This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anaesthesia
[{'content': 'Tracheostomy reduces dead space by \nSelect and explain. \nA. By-passing upper airway, B. Increased V/Q ratio, C. Reducing airflow resistance, D. By all of the above mechanisms', 'role': 'user'}, {'content': "Answer: A \nExplanation: Impoant effects of tracheostomy on respiratory physiologyTracheostomy decreases dead space as upper airways and nasal cavity are bypassedTracheostomy decreases ventilation/perfusion (V/Q) ratio. Increased dead space increases ventilation/perfusion ratio as the dead space (containing air) is ventilated but not perfused for gaseous exchange. Tracheostomy decreased the dead space, therefore it will decrease the V/Q ratioTracheostomy reduces the airflow resistance(Refer: Morgan and Mikhail's Clinical Anaesthesiology, 5th edition, pg no. 1237)", 'role': 'assistant'}]