Prior to applying a nonrebreathing mask to a patient, you must ensure that the

• A. flow rate is set at 6 L/min.
• B. patient has reduced tidal volume.
• C. reservoir bag is fully inflated.
• D. one-way valve is sealed.

Answer: (C)

The key idea is to make sure the reservoir bag is fully inflated before applying the nonrebreathing mask. That bag acts as an oxygen reservoir, so when it’s inflated, the patient can draw a high concentration of oxygen with each inhale rather than pulling in room air, giving a higher FiO2. If the bag isn’t inflated, ambient air will dilute the oxygen during inhalation and the patient won’t receive the intended high concentration. The flow rate needs to be high enough to keep the bag inflated throughout the breath; a setting like 6 L/min is generally insufficient for a nonrebreather. Reduced tidal volume isn’t a required condition for using the mask, and a functioning one-way valve is essential to prevent exhaled air from entering the reservoir—sealing it would disrupt proper delivery.