Which spirometry result best identifies restrictive lung disease?

Which spirometry result best identifies restrictive lung disease?

• A. FVC
• B. FEV1
• C. FEV1/FVC
• D. Peak expiratory flow

Answer: (A)

A reduced FVC is the spirometry finding most consistent with restrictive lung disease. In restriction, the lungs can’t expand fully, so total lung capacity and usable lung volume drop. This lowers the amount of air a person can forcibly exhale after a deep breath, giving a reduced FVC. Because the decrease often affects FEV1 and FVC proportionally, the FEV1/FVC ratio stays normal or may even be increased, which helps distinguish restriction from obstruction. Peak expiratory flow, while useful for assessing effort and large-airway flow, does not specifically reflect overall lung volume and is not the best indicator of restriction.

A reduced FVC is the spirometry finding most consistent with restrictive lung disease. In restriction, the lungs can’t expand fully, so total lung capacity and usable lung volume drop. This lowers the amount of air a person can forcibly exhale after a deep breath, giving a reduced FVC. Because the decrease often affects FEV1 and FVC proportionally, the FEV1/FVC ratio stays normal or may even be increased, which helps distinguish restriction from obstruction. Peak expiratory flow, while useful for assessing effort and large-airway flow, does not specifically reflect overall lung volume and is not the best indicator of restriction.