Nokea
Heparin is an anticoagulant produced by the basophils. The most likely mechanism heparin prevents blood clotting is by
- A. Inhibiting the formation of vitamin K-dependent clotting factors
- B. Preventing the activation of platelets
- C. Preventing the aggregation of platelets
- D. Binding to antithrombin III to inactivate thrombin
Correct Answer: D
Rationale: The correct answer is D because heparin binds to antithrombin III, enhancing its ability to inactivate thrombin. This prevents the conversion of fibrinogen to fibrin, thereby inhibiting blood clot formation. Choices A and B are incorrect because heparin does not affect vitamin K-dependent clotting factors or platelet activation. Choice C is incorrect because heparin does not directly prevent platelet aggregation.
You may also like to solve these questions
A 17-year-old female presents with cervical adenopathy and a history of daily fevers and drenching night sweats. A biopsy is performed and reveals classic Hodgkin lymphoma. Which of the following is least appropriate as part of the staging workup?
- A. Chest x-ray
- B. CT scan of chest, abdomen, and pelvis
- C. Functional imaging (PET scan)
- D. Lumbar puncture and cerebrospinal fluid (CSF) analysis
Correct Answer: D
Rationale: The correct answer is D: Lumbar puncture and cerebrospinal fluid (CSF) analysis. In Hodgkin lymphoma staging, CNS involvement is rare at initial presentation. Therefore, routine CSF analysis is not recommended unless there are specific neurological symptoms suggestive of CNS disease. A lumbar puncture carries risks of complications and should not be performed routinely. Choices A, B, and C are appropriate for staging in Hodgkin lymphoma to evaluate for distant metastases and characterize disease extent.
A 3-year-old boy is referred to you for evaluation of right leukocoria. Funduscopic examination under anesthesia reveals a large amelanotic mass occupying more than two-thirds of the vitreous space in his right eye, with massive retinal detachment, consistent with group E retinoblastoma. The left eye is normal. An MRI confirms the funduscopic findings and shows no extraocular disease. What is the most appropriate next step in the management of this child's disease?
- A. Enucleation
- B. Systemic chemotherapy
- C. Brachytherapy
- D. Needle biopsy
Correct Answer: A
Rationale: The most appropriate next step in the management of the child's retinoblastoma is enucleation (choice A). Enucleation, the surgical removal of the affected eye, is indicated when there is a large intraocular tumor with extensive retinal detachment, as in this case. Enucleation can provide local control of the disease and prevent systemic spread. It is considered the standard treatment for advanced retinoblastoma to prevent metastasis.
Systemic chemotherapy (choice B) is not the first-line treatment for advanced retinoblastoma with massive intraocular involvement. Brachytherapy (choice C) involves the placement of a radioactive source near the tumor, which may not be effective in this case of extensive intraocular disease. Needle biopsy (choice D) is not recommended as the primary management strategy due to the risk of seeding tumor cells outside the eye. Therefore, enucleation is the most appropriate next step in this scenario.
A 3-year-old boy is referred to you for evaluation of right leukocoria. Funduscopic examination under anesthesia reveals a large amelanotic mass occupying more than two-thirds of the vitreous space in his right eye, with massive retinal detachment, consistent with group E retinoblastoma. The left eye is normal. An MRI confirms the funduscopic findings and shows no extraocular disease. What is the most appropriate next step in the management of this child's disease?
- A. Enucleation
- B. Systemic chemotherapy
- C. Brachytherapy
- D. Needle biopsy
Correct Answer: A
Rationale: The correct answer is A: Enucleation. In this case, the child has a group E retinoblastoma in the right eye, with massive retinal detachment. Enucleation, or surgical removal of the eye, is the most appropriate next step as the tumor is extensive and poses a risk of metastasis. Enucleation helps prevent spread of the cancer to other parts of the body and provides the best chance for cure. Systemic chemotherapy (B) and brachytherapy (C) are not ideal for such advanced cases due to the high risk of metastasis. Needle biopsy (D) is not recommended as the diagnosis is already confirmed by funduscopic examination and MRI.
The pathophysiology of venous thrombosis is often explained by Virchow's triad, which includes hypercoagulability, endothelial injury, and venous stasis. Based on Virchow's triad and your knowledge of risk factors for thrombosis, which of the following pediatric patients has the greatest risk of hospital-acquired venous thromboembolism?
- A. 3-day-old full-term infant admitted to hospital pediatrics for hyperbilirubinemia
- B. 6-month-old male admitted to the infectious disease unit for respiratory syncytial virus
- C. Ex-28 week premature infant, requiring NICU-level care for necrotizing enterocolitis
- D. 7-year-old male with acute lymphoblastic leukemia receiving maintenance chemotherapy admitted to hematology/oncology unit for fever and neutropenia
Correct Answer: C
Rationale: The correct answer is C because the ex-28 week premature infant requiring NICU-level care for necrotizing enterocolitis has the greatest risk of hospital-acquired venous thromboembolism. Premature infants are at higher risk due to their immature coagulation system and prolonged immobility. Necrotizing enterocolitis further increases the risk due to inflammation and endothelial injury. Hypercoagulability is common in premature infants. Choices A, B, and D have lower risk as they do not have the same combination of risk factors as the premature infant in choice C.
A patient with a bleeding disorder is prescribed an infusion of plasma. What should the nurse explain as being the purpose of this infusion?
- A. Contains clotting factors
- B. Carries oxygen to the tissues
- C. Supports cellular metabolism
- D. Removes waste products from cells
Correct Answer: A
Rationale: The correct answer is A: Contains clotting factors. Plasma is the liquid component of blood that contains essential clotting factors necessary for blood coagulation. This infusion helps replenish clotting factors in patients with bleeding disorders, aiding in the formation of blood clots to stop bleeding. Choice B is incorrect as plasma does not carry oxygen; that is the role of red blood cells. Choice C is incorrect as plasma does not directly support cellular metabolism; that is the role of nutrients. Choice D is incorrect as plasma does not remove waste products; that is the role of the kidneys and liver.