Can anesthesia machines be set to become open systems?

Can Anesthesia Machines Be Set to Become Open Systems?

No, modern anesthesia machines cannot and should not be "set" to become open systems in the traditional sense—the term "open system" refers to a classification of anesthetic delivery methods (like insufflation or open-drop ether), not a configurable mode of contemporary anesthesia workstations. 1

Understanding System Classification

The confusion around "open systems" stems from outdated terminology. Anesthesia delivery is more accurately classified by technical construction principles rather than functional descriptors:

• Rebreathing systems (circle systems with CO₂ absorption) 1
• Flow- and valve-controlled non-rebreathing systems (Mapleson circuits, Bain circuits) 1
• Systems without reservoirs (historical open-drop techniques, insufflation) 1

The traditional classification into "closed, semiclosed, semiopen, and open systems" based on functional criteria is considered unclear and should be abandoned in favor of describing the technical hardware combined with the fresh gas flow rate used 1.

What You Can Actually Configure

Modern anesthesia workstations are rebreathing systems (typically circle systems) that can be operated at different fresh gas flow rates, but they remain fundamentally closed or semi-closed systems 1. You cannot convert them into true "open systems."

For Specific Clinical Scenarios Requiring Open Gas Delivery:

When managing fire risk during head/neck surgery with an ignition source:

• Use an open gas delivery device (face mask or nasal cannula) only if the patient is NOT oxygen-dependent and does NOT require moderate/deep sedation 2
• Before activating any ignition source around the face, head, or neck:
  • Stop supplemental oxygen delivery or reduce to minimum required to avoid hypoxia 2
  • Wait 1-3 minutes between decreasing oxygen flow and approving ignition source activation 2
  • If using nitrous oxide (unlikely with open delivery), stop it and wait 1-3 minutes before ignition 2

Critical caveat: A sealed gas delivery device (cuffed tracheal tube or laryngeal mask) should be used instead if moderate/deep sedation is required or if the patient exhibits oxygen dependence 2. Routine delivery of supplemental oxygen in an open system creates a high-risk situation and should be avoided 2.

Machine Preparation for Trigger-Free Anesthesia

If your question relates to preparing machines to avoid volatile anesthetics (creating a "vapor-free" system), this is entirely different:

• Remove vaporizers before flushing the machine 2
• Replace breathing circuits, fresh gas hose (when available), and soda lime 2
• Flush with maximum fresh gas flow ≥10 L/min for manufacturer-recommended duration 2
• Set tidal volume at 600 mL and frequency at 15 bpm during flushing if using mechanical ventilation 2
• Consider using activated charcoal filters if available to reduce volatile agent concentrations to <5 ppm in 2-3 minutes 2

Common Pitfalls

• Do not confuse "open system" with high fresh gas flow rates—these are different concepts 1
• Never attempt to manually convert a circle system into a true open system—this compromises safety features and monitoring capabilities 3, 4
• Avoid routine supplemental oxygen delivery via open devices (nasal cannula/face mask) in the operating room—this creates unnecessary fire risk 2
• Do not assume older terminology applies to modern workstations—contemporary machines are designed as integrated rebreathing systems with sophisticated monitoring 1, 3