At a flow rate of 3L/min, inspiratory (FUO2) concentration of 30–60% can be achieved by using a –: (A) Nasopharyngeal catheter, (B) Simple face mask, (C) Venturi mask, (D) Head box
Answer is A. Nasopharyngeal catheter deliver 32% of O2 (FiO2 → 0.32) at flow-rate 3 litre / minute.