Anesthesia Gas Machine- Table of Contents

The Anesthesia Gas Machine 2025 Historical picture

Michael P. Dosch PhD CRNA (retired), Professor Emeritus
Nurse Anesthesia, University of Detroit Mercy
This site is https://healthprofessions.udmercy.edu/academics/na/agm/index.htm.

Revised May 2025. Copyright Michael P. Dosch. Use for non-profit purposes only is granted.

Please note that this site does not collect confidential, private or semi-private information such as email addresses, email content, or email exchanges with visitors. No data is recorded or stored.

Table of Contents

Introduction	History of site, Author's Disclosure statement, Acknowledgments, How to contact author, Other resources for learning.
Components and systems	Introduction Numbers to remember General features of all anesthesia gas machines Features required by standard Path of gases within the machine Five tasks of oxygen Supply, Processing, Delivery, Disposal model Manufacturers
Supply of gases & electricity	Gas sources Pipeline Cylinders Standards; Capacity, color, markings; Components; Storage handling and installation; Medical gases; Use Electrical power supply Failures and faults (What happens when pipeline oxygen pressure or electrical power is lost?)
Fail-safe, Flowmeters, Hypoxic guard	Fail-safe system Flowmeters How they work Glass flowmeters Hybrids with needle valve controls, electronic capture and display) Gas mixers- electronic flow control, capture, and display EtC (end-tidal control) Classify by use (flowmeters for FGF, auxiliary oxygen, scavenging, and common gas outlet) Using flowmeters safely Proportioning systems (Hypoxic guard)
Vaporizers	Physical principles Classification Vaporizer interlock Operating principles of variable bypass vaporizers Effect of altitude How to fill vaporizers How much liquid agent does a vaporizer use per hour? Hazards and safety features of contemporary vaporizers Current models
Breathing circuits	Classification Breathing circuits- Non rebreathing (Mapleson and Bain) How do they work? Fresh gas flow requirements Pethick Test for the Bain Circuit Circle System King (limb within limb) Advantages and disadvantages
CO₂ absorption	General characteristics and composition Chemistry- soda lime Safe use Changing canisters Clinical signs of exhaustion
Ventilators	Classification Bellows classification New ventilator modes (PCV, PC-VG [Autoflow], SIMV, PSV) Typical ventilator alarms New features Piston ventilators Flexibility (New modes) Accuracy at lower tidal volumes (VCV) Compliance and leak testing Fresh gas decoupling versus compensation Suitability for low flows Current models Dräger Apollo, Perseus, Fabius GS GE ADU, Aisys, Avance, Aespire, Aestiva Other; Paragon, Anestar, Mindray Older or obsolete ventilators
Using breathing circuits and ventilators	Humidification Choosing the best fresh gas flow Low flows How to denitrogenate ("preoxygenate") Malignant hyperthermia implications for equipment. Ventilator and Breathing circuit problems and hazards Increased inspired carbon dioxide (troubleshooting and treatment)
Scavenging	Scavenging Systems Purpose, Interface (closed or open), Practice guidelines, Components, Hazards Avoiding occupational exposure to waste anesthetic gas
Gas machine Checkout, Medicolegal; Cleaning & sterilization	Anesthesia gas machine checklist Pre-Anesthesia Checklist Additions to the end of electronic checklists AWS Quick Check for emergencies (and every day) Checklist for older anesthesia gas machines Negative pressure leak check Medicolegal Risk management, Quality assurance, Monitoring standards, Manufacturing standards Cleaning and sterilization Sterilization-Moist heat, liquid and gas sterilization methods Care of specific equipment
New gas machines	Dräger Medical Inc. (Telford, PA)- Perseus, Fabius GS, Apollo GE (Madison WI)- Aisys, Avance, Aespire, Aestiva, Aestiva MRI Other - Paragon, Anestar Older or obsolete- Narkomed (6000/6400, GS, Julian, MRI, Mobile, 2C, 4), Kion, Ohmeda (Modulus SE, Excel 210/110)
Purchasing equipment	Education and training Advanced ventilation, Computer and monitor integration, Low flows, Laryngeal mask airway and mechanical ventilation, Electronic Checkout Operating costs Installation of new machines
Test yourself	Question and answer format.

