1
Q
What does “patient ready” imply?
A
- APL valve is open
- In bag mode
- flowmeters and vaporizers are OFF
- mask is on Y piece
- suction is on
- make sure monitors are ready
2
Q
What are the primary purposes and associated risks of the anesthesia machine?
A
- provide oxygen (may deliver a hypoxic mix)
- blend anesthetic gas mixture (may deliver incorrect anesthetic dose)
- allow ventilation of patient lungs (may give inappropriate ventilation)
3
Q
Describe the oxygen analyzer?
A
- Essential part of the machine check
- analyzes the percentage of oxygen delivery
- make sure it is calibrated to room air
- do this part of the test BEFORE the positive leak test since you will have to break the closed system
4
Q
What are some circumstances that defeat anti-hypoxic safeguards?
A
- wrong gas in oxygen pipeline or cylinders
- defective pneumatics or mechanics
- leaks downstream of flow control valves
- inert third gas administration
5
Q
What are the five functions/paths of oxygen?
A
- go to the flowmeter
- go to the O2 flush
- activate the oxygen pressure failure safety mechanism (fail-safe)
- activate oxygen low-pressure alarm
- power mechanical ventilator bellows
6
Q
How does scavenging work with the different types of ventilation?
A
- manual: gas enters scavenging system when peak pressure exceeds the opening pressure of the APL valve
- mechanical: gas enters during late exhalation and the expiratory pause after the vent bellows have returned to full position
- spontaneous: gas enters during late exhalation and the expiratory pause after the reservoir bag is full
7
Q
What are the safety mechanisms of the scavenging system?
A
- different size hoses (19mm or 30mm) as opposed to 22mm breathing hose
- positive pressure relief mechanism if the vacuum is not high enough
- negative pressure relief if vacuum too strong will not affect gases to be delivered to patient
8
Q
What is the positive pressure relief valve?
A
valve that opens when there is too much pressure, allowing waste gases to vent into the room and help prevent positive pressure in the patient circuit
9
Q
What is the negative pressure relief valve?
A
valve that opens when there is too much suction, allowing room air into the flow of waste gas to the vacuum suction in order to prevent a negative pressure in the patient circuit
10
Q
Describe the scavenging system?
A
- collects and disposes of excess gases for environmental safety
- may be active or passive
active: vacuum from hospital disposal system withdraws gas from scavenging system (uses negative pressure)
passive: slight positive pressure of excess gases in machine moves it into evacuation hose and into a disposal system
11
Q
What are the different parts of the scavenging system?
A
- collection hoses: come from the APL valve and ventilator pressure valve
- intake ports: where the hoses connect to the system (open ports should be capped!)
- reservoir: allows waste gases which enter the system in uneven delivery to be handled in a constant, continuous manner
- manifold: interfaces between the machine and the disposal system
- vacuum control: used in the active system; adjusts the amount of vacuum from hospital disposal influencing scavenging system
- exhaust port and evacuation hose: used in passive system; connects to the environment
12
Q
Describe the correct use of vacuum suction in the scavenging system.
A
- needle valve should be adjusted so flow out of manifold keeps the reservoir bag expanding and collapsing slightly and less than half full
- positive pressure relief valve opens with too much pressure
- negative pressure relief valve opens with too much suction
13
Q
Describe the breathing system.
A
-where fresh gas mixture passes from machine to patient includes: -fresh gas hose/inlet -inspiratory/expiratory unidirectional valves -breathing hoses -Y piece -APL or "pop off" valve -CO2 absorber housing -CO2 absorber canister - breathing system pressure gauge -reservoir bag -bag/vent switch -mechanical vent
14
Q
what is the function of the fresh gas hose or fresh gas inlet in the breathing system.
A
delivers from the CGO to the breathing system
15
Q
Describe the adjustable pressure limiting (APL) valve of the breathing system.
A
- during ventilation, APL valve is closed to amount of pressure needed to deliver a breath and anything over that pressure goes to the scavenging system
- if APL is set on “0” or “minimal”, anything above that goes to scavenging
- totally open APL valve is used to check the scavenging system
- totally closed APL valve is used to check the breathing system
16
Q
Describe the reservoir (ambu) bag of the breathing system.
A
- when full, pressure from the O2 flush starts transferring to the breathing system, creating risk for barotrauma
- does provide some flexibility to help minimize barotrauma
- different sizes are used for different ages
17
Q
Describe the bag/vent switch of the breathing system.
A
- switches between mechanical ventilation and ambu bag
- in vent mode, APL valve and reservoir bag do not function
- vent system has its own pressure valve
18
Q
What are the parts of the mechanical vent?
A
- vent drive gas tube
- vent hose
- vent bellows
- vent pressure relief valve (spill valve)
19
Q
Describe the breathing system’s positive leak test.
