Anesthesia Machine Flashcards
What is the purpose of the anesthesia machine?
Provides delivery of medical gases and vapors of volatile anesthetics in known concentration to a common gas outlet.
- Gases enter breathing system
- Delivered to patient during either spontaneous or mechanical ventilation
- Exhaled gases are removed from the breathing system
Who oversees standards of the anesthesia machine prior to 2000 and since 2000?
Prior to 2000- American National Standards Institute (ANSI)
After 2000- American Society for Testing and Materials (ASTM)
What other groups have say in anesthesia machine?
International Electrochemical Commission (IEC)
Compressed Gas Association (CGA)
Institute of Electrical and Electronic Engineers (IEEE)
Food and Drug Administration (FDA)
What are some contemporary components of anesthesia machine?
- Electrical Supply
- Batter back up (30 min)
- Alarms
- high medium and low prioriry
- Required monitors
- Oxygen supply
- pipeline,
- cylinder
- Vaporizors
- Flowmeters
- Oxygen flush valve
- waste gas system
What are some required monitors on the anesthesia machine?
- inspired o2
- expired o2
- oxygen supply failure
- hypoxic guard system
- anesthetic vapor concentration
- vitas signs
What are the components of the high pressure system
- Auxiliary E-cylinder
- Yoke assembly
- Burdon gauge
- High pressure regulator
High pressure system includes segments exposed to high pressure of auxiliary gas cylinders
<2000 psi
What is the most common gas cylinder size?
E
What tank sizes are used as back up for hospital supplies or banks?
Size G-H
What can tanks be made out of?
Steel
Aluminum (MRI)
What is the purpose of the yoke assembly?
- Orient tanks
- Gas tight seal
- Unidirectional flow of gases
Components
- contains a filter
- Some have check valves
- stop leaking into atmosphere
- stop transfer between tanks
- Pin index safety system (PISS)
What are the common PISS numbers for air, nitrous and oxygen?
Air (1,5)
Oxygen (2,5)
Nitrous oxide (3,5)
What is the capacity and pressure of the E cylinder?
660 L capacity
Pressure 1900 psi
What is the color of oxygen, physical state at room temp, volume of full tank, pressure of full tank and critical temp of O2?
- Color- Green
- Physical state- Gas
- Volume full tank (L)- 660
- Pressure, full tank- 2200psi
- Critical temperature -118
What is the color of nitrou oxide, physical state at room temp, volume of full tank, pressure of full tank and critical temp of N2O?
- Color- blue
- Physical state- liquid and gas
- Volume, full tank- 1590 L
- Pressure- 750 psi
- Critical Temp 36.5
What is the color of air, physical state at room temp, volume of full tank, pressure of full tank and critical temp of air?
- Color-yellow
- State- gas
- Volume -625L
- Pressure- 1800 psi
What are 2 cylinder safety systems?
Frangible disk
- burst under extreme pressure
Fusible Plug
- metls at predetermined temperature
- made of bismuth, lead, tin, and cadmium
- BLT with cheese
What is the function of th ehigh pressure regulator?
Reduces the high and variable pressure delievered from cylinder to a lower and more constant pressure suitable for anesthesia machine
- Pressure regulators preset by factory for 40-45psig
- Ensures hospital pipeline gas is used preferentially to cylinder
What are the components of the intermediate pressure system?
- Hospital supply (pipeline inlet)
- Oxygen flush vlave
- Pneumatic safety systems/electrical system (on switch)
- Auxiliary oxygen flowmeter
- Second stage regulator
Receives gases from pressure regulator and pipeline inlet
What are 2 pneumatic safety systems?
Oxygen supply failure alarms
Oxygen Failure protection devices
How is the hospital supply of oxygen stored?
- Typically stored as liquid
- -184 celsius
- Supplied to hospital as a gas at 50psi
- Multpile shut off valves b/w supply and anesthesia machine
What do hospital supply connetions contain?
- Utilize Diameter Index Safety System (DISS)
- Ensures only correct anesthesia gas connected
- sized and threaded diff
- body, nipple, nut combination
- Contains
- filter
- check valve
- pressure gauge
What do older hospital supply connectors use?
Quick connections
gas specific
manufacture specific
What is purpose of the oxygen flush valve? What does it provide? Potential hazards?
