Which of the following provide all of the patient's inspiratory flow and delivers a constant FiO2 over the patient's entire respiratory cycle? Select one: a. aerosol mask b. nasal cannula c. simple mask d. venturi mask

Answer

The correct answer is d. venturi mask. A Venturi mask is a high-flow oxygen delivery device that uses the Bernoulli principle to entrain room air in a precise ratio with source oxygen. Because it provides a high total flow rate that meets or exceeds the patient's peak inspiratory flow demands, the fraction of inspired oxygen (FiO2) remains constant and predictable, regardless of the patient's breathing pattern or respiratory rate. In contrast, low-flow devices like nasal cannulas and simple masks deliver oxygen at rates lower than the patient's inspiratory flow, causing the patient to draw in additional room air and making the actual FiO2 variable. Aerosol masks can provide high flow, but 'venturi mask' is the classic textbook answer for maintaining a specific, constant FiO2 across the respiratory cycle.