Certified Respiratory Therapist Practice Exam

When encountering an oxygen concentration of 55% being delivered by an air-entrainment mask that is set to provide 31% oxygen, the first step is to check the entrainment ports. The air-entrainment mask operates on the principle of mixing room air with a controlled flow of oxygen to achieve specific oxygen concentrations. If the measured concentration is significantly higher than what the device is set to deliver, this indicates a potential malfunction or blockage in the entrainment ports.

Checking the entrainment ports is essential because if they are obstructed by secretions, debris, or if the mask is improperly fitted, the mask may fail to mix ambient air properly with the oxygen, resulting in an unexpectedly high concentration of oxygen being delivered. Ensuring that these ports are clear guarantees that the device can function as intended, delivering the correct preset oxygen concentration.

This step is crucial in troubleshooting issues with the device and is typically the logical first action before adjusting more complex settings or considering the type of mask in use.