Pulmonary Diagnostic Tests

Question · easy

A 24-year-old with episodic wheeze undergoes spirometry. FEV1 is 2.10 L before bronchodilator and 2.45 L after (a 16.7% and 350 mL increase). Which criterion defines a positive bronchodilator response?

An increase in FEV1 or FVC of at least 12% AND at least 200 mL from baseline An increase in FEV1 of at least 200 mL, regardless of percentage Any return of FEV1 to at least 80% of the predicted value An increase in FEV1 of at least 15%, regardless of absolute volume

Question · easy

In which of the following conditions is the diffusing capacity for carbon monoxide (DLCO) most likely to be ELEVATED?

Idiopathic pulmonary fibrosis Diffuse alveolar hemorrhage Emphysema Pulmonary arterial hypertension

Question · medium

A 68-year-old never-smoker without respiratory symptoms has routine spirometry: FEV1/FVC 0.69, FEV1 88% of predicted. The age/sex/height-adjusted lower limit of normal (LLN) for the FEV1/FVC ratio is 0.66. How should this be interpreted?

Mixed obstructive-restrictive disease requiring TLC measurement Normal spirometry, because the ratio is above the LLN Restrictive pattern, because FEV1 is under 90% of predicted Mild airflow obstruction, because the ratio is below 0.70

Question · medium

A 45-year-old with progressive exertional stridor has spirometry showing flattening of BOTH the inspiratory and expiratory limbs of the flow-volume loop. Which diagnosis best fits this pattern?

Idiopathic pulmonary fibrosis Severe persistent asthma Fixed central airway obstruction (e.g., tracheal stenosis) Bilateral diaphragmatic paralysis

Question · hard

A 55-year-old with dyspnea and orthopnea has: FEV1 55% and FVC 52% of predicted (FEV1/FVC 0.82) seated, with FVC falling 28% from upright to supine; TLC 68% of predicted; RV 128% of predicted; DLCO 92% of predicted. Which mechanism best explains this pattern?

Parenchymal infiltration (e.g., idiopathic pulmonary fibrosis) Chest wall restriction from moderate obesity Respiratory muscle (diaphragmatic) weakness Severe chronic obstructive pulmonary disease