The Anesthesia Machine Flashcards
1
Q
Are there standards for CRNA practice?
A
Yes, written by AANA there are standards to ensure everything is functioning well
2
Q
Standard VIII: Adhere to appropriate safety precautions as established within the practice setting to minimize risks of fire, explosion, electrical shock and _______ malfunction. Based on the patient, surgical intervention or procedure, ensure that the ______ reasonably expected to be necessary for the administration of anesthesia has been ____ for proper functionality and document compliance.
A
Equipment
Equipment
Checked
3
Q
Standard VIII cont: When the patient is ventilated by an automatic mechanical ventilator, ____ the integrity of the breathing system with a device capable of detecting a disconnection by emitting an audible ____. When the breathing system of an anesthesia machine is being used to deliver oxygen, the CRNA should monitor inspired oxygen concentration continuously with an oxygen analyzer with a ___ concentration audible alarm turned on and in use.
A
Monitor
Alarm
Low
4
Q
What are the four subsystems of the machine?
A
1) Supply
2) Processing
3) Delivery
4) Disposal/Scavenging
5
Q
What is supply?
A
How gases and electrical power enter the machine
6
Q
What is processing?
A
Preparation of gases prior to delivery to the patient (amount in tank, etc)
7
Q
What is delivery?
A
Gases going to the patient and returning from the patient, their control and monitoring
8
Q
What is disposal/scavenging?
A
Disposal of gases
9
Q
Instead of looking at it like those 4 subsystems; we will look at it like these 4:
A
1) High pressure system
2) Low pressure system
3) Breathing system
4) Scavenging system
10
Q
What is the high pressure system?
A
Gas supplies connect to the machine (e-cylinder (backup system) or pipeline gas system that comes into machine)
11
Q
What is the low pressure system?
A
Blending of gases and volatile agent based on control settings (picking up vapors as goes through vaporizers)
12
Q
What is the breathing machine?
A
Fresh gas mixture passes form machine to patient
13
Q
What is the scavenging system?
A
Collects and disposes of excess gas (“separate system”; vacuum system that takes “contaminated” air and puts it in scavenging system (most likely released on the roof))
14
Q
What gas supplies do you need for the high pressure system?
A
Pipeline gas & Cylinder gas
15
Q
What are the pipeline gas inlets?
A
Pipeline supply hoses from the wall outlets connect to machine (on back)
16
Q
What does the filter do in pipeline gas inlets?
A
Removes damaging debris (required by standards) (inside machine)
17
Q
What are the check valves?
A
It prevents retrograde flow and leakage if pipeline supply is disconnected and cylinder supply is in use (makes sure gas is only going in one direction)
18
Q
What is the pressure gauge supposed to read for pipeline systems?
A
50 to 55 psig
19
Q
What is the safety system for pipeline gases and what does it do?
A
DISS (diameter index safety system) & quick connectors
Each gas hoseline connection has a different diameter, so you could not plug either end of the plug into another gas’s line.
20
Q
What is the cylinder gas inlet?
A
The reserve supply of gases (oxygen, nitrous and air)
21
Q
What is a hanger yoke?
A
It orients the cylinder, provides seal, and directs flow (also has filter, which is required)
22
Q
What is the check valve on the gas cylinders?
A
It prevents retrograde flow and transfilling to second cylinder of same gas
23
Q
What is the pressure regulator on cylinders?
A
It reduces the pressure to 45 psig (decrease the pressure so it will take from pipeline instead)
24
Q
What are the pressure gauges for the cylinders?
A
Bourdon-type gauges (start at 0)
25
What needs to be on cylinders to prevent leaks?
Washer
26
Why do you flush-out the O2 between the cylinder & gauge>
So you don't think you are using cylinder on accident
27
Why do you disconnect the pipeline to flush the O2 out?
So you are using the air from the cylinder and not the pipeline
28
__________ occurs if two cylinders of the same gas are both open and gas flows from the higher pressure cylinder instead of going to the flowmeters.
Transfilling
29
If you accidentally leave the O2 cylinder on, would you use that O2 or pipeline O2?
You would use pipeline O2 as long as pipeline pressure stays 50-55 psig. If pipeline pressure falls below 45 psig, then machine would use O2 from cylinder and not pipeline.
