Decreased FEV1 with a normal FEV1/FVC ratio is most consistent with which pulmonary condition?

Decreased FEV1 with a normal FEV1/FVC ratio is most consistent with which pulmonary condition?

• A. Emphysema
• B. Chronic bronchitis
• C. Restrictive pulmonary disease
• D. Pulmonary emphysema and chronic bronchitis

Answer: (C)

A key idea is how spirometry patterns separate obstructive from restrictive problems. When FEV1 is reduced but the FEV1/FVC ratio stays about normal, it points to a restrictive defect. In restriction, the lung volumes themselves are diminished (lower FVC and total lung capacity), so FEV1 falls roughly in line with FVC, keeping the ratio normal. In obstructive diseases like emphysema or chronic bronchitis, airway narrowing lowers expiratory flow more than lung volume, so FEV1 drops disproportionately and the FEV1/FVC ratio declines. So the described pattern—decreased FEV1 with a normal ratio—fits restrictive pulmonary disease, which can arise from interstitial lung disease, chest wall or neuromuscular problems, or decreased lung compliance in other ways.

A key idea is how spirometry patterns separate obstructive from restrictive problems. When FEV1 is reduced but the FEV1/FVC ratio stays about normal, it points to a restrictive defect. In restriction, the lung volumes themselves are diminished (lower FVC and total lung capacity), so FEV1 falls roughly in line with FVC, keeping the ratio normal. In obstructive diseases like emphysema or chronic bronchitis, airway narrowing lowers expiratory flow more than lung volume, so FEV1 drops disproportionately and the FEV1/FVC ratio declines. So the described pattern—decreased FEV1 with a normal ratio—fits restrictive pulmonary disease, which can arise from interstitial lung disease, chest wall or neuromuscular problems, or decreased lung compliance in other ways.