Exam 3- Compressed Gases and Vaporizers (7/10/23) Flashcards
1
Q
PSI stands for
A
Pounds per square inch
2
Q
What were examples of gases that do not liquefy at ordinary ambient temperatures regardless of the pressure applied?
A
- Helium
- Oxygen
- Air
3
Q
A liquified gas can become a liquid at ambient temperature and at pressures from ____- _____psi
A
- 25 to 1500 psi
4
Q
What were examples of liquified gases?
A
- Nitrous oxide
- Carbon dioxide
5
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
6
Q
Name the components of the cylinder:
A
- Body
- Valve
- Handle
- Pressure Relief Device
7
Q
What is the body of the cylinder made out of?
A
- Steel
- Steel Carbon Fiber
- Aluminum
8
Q
What kind of bases do the cylinders have?
A
- Flat Base
- Concave Base
9
Q
What is the valve of the cylinder made out of?
A
- Bronze
- Brass
10
Q
What is the function of the check valve on the cylinder?
A
- The valve is attached to the neck of the cylinder and allows refilling and discharge of gas
O2 tanks are now refilled away from the facility.
11
Q
What is used to open/close the cylinder?
A
- Handle
Handles should be attached to EVERY cylinder
12
Q
What component vents cylinder contents to the atmosphere if pressure increases to a dangerous level (overheating or filling)?
A
- Pressure relief device
Pressure relief device can be a disc or a plug.
*disk bursts, plug fuses, valve opens
13
Q
What is the Pin Index Safety System?
A
- Pins protrude from yokes and fit corresponding holes in the cylinder valves, providing a mostly “fool-proof” way of connecting the appropriate gas to the appropriate valve.
14
Q
How are cylinder sizes labeled?
What is the most common cylinder size on anesthesia machines?
A
- A (smallest) to H (largest)
- Cylinder size E on anesthesia machines
15
Q
What size cylinders are used for transport?
A
- Cylinder size D are used for transport
16
Q
What is the content and pressure of a full oxygen tank on an anesthesia machine?
A
- 600 L
- 1900 - 2200 psi
Non-liquefied gases: Pressure decreases as volume decreases. Half the volume, Half the psi.
17
Q
For liquefied gases, the pressure depends on ______. This makes pressure NOT an indication of remaining volume.
A
- Vapor Pressure
Note the volume of the full and half tank of Nitrous, but tanks have a pressure of 745 psi. Pressure is not an indicator of volume for liquefied gase.
18
Q
What are the Department of Transportation (DOT) regulations for cylinders?
A
- Name and address of manufacturer
- Service pressure
- Test date
- Expiration date of contents
- Diamond shaped label indicating hazard of gas…danger, warning, or caution
19
Q
Cylinder Standards: Valves, regulators, gauges never come into contact with what?
A
- Oil
- Grease
- Lubricants
20
Q
Cylinder Standards: Never subject cylinder to temps above ______
A
- 54 C (130 F)
21
Q
Cylinder Standards: Never cross use what?
A
- Hoses
- Regulators
- Gauges
22
Q
Cylinder Standards: What must not be altered?
A
- Original Markings on Cylinder
- Original Labels
23
Q
Associate the color with gas:
Green
Blue
Yellow
White
A
- Green = Oxygen
- Blue = Nitrous
- Yellow = Air
- White = Suction
24
Q
Describe the conditions of storage rooms for cylinder tanks.
A
- 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
25
Things to consider when 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 (slowly) to relieve excess pressure before bringing the cylinder to pt
* Face valve outlet away from people
* Check service pressure
* Correct leaks
26
How do oxygen, nitrous, and air get delivered throughout the hospital? What are pressures do these pipeline and terminal units?
* Pipeline Systems
* 50 psi
27
Where are possible locations for the Central Supply?
* Outdoors in an enclosure
* Indoors in secure area
28
A Central Supply "bank" must contain gas for at least how many days?
* 2 days
29
What cylinder size would an oxygen **b**ank be?
* G and H cylinders
30
Differentiate between a gaseous and liquid oxygen supply source.
* Gaseous oxygen supply is contained in large G/H cylinders, refilled on-site or transported
* Liquid oxygen supply is less expensive and more convenient to store, refilled by supply trucks, service not interupted when refilling
31
What are the three 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
32
Allow specific areas of the piping system to be isolated for problems /maintenance.
* Shut-off Valves
33
The area alarm system must be in at least how many places?
What places will have the gas alarm system?
* Found in critical life support areas
* 2 places
* The affected unit, maintenance, engineering
34
The area alarm system will be triggered if pressure increases/decreases ____ % from normal.
* 20%
35
Area system alarm must be ________ AND ________.
* audible
* visible
36
What are terminal units?
* Point in piped gas distribution where user connects and disconnects hose. (Uses DISS)
37
What safety system does the terminal unit use?
* Diameter Index Safety System (DISS)
## Footnote
DISS = Nipple and nut vary in bore and diameter
PISS for cylinders
DISS for wall units
38
What allows convenient connection with one/both hands to terminal units?
What is the drawback to this?
* Quick Connectors
* Drawback: Quick Connectors leak more
39
Where are possible locations for Quick Connects?
* Wall
* Ceiling -mounted
* Ceiling column
40
Volatile anesthetics exist in a liquid state below what temperature?
* 20C (68F)
41
In modern volatile anesthetics in a closed container, molecules escape liquid to __________ phase.
