Physician Assistant Pulmonary System Disorders 2 — Questions and Answers
Question 1: A 55-year-old smoker presents with progressive dyspnea, barrel chest, and decreased breath sounds bilaterally. Spirometry shows FEV1/FVC of 0.58. Which pathophysiologic mechanism best explains the air trapping?
- Loss of elastic recoil causing dynamic airway collapse (Correct answer)
- Bronchial wall thickening from eosinophilic inflammation
- Alveolar flooding with proteinaceous fluid
- Increased surfactant production reducing surface tension
Correct answer: Loss of elastic recoil causing dynamic airway collapse
In emphysema, destruction of alveolar walls reduces elastic recoil, causing small airways to collapse during exhalation and trapping air distally.
Question 2: A patient with a known pulmonary embolism develops sudden worsening of hypoxemia despite anticoagulation. Which mechanism most directly causes hypoxemia in acute PE?
- Diffusion impairment across the alveolar-capillary membrane
- Ventilation-perfusion mismatch with increased dead space (Correct answer)
- Hypoventilation from respiratory muscle fatigue
- Right-to-left intracardiac shunting
Correct answer: Ventilation-perfusion mismatch with increased dead space
PE creates high V/Q areas (dead space) where ventilation occurs without perfusion, and can also cause atelectasis leading to low V/Q areas, both worsening oxygenation.
Question 3: A 30-year-old with cystic fibrosis presents with increased sputum production and worsening FEV1. Sputum culture grows Pseudomonas aeruginosa. Which antibiotic combination is most appropriate for an acute exacerbation?
- Azithromycin and trimethoprim-sulfamethoxazole
- Piperacillin-tazobactam and tobramycin (Correct answer)
- Amoxicillin-clavulanate and doxycycline
- Vancomycin and metronidazole
Correct answer: Piperacillin-tazobactam and tobramycin
Anti-pseudomonal beta-lactam plus an aminoglycoside provides synergistic coverage against Pseudomonas in CF exacerbations and helps prevent resistance.
Question 4: A 68-year-old with a 6 cm solitary pulmonary nodule has a PET scan showing high SUV uptake. CT-guided biopsy reveals adenocarcinoma. Which staging workup is MOST critical before surgical planning?
- Bronchoscopy with BAL
- Brain MRI and mediastinoscopy (Correct answer)
- Echocardiography and stress test
- Bone scan and liver biopsy
Correct answer: Brain MRI and mediastinoscopy
Brain MRI detects occult CNS metastases and mediastinoscopy evaluates mediastinal lymph node involvement, both critical for determining resectability in NSCLC.
Question 5: A patient with sarcoidosis has bilateral hilar lymphadenopathy on CXR and an ACE level of 85 U/L. Serum calcium is 11.4 mg/dL. What is the mechanism of hypercalcemia in this condition?
- Increased PTH secretion from parathyroid gland hyperplasia
- 1-alpha hydroxylation of vitamin D by activated macrophages in granulomas (Correct answer)
- Bone destruction from osteolytic granulomatous lesions
- Decreased renal calcium excretion from tubular dysfunction
Correct answer: 1-alpha hydroxylation of vitamin D by activated macrophages in granulomas
Activated macrophages within sarcoid granulomas express 1-alpha-hydroxylase, converting 25-OH vitamin D to calcitriol, which increases intestinal calcium absorption.
Question 6: A 45-year-old with idiopathic pulmonary fibrosis develops acute worsening of dyspnea over 2 weeks with new bilateral ground-glass opacities on CT superimposed on honeycombing. What is this complication called?
- Acute exacerbation of IPF (Correct answer)
- Organizing pneumonia
- Acute respiratory distress syndrome
- Hypersensitivity pneumonitis flare
Correct answer: Acute exacerbation of IPF
Acute exacerbation of IPF is defined as rapid respiratory deterioration with new bilateral ground-glass opacities without an identifiable cause in a patient with established IPF.
Question 7: A 28-year-old presents with sudden right-sided pleuritic chest pain and dyspnea after a long flight. CXR shows a 25% right-sided pneumothorax. He is hemodynamically stable with SpO2 of 96%. What is the best initial management?
- Immediate needle decompression at 2nd ICS midclavicular line
- Observation with supplemental oxygen and repeat CXR in 6 hours (Correct answer)
- Chest tube thoracostomy at 5th ICS anterior axillary line
- Aspiration with 14-gauge angiocatheter and discharge if successful
Correct answer: Observation with supplemental oxygen and repeat CXR in 6 hours
A small-to-moderate primary spontaneous pneumothorax in a stable patient can be managed with observation and supplemental O2, which accelerates pleural air reabsorption.
Physician Assistant Pulmonary System Disorders 2
A 55-year-old smoker presents with progressive dyspnea, barrel chest, and decreased breath sounds bilaterally.
Spirometry shows FEV1/FVC of 0.58.
Which pathophysiologic mechanism best explains the air trapping?