24 – Anesthesia Equipment Flashcards
1
Q
What are the functions of an anesthesia machine?
A
- Delivery of O2 to patients
- Delivery of anesthetic gas
- Assistance with ventilation
- Removal of exhaled CO2 from patient
2
Q
Follow the air through the anesthesia machine
A
- O2 source (compressed gas)=high pressure
- Pressure gage
- Pressure reducing valve
- Line pressure gage
- Flow meter
- Vaporizer
- ‘fresh gas line’
a. Non-rebreathing or rebreathing circuit (depends on SIZE OF PATIENT)
3
Q
What are the basic components of the anesthesia machine?
A
- Medical gas source (O2, air)
- Regulator
- Flowmeter
- Vaporizer
- Fresh (common) gas outlet
- Breathing system
- *divide into HIGH and LOW pressure part
4
Q
What are your ‘2 options’ for medical gas source?
A
- Oxygen
- Medical air
5
Q
Oxygen delivery
A
- Compressed gas
a. E-cylinder (700L)
b. H-cylinder (7000L) - Liquid O2: can store more
**pipeline pressure: 50-60psi
**KEY TO CLOSE O2 tank (off=clockwise)
6
Q
What is medical air?
A
- Formed by drawing ambient air into the compressor
- Considered ‘clean’ (runs through series o filters and separators to remove water, oil and other impurities)
7
Q
What is the oxygen concentrator?
A
- Use it to filter and extract room air
- Removes N2, stores O2 as compressed gas
- Requires electrical supply
- *maximum of 5-10L/min (problem in large animal)
- 92-95% O2
- Need to change filters on regular basis
8
Q
What are the safety features?
A
- Colour coding
o O2=white or/and green - Pin-index safety system (PISS): E-cylinder
- Connecters (H-cylinder): Diameter index safety system (DISS)
o Body, nut, stem
9
Q
What is the regulators for an E-tank?
A
- one-stage regulator
- 2,200psi to 50-55psi
10
Q
What is the regulator for the pipeline supply?
A
- At the O2 sources
- 50-55psi
- *2 stage regulators allow for variable output pressure
11
Q
What is the role of flowmeters?
A
- Control rate of gas delivery of low-pressure area
- Determine fresh gas flow (FGF)
- Specific for gas (density, viscosity)
o Color coded
o O2=bigger nob, closest to vaporizer - L/min (read middle of ball, read at top of cylinder)
- *operated by needle valve
- *precision instrument
12
Q
What is the role of the vaporizer?
A
- Vaporizes anesthetic agent and delivers at set concentration (% output on dial)
- Agent specific
- *temperature compensated (via bi-metallic strip)
13
Q
What are the 2 paths for a variable-bypass vaporizer?
A
- Entering bypass chamber
- Diverted into vaporization chamber
*splitting depends on settings
14
Q
What are some safety features of the vaporizer?
A
- Colour coding
o Yellow: sevoflurane
o Purple: isoflurane - Key-indexed filler systems: don’t get exposed, very specific!
- Lock on dial
- Do NOT overfill
- Do NOT TILT vaporizer
- *do NOT want it to go into the bypass
15
Q
Anesthetic breathing systems
A
- Deliver O2 and anesthetic gases to patient
- Allow elimination of CO2
- Allow ventilation of lungs
- Different types based on CO2 removal
16
Q
Rebreathing systems
A
- Use chemical reaction to remove CO2 with absorber
- Used on animals LARGER than 10kg bodyweight
- *allow low/minimal flow anesthesia
17
Q
What is the advantage of rebreathing system?
A
- Decrease use of volatile anesthetics
- Improved T and humidity control
- Reduced environmental pollution
18
Q
What are the disadvantages of rebreathing system?
A
- Difficult to rapidly adjust anesthetic depth
19
Q
What are the components of a rebreathing system?
A
- Inspiratory one-way valve
- Inspiratory breathing tube
- Y-piece
- Expiratory breathing tube
- Expiratory one-way valve
- Reservoir bag
- CO2 absorber
20
Q
Breathing tubes of a rebreathing system
A
- Flexible, low resistance conduits between Y-pieces and one-way
- *Corrugations reduce likelihood of obstruction if bent
- Add length volume to system, increase resistance
- *F-circuit: co-axial system (inspiratory inside expiratory )
21
Q
What are the O2 flow rates for a circle system?
