This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'In upper airway obstruction, all of the following changes are seen except \nSelect and explain. \nA. Decreased maximum breathing capacity, B. RV decreased, C. Decreased FEV, D. Decreased vital capacity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Changes in lung function tests in obstructive lung diseases- Eg: Emphysema\nTLC- Increase\nRV- Increase\nFRC- Increase\nPeak expiratory flow rate- Decrease\nFEV1- Decreased out of proportion to FVC (Forced vital capacity)\nForced expiratory vital capacity (FEVC)- Normal to slightly decreased\nFEV1/FEVC- Decreased (May decrease as low as 20-30%)\n\xa0Changes in lung function tests in restrictive lung diseases\nTLC- Decreased\nRV- Decreased\nFRC- Decreased\nForced mid-expiratory flow rate- Decrease\nFEV1- Decreased in proportion to FVC (Forced vital capacity)\nForced vital capacity (FVC)- Decreased \nFEV1/FEVC- Near-normal or increased.\nLung compliance- decreased\nDiffusion capacity- decreased', 'role': 'assistant'}]