* Vapor
42
What is saturated vapor pressure (SVP)?
What is it dependent on?
* When equilibrium is achieved between liquid and vapor states at a constant temperature as a result of molecules hitting the walls of container.
* Characteristics and temperature of liquid
43
State Dalton's Law
* Sum of Partial Pressure = Total Pressure
* Part of the total pressure of any one gas in a mixture
44
Partial pressure is dependent on _______.
* Temperature
45
The concentration of a gas in a mixture expressed as a percentage
* Volume percent
46
Partial Pressure / Total Pressure =
* Volume percent
47
Saturated Vapor Pressure is independent of _______
* Atmospheric Pressure (Barometric Pressure)
48
Vapor pressure is dependent on ________
* Characteristics of liquid
* Temperature of liquid
49
Vapor Pressure of Halothane (Fluothane)
* 243 mmHg
* Mac 0.76
50
Vapor Pressure of Isoflurane (Forane)
* 238 mmHg
* MAC 1.17
51
Vapor Pressure of Desflurane (Suprane)
* 669 mmHg
* MAC 6.6
52
Vapor Pressure of Sevoflurane (Ultane)
* 157 mmHg
* MAC 1.8
53
The temperature at which vapor pressure equals to atmospheric pressure.
* Boiling point
54
Which volatile anesthetic has a vapor pressure almost equal to atmospheric pressure?
* Desflurane (Suprane)
* Boiling point of Desflurane 22.8C (73F)
55
The number of calories necessary to convert 1 gram of liquid into vapor (or 1 mL of liquid to vapor).
* Heat of Vaporization
56
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, causing vapor pressure to drop
* There will be an equilibrium shift, more molecules in a liquid state
* Output of vapor will decrease
## Footnote
More heat will be needed to increase vapor output.
Vapor pressure is dependent on heat (temperature).
57
Number of calories required to raise the temperature of 1 g of a substance 1 degree C
* Specific Heat
## Footnote
The higher the specific heat, the more heat required to raise the temp of the substance
58
Specific Heat of Water
Water is the standard
1 cal/g of H20
59
Material with higher specific heat minimizes _________.
* Temperature Variation
60
The ‘speed’ at which heat flows through a substance
* Thermal Conductivity
## Footnote
The higher the thermal conductivity, the better the substance conducts heat
61
Metals with high thermal conductivity minimize ____________ during vaporization.
* temperature swings
## Footnote
* Copper and Aluminum have the best thermal conductivity
62
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
63
Modern vaporizers are _________-calibrated and variable bypass.
* Concentration
64
Where is the vaporizer located?
* Between flow meter and common gas outlet
65
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
66
What regulates the concentration of the volatile in the vaporizer (variable bypass)?
* The concentration dial
67
What makes up the splitting ratio?
* Vaporizing chamber flow rate
* By pass pathway flow rate
## Footnote
Higher splitting ratio means more flow will go through vaporizing chamber, higher anesthetic gas delivery.
68
What are the two types of vaporizers?
* Flow-over (modern)
* Bubble through (older)
69
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.
70
What factors can influence vaporizer output?
* Incorrect gas in vaporizer
* Tipping
* Overfilling
* Leaks
* Flow Rate
* Pumping Effect
* Effects of Rebreathing
* Barometric Pressure
71
Why is placing the incorrect volatile agent in the vaporizer unlikely?
* Filling systems are agent-specific
72
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 incorrect agent is added to the vaporizer
73
What happens to the vaporizer output if the flow rate is less than 250 ml/min?
* Output will be less than setting
* High density of volatile prevents upward movement of molecules
74
What happens to the vaporizer output if the flow rate is greater than 15 L/min?
* Output will be less than setting
* Failure to saturate carrier gas because the carrier gas is too fast.
75
What are two common causes of the anesthesia machine's intermittent back pressure (pumping effect)?
* Positive Pressure Ventilation
* Oxygen Flush Valve
76
The pumping effect is more pronounced with:
* Low flow rates
* Low dial settings
* Low levels of liquid in the vaporizing chamber
77
What problem does the pumping effect have on vaporizer output? What can you do to mitigate this effect.
* **Inconsistency in maintaining alveolar pressure** of anesthetic vapors
## Footnote
Negate the pumping effect by maintain adequate flow rate and dial setting
78
What object in the anesthesia machine counters the pumping effect?
* Machine Outlet Check Valve
79
What are 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
80
Effects of rebreathing with high FGF
Effects of rebreathing with low FGF
* Little exhaled gas rebreathed
* Significant rebreathing with low FGF
81
Vaporizers are calculated at __________
* sea level (760 mmHg)
82
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
83
How does tipping affect vaporizer output?
* There will be an excessively high output due to liquid entering the bypass chamber
84
Vaporizer leaks can be caused by:
* Loose filler caps
* Drain valves
* Vaporizer/mounting bracket interface
85
What would be indicators of vaporizer leaks?
* Odor of gas
* Lower than expected inhaled concentration
86
What will be the patient consequence of a vaporizer leak?
* Patient awareness
87
What are vaporizer safety standards?
* Average concentrations +/- 20% of setting
* Gas may not pass through more than 1 vaporizer
* Output of vaporizer <0.05% in OFF
* All control knobs counterclockwise
* Filling levels displayed
* Can’t overfill when in use
88
What are the 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)
89
What prevents more than 1 vaporizer from being turned on at a time?
* Interlock Device