Introduction

History of site, Author's Disclosure statement, Acknowledgments, How to contact author, Other resources for learning.

Components and systems

Introduction
Numbers to remember
General features of all anesthesia gas machines
- Features required by standard
- Path of gases within the machine
- Five tasks of oxygen
- Supply, Processing, Delivery, Disposal model
Manufacturers

Supply of gases & electricity

Gas sources
- Pipeline
- Cylinders
  - Standards; Capacity, color, markings; Components; Storage handling and installation; Medical gases; Use
Electrical power supply
Failures and faults (What happens when pipeline oxygen pressure or electrical power is lost?)

Fail-safe, Flowmeters, Hypoxic guard

Fail-safe system
Flowmeters
- How they work
  - Glass flowmeters
  - Hybrids with needle valve controls, electronic capture and display)
  - Gas mixers- electronic flow control, capture, and display
  - EtC (end-tidal control)
- Classify by use (flowmeters for FGF, auxiliary oxygen, scavenging, and common gas outlet)
- Using flowmeters safely
Proportioning systems (Hypoxic guard)

Vaporizers

Physical principles
Classification
Vaporizer interlock
Operating principles of variable bypass vaporizers
- Effect of altitude
How to fill vaporizers
- How much liquid agent does a vaporizer use per hour?
Hazards and safety features of contemporary vaporizers
Current models

Breathing circuits

Classification
Breathing circuits- Non rebreathing (Mapleson and Bain)
- How do they work?
- Fresh gas flow requirements
- Pethick Test for the Bain Circuit
Circle System
- King (limb within limb)
Advantages and disadvantages

CO₂ absorption

General characteristics and composition
Chemistry- soda lime
Safe use
- Changing canisters
- Clinical signs of exhaustion

Ventilators

Classification
- Bellows classification
New ventilator modes (PCV, PC-VG [Autoflow], SIMV, PSV)
Typical ventilator alarms
New features
- Piston ventilators
- Flexibility (New modes)
- Accuracy at lower tidal volumes (VCV)
  - Compliance and leak testing
  - Fresh gas decoupling versus compensation
- Suitability for low flows
Current models
- Dräger Apollo, Perseus, Fabius GS
- GE ADU, Aisys, Avance, Aespire, Aestiva
- Other; Paragon, Anestar, Mindray
Older or obsolete ventilators

Using breathing circuits and ventilators

Humidification
Choosing the best fresh gas flow
- Low flows
How to denitrogenate ("preoxygenate")
Malignant hyperthermia implications for equipment.
Ventilator and Breathing circuit problems and hazards
- Increased inspired carbon dioxide (troubleshooting and treatment)

Scavenging

Scavenging Systems
- Purpose, Interface (closed or open), Practice guidelines, Components, Hazards
Avoiding occupational exposure to waste anesthetic gas

Gas machine Checkout,
Medicolegal;
Cleaning & sterilization

Anesthesia gas machine checklist
- Pre-Anesthesia Checklist
- Additions to the end of electronic checklists
- AWS Quick Check for emergencies (and every day)
- Checklist for older anesthesia gas machines
Medicolegal
- Risk management, Quality assurance, Monitoring standards, Manufacturing standards
Cleaning and sterilization
- Sterilization-Moist heat, liquid and gas sterilization methods
- Care of specific equipment

New gas machines

Dräger Medical Inc. (Telford, PA)- Perseus, Fabius GS, Apollo
GE (Madison WI)- Aisys, Avance, Aespire, Aestiva, Aestiva MRI
Other - Paragon, Anestar
Older or obsolete- Narkomed (6000/6400, GS, Julian, MRI, Mobile, 2C, 4), Kion, Ohmeda (Modulus SE, Excel 210/110)

Purchasing equipment

Education and training
- Advanced ventilation, Computer and monitor integration, Low flows, Laryngeal mask airway and mechanical ventilation, Electronic Checkout
Operating costs
Installation of new machines

Test yourself

Question and answer format.