E3- Compressed Gases and Vaporizers Flashcards
1
Q
PSI stands for
A
Pounds per square inch
2
Q
Cylinder - primary vs emergency source
A
o Primary – used for transport
o Emergency – if pipeline fails + use tanks on back of machine
3
Q
What are the colors of each gas?
A
o Oxygen = green
o Air = yellow
o Nitrous = blue
o Vacuum = white
4
Q
- Define Non-Liquified gas.
- What were examples?
A
- gases that do not liquefy at ordinary ambient temperatures regardless of the pressure applied
- Oxygen
- Air
- Helium
5
Q
A liquified gas can become a liquid at _________ temperature and at pressures from ____- _____psi
A
- ambient
- 25 to 1500 psi
6
Q
What were examples of liquified gases?
A
- Nitrous oxide
- Carbon dioxide
7
Q
What government agencies are involved with compressed gases used in the OR?
A
- FDA (purity of substance)
- DOT (marking, labeling, storage, handling)
- OSHA (employee safety)
- National Fire Protection Association
8
Q
Name 4 components of the cylinder:
A
- Body
- Check Valve
- Handle
- Pressure Relief Device
9
Q
What is the body of the cylinder made out of?
A
- Steel
- Steel Carbon Fiber
- Aluminum - for MRI
10
Q
What kind of bases do the cylinders have?
A
- Flat Base
- Concave Base
11
Q
What is the check valve of the cylinder made out of?
A
- Bronze
- Brass
12
Q
What is the function of the valve on the cylinder?
A
- The valve is attached to neck of the cylinder
- allows refilling and discharge of gas
13
Q
What is used to open/close the cylinder?
A
- Handle
- Handles should be attached to EVERY cylinder*
14
Q
What component vents cylinder contents to the atmosphere if pressure increases to a dangerous level (overheating or filling)?
A
- Pressure relief device
- (Safety relief)
15
Q
What is the Pin Index Safety System?
A
- Prevents crossover of the wrong tank into the wrong fitting
- Holes on cylinder valve positioned in an arc below outlet port
- Pins on the yoke or pressure regulator are positioned to fit into these holes
Oxygen = 2, 5 … Nitrous = 3, 5
16
Q
What are 3 methods a pressure relief device works?
A
- Disc that bursts
- Fusible plug melts
- Valve opens + raises to let gas out or compresses a spring
17
Q
How are cylinder sizes labeled?
What is the most common cylinder size on anesthesia machines?
A
- Letter code :: A-H
- A = smallest
- H = largest - for refilling smaller tanks
- E = most commonly on back of anesthesia machines
- D = for transport
18
Q
What size cylinders are used for transport?
A
- Cylinder size D are used for transport
19
Q
Pressure decreases as volume decreases .. with what type of gas ?
A
Non-Liquified
oxygen, air, helium
20
Q
- what is the approx psi of cylinder?
- must remain ______. why?
A
- 45 psi
- closed - audible alarm that signals changing from wall to tank
21
Q
Non-Liquified Gas
Pressure and volume when full?
Half full?
Quarter full?
Empty?
A
- 600 L @ 1900 psi
- 330 L @ 950 psi
- 165 L @ 475 psi
- 0 L @ 0 psi
22
Q
- With liquified gas, pressure depends on what?
- the ___________ is not an indication of remaining ________________
A
- vapor pressure
- pressure ,, volume
23
Q
Liquified Gas
What are the weight, volume, + pressure of nitrous oxide at….
* Full?
* Half Full?
* No liquid remaining (vapor only)?
* Nearly empty (no vapor either)?
A
- 20.7 lb ,, 1590 L ,, 745 psi
- 17.3 lb ,, 745 psi
- 14.2 lb ,, 250 L ,, 745 psi
- 14.1 lb ,, 125 L ,, 350 psi
PSI doesnt fall until nearly empty
24
Q
What are the Department of Transportation (DOT) regulations for cylinders?
A
- Service pressure
- Test date
- Diamond shaped label indicating hazard of gas…danger, warning, or caution
- Name and address of manufacturer
- Expiration date of contents
25
Cylinder Standards: Valves, regulators, gauges never come into contact with what?
* Oil
* Grease
* Lubricants
26
Cylinder Standards: Never subject cylinder to temps above ______
* 54 C (130 F)
27
Cylinder Standards: Never cross use what?
