Pulmonology Flashcards

A 54-year-old man with BMI 47 kg/m² is evaluated for hypersomnia and morning headaches. ABG on room air: pH 7.37, PaCO2 54 mmHg, PaO2 57 mmHg, HCO3 30 mEq/L. Polysomnography shows AHI of 41/hr with prolonged hypopneas and oxygen nadir of 69%. Serum TSH and spirometry are normal. Which treatment strategy has the strongest evidence for reducing mortality compared to CPAP alone in this patient's condition?

Answer: Bilevel positive airway pressure with a spontaneous-timed backup rate (BPAP-ST)

This patient has obesity hypoventilation syndrome (OHS) — defined by BMI ≥30 kg/m², awake hypercapnia (PaCO2 ≥45 mmHg), and exclusion of other causes. OHS involves both upper-airway obstruction and impaired central ventilatory drive, so CPAP alone often fails to correct hypoventilation. BPAP-ST provides dual-pressure support plus a mandatory backup rate to treat hypoventilation directly, and trials (including the PICKWICK study) demonstrate superior PaCO2 correction and survival benefit over oxygen or CPAP. ASV is contraindicated in heart failure with EF ≤45% (SERVE-HF trial) and is not indicated for OHS-related hypoventilation. Supplemental oxygen alone can worsen hypercapnia by removing the hypoxic drive.

A 31-year-old woman with idiopathic pulmonary arterial hypertension undergoes right heart catheterization. Baseline: mPAP 55 mmHg, PAWP 8 mmHg, cardiac output 3.9 L/min, PVR 11.7 WU. After 10 minutes of inhaled nitric oxide (iNO) 40 ppm: mPAP 39 mmHg, PAWP 9 mmHg, cardiac output 5.1 L/min, PVR 5.7 WU. Which statement best characterizes the vasoreactivity result and its clinical implication?

Answer: Positive response; long-term high-dose calcium channel blocker therapy is appropriate

Per AHA/ESC guidelines, a positive vasoreactivity response requires ALL three criteria: (1) decrease in mPAP ≥10 mmHg, (2) absolute mPAP ≤40 mmHg, and (3) cardiac output unchanged or increased. This patient meets all three: mPAP fell 16 mmHg (≥10), reached an absolute value of 39 mmHg (≤40), and cardiac output rose from 3.9 to 5.1 L/min. A positive response identifies the small subset (~10%) of IPAH patients who respond long-term to CCBs (nifedipine, amlodipine, or diltiazem). The threshold is ≥10 mmHg reduction, not ≥15 mmHg; the cardiac output rise is expected in a true responder, not a disqualifier; and a single agent (iNO, adenosine, or IV epoprostenol) is sufficient for testing.

A 68-year-old with GOLD stage IV COPD presents with acute hypercapnic respiratory failure. Initial ABG on 28% FiO2: pH 7.24, PaCO2 78 mmHg, PaO2 52 mmHg. NIV is initiated with appropriate settings. Reassessment at 90 minutes shows pH 7.26, PaCO2 74 mmHg. The patient remains alert with GCS 14. Which factor, present at initial evaluation, is the STRONGEST independent predictor of subsequent NIV failure requiring intubation?

Answer: Failure of pH to improve to ≥7.30 within the first 60–120 minutes of NIV

Multiple prospective studies identify failure of pH to improve within 1–2 hours of NIV as the single strongest predictor of NIV failure in acute hypercapnic COPD exacerbation. This patient's pH improved only from 7.24 to 7.26 at 90 minutes — a minimal response that portends intubation. Initial PaCO2 level alone does not independently predict failure; many patients with very high PaCO2 respond well. While a low GCS (particularly <8–11) is a contraindication to NIV, this patient has a GCS of 14. Pneumonia as a trigger carries a worse prognosis but is not the strongest independent predictor of NIV failure per se. The early pH trajectory is the key decision-making signal.

A 47-year-old woman is diagnosed with cryptogenic organizing pneumonia (COP) confirmed by transbronchial biopsy. She is started on prednisone 1 mg/kg/day. At 10 weeks, CT shows near-complete resolution, and steroids are tapered and discontinued by week 14. At week 20, she returns with dyspnea, fever, and new bilateral peripheral consolidations on CT. Which management approach is most appropriate?

Answer: Restart prednisone at 1 mg/kg/day and plan a gradual taper over 12 months

COP has a relapse rate of up to 50–58% after steroid discontinuation, especially when steroids are tapered too quickly or the course is too short (<6 months). This patient's presentation — symptom recurrence after taper cessation with the same radiographic pattern — is classic relapse, not steroid-refractory disease. The correct approach is to restart prednisone at the full therapeutic dose (1 mg/kg/day) and then taper very slowly over 6–12 months to prevent re-relapse. Cyclophosphamide is reserved for truly refractory cases after multiple failed steroid courses. Surgical biopsy is not warranted when clinical and radiographic features are diagnostic of relapse. Antibiotics alone would be inappropriate without evidence of bacterial superinfection.

A 44-year-old woman who keeps pet parakeets presents with 9 months of progressive dyspnea. HRCT shows bilateral centrilobular ground-glass nodules, mosaic attenuation on expiratory imaging, and mild basal reticulation without honeycombing. PFTs reveal FVC 67% predicted, DLCO 51% predicted, FEV1/FVC 0.78. Bronchoalveolar lavage (BAL) is performed. Which BAL profile is most characteristic of her likely diagnosis?

Answer: Lymphocytosis >40% with a CD4:CD8 ratio less than 1.0

This patient's clinical syndrome — antigen exposure (pet birds), subacute progressive dyspnea, HRCT showing centrilobular nodules, mosaic air trapping, and restriction with impaired DLCO — is highly characteristic of hypersensitivity pneumonitis (HP; bird fancier's lung). BAL in HP shows a markedly lymphocytic alveolitis (>40% lymphocytes, sometimes >60%) with an inverted CD4:CD8 ratio (3.5). Neutrophilia is more characteristic of infection or acute lung injury. Eosinophilia >25% suggests eosinophilic pneumonia. Elevated surfactant proteins are seen in pulmonary alveolar proteinosis.

A 50-year-old man who received bilateral lung transplantation for COPD 5 years ago presents with 7 months of progressive exertional dyspnea. His best post-transplant FEV1 was 2.8 L. Current spirometry: FEV1 1.72 L (61% of baseline), FEV1/FVC 0.52. HRCT shows expiratory air trapping and subtle bronchiectasis. Bronchoscopy reveals grossly normal airways. BAL is negative for bacteria, fungi, and viruses. Transbronchial biopsies show no acute rejection and no lymphocytic bronchiolitis. Which statement regarding diagnosis and treatment is most accurate?

Answer: This is BOS grade 2; first-line therapy includes azithromycin and optimization of immunosuppression

Bronchiolitis obliterans syndrome (BOS) is defined and graded clinically by sustained FEV1 decline from the post-transplant baseline, after excluding other causes: BOS grade 1 = 66–80%, grade 2 = 51–65%, grade 3 = ≤50%. This patient's FEV1 is 61% of his personal best, placing him in BOS grade 2. BOS is a CLINICAL diagnosis — transbronchial biopsy has poor sensitivity for the patchy small-airway fibrosis and is NOT required. Normal-appearing central airways are expected, as BOS affects small bronchioles beyond bronchoscopic visualization. First-line management includes azithromycin (anti-inflammatory/immunomodulatory), optimization of calcineurin inhibitor levels, and adding or switching mycophenolate. Extracorporeal photopheresis is a second- or third-line salvage option for progressive BOS refractory to standard therapy.