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NU 568

Exam 2 - Anesthesia Machine - Lecture 1

What comprehensive model is useful in the understanding of the components of the anesthesia machine? Supply Processing Delivery Disposal model (SPDD)
What does the SPDD model follow? The path of gas and how it is supplied to and ultimately disposed from the anesthesia machine
What is the ultimate destination for all gases? scavenger system
What is the most essential delivered gas in the SPDD model? oxygen
Name the 10 ways gases can be delivered to the AM. (Pipeline, wall outlets, connecting valves/hoses, filter and check valves, pressure gauges) and [cylinders, hanger yokes (yoke block), filters and check valves, pressure gauge, pressure regulators]
What are 4 potential hazards associated with the AM? dis- or mis-connect, loss of supply, contamination, theft of gases
How is oxygen produced in preparation for hospital use? Fractional distillation of liquid air
Oxygen is delivered to and stored at facilities at what temperature? -184 degrees celsius
Liquid O2 is converted to a gas and delivered via hospital pipelines at what psi? 50
Liquid O2 is converted to a gas and delivered via hospital pipelines at what kPa? 344
What does ASME stand for? American Society of Mechanical Engineers
Which organization regulates hospital pipelines? ASME
What are the 3 regulating bodies related to medical gases? DOT, ASTM F1850, FDA
What is the role of the DOT? Manufacturing, handling, transport, storage, and disposal of gas cylinders
What is the role of the ASTM F1850? Monitors anesthesia machines and their components
What is the role of the FDA? Regulates the purity of medical gases
What are hospital pipelines made of? copper
What organization sets the standards for the copper content in pipelines? NFPA
What does NFPA stand for? National Fire Protection Association
What does the NFPA require in regards to hospital pipelines? Seamless or standard weight copper with copper tubing being thoroughly cleaned and dried prior to installation
How often are pipelines labeled? Every 20 ft
How often are pipelines inspected? Every 5 years
Which organization inspects and certifies hospital pipelines? NITC
What does NITC stand for? National Inspection Testing Certification
What chemical is used to blow pipelines free of foreign matter? Oil-free dry nitrogen
Describe the Pipeline Purge Test. High intermittent purging into a white cloth is performed until there is no more discoloration to the fabric (prevents dirt and debris from coming out of the system)
What is the Standing Pressure Test? The pipeline is exposed to 24hrs of pressure at 20% above working pressure and monitored for leaks
What are 3 advantages of pipeline delivery of gases? 1) cheaper (stores large quantities) 2)less dangerous than cylinders (gas stored at lower pressures) 3)convenient (vs. constant cylinder changing)
At what psi is gas delivered to a hospital from central supply? 55 psi
How does the SPDD model organize the AM? Based on how the components are used
What are the 3 pressure systems in the AM? High, medium, low
The high pressure components in the AM are all related to what item? The cylinder
What are the components of the high-pressure system? (4) Hanger yoke, yoke block w/check valves, cylinder pressure gauge, cylinder pressure regulators
What are the intermediate pressure components of the AM? (6) 1)Pipeline inlet, check valves, press. gauges 2)ventilator power inlet 3)O2 pressure-failure devices 4)flowmeter valve 5)O2 2nd-stage regulator 6)flush valve
At what pressure is gas delivered via the intermediate pressure pipeline inlet? 55 psi
What is the function of the O2 2nd stage regulator? Reduce pressure going into the AM
What intermediate component directly reduces pressure going into the anesthesia machine and how much does it reduce psi? O2 2nd-stage regulator, 16 psi
The intermediate pressure system is exposed to ________ pressures. Pipeline
The high pressure system is exposed to _______ pressures. Cylinder
What are the low pressure components of the AM? (4) 1)flowmeter tubes 2)vaporizers 3)check valves (if present) 4)common gas outlet
Where are the low pressure components of the AM located? Distal to the flowmeter needle valve
What safety feature prevents the delivery of a hypoxic NO2-O2 mixture? Proportioning system
What do Proportioning Systems prevent? Hypoxic delivery of gases
All medical gas systems are required to have what safety feature? Shut-off valve
Where are shutoff valves located? Throughout the hospital, both main and partial areas
What is the purpose of a gas shutoff valve? Isolate sections of the hospital where there may be a gas leak, interrupt gas supply in case of fire, allow for repairs
Shutoff valves are contained behind a ______________ and have a _________ in the center to allow for easy removal. glass window, ring/handle
How far does the handle have to be turned to shut off gas flow from a shut-off valve? 1 quarter turn
Where is the manual shut off lever located in surgery? Outside of the operating room suite
What are wall outlets or and gas hoses dropped from the operating room ceiling finished with? Quick connect couplers
What do quick connect couplers allow for? Tool-less connection of the AM to the wall outlet via AM supply hoses
What is a drawback to quick connect couplers and why? Common source of leaks b/c attachment is not as secure vs. wrench tightened connections
