1. Parts of the Anesthetic Machine Parts 1 & 2: A&A pages 99-116
Objective: To be able to safely and
efficiently operate an anesthetic
machine, and trouble shoot any
problems that may arise.

2. Purpose of the Anesthetic Machine2
A liquid inhalant anesthetic is vaporized into a carrier gas, and precisely delivered to the patient via a breathing circuit.
*Maintains general _________________.
Carrier gas is delivered at a controlled rate
Unit is _________
Inhalant is delivered at a precise rate
Expressed as a ___________________
*Can also be used to deliver just oxygen
during recovery or in an emergency*

3. Components of the Anesthetic Machine
1. Compressed gas supply
Gas tanks, their pressure gauges, pressure reducing valves, line pressure gauge, flow meter, flush valve, key
2. Anesthetic vaporizer
Precision, out-of-circuit vaporizer is ideal
Vaporizer inlet port and vaporizer outlet port/common gas outlet
3. Rebreathing system
Fresh gas inlet, unidirectional valves, pop-off valve,CO2 canister, pressure manometer, negative pressure relief valve
4. Scavenging System
Disposes of excess and waste anesthetic gases; consists of a tube and the scavenger

4. PART 1: Compressed Gas Supply

5. Compressed Gas Cylinders
Most commonly used carrier gas is ___________
It comes compressed in a metal cylinder and held under pressure- up to _______ psi
Available in various sizes:
“E” tanks hold about 660 L of oxygen
“H” tanks hold about 6600 L of oxygen
*Tanks are delivered and picked up by the oxygen supply company as needed

6. Compressed Gas Cylinders
Tanks are color coded for safety and recognition
Oxygen tanks: ___________
Nitrous oxide tanks: _________
Carbon dioxide tanks: ________
*not used for anesthesia

7. Compressed Gas Cylinders
E tanks/cylinders, attach to the anesthetic machine via a ________.
H tanks/cylinders are usually stored in a central gas supply room
Can be attached via hoses or pipes to supply entire hospital.

8. Gas lines may be used to bring the oxygen into the surgical area from another room.

9. Gas Cylinders- Safety
In addition to color-coded tanks, the yokes are also gas-specific.
Ex. The valve on the oxygen tank matches the ______ _______________ on the yoke that is specific to oxygen
An oxygen yoke has two pins below the outlet port

10. Gas Cylinders- Safety Combustible gases- avoid flames and sparks!
Tanks must be stored in a secure location
If dropped, has the potential to act as a torpedo
Never leave a cylinder unattended!

11. Tank Pressure Gauge
Display of the pressure of gas currently in the tank.
Measures in ________.
Displays a reading when the tank is opened.
To open tank: use built in lever OR use the _______
Only open once tank has been connected to a yoke! OR
Your tank should be opened first thing in the morning so it is ready to go!

12. Tank Pressure Gauge

13. Tank Pressure Gauge Readings
Gauge reads the current PSI when the tank is open
Gauge reads zero when the tank is open and empty
Gauge STILL reads the current PSI when the tank is closed
Gauge reads zero when the tank has been closed and the lines have been flushed
**Ensure the gas cylinder has oxygen BEFORE starting every anesthetic procedure**

14. Tank Pressure Gauge (psi)
Refill line is at 500 psi
Replace w/ new tank when the pressure is 100 psi
*Some clinics will require tanks to be changed much earlier.
Special VTI note:
Pressure gauge gives you the amount of O2 in psi but you set your flow rate in liters/minute
How can you tell how long your oxygen will last until empty???

15. First Calculate Oxygen Volume in Liters
Total volume of O2 left in your tank (liters) can be calculated by multiplying the pressure (psi) by:
____ for E tanks and _____ for H tanks
Example:

16. Anesthetist should change the tank as soon as 500 psi is reached.
Nitrous Oxide
A full E cylinder contains 760 psi.
Nitrous oxide is present in liquid AND gas forms
inside the tank.
When the tank is open, liquid evaporates into a
gas as other gas leaves the tank.
The pressure of the tank doesn’t change (because of the constant replacement of the gas) until all liquid has been volatilized.
*The gauge will not drop until almost empty*
Anesthetist should change the tank as soon as 500 psi is reached.

