The Anesthesia Gas Machine

Michael P. Dosch CRNA MS
University of Detroit Mercy Graduate Program in Nurse Anesthesiology
This site is http://www.udmercy.edu/crna/agm/.

Supply, Processing, Delivery, and Disposal Model (SPDD)

Supply

How do gases come to the anesthesia gas machine?
(Site: back of the machine)

Pipeline

Wall outlets
Connecting valves and hoses
Filters and check valves
Pressure gauges

Cylinders

Hanger yokes (yoke block)
Filters and check valves
Pressure gauge
Pressure regulators

Processing

How does the anesthesia gas machine prepare gases before their delivery to the patient?
(Site: within the machine, proximal to common gas outlet)

Fail-safe (oxygen pressure-failure devices)
Flowmeters (main and auxiliary)
Oxygen flush
Low oxygen pressure alarms
Ventilator driving gas
Proportioning systems (hypoxic guard)
Oxygen second-stage regulator (if present)
Vaporizers
Check valves distal to vaporizers (if present)
Common gas outlet

Delivery

How is the interaction of gases with the patient controlled and monitored?
(Site: breathing circuit)

Gas delivery hose connecting common gas outlet and breathing circuit
Breathing circuits
- Nonrebreathing
- Circle
Carbon dioxide absorption
Ventilators
Integral monitors
- Oxygen analysis
- Disconnect
- Spirometry
- Capnography
- Airway pressure
- Ventilator alarms
Addition of positive end-expiratory pressure
Means of humidification

Disposal

How are gases disposed of?
(Site: scavenger)

Scavenger systems
- Closed (active and passive)
- Open

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