Module 2 Anesthesia Machine Flashcards
1
Q
High Pressure System
A
Consists of the parts of the anesthesia machine that receive gas at cylinder pressure (2000 psi to approximately 45 psi)
- Cylinder Pressure
- Begins at cylinder, ends at cylinder regulators
- Located on the back side of the anesthesia machine
2
Q
Name the components of the anesthesia machine
High Pressure System.
A
- Hanger Yolk
- Yolk Block with Check Valves
- Cylinder Pressure Gauge
- Cylinder Pressure Regulator (First-Stage)
3
Q
Intermediate Pressure System
A
All parts of the anesthesia machine receiving reduced pressure cylinder gas 45 to 55 psi.
- Pipeline = 50 psi
- Tank = 45 psi
- Includes gas received from cylinders down regulated at First Stage Regulator (~35-45 psi)
- Includes pipeline gas inlets and pressure gauges
- Begins at Pipeline and ends at Flowmeter Valves
- Includes oxygen flush valve, oxygen failure safety valve, and oxygen supply failure alarm
- Located in the “middle” of the anesthesia machine
4
Q
Name the components of the anesthesia machine Intermediate Pressure System.
A
- Pipline Inlets
- Pressure Gauges
- Oxygen Pressure Failure Device
- Oxygen Second Stage Regulator
- Oxygen Flush Valve
- Ventilator Power Inlet
- Flowmeter Valves
5
Q
Low Pressure
System
A
All parts receiving gas from either a pipline or cylinder source at approximately 15-30 psi
- Slightly above atmospheric pressure but variable
- Second Stage Regulator drops pressures from intermediate to low pressures at approximately 16 psi
- Allows safe delivery of gases to patients
- Begins at Flowmeter and ends at Common Gas Outlet.
- Includes:
- Flowmeters, Vaporizers, Common Gas Outlet
- Located in the front of the anesthesia machine
6
Q
Name the components of the anesthesia machine
Low Pressure System.
A
- Flowmeter tubes (Thorpe tubes)
- Vaporizers
- Check valve (if present)
- Common Gas Outlet
7
Q
A safety system utilized in the pipeline system that prevents improper connection of gas supply hoses, but does no prevent a hypoxic gas mixture.
A
Diameter Index Safety System
8
Q
Describe the characteristics of Cylinders.
A
- Regulated by the US Department of Transportation
- Range in size from A-H
- Various gases at differing pressures
- Some gases available in different grades depending on use
- Sizes A-E use P.I.S.S. to reduce misconnections and delivery of hypoxic mixtures
- Color coded for safety
9
Q
What is the most common cylinder utilized in anethesia?
A
Size E Cylinders
10
Q
Name the common components of cylinders and their function.
A
- Body - usually composed of steel; may be aluminum
-
Valve - attached at neck
- used for filling and discharge
- may be made of bronze or brass
- regulates pressure down
-
Port - point of exit for gas
- usually covered until cylinder “cracked”
-
Stem - within the valve
- closes valve by sealing against seat
- moves upward and away from seat when opened.
11
Q
A component of the cylinder that is typically made of steel but may also be made of aluminum.
A
Body
12
Q
A component of a cylinder that is attached to the neck, is used for filling/discharging, that may be made of bronze or brass, and regulates pressure down.
A
Valve
13
Q
A component of cylinders that is the point of exit for gas and is typically covered until the cylinder is “cracked’.
A
Port
14
Q
A component of cylinders that is located within the valve and closes the valve by seating against the seal. When opened this component moves upward and away from the seat.
A
Stem
15
Q
A component of the cylinder valve that allow for the safe escape of gases when temperature and pressure increases within the cylinder.
A
Pressure Relief Device
16
Q
Name the types of pressure relief devices and how they function.
A
- Rupture Disc - breaks off at high internal pressure allowing for complete emptying of cylinder contents
- Fusible Plug - made of Wood’s metal which melts at certain external temperature allowing for complete emptying of contents
- Combination Disc/Plug - responds to internal pressure and external temperature
- Spring-loaded - lifts upward at increased pressure and allows release of gas until internal pressure within cylinder normalizes
17
Q
A unique configuration of holes on each cylinder valve that corresponds to the cylinder contents and its intended use. It is an additional means of preventing cylinder misconnections.
A
Pin Index Safety System
(PISS)
18
Q
Name the color and PISS of Air cylinders.
A
- Yellow
- Pin Position: 1,5
19
Q
Name the color and PISS of Oxygen cylinders.
A
- Green
- Pin Position: 2,5
20
Q
Name the color and PISS of Nitrous Oxide cylinders.
A
- Blue
- Pin Position: 3,5
21
Q
The attachemtn on the anesthesia maching where cylinders are set.
A
Cylinder Hanger Yolk
22
Q
Namet he components of the Hanger Yoke.
