Anesthesia Machine Review

Learning how a real anesthesia machine is supposed to work? Each of the following sections explains some learning objectives and how anesthesia machine functions are simulated in VAM.

High Pressure System

Color coding of gases

You might be in for a surprise when you work outside the United States!



The color code for oxygen is green in the U.S. but white internationally.

Several countries have their own unique color codes.

Connection systems

The role of the quick-connect & pin-index safety systems in preventing accidents.



Cylinder vs. pipeline oxygen supply

What are pressure regulators and how do they work?



Pressure gauge readings

Can a cylinder be empty with the gauge still indicating a positive pressure?



Function of the fail-safe device

Will the fail-safe device always prevent delivery of a hypoxic mixture?



Low pressure alarm

Will a decrease in oxygen pressure always trigger the low pressure alarm?

Low pressure alarm (when the pressure increases, the alarm goes off and the canister fills, but when the pressure decreases, the canister will empty, causing the alarm to go off again).



Ventilator drive gas circuit

Will the ventilator function in the absence of a pressurized O2 supply?



Using the oxygen flush

What happens if the oxygen flush is pressed during the inspiratory phase of mechanical ventilation?

What happens if oxygen flush is pressed during the expiratory phase of mechanical ventilation?

Should you / can you use the O2 flush for jet ventilation?

Low Pressure System

Mandatory minimal flow of oxygen

Why you can't turn the oxygen flowmeter to zero when the machine is turned on.



Hypoxic safe-guard

The Link-25 system. Does it always safeguard against hypoxia?



Common gas outlet check valve

What could happen if there was no check valve on the common gas outlet.



Contribution of fresh gas flow to the tidal volume

Why high fresh gas flows may contribute significantly to tidal volumes.

The Breathing Circuit

Function of inspiratory and expiratory unidirectional valves

Determining the amount of dead space in the circuit.



CO2 absorber function

How to create a non-rebreathing system.

Manual and Mechanical Ventilation Systems

Mechanical ventilation

The function of the ventilator spill valve (also called the pressure relief valve or exhaust gas valve).

The function of the proportional flow control valve.

The different locations of the APL (Adjustable Pressure Limiting) valve in Modulus I and II machines and how this may affect your delivered tidal volume during mechanical ventilation.

Manual ventilation

The function & different settings of the APL valve.

Why the increase in compliance of the manual bag with increasing bag volume may be important.

Scavenging System

The Scavenging bag

What is its function?

What happens when it is overinflated?



The positive and negative pressure relief valves

Their function and the reason why they could prevent accidents.



The vacuum adjustment valve

What is the optimal setting ? What if you suction too much or too little ?

