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: Anaesthesia
[{'content': 'Tracheostomy reduces dead space by ? \nSelect and explain. \nA. By-passing upper airway, B. Increasing V/Q ratio, C. Reducing airflow resistance, D. By all of the above mechanisms', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is'a'i.e., By-passing upper airway (Ref: Morgan 4tu/e p. 553) Impoant effects of tracheostomy on respiratory physiologyTracheostomy decreases dead space as upper airways and nasal cavity are bypassed.Tracheostomy decreases ventilation/perfusion (V/Q) ratio.Tracheostomy reduces the airflow resistance.", 'role': 'assistant'}]