A
- Body Retaining Screw
- Nipple
- PISS
- Washer
- Check valve
23
Q
What kind of gauge measures the pressure within a given cylinder?
A
High Pressure Cylinder Gauge
(Bourdon Gauge)
24
Q
What common cylinder pressure gauge consists of coiled tube connected to the cylinder in which pressure is sensed?
A
Bourdon Gauge
25
Works to control variable cylinder pressure and reduces high cylinder pressure to approximately 45 psi. Typically part of a series of two.
High Pressure Regulator
## Footnote
or
*First-Stage Regulator*
26
The 5 Tasks of Oxygen are:
1. Power outlet accessory (*it proceeds to Fresh Gas Flowmeter*)
2. O2 flush valve (*powers O2 flush*)
3. Low Presssure sensor shut-off valve (*activates fail-safe mechanisms*)
4. Supply failure alarm system (*activates O2 low-pressure alarms*)
5. Second-stage pressure regulator (Flowmeter) [*compresses the bellows of mechanical ventilator*]
* Nagelhout references *Italicized* on this slide
27
*_Acts as power outlet accessory_* (driving gas for the ventilator) and proceeds to the fresh gas flowmeter.
First Task of Oxygen
28
Located at machine outlet to circuit, powers the *_oxygen flush valve_* with a flush of 35-75L/min.
Second Task of Oxygen
29
Activation of fail-safe mechanisms.
O2 @ ~50psi holds open *_Low Pressure sensor shut-off valve_* allowing N2O to flow to flowmeter, and will remain open as long as psi is \>25. If psi drops below 25 psi, N2O flow shuts off.
Third Task of Oxygen
30
Activates O2 low-pressure alarms. The *supply failure alarm system* activates when O2 drops below 28 psi. Alarm sounds before 25 psi (the point at which N2O flow will cease).
Fourth Task of Oxygen
31
Gas passes by *second-stage pressure regulator (Flowmeter)* and is decreased to a constant pressure of 16 psi. After passing second-stage regulator, O2 sits in "stand by" at flow control valves.
Compresses bellows of mechanical ventilator.
Fifth Task of Oxygen
32
Includes a valve that shuts off flow of all other gases when O2 pressure falls below 20-25 psi. Activates with decreased flow of O2. Has **audible and visual alarm**. Does **NOT PREVENT** delivery of hypoxic mixture.
Oxygen Failure System
33
How does an anesthesia provider determine time until oxygen tank exhaution?
Divide remaining O2 volume in cylinder by rate of consumption of O2
* O2 Vol (L) / Rate of O2 consuption (L/min)
Remaining O2 vol derived:
* (Cylinder psig / 2000 psig) x 660 L
Rate of Consumption during *mechanical ventilation* derived:
* O2 flow (L/min) + minute ventilation (L/min)\
Minute ventilation derived:
* VT (L) x RR (breaths/min)
34
Provides O2 at 35-55 L/min directly to common gas outlet, bypassing flowmeters and vaporizers.
Used to rapidly refill or flush breathing circuit.
Must have built-in rim to prevent accidental activation.
Use can lessen depth of anesthesia if N2O or inhaled agents have already been established in breathing cicuit.
Part of the Intermediate Pressure System
Located on front of anesthesia machine
The "DO NOT USE" button.
Oxygen Flush Valve
35
These valves are touch and color-coded to prevent use of wrong gas.
O2 knob is fluted, larger, protrudes further, and located furthers to the right
Flow Valves
36
Used to ensure Nitrous Oxide can only be delivered in the presence of Oxygen.
Prevents delivery of hypoxic gas mixture.
Maintains minimum O2/N2O ratio 1:3 (21-25% O2).
Automatically mixes O2 and NO2 to selected dial setting.
Oxygen Proportioning Device
37
Consist of the knob, needle valve, flow tube, and indicator float.
They are gas specific in design and calibration; cannot be interchanged.
Part of the *Low Pressure System*
Flowmeters
38
To ensure oxygen is always deliverd, what is the minimum setting of constant oxygen flow even when the oxygen flowmeter is "OFF" ?
50-150 mL/min
39
Where is the oxygen flow meter located and why is this significant?
1. Oxygen is furthest to the right
2. In the event of a leak, the chance of a hypoxic mixture is lessened
40
The two types of vaporizers are:
* Variable Bypass
* Injector
41
A component of the anesthesia machine that is precisely designed and calibrated to convert Volatile Anesthetic Agents (VAA) from a liquid state into a "gaseous state" at a standard temperature and pressure for inhalation.
Agent specific.
Part of the *Low Pressure System*.
Vaporizer
42
A safety mechanism that ensures only one vaporizer is on at one time, directing gas flow to the vaporizer that is activated and that trace vapor output is minimized when vaporizer is off.
Allows for vaporizers to be "locked" into gas circuit, ensuring proper seating.
Vaporizer Interlock Mechanism
43
Type of vaporizer that utilizes *flow over method of vaporization*.
