A 58-year-old male smoker from Delhi presents with progressive dyspnea on exertion for 6 months. He denies chest pain or orthopnea. On examination, he has diminished breath sounds bilaterally and prolonged expiration. Spirometry shows: FEV₁ = 52% predicted, FVC = 78% predicted, FEV₁/FVC ratio = 0.58. DLCO is reduced at 65% predicted. Which of the following best describes the spirometric pattern?

Explanation

## Spirometric Pattern Interpretation ### Key Findings Analysis **Key Point:** The FEV₁/FVC ratio of 0.58 (normal >0.70) is the hallmark of airflow obstruction. Combined with reduced FEV₁ and preserved/near-normal FVC, this defines an obstructive pattern. ### Diagnostic Criteria Table | Parameter | This Patient | Obstructive | Restrictive | Mixed | |-----------|-------------|------------|------------|-------| | FEV₁/FVC | 0.58 | <0.70 | >0.70 | <0.70 | | FEV₁ | 52% | ↓ | ↓ | ↓↓ | | FVC | 78% | Normal/↑ | ↓ | ↓ | | DLCO | 65% | ↓ (emphysema) | Normal | Variable | ### Clinical Correlation **High-Yield:** DLCO reduction in an obstructive pattern specifically points to **emphysema** (destruction of alveolar walls and capillary bed) rather than chronic bronchitis (which has normal DLCO). This patient's smoking history, prolonged expiration, and diminished breath sounds all support emphysematous COPD. **Clinical Pearl:** In pure obstructive airway disease (asthma, bronchitis), DLCO is typically normal because the alveolar-capillary membrane is intact. Reduced DLCO + obstruction = parenchymal destruction = emphysema. ### Why This Is Obstructive, Not Restrictive - FVC is 78% (near-normal), not severely reduced - FEV₁/FVC <0.70 confirms airflow obstruction - If this were restrictive, both FEV₁ and FVC would be proportionally reduced, maintaining FEV₁/FVC >0.70 [cite:Harrison 21e Ch 246]