Which statement about restrictive lung disease is NOT true?

• A. It does not involve reduced lung volumes
• B. Morbid obesity, sarcoidosis, pulmonary fibrosis, TB, CHF, kyphoscoliosis can cause restrictive patterns
• C. Volumes include TLC, FRC, RV
• D. It is characterized by reduced volumes and expiratory flow rates

Answer: (A)

Restrictive lung disease is defined by reduced total lung capacity and other volumes due to limited expansion of the lungs or chest wall. When the lungs cannot fill to their normal size, all the resting lung volumes that depend on filling are smaller: TLC drops, and because TLC is smaller, the volumes that sit on top of it, like FRC and RV, are also reduced. That makes statements about reduced volumes a hallmark of restrictive disease.

The idea that it does not involve reduced lung volumes is not true, because restriction by definition lowers lung volumes. The other statements fit what we know: many conditions such as morbid obesity, sarcoidosis, pulmonary fibrosis, TB, congestive heart failure, and kyphoscoliosis can produce a restrictive pattern by limiting chest wall stretch or parenchymal expansion. And the volumes affected in restriction include TLC, FRC, and RV—these are the volumes typically reduced. While expiratory flow rates can be affected, the key feature is the overall reduction in lung volumes with a normal or increased FEV1/FVC ratio rather than a universal complaint of reduced expiratory flow rates.