A 60-year-old smoker has FEV1 = 1.2 L, FVC = 2.8 L, and FEV1/FVC ratio = 43%. TLC is 7.5 L. What is the pattern of spirometry abnormality?
- A Restrictive pattern
- B Obstructive pattern ✓
- C Mixed obstructive and restrictive pattern
- D Normal spirometry
Correct answer: B. Obstructive pattern
Explanation
An obstructive pattern is defined by FEV1/FVC ratio below 0.70 (70%). This patient's ratio of 43% with an elevated TLC (indicating air trapping) is classic for obstructive lung disease such as COPD or emphysema. Restrictive disease shows reduced FVC and TLC with a preserved or elevated FEV1/FVC ratio. Mixed pattern would show both a reduced ratio and a reduced TLC.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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