Sunday, January 13, 2008

9 - respiratory system mcqs - 41 to 45

Question 41

A 30-year-old woman is in the 28th week of an uncomplicated pregnancy when she experiences the sudden onset of severe abdominal pain, followed by vaginal bleeding, then the onset of labor. A girl infant is delivered on the way to the hospital. On arrival within an hour, the baby is in respiratory distress and requires intubation and mechanical ventilation. A day later, a chest radiograph shows opacification of both lungs. The baby's respiratory status does not improve. Which of the following histopathologic findings is most likely to be present in this baby's lungs?

A Neutrophilic exudates in the alveoli

B Irregular fibrosis with airspace dilation

C Decreased lamellar bodies in type II pneumocytes

D Diffuse alveolar hemorrhage

E Interstitial lymphocytic infiltrates


(C) CORRECT. The baby has been born prematurely, with incomplete lung development, and the lack of pulmonary surfactant production leads to hyaline membrane disease with respiratory distress in the newborn.

(A) Incorrect. A congenital pneumonia is unlikely to have developed in this rapid a time.

(B) Incorrect. These are findings of bronchopulmonary dysplasia, which may occur later in the course.

(D) Incorrect. Hemorrhage can occur with a coagulopathy in a newborn, but is unusual in this emergent situation.

(E) Incorrect. Lymphocytic infiltrates suggest a viral process, but congenital pneumonias are typically caused by bacterial organisms.

Question 42

A 41-year-old woman has a 1 year history of episodic dyspnea. On physical examination there are expiratory wheezes. Her chest radiograph shows a few small 0.5 cm perihilar nodules. Laboratory studies show an elevated serum IgE along with peripheral blood eosinophilia. A sputum sample shows eosinophils. Which of the following pathologic findings is most likely present in her bronchi?

A Non-invasive aspergillosis

B Blastomycosis

C Invasive candidiasis

D Wegener granulomatosis

E Cytomegalovirus


(A) CORRECT. She has an allergic bronchopulmonary aspergillosis. Her asthma is exacerbated by a type I hypersensitivity reaction to the fungus in the bronchi.

(B) Incorrect. Blastomycosis is an uncommon form of fungal disease that is likely to produce a granulomatous response.

(C) Incorrect. Candidiasis is more likely to be seen in immunocompromised patients.

(D) Incorrect. Wegener granulomatosis is not associated with asthma.

(E) Incorrect. CMV is seen in immunocompromised patients. CMV is not associated with eosinophilia.


Question 43

A male infant has initial Apgar scores of 5 and 6 at 1 and 5 minutes following birth by normal vaginal delivery at 30 weeks gestation. However, increasing respiratory distress in the next hour requires intubation and positive pressure ventilation. Two months later, the infant is finally taken off the ventilator, but still does not oxygenate normally. Which of the following diseases has this infant most likely developed?

A Diffuse alveolar damage

B Bronchial asthma

C Bronchiectasis

D Tracheo-esophageal fistula

E Bronchopulmonary dysplasia


(E) CORRECT. The BPD is a complication of the treatment for neonatal respiratory distress. The positive pressure ventilation with the higher FIO2's, and the prolonged intubation, all contribute. Generally, these are premature infants who had a respiratory complication following birth, such as hyaline membrane disease.

(A) Incorrect. Diffuse alveolar damage (DAD) is an acute condition more likely to be seen in adults with severe lung injury.

(B) Incorrect. Asthma is not typically a neonatal disease, and asthma tends to be episodic, without development of chronic lung disease.

(C) Incorrect. Bronchiectasis is unusual at this age, because the bronchial obstruction and inflammation usually develop over months to years.

(D) Incorrect. A T-E fistula is a congenital anomaly that can predispose to aspiration and pneumonia, not to immediate respiratory distress following birth.

Question 44

A 6-year-old child has the sudden onset of dyspnea with wheezing. On physical examination he is afebrile but has absent breath sounds on the right. His temperature is 37 C, pulse 82/minute, respiratory rate 28/minute, and blood pressure 100/60 mm Hg. An arterial blood gas measurement shows pO2 95 mm Hg, pCO2 25 mm Hg, and pH 7.55. Following administration of 100% FiO2 by nasal canula, a repeat measurement shows pO2 95 mm Hg, pCO2 25 mm Hg, and pH 7.55. Which of the following is the most likely diagnosis?

A Foreign body aspiration

B Bronchial asthma

C Paraseptal emphysema

D Thromboembolism

E Carcinoid tumor


(A) CORRECT. An inhaled object could obstruct a bronchus completely, with air resorbtion and collapse of lung distal to the point of obstruction. This produces a shunt defect with a V/Q mismatch. Since there is perfusion but no ventilation, even 100% oxygen will not make a difference. His hyperventilation has acutely produced an uncompensated respiratory alkalosis.

(B) Incorrect. Asthma can produce acute bronchoconstriction, but bilaterally.

(C) Incorrect. Paraseptal emphysema can produce focal bullae that can rupture, with sudden pneumothorax, but this is not common in a child.

(D) Incorrect. Thromboembolism affects the pulmonary arterial vasculature, not the airways.

(E) Incorrect. A carcinoid tumor can obstruct a bronchus, but usually not acutely, and such a tumor is rare in a child.


Question 45

A 60-year-old woman develops multiple organ failure 3 weeks following a pneumonia complicated by septicemia. Antibiotic therapy has resulted in sputum and blood cultures that are now without growth of organisms. Nevertheless, she requires intubation with mechanical ventilation, but it becomes progressively more difficult to maintain her oxygen saturations. Ventilatory pressures must be increased. A portable chest radiograph shows increasing opacification of all lung fields. Which of the following pathologic processes is most likely now to be present in her lungs?

A Pulmonary arterial vasculitis

B Diffuse alveolar damage

C Extensive neutrophilic alveolar exudates

D Extensive intra-alveolar hemorrhage

E Widespread bronchiectasis


(B) CORRECT. Diffuse alveolar damage (DAD) is the pathologic term for adult respiratory distress syndrome (ARDS) that is the final common pathway for many acute lung injuries. DAD produces increasing interstitial thickening with mixed inflammation and features of an acute restrictive lung disease.

(A) Incorrect. Multiple organ failure does not lead to vasculitis, which is not common in the lung.

(C) Incorrect. With negative cultures, it is unlikely that her pneumonia is still present.

(D) Incorrect. Diffuse alveolar hemorrhage can occur in persons with organ transplants and coagulopathies, but is not a major feature of multiple organ failure.

(E) Incorrect. Bronchiectasis occurs over a longer period of time, with continuing inflammation and destruction of bronchi.

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