Which statement best describes the Venturi mask?

• A. It humidifies inspired air.
• B. It delivers variable FiO2 based on flow.
• C. It provides flow-independent oxygen.
• D. It provides precise, fixed FiO2 settings.

Answer: (D)

The Venturi mask is designed to deliver a precise, fixed FiO2 by using fixed-diameter diluters (jet nozzles) that mix a specific amount of room air with the supplied oxygen. The adapter is color-coded to set an exact oxygen concentration, such as 24%, 28%, 35%, 40%, or 50%. Because the amount of entrained room air is calibrated, the delivered FiO2 stays constant across a range of patient inspiratory efforts, giving a reliable, exact oxygen concentration when that level is needed.

It does not inherently humidify inspired air—the mask’s job is to control the oxygen concentration, not add humidity. It’s not a device where FiO2 varies with how hard the patient breathes; rather, it is meant to provide a stable, predetermined FiO2. The idea of “flow-independent” oxygen isn’t the standard way to describe it; the key point is the FiO2 is fixed by the adapter, not by changing flow.