Provides 100% oxygen to anesthesia circuit
Enters circuit downstream from vaporizer-directly to common gas outlet
Flow rate 35-75L/Min
Protected by rim to lessen chance of accidental activation
Hazards
- barotrauma
- stuck valve
- if used during inspiratory phase
- older- ventilator relief valve closed and apl out of circuit
- newer- fresh gas decoupling valve
- Awareness
- dilutes anesthesia gases
What is the oxygen supply failure alarm?
- On Older Ohmeda machines
- audible indication when pneumatic system turned on (oxygen filling whistle)
- When oxygen pressure drops <38 psig, whist valve opens
- whistle sounds until o2 pressure drops <6 psig
- At 30 psig, anesthetic gases are stopped
What are the fail safe devices used and how does it work?
- Designed to help prevent delivery of hypoxic gas mixture form the machine in event of failure of oxygen supply
- monitor pressure not flow
- protects agianst unrecognized exhaustion of oxygen delivery form either pipeline or oxygen tank
- Either proportionally decrease the flow or shuts off flow of all other gases except oxygen
What are the limits of the fail-safe device?
Does not prevent anesthesia gases from flowing
works even if wrong gas supplied
How does the fail safe device work in drager?
Needle valve in n2o pipeline that will be pushed open as long as 50 psig o2 flowing
If o2 decreases to 25psig, the n2o will also be decreased to 25 psig
If 0 psig in o2, then n2o flow stops
How does the fail safe valve work in the datex ohmeda machine?
Pressure sensor shut off valve is open if oxygen supply >20 psig. Valve will shut off automatically if oxygen is <20 psig.
No proportion
What is the purpose of the auxiliary oxygen flowmeter?
Not mandatory requirement
Allows for use of low flow oxygen without using anesthesia circuit
- used to MAC
Accessible when pneumatic power switch is off
- can be used in emergency
- but if pipeline contaminated, will still work
May serve as source of oxygen for jet ventilation
What is the second stage pressure regulator?
- Located downstream from gas supply sources in intermediate pressure system
- Supply constant pressure to flow contorl valves and proportioning system
- protects against fluctuations of pipeline pressure
- Lowers pressure to 14-35 psi
- depends on workstation
- typically
- oxygen : 14psi
- nitrous oxide: 26 psi
- Ensure gas is last gas flowing
What are the components of the low pressure system?
- FLowmeters
- hypoxia prevention safety devices
- unidirectional valve
- pressure relief devices
- anesthesia vaporizers/vaporizer manifold
- common gas outlet
Where is the low pressure system? Features?
Located b/w flow control devices and common gas outlet
Pressure in this section is slightly above atmospheric
pressure in this section is variable
What does the flowmeter consist of?
Flow control knob
tapered needle valve
valve seat
valve stops
float
float stops
What is the purpose of the flowmeters?
- Regulates the flow of gases entering the breathing circuit
- traditional are mechanically controlled
- newer are electronic interface
- oxygen and nitrous flow valves are linked mechanically or pneumatically to prevent hypoxic mixture
- selected flows are directed to vaporizer
Descirbe the features of the mechanical flow tubes.
- Variable orifice or thorpe tubes
- narrow at bottom and widen vertically
- annular space- between float and tube
- laminar- low flow- depends on viscosity
- turbulen-high flow- density of gas
- calibrated for specific gas
- placed in series
- indicator float, hovers at equilibrium
How do electronic flow tubes work?
Depend on electrical power to provide dislay
must have back up control and display o2 flows
Chamber of known volume- amoutn of heat required to maintain set temp is proportional to specific heat and gas flow rates
Which gas is last in flow meters?
O2
What is the sensitive oxygen ratio controller system?
System used on Drager to prevent hypoxic mixture
Opening oxygen flow creates backpressure in chamber allowing opening of nitrous oxide
Maintains ratio of 25% oxygen to 75% nitrous oxide flow into breathing circuit
needs at least 200mL/min to operate
What is the LInk-25 proportion limiting system?
Used to prevent hypoxic mixture in Datex-Ohmeda machines
- can adjust either valve, but always maintains flow 3:1
- Balanced secondary regualtor
- oxygen @30psig
- nitrous pressure based on oxygen pressure
- Maintains o2 concentration of at least 25%
What are the number of teeth on nitrous knob versus o2 knob on ohmeda machine?