30
What is the safety system for gas cylinders and what does it do?
Pin Index Safety System (PISS) Indentions on cylinders located in different places based on type of gas it is. Has pins sticking out, so only O2 would fit in O2 yoke, etc.
31
What are the pin positions in the PISS of oxygen?
2 & 5
32
What are the pin positions in the PISS of nitrous?
3 & 5
33
What are the pin positions in the PISS of air?
1 & 5
34
In the high pressure system, what is the pressure gauge?
Bourdon-type pressure. Flexible tube within the gauge straightens when exposed to gas pressure, causing gear mechanism to move the needle pointer.
35
Need to bleed high pressure to allow gauge to read ____.
0
36
If 0 is not the baseline, the gauge will only read accurately pressures that are _______ than the baseline
Higher
37
Cylinders must be at least _____ full
Half
38
What is the O2 power outlet in the high pressure system?
It is connected to the mechanical ventilator and O2 flush valve
39
What is the second-stage regulator in the HPS?
It decreases O2 pressure to 16-20 psig (n2O reduced to 32 psig)
40
What is the O2 flush valve in the HPS?
It bypasses flowmeters, vaporizers, and delivers directly to breathing system (50 psig)
41
How much O2 does the O2 flush valve deliver?
35-75 L/min of O2
42
What can the O2 flush be used to do?
Re-inflate reservoir and bellows
43
What is a caution when using the O2 flush valve?
It can cause barotrauma. (APL valve, inspiratory phase during mechanical ventilation; safety rim) (if hit during expiratory phase, then it's fine)
44
What powers the bellows?
Oxygen; it goes on top and bottom and the O2 on top compresses the bellows and delivers O2
45
If you hit the O2 flush valve what rate does it deliver O2 at?
A super high rate & can cause barotrauma
46
If in bag mode & not ventilator mode, what does the O2 flush valve do?
Fills the reservoir bag
47
If the reservoir bag goes past full, where does the O2 from the O2 flush valve go?
It will deliver to the patient
48
What is safety feature of the HPS?
The low O2 supply pressure alarm
49
What is the low O2 supply pressure alarm?
It must sound within 5 seconds if oxygen supply pressure drops below 30 psig (empty cylinder, pipeline shuts off, etc) (sound stops when pressure in can, reed & pipeline are equal)
50
What is the O2 pressure failure safety mechanism (fail-safe) in the HPS?
Causes the cessation of flow of non-oxygen gases if the O2 pressure falls to or below 25 psig
Theoretically, to prevent delivery of a hypoxic mixture
Can be circumvented if the pipeline or oxygen cylinder is pressured by some other gas (just looks at pressure, can't determine type of gas)
51
What are the flowmeters in the low pressure system?
Knob, needle valves: controls gas flow
52
What are the Flow control valves in the LPS?
Controls gas flow through the flowmeter
53
What are the flow tubes in the LPS?
Thorpe tubes: tapered, calibrated to specific density and viscosity of gas, coated with conductive substance to minimize static electricity
54
What is the indicator float in the LPS?
Rotates to minimize friction, center (reading is at center of sphere)
55
Should you turn flows off before turning machine off?
Yes
56
What is the common gas outlet flowmeter in the LPS?
Tube with float indicates total gas flow- note it reads 4 l/m; you can see on digital readout that 2 l/m is oxygen, 1 l/m is air, and 1 l/m is nitrous oxide.
57
What is the touch-index O2 flow control knob safety feature in the LPS?
knob is fluted, size difference, protrudes further, most right
Knobs are configured differently so you can't accidentally change nitrous if trying to change O2
58
What is the proportioning system safety feature in the LPS?
- It prevents delivery of hypoxic mixture
- Delivers at least 25% + 4% O2 (some machines can go down to 21%, some 29%)
- Ratio of N2O to O2 is not more than 3:1
59
What is the Link-25 system in the LPS?
Flow control knobs linked by chain; connects O2 and N2O flow meters, making it impossible to make the ratio higher than 3:1; moves O2 up if trying to move N2O up
60
What is the Oxygen ratio monitor controller (ORMC) in the LPS?
Pneumatic, mechanic control (pressure related) (pressure portioning system; won't let you go higher if go to flow that goes over 3:1 ratio; no hypoxic mixture)
Same as the Sensitive Oxygen ratio controller (S-ORC)
61
What is the minimal oxygen flow safety feature in the LPS?
