A 62-year old patient has been diagnosed with a restrictive pulmonary disease. Which of his following measurements is likely to be normal?

In restrictive lung diseases, FEV1 and FVC are reduced, but FEV1 is larger in comparison. So the FEV1/FVC ratio will be normal or slightly increased.RV, TLC, and FRC are also decreased in restrictive lung diseases(fibrosis). Reduction in FEV1 and FVC are related to the reduction in TLC. In obstructive lung diseases, FVC and FEV1 are reduced, FEV1 is much smaller. As a result, the FEV1/FVC ratio will be decreased. Here, RV and FRC will be increased due to obstruction and hyperinflation. Reference: Harrison'ss Medicine-18th edition, page no:2086.