15 N2O
29 O2
What is the common gas outlet?
Receives all gases and vapors form machine and delivers mixture ot breathing circuit
15 mm female slip join fitting
should not be used to administer supplemental oxygen to a patient
What are the 5 oxygen pathways?
- Flow to fresh gas flowmeter
- Powers the oxygen flush valve
- Activates the fail safe valve/mechanism
- Activated the oxygen supply low pressure alarm
- compresses the bellows of the ventilator
What is the broad overview of the machine check?
- Emergency equipment
- High pressure system check
- low pressure system check
- oxygen sensor
- scavenging system
- ventilator
- breathing system
- monitors
- final check
What emergency equipment are you checking for?
Ambu bag
Back up o2 cylinder >1000 psig
Functioning suction with yankauer
What are you checking durign high pressure system check?
- Check o2 cylinder supply
- open cylinder and check psi >1000
- close cylinder
- depress o2 flush
- Disconnect pipeline suppy from wall
What do you check during low pressure system check?
- Check vaporizers
- mounted, filled and interlock works
- Check low pressure system
- suction buld to common gas outlet
- squeeze buld until fully collapsed
- verify bulb deflated for 10 seconds
- Turn on master switch
- listen to oxygen disconnect alarm
- reconnect pipeline pressure
- ensure pipeline pressure >50 psig
- Test flowmeters
- adjust flow of all gases through their range
- attempt to make hypoxic mixture
How do you check oxygen sensor and breathing circuit?
- Calibrate o2 sensor
- ensure reads 21% in RA
- Verify low o2 alarm (set to 30%)
- Reinstall sensor and flush with O2- now read >90%
- Install breathing circuit
How do we check scavenging system?
- Ensure proper connection of scavenging system
- adjust waste gas vacuum
- fully open apl valve
- occlude y piece and ensure gauge reads <10 cm h2o
- With y-piece occluded, depress o2 flush, ensure reservoir bag distends, and pressure guage reads <10 cmh2o
How do you check ventilation system during machine check?
- Place second breathing bag on Y piece
- Set appropriate ventilator setting for next patient
- set o2 at 5L
- turn ventilator on and fill bellow with flush valve
- verify bellows deliver adquate tidal volume
- check function of unidirectional vlves
- squeeze bag and check over pressure alarm
- set to manual ventilator mode
- ensure ability to manually ventilate
- turn off ventilator and remove breathing bag
How do you perform the positive pressure check?
- Set all gas flow to zero
- Close apl valve and occlude y piece
- pressurize the breathign system to 30 cm H2O
- Ensure pressure remains fixed for at least 10 seconds
- fully open apl valve and allow bag to self deflate and flows through the scavenger
What is the final check composed of?
- Vaporizers off
- APL valve open
- sleector switch set to bag
- all flowmeters set to zero
- suction available
- monitors set appropriately
- circuit on, co2 sampling line connected, correct mask on
What color is carbon dioxide gas in the US color code and ISO color code system?
GREY
What color is the WAGD (Evac) in US color and ISO color
PURPLE IN BOTH
What color is suction in US color code and ISO color code?
White- US
Yellow- Iso
What color is oxygen in US color code and ISO color code?
Green in US
White in ISO
What color is o2-He in US color code and ISO color code?
Green &Brown in US
White and Brown in ISO (remember o2 is white in ISO)
What color is nitrous oxide in US color code and iso color code
Blue in both
What color is nitrogen in US color code and Iso?
Black in both
What color is medical air in US color code and ISO color code?
US- Yellow
ISO -BLACK AND WHITE
(think N and O compose air, in ISO color code, N is black, O is white. So “air” is black and white)
What color is instrument air?
Red
What color is He-O2 in us and iso color code
Brown and green- US
Brown and white- ISO
US DOT issue regulations for:
- Manufacture
- Marking/labeling
- Filling Handling
- Transport
- Storage
- Disposal of cylinders
What is capacity for h cylinder?
6900 L
2200 PSI
weight-
What is the e-cylinder capacity, max psi and weight?
660 L capacity
1900 psi
Weight 5.4 kg
piss
What do fail safe devices work off of?
Pressure not flow!
In what machine is the SORC system?
In what machine is the link 25 proportioning system
Datex-Ohmeda