Minimal oxygen flow is 150 mL/min through oxygen when machine is on (meets basal needs of patient with low flow even if the operator forgets to turn flow on)
62
What is the positioning of the flowmeters in the LPS?
- Oxygen flowmeters are always nearest to the vaporizers (downstream, on right)
- To minimize risk of hypoxic mixture being delivered if leak occurs in the flowmeters (will still be hypoxic if leak occurs within the oxygen flowmeter or downstream of it)
63
What is the manifold in the LPS?
Where gases from different flowmeters mix together and have opportunity to enter into a vaporizer which is attached here (leaks in upstream are less likely to affect oxygen when it is the last gas to enter the machine)
64
What are calibrated vaporizers in LPS?
Add vaporized anesthetic agent to gas flow
65
What is the interlock-exclusion system safety feature of the LPS?
Prevents using more than one vaporizer at a time. (when one vaporizer is turned on, you can't turn another one on) (to work, vaporizers must be right next to each other)
66
What does the check valve do?
Helps prevent oxygen flow from flow backwards (upstream); prevents oxygen flow from flowing back to the nitrous oxide flowtube and leaking to atmosphere through the damaged flowtube
67
What is the common gas outlet in the LPS?
- Supplies gas mixture to breathing system
- "Fresh gas outlet"
- Perform low-pressure circuit leak test
- Safety feature: anti-disconnect device
68
How do you perform a leak test with the common gas outlet?
- Low pressure leak test
- Machine off for test
- Open common gas outlet
- Use bulb & adapter
- Compress and attach to outlet
- If stays compressed for 10 seconds = no leak
- Then check each vaporizer one at a time
- Ensure you are not the reason for the leak; check you retightened cap on vaporizer
69
Electrical supply system switch. What is ON?
- Allows electricity to flow to ventilator, monitors, desflurane vaporizer
- Connects O2 supply to shutoff valves, the low O2 supply alarm and to the flowmeters
(some parts of machine need electricity, some do not)
70
Electrical supply system switch. What is OFF?
- System vents O2 pressure to atmosphere
- Check valve present (allows for negative pressure test)
71
After you check the machine in the morning, do you turn it off?
No, leave machine on all day until leave or close the room
72
In the electrical supply, what is the power source?
Single power cord source
73
What is the battery backup time of the machine?
At least 30 minutes
(limited function varies with manufacturer)
(May lose patient monitors and ventilator function)
(Typically fresh gas flow, vaporizers, and manual ventilation function (know specific in operator's manual) are maintained)
(Once battery power is lost, may have only oxygen delivery continuing)
(There are convenience receptacles & circuit breakers)
74
What is the circle breathing circuit?
What patients exhale, they can pick back up in system and reinhale
(CO2 absorbant changes CO2 to O2)
75
What is the APL valve?
Adjustable pressure limiting valve; any pressure above the limiting pressure does not go to patient; goes to scavenging
76
What is all the way open on the APL valve?
Minimal or zero
77
What is the Fresh gas hose/ Fresh gas inlet of the breathing system?
Delivers gas from CGO to breathing system
78
What kind of valves are the inspiratory and expiratory valves?
Unidirectional
79
What are some other parts of the breathing system
- Breathing hoses of circuit
- Y-piece (where 2 sides come together)
- CO2 absorber housing
- CO2 absorbent canister
- Breathing system pressure gauge
- Reservoir bag (can change granules out; litmus paper to see if it is still acidic, working like it should; pink/purple when change)
- Bag/ventilator selector switch
80
What are the parts of the mechanical ventilator of the breathing system?
- Ventilator drive gas tube (O2 on top of bellows drives bellows)
- Ventilator hose (can see where O2 comes out of bellows & into scavenger system)
- Ventilator bellows
- Ventilator pressure relief valve (spill valve)
81
What is the anti-disconnect fresh gas hose connector safety feature?
Spring activated system; has to be intentional; can't just pull off
82
What is the anti-disconnect pressure sampling line safety feature?
Louer lock system (make sure not disconnected)
83
What is the ventilator low airway pressure alarm safety feature?
Alarms when there is low pressure
84
What is the ventilator pressure-limiting adjustment knob safety feature?