* Hoses
* Regulators
* Gauges
28
Cylinder Standards: What must not be altered?
* Original Markings on Cylinder
* Original Labels
29
# Cylinder Standards
* connections always ______
* cannot be ________
* valve kept ______ at all times
* properly ________ to revent fall
* tight
* dropped, drug, slid
* closed
* secured
30
Associate the color with gas:
Green
Blue
Yellow
White
* Green = Oxygen
* Blue = Nitrous
* Yellow = Air
* White = Suction
31
Describe the 6 conditions of storage rooms for cylinder tanks.
* Adequate ventilation
* “No smoking,” or “No Combustibles” signs
* Cylinders are not exposed to corrosive chemicals, fumes
* Stored upright in bins
* Full tanks separated from empty tanks
* Do not wrap or drape cylinders
32
8 things to consider prior to using gas cylinders.
* Inspect label, pin index holes, regulator, valve outlet
* Check if tamper seal is removed
* Check if washer is in place
* Open the valve to relieve excess pressure before bringing cylinder to pt
* Face valve outlet away from people
* open slowly
* Check service pressure
* Correct leaks
33
Pipeline systems are used to deliver what kind fo gas?
Non-flammable gases
nitrous, oxygen, air
34
What are the 3 components of pipeline systems?
1. central supply
2. piping - receiving at 50 psi
3. terminal units - maintains approx 50 psi
35
Where are possible locations for the Central Supply?
* Outdoors in an enclosure
* Indoors in secure area
36
A Central Supply "bank" must contain gas for at least how many days?
* 2 days
37
What cylinder size would an oxygen bank be?
* G and H cylinders
38
Differentiate between a gaseous and liquid oxygen supply source.
* Gaseous supply = contained in large G/H cylinders + refilled on-site or transported
* Liquid supply = less expensive and more convenient to store, refilled by supply trucks, service not be interrupted
39
What are the 3 classes of piping?
* Main lines = connect gas source to risers
* Risers = **vertical** pipes connecting main line with branch lines on each level of the facility
* Branch = sections supplying a room or group of rooms on one level of the facility (**horizontal**)
40
Permit specific areas of the piping system to be isolated for problems /maintenance.
* Shut-off Valves
41
The area alarm system must be in at least how many places?
What places will have the gas alarm system?
* 2 places
* The affected unit, critical life support area, maintenance, engineering
42
The area alarm system will be triggered if pressure increases/decreases ____ % from normal.
* 20%
43
Area system alarm must be ________ AND ________.
* audible
* visible
44
What are terminal units?
* Point in piped gas distribution where **user connects and disconnects** by hose
45
What safety system does the terminal unit use?
* Diameter Index Safety System (DISS)
* "quick connects"
## Footnote
DISS = Nipple and nut vary in bore and diameter
46
differentiate bw PISS + DISS
PISS = cylinders :: hanger yoke pins + holes
DISS = terminal wall units :: nipple + not vary in bore + diameter
47
What allows convenient connection with one/both hands to terminal units?
What is the drawback to this?
* Quick Connectors
* Drawback: Quick Connectors leak more
48
Where are possible locations for Quick Connects?
* Wall
* Ceiling -mounted
* Ceiling column
49
Define Vaporizer.
* A device that
* changes a liquid anesthetic agent to a vapor
* adds controlled amt of vapor to FGF breathing system
50
Volatile anesthetics exist in a liquid state below what temperature?
* 20C (68F)
51
* In a closed container, molecules escape liquid to __________ phase.
* These molecules borbard container walls + create _____________________
* Vapor
* vapor pressure
52
What is saturated vapor pressure (SVP)?
* When equillibrium is achieved bw liquie + vapor phase @ constant temp ... from molecules hitting walls of container
* Gas phase above liquid contains all the vapor it can hold
* highest amt of vapor pressure
53
# *Saturated Vapor Pressure*
What is SVP dependent on?
What is SVP independent of?
* characteristics + temperature of liquid
* atmospheric pressure - altitude does not change vapor pressure
54
Part of the total pressure of any one gas in a mixture
Partial pressure
55
State Dalton's Law
* Sum of Partial Pressure = Total Pressure
* Part of the total pressure of any one gas in a mixture
56
Partial pressure is dependent on _______.
