Tracheostomy reduces dead space by: (A) By-passing upper airway, (B) Increased V/Q ratio, (C) Reducing airflow resistance, (D) By all of the above mechanisms
Answer is A. 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)