A
- 10-30ml/kg/min
22
Q
What is a low O2 flow rate for a circle system?
A
- 4-10ml/kg/min
23
Q
Y-piece
A
- Connects ET-tube to inspiratory and expiratory breathing tubes
- Contributes to dead space
- Septum may be present to decrease dead space
24
Q
Universal F breathing system
A
- Co-axial (hose inside a hose)
o Inner carriers fresh gas flow - less bulk and less DEAD SPACE
25
Q
Reservoir bag
A
- Size: 6-10x tidal volume
- Reservoir of gases during inspiration
- Allows monitoring of respiratory movements
- Ventilate lungs
26
Q
Breathing tubes/hoses
A
- Provided connection and reservoir for gases
- Apparatus dead space: potential area of CO2 collection
27
Q
Rebreathing system: denitrogenization
A
- Required for all of them
- Body and anesthetic machine are equilibrated with air
- Once connect and 100% O2 flow
o N2 moves down partial P gradient from body into breathing system
o Takes 20mins - *high FGFs(fresh gas flow) used (30mg/kg/min) for first 20mins to ‘flush out N; and reduce risk of inhaling hypoxic mixtures
28
Q
One-way valve: rebreathing system
A
- Prevent rebreathing of exhaled gas
- Gases enter unidirectional valve from below and raise disc
- *allow gas to pass in one direction only=adds resistance
o Why use on larger patients only
29
Q
CO2 absorber: rebreathing system
A
- Contains chemical absorbent for removing CO2 from exhaled gases
- Exothermic reaction, produces water
- pH increases (pH sensitive indicator=leads to colour change)
o granules turn from white to purple as they become exhausted - usually lasts 8-10hrs
30
Q
Non-rebreathing systems
A
- Use high gas flow to flush out CO2
o 150-300ml/kg/min (10x plus higher than rebreathing) - *smaller patients
31
Q
What are the advantages of a non-rebreathing system?
A
- Less resistance to breathing
- Less mechanical dead space
- Rapid manipulation of anesthetic depth
32
Q
What are the disadvantages of a non-rebreathing system?
A
- Significantly higher waste of both carrier gas
- High flow od dry cool gas (heat and humidity loss)
33
Q
What happens with failure to remove CO2 in a non-rebreathing system?
A
- Inadequate fresh gas flow
- Kinked inner tube Bain
- Hidden tears or disconnections in coaxial systems
34
Q
What happens with failure to remove CO2 in a rebreathing system?
A
- Stuck 1-way valves
- Exhausted CO2 absorber in rebreathing system
35
Q
Circuit pressure gage (manometer)
A
- *pressure generated in patient breathing circuit
- Guide for positive pressure ventilation of lungs and system leak test
- Not greater than 10-25 cmH2O pressure for lung ventilation
- *highest number corresponds to peak inspiratory pressure reached (PIP)
- *watch chest expansion of animal=give a normal breath
36
Q
Scavenging system
A
- Conducts waste anesthetic gases away from workspace
- Passive: charcoal canisters
- Active: negative pressure system
- *pink coloured hose for safety
37
Q
Adjustable pressure limiting (APL) valve (pop-off valve/exhaust valve/scavenging valve)
A
- Allow excess gas withing breathing system to be vented into waste gas
- *always leave open during spontaneous breathing
- Only closed during lung ventilation and leak test
- Attach scavenging hose to exhaust valve shroud
38
Q
O2 flush
A
- Allow O2 to bypass flowmeters and vaporizers
- O2 delivered at high flow and pressure (40-70L/min)
- Only be used with CIRCLE SYSTEM
o used to flush out circle system of anesthetic in emergency - can be used for leak test
- NEVER use when a non-breathing system is connected to patient
- *NOT when attached to patient
39
Q
What are ventilators used for?
A
- Provide intermittent positive pressure ventilation (IPPV)
o Dedicated person can provide IPPV
o But this allows them to attend to other jobs - May require driving gas (O2, air) and electricity
- *bellows replaces the rebreathing bag
40
Q
What are the indications to use a ventilator?
A
- Open thorax: diaphragmatic hernia repair
- Neuromuscular blockage: skeletal muscle paralysis
