190722_Gas Systems Flashcards
SOURCES OF GASES
Piped in Gas
E-Cylinders
DISS - PIPELINE
Diameter Index Safety System:
- Provides non-interchangeable connections for the medical gas lines
- Connection consists of a body, nipple, and nut combination
- Only properly mated parts will fit together and allow the threads to engage
- Required for every anesthesia machine
PISS - Cylinder
PIN INDEX SAFETY SYSTEM:
• Required for every anesthesia machine
• Uses a series of pins to connect associated gas cylinders valves with its matching yoke clamp
- Position of holes on the cylinder valves corresponds with the pins on the yoke attached to the equipment
- Each gas has a unique pin configuration
- Prevents connection of the wrong cylinder to a yoke
CO2 PISS
1,6
Helium US color code
Brown
Oxygen
2000-2200 psi
625-700 L
Air
1900-2000 psi
625 L
N2O*
745 psi
1590 L
*Full N2O cylinder would read pressure of 745 psi and have ~1590 liters and stored as a liquid. Pressure does NOT indicate amount left in tank
N2O*full weight
20.7 lbs
N2O*1/2 full weight
17.3 lbs
N2O*no liquid weight
14.2 lbs
N2O*empty weight
12.9 lbs
- Full tank 2200 psi, 650 liters
- Current tank: 750 psi, ??? Liters
Question: Figure out how many Liters you have left in the current tank. Then, if you are running 2 L/min flow, figure out how many minutes you have left to use before you run out. How many hours left?
Current tank volume = 650L/2200psi x 750 psi = 221.6L
Time remaining = 221.6L/(2L/min) = 110.8 min = 1.9 hrs
Purity of medical gases is specified in the
US Pharmacopoeia
Purity of medical gases is specified in the US Pharmacopoeia and enforced by the
FDA
The _______ establishes the requirements for manufacturing, filling, qualification, transportation, storage, handling, maintenance, re-qualification, and disposition of medical gas cylinders and containers.
DOT
CYLINDER MARKINGS
Permanent Markings: The DOT regulations require specific marking on each cylinder
CYLINDER LABELS
Labeling: Each cylinder must have a label or decal on the side or on the shoulder, but may not cover any permanent markings
CYLINDER TAGS
Tags: Full, In Use, Empty connected by perforations. Denotes the amount of cylinder contents and is not used for identification purposes.
Once opened tare off Full tag. Once empty tare off In Use tag.
SAFE HANDLING PROCEDURES FOR CYLINDERS
- Never stand a cylinder upright without support
- Never leave empty cylinders on the machine
- Never leave the plastic tape on the port while installing the cylinder
- Never rely only on the a cylinder’s color for identification of its contents
- Never oil valves
- Before any fitting is applied to the cylinder valve, particles of dust, metal shavings, and other foreign matter should be cleared from the outlet by slowly and briefly “cracking” the valve.
- The valve should always be fully open when a cylinder is in use.
Why is it important to “crack” the valve away from you and/or other personnel.
FIRE!!!! and exposure to pressure and gas
The valve should always be fully open when a cylinder is in use. Marginal opening may result in…….
failure to deliver adequate gas.
Vaporization is__________
Why is this important?
the conversion of liquid to a gas.
The inhalation agents we use today are liquids that must be converted to a vapor to be inhaled.
Anesthetic gases are also referred to as __________ because they are liquids that have a ___________ to vaporize into gas form.