What is a benefit of gas delivery from a wall outlet? Simple design
What is a disadvantage of gas delivery from a wall outlet? Hoses laying on the floor pose as a hazard
Besides wall outlets, where else can gas delivery outlets be found? Swing boom (beam) and rigid columns
What are two advantages of having swing boom and rigid column gas outlets? Inexpensive, reduces clutter
What does DISS stand for and what is its function? Diameter Index Safety System. Makes cross-connection/mis-connection between nitrous and O2 more difficult
How does the DISS system work? Gas piping connections for N20 and O2 are sized and threaded differently
What do supply hoses connect? Pipeline inlets on the back of the machine to wall outlets
What are 3 safety features located at the pipeline inlet? Filter, check valve, pressure gauge
What is the function of a check valve? Ensure unidirectional flow of gas
What is the function of the pipeline inlet filter? Helps prevent damage to the machine from particulate matter in the pipeline gas supply
What does ASTM stand for? American Society for Testing and Materials
The standard specifications for anesthesia workstations and their components is written in __________________. ASTM F1850
What is the European equivalent of the ASTM F1850? EN740
Filters at the pipeline inlet of an AM are required by the _____________. ASTM F1850
What are 6 possible problems associated with pipeline supply? 1)pressure loss 2)cross-connection 3)contamination 4)excessive pressure 5)leaks 6)theft
The theft of anesthetic gas occurs primarily with _____________. nitrous oxide
Where would loss of pipeline pressure be indicated? Pipeline pressure gauge
The pipeline pressure gauge is also known as the ___________. Bourdon gauge
An O2 low pressure alarm will sound if O2 pressure falls below what level? 30mmHg
What will happen if O2 pressure falls below 30mmHg? An O2 low pressure alarm will sound and the fail safe valve will halt the delivery of all other gases
What is the difference between older and newer anesthesia machines in reference to the O2 low pressure alarm? The alarm will sound when pressure is <30mmHg for older machines, <37mmHg for newer machines
What will drive the machine bellows in the event of an oxygen pressure loss? Air
What are 4 goals to achieve in the event of an oxygen pressure loss? Maintain oxygenation, ventilation, depth of anesthesia, ensure the safety of the O2 supply
What steps are taken in the event of a pressure loss alarm? 1)Maximally open the E cylinder tank, disconnect the pipeline, consider low FGF and manual ventilation to conserve emergency supply
Why is the E cylinder maximally opened in an O2 pressure loss scenario? If it is not maximally opened, flow may end before the cylinder is completely empty
Why is the pipeline disconnected in an O2 pressure loss scenario? Prevents retrograde flow from the machine to the pipeline
In an O2 pressure loss scenario, the patient is ventilated through what system? Manually through the circle system (ventilator off)
When should a patient be reconnected to the pipeline supply after an O2 pressure loss scenario? Only after the gas supply has been tested
If unable to use the circle system to ventilate in an O2 pressure loss scenario, how can the patient be ventilated? With O2 from a free-standing cylinder or with RA via mask
If unable to use the circle system for ventilation, how is depth of anesthesia maintained? TIVA
Excessive pipeline pressures (will/will not) trigger alarms in the anesthesia machine. will not
The FiO2 at 1L/min of oxygen and at 10L/min of oxygen is (different/identical). Identical -- it is 100% at both rates of delivery
In the event of an oxygen pressure loss, what should be done to fix the gas analyzer? Nothing--the oxygen analyzer should be trusted until proven wrong
What needs to be accounted for when utilizing a VAA to maintain anesthesia in an O2 pressure loss scenario? Need to maintain appropriate FiO2-to-agent concentration while utilizing low-flow from the cylinder
Besides an appropriate VAA-to-oxygen concentration, what else should be calculated and what action should be taken in an O2 pressure loss scenario? Calculate the time remaining before the current cylinder is empty and call for backup cylinders
After turning on an E cylinder in an O2 pressure loss alarm, what should the anesthetist see a rise in? Fraction of inspired oxygen
Before using an anesthesia machine, the anesthetist should always check for what two things? Alternate ventilating device (BMV) and presence of a full E cylinder
Why do older ventilators deplete O2 from E cylinders faster than newer machines? Older ventilators use oxygen to compress the bellows
Why are supply lines disconnected in the event of an O2 pressure loss? Precautionary measure against simultaneous failure of check valves
What safety measure is ensured with disconnection of supply lines during an O2 pressure loss with simultaneous failure of check valves? Prevents retrograde gas flow back to supply lines
Where can cross-connection errors occur? Anywhere in the system, from the liquid oxygen supply, to wall outlets, to the internal circuitry of the AM
A fatality related cross-connection error has been reported as recently ___________. 2002
What is a common factor associated with patient injury in relation to cross-connection errors? Failure to utilize a gas analyzer
What is the most common cross-connect error? N20 connected into O2