A
- APL valve totally closed
- flowmeters all off
- Y piece occluded
- in bag mode
- Hit the O2 flush and drive gauge pressure >30 cmH2O
- If the pressure stays up at least 10 seconds, there is no leak
- to release pressure, OPEN the APL valve!
- ALWAYS perform test after any breaks in the system and before each case
20
Q
What are the safety features of the breathing system?
A
- antidisconnect fresh gas hose connector
- antidisconnect pressure sampling line connection
- ventilator low airway pressure alarm (“apnea alarm”)
- ventilator pressure limiting adjustment knob (prevents barotrauma)
- ventilator pressure relief valve (any set pressure increase spills out)
21
Q
Describe the low pressure system.
A
-blending of gases and volatile agent based on control settings includes: -flowmeters -vaporizers -common gas outlet (CGO)
22
Q
What are the flow control valves?
A
- control gas flow through the flowmeter
- used for carrier gas
- calibrated to the density and viscosity of specific gases
include: needle valve, flow tubes, and indicator float
23
Q
What is the function of the needle valve of the flow control valve?
A
control gas flow
24
Q
Describe the flow tubes of the flow control valves.
A
- Thorpe tube
- tapered
- calibrated to specific gas
- coated with a conductive substance to minimize static electricity
- may have two tubes, first tube being smaller and more precise for doses less than 1 L/min
25
Describe the indicator float of the flow control valves.
- rotates to minimize friction
- in the center
- ball float read at the center of the ball
- tapered float read at the top of the float
* a float stop at the top may cause damage if float shoots to the top, so be sure to have all flowmeters off when turning on to avoid damage
26
What are safety features of the low pressure system?
- touch index O2 flow control knob
- proportioning system: link-25, ORMC
- minimal O2 flow
- positioning of flowmeters
- interlock-exclusion system on vaporizers
- antidisconnect device on the CGO
27
Describe the touch index O2 flow control knob safety system.
O2 knob is fluted, has a big size difference, protrudes further, and is positioned most right for distinction
28
Describe the proportioning safety system.
- used to prevent delivery of hypoxic mixes
- delivers at least 25% (+-4%) O2
- maintains the ratio N2O:O2 at no more than 3:1
- includes the link-25 and ORMC systems
29
Describe the Link-25 safety system.
- flow control knobs of N2O and O2 are linked by a chain
- if N2O is turned up, O2 goes up as well to maintain the 3:1 ratio
* O2 does not come down with N2O so you must turn O2 down
30
Describe the oxygen ratio monitor controller (ORMC) safety system.
- pneumatic, mechanic control
- will not allow you to turn up N2O past O2, but will allow O2 increase which then allows you to increase N2O up to a 3:1 ratio
- must turn back down
31
Describe the minimal O2 flow safety system.
- if the machine is on it will automatically deliver 150 ml/min of O2 meeting the basic needs of the patient if the operator forgets to turn on oxygen flow
* reason machine needs to be off during low pressure leak tests
32
Describe the safety mechanisms of flowmeter positioning.
oxygen flowmeters are always nearest to the vaporizers which is downstream, furthest right
* minimizes the risk of delivering a hypoxic mixture if a leak occurs within flowmeter
* will still be hypoxic if the leak is within the O2 flowmeter or downstream of it
33
Describe the interlock-exclusion system of vaporizers.
- prevents using more than one vaporizer at one time
- locking lever locks in place on the manifold port valves
- interlock rods on vaporizers will not permit more than one vaporizer to be turned on at once
34
What is the manifold?
where gases from different flowmeters mix together and have opportunity to enter into a vaporizer which is attached here
35
What is the check valve of the manifold?
valve that helps prevent O2 flow from going backwards (upstream)
-if a crack or leak develops in N2O flowtube, this valve helps prevent O2 flow from flowing back to N2O flowtube and leaking to the atmosphere
36
Describe the common gas outlet (CGO).
- supplies gas mixture to the breathing system
- "fresh gas outlet"
- here you perform the low pressure circuit leak test
- includes the antidisconnect safety feature
37
Describe calibrated vaporizers.
- add vaporized anesthetic agent to gas flow
- use a "keyed" system to fit
- includes the interlock-exclusion safety feature
38
Describe the low pressure circuit leak test (negative pressure leak test).
- looks at vaporizers and flowmeters
- all vaporizers and flowmeters off
- connect bulb to CGO
- compress suction bulb
- want it to stay compressed for 10 seconds
- then open each vaporizer one at a time, recompress bulb and look for each to stay compressed 10 seconds
* vaporizers commonly have leaks
39
Describe the high pressure system.