17. Pressure Reducing Valve aka Pressure Regulator
Regulates the pressure of the gas leaving the tank
Reduces the pressure of oxygen from 2200 psi to a safer _________ psi.
Allows a constant flow of gas into the machine, despite pressure changes within the tank.
Can be measured with a line pressure gauge
*In E tanks the line pressure is preset at 50 psi, so there is usually no gauge seen.
Know what line we are measuring the pressure in

18. Flow Meter
Allows the flow rate of oxygen traveling through the machine to be adjusted by the anesthetist.
Reduces the psi AGAIN: to __________.
Oxygen does not reach the patient unless this is turned on.
Inhalant will not reach the patient either!
Measured in ________ ___ _________
Ball rises in height, proportional to gas flow
*Read at center of ball

19. Oxygen Flow Rates Mask Induction: _____ L/min
Chamber Induction: _____ L/min
*NOTE: The isoflurane will be at 5% for induction
Intubated patient to maintain anesthesia:
We will calculate at a later time…
*Rate may be increased/decreased if you are inducing, changing anesthetic depth, or recovering the patient.

20. Calculating How Much Time is Left of O2
We already figured out the # of liters of oxygen in the tank from the previous example.
Divide that amount by the flow rate you’re using:
Let’s say it’s 1 L/min
Ex: What if we change the flow rate to 2 L/min?

21. PRACTICE: Calculate Time of Tank Use Left
Ex: If you have a full E tank (2200 psi) and a flow rate of 2 L/min:
Ex: If you have a full H tank (2200 psi) and a flow rate of 1.5 L/min:

22. Oxygen Flush Valve Button that when depressed, rapidly delivers pure,
100% oxygen at a high, variable flow rate of ___________ and a pressure of _____________.
Pure because:
High rate because:
*O2 goes directly from pressure reducing valve  breathing system  lungs
Ideally, should not be depressed while
connected to the patient

23. Oxygen Flush Valve
Seems dangerous…when would we ever use this? 1. To dilute anesthetic in lines: 2. To fill reservoir bag (to give a breath) *Note about that breath: _______________________ What is a better alternative? ___________________ 3. To leak test the machine before use If using connected to the patient, watch the manometer!

24. PART 2: Anesthetic Vaporizer
Next stop as oxygen travels from the flow meter
Now that the carrier gas is in the machine, it’s job is to mix with the liquid anesthetic and be delivered to the patient.
Enters through the vaporizer inlet port

25. Vaporizer Converts the liquid anesthetic agent into a vapor
Adds a controlled amount of these vapors to the carrier gas, making _______ ________.
The vaporizer must be on to deliver any inhalant anesthetics to the patient.
Must press down on ________ _______ to turn dial on
What about to turn off?
*The flow meter must be on to supply the oxygen!

26. Vaporizer Should be full before beginning any anesthetic procedure.
Amount of anesthetic liquid in vaporizer is visible in the _____________ _____________.
Only fill to the bottom of the “full” letters
Make sure vaporizer is OFF
Refill by unscrewing cap of fill port and watching the indicator window.
DO NOT OVER FILL

27. Vaporizer Use the correct anesthetic for the vaporizer! (Iso vs. Sevo)
Matching anti-spill devices
Do not throw away!!

28. Precision Vaporizers
Precision vaporizers deliver a precise, controlled amount of anesthetic to the patient 
Expressed as a % which is chosen based on an anesthetic’s MAC and the patient’s requirements
Commonly used anesthetics can reach concentrations as high as 30% + if they are not controlled!
Precision vaporizers are located ______________ of the breathing circuit (VOC)

29. Flow of Carrier Gas through Vaporizer

30. Factors Affecting Vaporizer Output
Precision vaporizers compensate for the factors that determine the concentration of anesthetic delivered.
(other than what you set the dial to)
Factors that are compensated for:
_____________ changes
Inhalant anesthetics vaporize more rapidly at high temperatures
If not compensated for (non-precision):

31. Precision Vaporizer Compensation
2. Carrier gas flow rates and respiratory rate effect amount of anesthetic delivered
 If not flow-compensated (non-precision):
3. Back pressure: Squeezing the reservoir bag while bagging your patient exerts pressure on the vaporizer outlet port
If not back pressure compensated (non-precision):

32. Vaporizer Safety
If the vaporizer is tipped over (usually the whole machine), shaken, OR overfilled:
Lethal doses of inhalant are spilled into outlet port hoses
Turn the vaporizer off and run oxygen only through the machine for ____________ to flush it out.
Must be done in a well ventilated area, away from personnel
Can drain the inhalant if transporting machine!

33. Old School Vaporizers
Non-precision vaporizers are simple, cheaper, and are typically used for anesthetics with low vapor pressure.
Non-precision vaporizers are located within the breathing circuit (VIC)
Gas flows from the flow meter into the breathing tubes, which contain the vaporizer.
*They are no longer commonly used;
we will focus on precision vaporizers.

34. Non-precision Vaporizer

35. Vaporizer Fresh gas leaves through the vaporizer outlet port
The outlet port either leads to a free hanging hose, OR a hose which goes into the machine and comes out the front
If into the machine: it comes out of the Common Gas Outlet OR
Common/Fresh Gas Outlet
&
Fresh Gas Inlet