Breathing Systems
Bailey Freeman, DNP, CRNA and Angela Mordecai
Quick Facts
- Breathing circuits deliver oxygen and anesthetic gases to the patient and remove carbon dioxide (CO₂).
- Rebreathing (Circle) Systems: Use CO₂ absorbers; allow partial re-use of exhaled gas.
- Non-Rebreathing Systems: Do not remove CO₂; all exhaled gas is vented and replaced by fresh gas.
- Major components include: fresh gas inlet, inspiratory/expiratory limbs, APL valve, reservoir bag, and CO₂ absorber (for circle systems).
Procedure
Setup and Use
- Connect the breathing circuit to the anesthesia machine securely.
- Ensure all components (bag, valves, absorber) are intact and leak-free.
- Set fresh gas flow based on circuit type and patient needs.
- Perform pre-use checks before connecting to the patient.
- Monitor circuit behavior and pressures during use.
- After the case, discard or sterilize components per facility policy.
Pre-Use Checks
- Leak test: Check for airtight seal throughout the system.
- CO₂ absorber: Confirm color change or duration of use per protocol.
- APL valve: Verify range of motion and test pressure settings.
Confirmation Steps
- Ensure visible movement of the reservoir bag with patient breaths or manual ventilation.
- Verify effective ETCO₂ waveform and consistent oxygen saturation.
- Check scavenging system for proper gas removal.
Documentation Requirements
- Breathing circuit type (rebreathing vs. non-rebreathing).
- Fresh gas flow rate and circuit configuration (e.g., pediatric vs. adult).
- Notes on any component malfunctions or substitutions.
Scope Guide
Strategies
- Select the appropriate breathing circuit for patient age, size, and ventilation needs.
- Teach learners how gas flows through the circuit using a visual diagram or animation.
- Discuss pros/cons of each system (e.g., rebreathing conserves heat and moisture).
Clinical Optimization
- Monitor for increased resistance or high peak airway pressures indicating circuit obstruction.
- Replace CO₂ absorber when exhaustion is suspected (e.g., rising ETCO₂ despite ventilation).
- Use low-flow anesthesia in rebreathing systems to conserve volatile agents.
Pearls
- Non-rebreathing systems are ideal for short cases or small patients (less resistance).
- Ensure APL valve is properly adjusted to avoid inadvertent high pressure or hypoventilation.
- Always perform a machine and circuit check before every case, even for simple setups.
References
- StatPearls. Anesthesia Breathing Systems. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK574503/
- OpenAnesthesia. Anesthesia Breathing Systems. https://www.openanesthesia.org/keywords/anesthesia-breathing-systems/
- How Equipment Works. Circle Breathing System. https://www.howequipmentworks.com/circle_breathing_system/
