A 58-year-old male smoker presents to the pulmonary clinic with a 10-year history of progressive dyspnea on exertion. He has a 40 pack-year smoking history and reports chronic productive cough. On examination, he has barrel chest and pursed-lip breathing. Spirometry shows FEV₁ 42% predicted, FVC 65% predicted, and FEV₁/FVC ratio 0.58. His TLC is 125% predicted and RV is 220% predicted. What is the primary spirometric pattern and the most likely diagnosis?

Explanation

## Spirometric Pattern Analysis **Key Point:** The FEV₁/FVC ratio of 0.58 (< 0.70) is diagnostic of airflow obstruction. Combined with elevated TLC and markedly elevated RV, this indicates air trapping characteristic of emphysema. ### Interpretation of Values | Parameter | Patient Value | Normal | Interpretation | | --- | --- | --- | --- | | FEV₁/FVC | 0.58 | > 0.70 | **Obstructive** | | FEV₁ | 42% | > 80% | Severe reduction | | FVC | 65% | > 80% | Mildly reduced | | TLC | 125% | 80–120% | Hyperinflation | | RV | 220% | 100–150% | **Severe air trapping** | **High-Yield:** The disproportionate elevation of RV relative to TLC (RV/TLC ratio > 50%) is pathognomonic for emphysema. This reflects loss of elastic recoil and premature small airway collapse during expiration. ### Clinical Correlation **Clinical Pearl:** Barrel chest, pursed-lip breathing, and 40 pack-year history are classic signs of COPD with emphysematous predominance. The FEV₁ of 42% predicted places him in GOLD Stage 3 (severe airflow limitation). **Mnemonic:** OBSTRUCTIVE spirometry = **FEV₁/FVC < 0.70** - FEV₁ may be severely reduced - FVC relatively preserved or mildly reduced - TLC and RV elevated (air trapping) ### Why This Is Emphysema, Not Asthma Asthma typically shows reversibility with bronchodilators and does not produce the chronic, irreversible air trapping and hyperinflation seen here. The clinical history of chronic smoking and progressive, irreversible obstruction confirms emphysema.