibly because of lower levels of plasminogen. (Rogers, MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp. 1424.)

24. E Disorders in children that are treated with chronic anticoagulants include cardiac disorders (prosthetic valves, Blalock-Taussig shunts, endovascular shunts), some cerebrovascular events, and Kawasaki's disease. All of the above statements are correct.

(Nathan, DG, et al. Nathan and Oski's Hematology of Infancy and Childhood, 5th Edition; pp. 1704.)

25. C, D, A Aspirin is a potent and irreversible inhibitor of cyclooxygenase and thromboxane A2. Sulfinpyrazone, like aspirin, is also a nonsteroidal anti-inflammatory agent that reversibly inhibits cyclo-oxygenase. (Gilman, AG, et al. Goodman and Gilman's

The Pharmacological Basis of Therapeutics, 8th Edition; pp. 652, 1524.)

26. D Thromboprophylaxis for prosthetic heart valves has reduced the occurrence of thromboembolic events from approximately 6% to less than 2%. The other statements are true. (Michelson AD, et al. Chest 1998; 114(5 Suppl): 748S-769S.)

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