What are the two types of breathing systems?

• A. Semi-open and full closed
• B. Mixed and pure
• C. Open system and closed system
• D. Single-use and reusable

Answer: (C)

In anesthesia practice, breathing systems are classified by whether exhaled gas is rebreathed or vented to the atmosphere. The two forms are open systems and closed systems.

In an open system, fresh gas is delivered to the patient and the exhaled gas escapes to the surrounding environment, with little to no rebreathing and typically higher fresh gas flow. In a closed system, exhaled gas is captured, passed through a carbon dioxide absorber, and rebreathed by the patient, which means a lower fresh gas flow is used and the gas is recycled to some extent.

That’s why open system and closed system is the best answer. Other options mix different concepts or describe equipment usage rather than the fundamental mode of handling gases.