Anesthetic concentration determined by flow ratio.
Includes the *Tec 4, Tec 5, and Tec 7ADU*
Has *Automatic* temperature compensation.
*Can compensate for changes in elevation.*
Variable Bypass Vaporizer
44
Vaporizer made specifically for *Desflurane*.
Utlizes a *gas/vapor blender* where heat creates vapor that is put into fresh gas.
Temperature is *electronically controlled at 39 C*
Includes the *Tec 6*
Does *NOT* compensate for elevation.
Injector Vaporizer
45
Caused by *Pumping Effect* due to inspiratory positive pressure from manual/assisted ventilation or use of O2 flush valve transmitted back to vaporizer.
Seen with *LOW FLOWS.*
Overdosing
46
Caused by *Pressurizing Effect* with manual/assisted ventilation or O2 flush valve use.
Seen with *HIGH FLOWS*
Inadequate dose
47
Also known as fresh gas outlet and is the only outlet on the anethesia machine.
Must have an anti-disconnect device to prevent accidental disconection from breathing circuit.
Oxygen from fush valve enters directly from intermediate pressure system into this outlet directly to patient.
Part of the *Low Pressure System*
Common Gas Outlet
48
is NOT part of the low pressure system.
* Contains:
* Fresh gas inflow
* Unidirectional valves
* Corrugated tubes
* Y-piece
* APL valve
* Reservoir bag
* CO2 Absorbant
Circle System
49
A part of the circle system when manually ventilating via bag.
Bypassed during mechanical ventilation.
Usually fully open during spontaneous ventilation.
MUST be partially closed during manual/assisted ventilation
If closed too tighly, can create high airway pressure due to increased VT.
If open too wide, can create low VT.
Adjustable Pressure Level (**APL**) Valve
50
These mechanisms maintain the flow of anesthetic gas in the proper direction.
One for inspiratory limb; one for expiratory limb
Malfunctioning of either inspiratory or expiratory device can cause CO2 rebreathing
Unidirectional Valves
51
Valve exposed to moisture from patient airway.
Prone to sticking, increasing resistance
Expiratory Unidirectional Valve
52
Valve that allows for forward flow of gas towards patient.
Inspiratory Unidirectional Valve
53
Allows for rebreathing of alveolar gases, conserving heat and moisture; decreasing the need for high flow gases.
Removes expiratory CO2
Allows for economical recirculation of gases and anesthetic agents.
Allows for the existence of Circle System.
Carbon Dioxide Absorbent
54
The most commonly utilized CO2 absorbent
Soda Lime
55
Both Soda lime and Baralyme produce this byproduct of CO2 neutralization.
Heat, Water, and Calcium Carbonate
56
Interaction of this gas with strong bases in soda lime or baralyme forming degredation products that are toxic to animals in high doses.
Sevoflurane
57
A toxic, degredation byproduct of sevoflourane that increases with total gas flow rates below 1 L/min and the use of baralyme.
Compound A
58
Factors that increase production of *Compound A*
* *Total gas flow \< 1 L/min and/or \> 2 MAC hours*
* Use of baralyme CO2 absorbent vs. soda lime
* Increased absorbent temperatures
* Increased concentrations of Sevo
* Dry CO2 absorbent
* Fresh soda lime
* Leaving machine on overnight
59
CO2 absorbent degradation product of desflurane and isoflurane.
Produced more by Des than Iso
Higher concentrations noted with absorbers that have not been used for 24 or more hours
Carbon Monoxide
60
Factors that increase Carbon Monoxide
* Use of baralyme vs. soda lime
* High temperatures in absorber
* *Dry absorbent*
* High anesthetic concentrations
* Length of time
61
Required at all times when anesthesia machine is in use
May be polarographic (Clark electrode) or galvanic (fuel cell) which require calibration
Can be paramagnetic and self-calibrating; able to detec inspired and expired O2 concentrations
Must have low-level alarms that are active while machine is on.
Oxygen Sensor
62
Classified as active or passive and are part of the Circle System
Humidifiers
63
A commonly used passive humidifier that is an economical way to add heat and moisture to inhaled gases by trapping heat/moisture contained in exhaled gases.
Heat and Moisture Exchangers (HME)
64
Active humidifiers may cause these complications
* Transmission of nosocomial infections
* Thermal lung injury
* Increased airway resistance from excessive condensation
65
Allows for the anesthetist to be hands free to do other tasks while supporting patient ventilation
May be classified as having ascending or descending bellows.
Ventilator
66
Rises as the patient exhales.
Will drop and will not rise again if there is a disconnection, allowing for vigilence in detecting disconnections.
Most commonly used.
Ascending Bellows
67
A system used to provide a way for waste anesthetic gases (WAGs) to be removed from the breathing circuit via the APL valve or ventilator spill valve and out of the OR.
Can be Active or Passive
Scavenger System
