Anaesthesia General d604c033 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 High-Yield Explanation Nasopharyngeal catheter deliver 32% of O2 (FiO2 → 0.32) at flow-rate 3 litre / minute.