NOT dependent on ___________
* Temperature
* atmospheritc pressure
57
The concentration of a gas in a mixture expressed as a percentage
* Volume percent
58
Formula for volumes percent
Partial Pressure / Total Pressure = vol percent
59
Vapor pressure is independent of _______
* Atmospheric Pressure (Barometric Pressure)
60
Vapor pressure is dependent on ________
* Characteristics of liquid
* Temperature of liquid
61
Vapor Pressure of Fluothane
* 243 mmHg
| Halothane
62
Vapor Pressure of Forane
* 238 mmHg
| Isoflurane
63
Vapor Pressure of Suprane
* 669 mmHg
| Desflurane
64
Vapor Pressure of Ultane
* 157 mmHg
| Sevoflurane
65
What are the trade names for Halo, Iso, Des, + Sevo?
* halo = fluothane
* iso = forane
* des = suprane
* sevo = ultane
66
# %%%
The temperature at which vapor pressure equals to atmospheric pressure.
* Boiling point
67
Which volatile anesthetic has a vapor pressure almost equal to atmospheric pressure?
* Desflurane (Suprane)
* Boiling point of Desflurane 22.8C (73F)
68
Define Heat of Vaporization
The number of calories necessary to convert 1 gram of liquid into vapor (or 1 mL of liquid to vapor).
69
What happens to the liquid temperature and vapor pressure as carrier gas flows through the vaporizer, causing the vapor molecules to leave?
* Liquid temperature drops >> vapor pressure drop
* >> **equilibrium shift** - more molecules in a liquid state
* >> Output vapor decrease
| **More heat needed** to increase vapor out - Vapor p dependent on temp
70
Define specific heat
Number of calories required to raise the temperature of 1 g of a substance 1 degree C
71
The higher the specific heat, the __________ heat required to raise the temp of the substance
more
72
Specific Heat of Water
1 cal/g
## Footnote
The Standard
73
* Specific heat is considred when choosing ________ for vaporizer.
* Material with higher specific heat minimizes _________.
* material
* Temperature Variation
74
Define thermal conductivity
The ‘speed’ at which heat flows through a substance
75
The _________ the thermal conductivity, the better the substance conducts heat
higher
76
Metals with high thermal conductivity minimize ____________ during vaporization.
Examples??
* temperature swings
* Copper + aluminum
## Footnote
* Copper and Aluminum have the best thermal conductivity
77
A device that changes a liquid anesthetic agent to a vapor and adds a controlled amount of that vapor to fresh gas flow in the breathing system.
* Vaporizer
78
Modern vaporizers are
_________-calibrated and _______ bypass.
* Concentration
* variable
79
Where is the vaporizer located?
* Between flow meter and common gas outlet
80
Where can a caporizer NOT be placed? Why?
after common gas outlet ,
bc not calibrated for high flows of oxygen flush
81
What happens if the vaporizer is before the flow meter?
What happens if the vaporizer is after the common gas outlet?
* Carrier gas will be on the wrong side and will not be able to pick up adequate vapor molecules
* There will be less stability and flow of vapor molecules delivered to the patient
82
What regulates the concentration of the volatile in the vaporizer (variable bypass)?
* The concentration dial
83
What is the splitting ratio?
ratio depends on size of adjustable orfice (hole)
* determines how much FGF bypaasses or goes into vaporizer chamber
84
What makes up the splitting ratio?
* **Vaporizing chamber** flow rate
*** Bypass pathway** flow rate
## Footnote
Higher splitting ratio means more flow will go through vaporizing chamber, higher anesthetic gas delivery.
85
What are the two types of vaporizers?
* Flow-over (modern) - wicks
* Bubble through (older)
86
# %%%%%%%%%%
Why is desflurane heated in the vaporizer when its boiling point is at room temperature?
* There is a lot of variability at room temperature.
* Desflurane is heated to a precisely **controlled** temperature and stable vapor phase.
* The heated vapor is then “injected” into the fresh gas flow to deliver a **precise anesthetic concentration**.
87
* in modern vaporizers, there are electronic temperature _______.
* what changes as temperature changes?
* ____________ temperature leads to more vapor amt
* sensor
* splitting ratio nchanges as temperature changes
* high
88
What are 8 vaporizer hazards?
