1 Core Components
Angela Mordecai and Bailey Freeman, DNP, CRNA
Quick Facts
- The anesthesia machine delivers oxygen and anesthetic gases safely and precisely to the patient.
- Core components include gas sources, vaporizers, flowmeters, and breathing circuits.
- Monitoring interfaces (e.g., flowmeters, pressure gauges, capnography) provide continuous patient safety data.
- Understanding the basic functions of each component is essential for troubleshooting and safe use.
Procedure
Core Components
- Oxygen Source: Provided from a pipeline or cylinder; powers alarms and drives ventilation.
- Flowmeters: Measure and regulate gas flow rates in liters per minute (L/min).
- Vaporizers: Convert liquid anesthetic into a calibrated gas mixture added to the circuit.
- Fresh Gas Outlet: Delivers the final gas mixture to the breathing circuit.
- Oxygen Flush Valve: Delivers 100% oxygen at high flow (~35–75 L/min); used cautiously.
Monitoring Interfaces
- Pressure Gauge: Monitors circuit pressure in cmH₂O; important during manual ventilation.
- Volume Monitors: Measure tidal volume and minute ventilation; help confirm adequate delivery.
- Capnography (ETCO₂): Measures end-tidal CO₂ to assess ventilation and circuit patency.
- O₂ Analyzer: Continuously measures oxygen concentration in the circuit.
Confirmation Steps
- Confirm gas source is connected and pressure adequate.
- Verify vaporizers are filled and securely mounted.
- Check that flowmeters move smoothly and reflect accurate flows.
- Ensure all monitors display expected values during pre-case machine check.
Documentation Requirements
- Record oxygen flow rate and volatile agent used.
- Note any circuit pressure readings if abnormal.
- Document machine check completion before patient arrival.
Scope Guide
Strategies
- Perform a full anesthesia machine check at the start of the day, including both components and monitors.
- Understand the backup systems (e.g., battery, manual bagging) in case of equipment failure.
Clinical Optimization
- Use O₂ analyzer and capnography in every case to monitor real-time ventilation and oxygenation.
- Adjust flow rates and vaporizers deliberately; confirm settings match the anesthetic plan.
Pearls
- The oxygen flush valve bypasses vaporizers—avoid activating it during inspiration to prevent barotrauma.
- Flowmeters are gas-specific—read at the center of the float ball for accuracy.
- Early troubleshooting is key: pressure spikes or sudden monitor changes often signal disconnections or obstruction.
References
- StatPearls. Anesthesia Machine. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/books/NBK572060/
- OpenAnesthesia. Gas Flow and Vaporizers. https://www.openanesthesia.org/keywords/vaporizers/
- How Equipment Works. Flowmeters and Vaporizers. https://www.howequipmentworks.com/
