Which statement correctly identifies the reservoir bag in a partial rebreathing mask?

Which statement correctly identifies the reservoir bag in a partial rebreathing mask?

• A. The bag should be kept fully collapsed during inspiration
• B. The bag should never be used with this mask
• C. The reservoir bag should be kept half full during inspiration
• D. The bag should be filled with humidified air only

Answer: (C)

The main idea here is how the reservoir bag in a partial rebreathing mask should behave to ensure proper gas delivery. In this setup, some of the exhaled gas is directed into the bag to be rebreathed on the next breath, so having a reserve of gas available is important. Keeping the reservoir bag about half full during inspiration provides enough volume for the inspiratory effort while still allowing room for the bag to expand as needed. If the bag were fully collapsed, there wouldn’t be enough reservoir gas for rebreathing and the patient would end up drawing in more room air. If the bag were kept completely full, it could impede easy inhalation and disrupt the flow dynamics needed for effective rebreathing. It’s not correct to say the bag is never used with this mask, since the reservoir is a defining feature of a partial rebreathing mask. It’s also not accurate to describe the bag as filled with humidified air only; while humidification may occur, the bag’s role is to hold a reserve of oxygen-rich gas and a portion of exhaled gas for rebreathed oxygen, not just humidified air.

The main idea here is how the reservoir bag in a partial rebreathing mask should behave to ensure proper gas delivery. In this setup, some of the exhaled gas is directed into the bag to be rebreathed on the next breath, so having a reserve of gas available is important.

Keeping the reservoir bag about half full during inspiration provides enough volume for the inspiratory effort while still allowing room for the bag to expand as needed. If the bag were fully collapsed, there wouldn’t be enough reservoir gas for rebreathing and the patient would end up drawing in more room air. If the bag were kept completely full, it could impede easy inhalation and disrupt the flow dynamics needed for effective rebreathing.

It’s not correct to say the bag is never used with this mask, since the reservoir is a defining feature of a partial rebreathing mask. It’s also not accurate to describe the bag as filled with humidified air only; while humidification may occur, the bag’s role is to hold a reserve of oxygen-rich gas and a portion of exhaled gas for rebreathed oxygen, not just humidified air.