* Placing incorrect agent in the vaporizer
* FGF Flow Rate
* Pumping Effect
* Effects of Rebreathing
* Barometric Pressure
* Tipping
* Overfilling
* Leaks
89
Why is placing the incorrect volatile agent in the vaporizer unlikely?
* Filling systems are agent-specific
* each type has different "key" hole for each gas type
* monitor will show 2 different vapors
90
How do you fix this issue if you somehow get the wrong agent in the vaporizer?
* Vaporizer must be completely drained, and all liquid discarded
* Run FGF at 8-10 L/min until no vapor is detected
## Footnote
The monitor will detect 2 vapors if incrorect agent is added to the vaporizer
91
What does FGF have to be between to have no vaporizer problems?
250 mL/min -- 15 L/min
92
What happens to the vaporizer output if the flow rate is less than 250 ml/min?
* vaporizer Output < setting
* High density of volatile prevents upward movement of molecules
93
What happens to the vaporizer output if the flow rate is greater than 15 L/min?
* vaporizer Output < setting
* Failure to saturate carrier gas
94
What are two common causes of the anesthesia machine's intermittent back pressure (pumping effect)?
* Positive Pressure Ventilation
* Oxygen Flush Valve
95
The pumping effect is more pronounced with:
* Low flow rates
* Low dial settings
* Low levels of liquid in the vaporizing chamber
96
What problem does the pumping effect have on vaporizer output?
* Inconsistency in maintaining alveolar pressure of anesthetic vapors
## Footnote
Negate the pumping effect by maintain adequate flow rate and dial setting
97
What object in the anesthesia machine fixes/inhibits the pumping effect?
* Machine Outlet Check Valve
98
What are 4 measures to attenuate the pumping effect besides the machine outlet check valve?
* Smaller vaporizing chamber
* Baffle system
* Longer tube for the inlet of the vaporizing chamber
* addition of check valve
99
Effects of rebreathing with high FGF?
Effects of rebreathing with low FGF/high Vm?
* Little exhaled gas rebreathed
* Significant rebreathing with low FGF
100
Remember :: vapor pressure is _________ of barometric/atm pressure
independent
101
Vaporizers are ALWAYS calculated at __________
* sea level (760 mmHg)
| Unless requesed to be another level - denver
102
# %%%
Why will an increase in altitude not affect the delivery of Isoflurane or Sevoflurane?
* Isoflurane and Sevoflurane are not pressurized. They operate as a function of atmospheric pressure.
* At sea level, atm = 760 mmHg. This pressure keeps molecules down in the liquid phase.
* So, in higher elevations, there will be less atmospheric pressure. Which means more molecules can escape as a gas.
* The **decrease in atmospheric pressure and the increase in the volume percent of gas will equal the partial pressure** of gas delivered at sea level.
* Refer to the math below or watch the YouTube link.
* https://www.youtube.com/watch?v=UgViWCNVgOA&ab_channel=CountBackwardsFrom10
103
Why is altitude increase controversial?
* volumes % increase significtnly
* partial pressure changes lesser
* anesthetic dpeth is partial pressure in brain
104
How does tipping affect vaporizer output?
Fix?
what type of vaporizer isolates vaporizer + bypass chamber with transport dial?
* There will be an excessively high output due to **liquid entering the bypass chamber**
* hook up to FGF + dry it up
* drager
105
What problem is seen when liquid enters bypass chamber + excess dose delivered to pt? Now fixed with preventative design.
Overfilling
106
Vaporizer leaks can be caused by:
* Loose filler caps
* Drain valves
* Vaporizer/mounting bracket interface
107
What would be indicators of vaporizer leaks?
* Odor of gas
* Lower than expected inhaled concentration (Fi)
108
What will be the patient consequence of a vaporizer leak?
* Patient awareness
109
What are 5 vaporizer safety standards?
* Average concentrations +/- 20% of setting
* Gas may not pass through more than 1 vaporizer - INTERLOCK
* Output of vaporizer <0.05% in OFF
* All control knobs counterclockwise
* Filling levels displayed
110
What are 4 mounting standards of the vaporizer?
* Detachable
* Weight of vaporizer and "O" ring creates seal
* Locking lever on the back
* Easily removed and replaced (especially for MH)
111
What prevents more than 1 vaporizer from being turned on at a time?
* Interlock Device