Set PIP & Tidal volume
85
Where is the ventilator pressure relief valve?
On back of the machine
86
Where is the scavenger system located?
On breathing system side; usually on back of the machine
87
Are there environmental safety concerns about the scavenging system?
Yes
88
What is the active system of the scavenging system?
Vacuum (negative pressure) from hospital disposal system withdraws gas from the scavenging system
89
What is the passive system of the scavenging system?
Slight positive pressure of the excess gases in the machine moves it into the evacuation hose and into the disposal system (medical missions)
90
What is the positive pressure relief valve on the scavenging system?
Opens with too much pressure to vent waste gases into the room and helps prevent a positive pressure in the patient cicuit
91
What is the negative pressure relief valve on the scavenging system?
Opens with too much suction to allow room air into the flow of waste gas to the vacuum source and helps prevent a negative pressure in the patient circuit
92
What happens if there is too much suction in the scavenging system?
Gas could be sucked out of the patient's breathing system
93
What happens if there is not enough suction in the scavenging system?
Pressure build up that can effect patient
94
How do you check the scavenging system to ensure appropriate suction?
Watch for bag to ensure never too full or full compressed; bag should fill up and get full then collapse; if no bag, the floating ball should be between 2 white lines
95
What are the collecting hoses of the scavenging system?
From APL valve and ventilator pressure relief valve
96
What are the intake ports of the scavenging system?
Hoses connect to system
97
What is the reservoir of the scavenging system?
Allows the waste gases which enter the system in uneven delivery to be handled in a constant, continuous manner
98
What is the manifold of the scavenging system?
Interfaces between the machine and the disposal system
99
What is the vacuum control (active system) of the scavenging system?
Adjusts the amount of vacuum from the hospital disposal influencing the scavenging system
100
What are the exhaust port and evacuation hose (passive) of the scavenging system?
Connects to the environment
101
What are some safety features of the scavenging system?
Different size hoses (19 mm or 30 mm) versus 22 mm breathing hoses, closed interface, and open interface
102
What is the closed interface of the scavenging system?
- Positive pressure relief mechanism: if vacuum not high enough, pressure will not back up into breathing system (valve prevents pressure build up and barotrauma to pt) (above 10 without flush when not working)
- Negative pressure relief mechanism: if vacuum is too strong, the gases to be delivered to the patient will not be affected (if pressure is <0/negative, it is not working) (valve prevents pulling from patient breathing system)
103
What is the open interface of the scavenging system?
- newer machines/workstations
- need appropriate suction or exhalation pollutes OR
104
What is the manual ventilation of the scavenging system?
Gas enters the scavenging system when the peak pressure exceeds the opening pressure of the APL valve
105
What is the mechanical ventilation of the scavenging system?
During late exhalation and the expiratory pause after the ventilator bellows have returned to full position
106
What is spontaneous ventilation of the scavenging system?
During late exhalation and the expiratory pause after the reservoir bag is full
107
What are the 5 functions/paths of oxygen?
1) Go to oxygen flowmeter (common manifold -> vaporizers -> CGO -> breathing system -> patient -> scavenger system -> disposal)
2) Go to O2 flush (dilute out sevo & other vaporizers when hit O2 flush)
3) Activate oxygen pressure failure safety mechanism (fail-safe) (if pressure too high)
4) Activate oxygen low-pressure alarm (past reed to canister to tell machine about low pressure)
5) Powers the mechanical ventilator bellows
108
What are some ways the anti-hypoxic safeguards can be "defeated?"
- Wrong gas in the oxygen pipeline or cylinder
- Defective pneumatics or mechanics
- Leak downstream of flow control valves
- Inert third gas administration
(This is why an oxygen analyzer is important)
109
Why is an oxygen analyzer essential?
Irreversible hypoxic brain injury occurs after 4 minutes of arterial desaturation; the oxygen analyzer is connected into inspiratory part of system; O2 reading should be 21%; if hit O2 flush, want to see analyzer go above 90%
110
What are the 3 primary purposes of the machine?
1) To provide oxygen
2) To blend an anesthetic gas mixture
3) To allow ventilation of patient's lungs, whether spontaneous, assisted, or controlled
111
What is a potential injury of providing oxygen through the machine?
