What feature is characteristic of a continuous flow oxygen system?

In a continuous flow oxygen system, the defining characteristic is that it provides a constant flow of oxygen to the user, regardless of their breathing pattern. This contrasts with systems that may provide oxygen only during specific phases of breathing, such as exhalation.

The option that suggests a reservoir bag is involved is inaccurate for a continuous flow system. Instead, a continuous flow system does not utilize a reservoir bag because it continuously delivers oxygen at a set flow rate, thereby eliminating the need for a bag to collect excess oxygen.

The other features mentioned, such as the reliance on pressure demand, provide oxygen only during exhalation, or mixing ambient air, do not apply to a continuous flow system. In fact, a continuous flow system typically delivers oxygen at a constant rate and does not mix with ambient air in the same manner as demand systems might. Thus, the correct understanding highlights the continuous delivery aspect as the hallmark of this type of oxygen system.