Which type of system is referred to as a closed rebreathing system?

A closed rebreathing system is characterized by its design that allows for the recirculation of exhaled gases with minimal release into the environment. In this type of system, the pop-off valve—which typically allows excess gas to escape—remains nearly closed, allowing the gases that are exhaled by the patient to be reused after being processed through a CO2 absorbent. This configuration ensures that the system maintains a higher concentration of anesthetic agents and preserves the heat and moisture from the patient’s breath.

By contrast, a system with continuous oxygen flow would not be classified as closed, as it actively introduces new gas and typically allows for significant amounts of exhaled gases to escape, preventing adequate rebreathing. High oxygen flow systems also do not retain exhaled gases, as they provide an excessive amount of fresh gas flow, making it unsuitable for a closed rebreathing setup. Similarly, a system that uses only fresh gas explicitly does not allow for the rebreathing of exhaled gases, which is contrary to the principles behind a closed rebreathing system.