Delivering a hypoxic mixture
112
What is a potential injury of blending anesthetic gas mixtures through the machine?
Delivering incorrect anesthetic dose
113
What is a potential injury of allowing ventilation of patient's lungs through the machine?
Ventilate inappropriately (overpressurizing can lead to an incorrect dose (Henry's law))
114
What are the steps in the pre-anesthesia checklist (2008)?
1) Auxillary O2 and ambu bag (alternate source of O2, ambu bag in back)
2) Suction
3) Power on- confirm AC power
4) Monitors/alarms
5) O2 cylinder pressure (may only be 1 canister; at least half full)
6) Pipeline pressure (open, check, disconnect, bleed out, reconnect, see pressure (recheck): want 50-55)
7) Vaporizers filled and closed
8) Leak test of lines between flowmeters/CGO (manual low pressure leak test)
9) Scavenger system (everything hooked up/lines, vacuum, etc)
10) Calibrate O2 sensor, check low oxygen alarm
11) Carbon dioxide absorbent (white or purple)
12) Breathing system leak test
13) Gas flow: unidirectional valves (look as hitting O2 flush)
14) Document check (electronic charting, say you checked machine)
15) Patient ready mode: APL valve all the way open (min, or zero), bag in bag mode, all flows off, mask in place
115
What emergency ventilation equipment should you have available?
Ambu bag, ensure it is appropriate size
116
How do you check the high-pressure system?
1) Open cylinder and look at cylinder pressure (want at least half full)
2) Close cylinder back
3) Disconnect pipeline and hit O2 flush to bleed out O2
4) Reconnect pipeline
5) Look at all pipelines and pressure (should be 50-55)
117
How do you check the low pressure system?
1) All flows off
2) Ensure vaporizers are off & full
3) Disconnect from fresh gas outlet
4) Connect adapter in drawer (suction bulb) to FGO
5) Compress bulb until it collapse and ensure it stays compressed for at least 10 seconds
6) Open first vaporizer and compress bulb again, want to stay at least 10 seconds
7) Close vaporizer and repeat for each one
118
How do you check the scavenging system?
1) Turn machine on
2) Occlude y-piece
3) Turn APL valve all the way open and look at breathing system pressure gauge, make sure it doesn't go below 0
4) Then hit O2 flush so breathing system gauge goes up (after filling reservoir) and ensure it does not go above 10
5) Ensure bag in scavenging system gets full and then collapses completely
119
How do you check the breathing system?
1) Ensure analyzer is connected & gas sampling line is connected
2) Ensure you can generate positive pressure with no leak
3) Check flowmeters & try to turn on nitrous without O2 and see if it lets you
4) Turn APL valve all the way closed (70)
5) Turn machine on to bag mode
6) Turn all flows off
7) Occlude the y-piece (creates pressure in system)
8) Hit O2 flush and watch for the gauge to go up to 30 and stop
9) Want it to hold that pressure for 10 seconds (this means we can generate positive pressure to manually ventilate)
10) Open APL valve (pressure decreases; don't let go of y-piece (so that none of the dust goes into circuit, instead goes to scavenging))
120
How do you check the manual and automatic ventilation systems?
1) Open another circuit and get out a 2nd breathing bag and put on end of circuit
2) Hit O2 flush and fill bag to some degree
3) Switch to vent mode
4) Bellows & reservoir should be filled and should see bag expanding and contracting when bellows compress (it should go all the way back to the top)
5) Increase flows to 5 L and watch the breathing system gauge (look for intrinsic peep of 4, make sure it doesn't increase/pressure doesn't build)
6) Switch back to bag mode
7) Squeeze reservoir bag & ensure "lung" expands (so can manually ventilate)
121
How do you check the monitors?
Check to ensure there are alarms on and O2 is reading correctly
122
Final position: patient ready is what?
1) Vaporizers off
2) APL valve all the way open (min)
3) Machine in bag mode
4) All flows off
5) Patient suction level adequate
6) Mask in place
123
Can gases flow through safety mechanisms?
Yes, (nitrous, air, etc) can only flow through safety mechanism if there is sufficient O2 pressure in safety device to prevent accidental hypoxic mixture
124
The linkage of nitrous to O2 ensures a minimal concentration of what of oxygen?
25%