- gas supplies connected to the machine
| includes: pipeline, cylinder, O2 power outlet
40
What is the pipeline gas inlet?
pipeline supply of gas through hoses from wall outlets
41
What is the function of pipeline filters?
remove damaging debris
42
What is the function of pipeline check valves?
prevents retrograde flow and leakage if the pipeline supply is disconnected and cylinder supply is in use
*gas can't flow backwards and there won't be any cross filling between the pipeline and cylinder
43
what should a pipeline pressure gauge read?
50-55 psig
44
What are some pipeline safety features?
Diameter index safety system (DISS)
| Quick Connectors
45
What is the cylinder gas inlet?
reserve supply of gases (O2, N2O, and air)
46
what is the function of the cylinder hanger yoke?
- orients the cylinder
- provides a seal (washer)
- directs flow
- also contains a required filter
47
what is the function of the cylinder check valve?
prevent retrograde flow and transfilling to a second cylinder of some gas
*transfilling occurs if both cylinders are open and gas flows from the higher to lower pressure cylinders instead of flowmeters
48
what is the function of the cylinder pressure regulator?
- reduces pressure to 45 psig
| * if the pipeline and cylinder are open, pressure prefers to come from the pipeline since its pressure is higher
49
Describe the cylinder's pressure gauge.
- Bourdon-type gauge: flexible tube within the gauge that straightens when exposed to gas pressure, causing gear mechanism to move needle pointer
* should start at 0
* need to bleed pressure gauge back down to 0 if cylinder has been opened
* if baseline is not 0, gauge will only read accurately pressure higher than the baseline
50
what is the cylinder's safety system?
pin index safety system (PISS)
51
Describe the O2 power outlet.
connected to the mechanical ventilator and the O2 flush valve
52
Describe the O2 flush valve.
- bypasses flowmeters and vaporizers directly to the breathing system (50 psig)
- delivers 35-75 L/min
- reinflates the reservoir when it is not full and the vent bellows
* important to disconnect the ETT and patient and clamp the Y tube to ensure extra pressure is not sent to the pt
* safety rim around the button to prevent accidental push
* can cause barotrauma from high pressures
53
what are safety features of the high pressure system?
- low O2 supply pressure alarm
- O2 pressure failure safety mechanism (fail-safe)
*must continue to monitor inspired O2 concentration (FiO2) since these only look at pressure and cannot verify correct gas
54
Describe the low O2 supply pressure alarm safety system.
- reservoir reed device sounds on initiation of pressure as O2 fills the reservoir and sounds as pressure drops and O2 begins to escape reservoir
* must sound within 5 seconds of O2 supply pressure drop below 30 psig
* does not prevent hypoxic mixtures
55
Describe the fail-safe system.
- causes a cessation of flow of non O2 gases if O2 pressure falls below 25 psig
- prevent hypoxic mixture
* can be overcome if pipeline/cylinder has the wrong gas since it only reads pressure
56
Describe the electrical supply of the anesthesia machine.
- single power cord
- battery backup of at least 30 min
- convenience receptacles and circuit breaker
57
The "on" switch of the machine does what?
- allows electricity to flow to ventilator monitors and desflurane vaporizer
- connects the O2 supply to shutoff valves, the low O2 supply alarm, and to the flowmeters
58
The "off" switch of the machine does what?
- causes the system to vent O2 pressure to the atmosphere
| - check valve is present, allowing for negative pressure test
59
Describe proper use of convenience receptacles and circuit breaker.
- unplug the last thing plugged in if circuit breaker closes
- do not plug bear huggers or cauterizers into receptacles
- know where the circuit breaker Is on the machine
60
Describe battery back up.
- at least 30 minutes
- limited function varies with manufacturer
- may lose patient monitors, vent function, fresh gas flow, vaporizers, and manual vent function
- once battery power is lost, may only have delivery of O2
* switch from vent to manual
* switch to cylinder to preserve O2
61
What devices or techniques do not rely on wall outlet electrical power?
- spontaneous or manually assisted ventilation
- mechanical flowmeters
- scavenging
- laryngoscope, flashlights
- IV bolus or infusion
- battery operated peripheral nerve stimulators or IV infusion pumps
- patient monitoring using the 5 senses
- variable bypass vaporizers
Principles I
flashcards
Decks in class (18)
# Cards
-
Physics107
-
Medical Gas35
-
Environmental Safety40
-
Anesthesia Machine61
-
anesthesia breathing systems36
-
CO2 Absorption15
-
Vaporizers29
-
anesthesia ventilators and pulmonary management73
-
ventilator modes12
-
respiratory monitoring52
-
Basic EKG109
-
12 lead EKG45
-
interpretation of monitoring data47
-
CV and PA catheters59
-
basic transesophageal echocardiography34
-
caridac output monitoring and oxygen delivery22
-
invasive and non-invasive BP monitoring45
-
neurological and level of consciousness monitoring54
