In upper airway obstruction, all of the following changes are seen except

Changes in lung function tests in obstructive lung diseases- Eg: Emphysema TLC- Increase RV- Increase FRC- Increase Peak expiratory flow rate- Decrease FEV1- Decreased out of proportion to FVC (Forced vital capacity) Forced expiratory vital capacity (FEVC)- Normal to slightly decreased FEV1/FEVC- Decreased (May decrease as low as 20-30%)  Changes in lung function tests in restrictive lung diseases TLC- Decreased RV- Decreased FRC- Decreased Forced mid-expiratory flow rate- Decrease FEV1- Decreased in proportion to FVC (Forced vital capacity) Forced vital capacity (FVC)- Decreased FEV1/FEVC- Near-normal or increased. Lung compliance- decreased Diffusion capacity- decreased