“Volatile Agents”
high propensity
Vaporization is dependent on:
- Vapor pressures
- Temperature
- Amount of carrier gas used
Molecules of a volatile agent in a closed container are distributed between what phases?
liquid and gas
The gas molecules bombard the surface of the liquid and the walls of the container creating __________.
vapor pressure
VOLATILE AGENTS VAPOR PRESSURE:
Sevoflurane
160mmHg
Yellow
VOLATILE AGENTS VAPOR PRESSURE:
Enflurane
172mmHg
Orange
VOLATILE AGENTS VAPOR PRESSURE:
Isoflurane
240mmHg
Purple
VOLATILE AGENTS VAPOR PRESSURE:
Halothane
244mmHg
Red
VOLATILE AGENTS VAPOR PRESSURE:
Desflurane
669mmHg
Blue
VAPORIZATION OF LIQUIDS: Heat added
more molecules inter vapor phase (VP increase)
VAPORIZATION OF LIQUIDS: Cool
more molecules inter liquid phase (VP decrease)
Passing carrier gas over the liquid causes
shift toward vapor phase
heat of vaporization is supplied by remaining liquid, causing a drop in temperature
LATENT HEAT OF VAPORIZATION
Number of calories required to change 1 gram of liquid into vapor without a temperature change
*note 1g=1mL
The energy for vaporization comes from__________.
the liquid itself (or from an outside source)
In the absence of outside source of energy, the temp of liquid itself will _______ during vaporization… rate of vaporization will_______. We need some sort of system where temp of liquid……….
decrease
further decrease
remains constant
The number of calories required to increase the temperature of one gram of a substance by one degree centigrade is known as what?
SPECIFIC HEAT
• The substance can be liquid, solid or gas
A measure of speed with which heat flow through a substance is known as what?
THERMAL CONDUCTIVITY
The higher the thermal conductivity, the better the substance __________.
conducts heat
VAPORIZERS
- Agent Specific
- Temperature Compensated
- Variable Bypass
KISS
key index safety system
VARIABLE BYPASS VAPORIZER
- A portion of the gas flow will pass into the vaporizing chamber where it will become saturated with vapor.
- This vapor-laden portion then rejoins the gas flow for dilution to deliverable concentrations.
REVIEW SLIDES 29 and 30!!!
TEC 6 VAPORIZER
REVIEW SLIDES 31 and 32!!!
ALADIN CASSETTES
computer controlled variable bypass
COPPER KETTLE
- Measured flow, Bubble Through vaporizer
- Dedicated flowmeter for the kettle (MEASURED FLOW) • Gas comes up through central tube inside of the vaporizer to the LOVING CUP
- Flow of gas is then directed down toward the liquid (BUBBLE THROUGH)
- Highly concentrated vapor then exits the vaporizer and is
- Diluted into the fresh gas flow
COPPER KETTLE CALCULATIONS:
Vapor Output
Vapor Output = (CG x VP) / (BP – VP)
• Where CG is the flow rate of the carrier gas in lpm, VP is the vapor pressure of the anesthetic agent and BP is the Barometric pressure.
***CG is manipulated to produce desired vapor output
COPPER KETTLE CALCULATIONS:
Anesthetic Concentration
Anesthetic Concentration =
Vapor output in mL/min Total gas flow in ml/min
***Total gas flow is manipulated to produce desired concentration
ALTITUDE increase: EFFECT ON VAPORIZATION
Increased altitude – ↓ barometric pressure
ALTITUDE decrease: EFFECT ON VAPORIZATION
Decreased altitude – ↑ barometric pressure
The % delivered is relative to the ____ vapor pressure in comparison to the _______ pressure.
agent’s
barometric
• Vaporizer must be re-calibrated to assure accurate % delivered anesthetic gas
ALTITUDE: EFFECT ON VAPORIZATION calculated
2% agent @ STP (sea level) = 0.02 x 760mmHg = 15.2mmHg (VP agent)
X elevation ambient pressure = 380mmHg
15.2mmHg (VP agent) / 380mmHg = 0.04
= 4% agent at X elevation
POTENTIAL VAPORIZER HAZARDS
• Wrong Agent in the vaporizer ?????????? - High VP – Low VP – High Concentration - Low VP – High VP - Low Concentration • Contamination • Tipping • Overfilling • Simultaneous Administration of More than One Vapor • Leaks • Pumping Effect
Simultaneous Administration of More than One Vapor is avoided by……
the interlocking system.