What is the benefit of a gas analyzer in the case of a cross-connection? Detects declining concentrations of oxygen if misconnected with nitrous oxide
What should be done in the event of a cross-connect, what actions should be performed? Maximally open the E cylinder and disconnect the pipeline hoses
The cross connection of nitrous into the O2 inlet would lead to _____________ hypoxia if used during an anesthetic case. diffusion
What is the purpose of the scavenger system? Dispose of anesthetic waste
What is the purpose of having cylinders on the anesthesia machine? Reserves for emergency use
When should cylinders be opened? Upon checking and when the pipeline supply is unavailable
At least one cylinder on the AM should have a PSI of ______________. 1000
What is the most fragile part of a cylinder? cylinder valve
What are cylinders made of? 1/4" steel
What are MRI safe cylinders made of? aluminum
Cylinders are _____________, ____________, and ______________. Labeled, marked, color coded
True/False: Cylinders are identified by the same international standards. False--service and color may vary
Name the 8 different identifiers on a cylinder tank: 1)cylinder specification 2)cylinder serial number 3)date of manufacture 4)neck ring markings 5)retest markings 6)barcode label 7)manufacturers inspection markings 8)cylinder tare
What does tare weight refer to? The empty weight of a cylinder
What are the 3 parts of a cylinder specification? DOT, cylinder material, service or working pressure in PSI
What do neck ring markings indicate? The original owner
What is the purpose of the barcode label on a gas cylinder? Tracking, also identifies the cylinder content (i.e. liquid o2 = "LOX")
What does PISS stand for and what is its purpose? Pin Index Safety System, prevents misconnections of cylinders by using a proprietary arrangement of pins that line up with their corresponding yoke
The point where cylinders are attached to the anesthesia machine is called the ________. yoke
What are the PISS arrangements for air? Oxygen? Nitrogen? Air=1&5, Oxygen=2&5, Nitrogen=3
What are the means by which the PISS system can be defeated? Pins are missing or removed, use of >1 washer
What three things should an anesthetist check before replacing a cylinder? Pins, washers, cylinder size
In what measurement is the service pressure of a cylinder recorded? PSI
What is the service pressure of air? Oxygen? N2O? 1900, 1900, 745
What is the capacity of an air E cylinder? Oxygen? N2O? 625, 660, 1590
In the U.S., what is the E cylinder color for air? Oxygen? N2O? Yellow, green, blue
What is the most fragile part of a cylinder? valve
Where are the index pins located in regards to cylinder attachment? The yoke
The sealing washer on a cylinder valve connects to the ___________. Gas inlet on the yoke
What part of the cylinder must be protected during transport? Cylinder valve
What are the different parts of the cylinder valve? Body, gas exit port, conical depression, PISS pins, safety relief devices
Where are safety relief devices located and what is their function? Cylinder valve -- release cylinder contents in a controlled fashion in the event that cylinder pressures and temperatures increase (i.e. fire)
What are 3 different types of safety release devices on cylinders? frangible disk, valve that opens under extreme pressure, fusible plug made of Wood's metal
How does the frangible disk safety release device work? Bursts under pressure
How does the fusible plug, made of Wood's metal, on a safety release device work? Melts at elevated temperatures
What are the 3 functions of the hanger yoke? 1)orients the cylinder 2)gas tight seal 3)unidirectional flow
What are two important features of the E cylinder yoke and which one is a requirement by standard? filter and check valve, filter is required
What is the function of the yoke check valve? Minimizes the likelihood of transfilling or leakage of contents to the atmosphere (if a yoke is empty)
True/False: Cylinders cannot be replaced during use. False - check valves allow for changing during use
What is transfilling? The movement of gas from a cylinder of higher pressure into a cylinder of lower pressure if two cylinders on the AM are open
What is the potential hazard of transfilling? Fire hazard b/c filling a cylinder generates heat due to kinetic energy
What is the device immediately distal to the hanger yoke for each gas? Pressure regulator
What is the purpose of a pressure regulator? Convert cylinder pressure to a constant downstream pressure of 45 psi (40-48 psi on the AM quiz)
What is the reason that pressure regulators decrease gas flow to a level only slightly less than pipeline pressure? Prevents silent depletion of cylinder contents
Why should cylinders be closed after checking contents? The AM will not sound an alarm if pipeline pressure falls below 45 psi because it will draw O2 from the cylinder
What is working pressure for the AM? 45 psi
About how long will it take to deplete a full E cylinder if it is used to run the AM? 1 hour
Besides the DOT, what other industry advisory groups play a role in setting cylinder standards? Compressed Gas Association (CGA) and National Fire Protection Agency (NFPA)
What must the anesthetist be aware of in regards to the pressure in a gas cylinder? Gas under pressure has enormous potential energy which could be lethal if released in an uncontrolled fashion with cylinder valve damage
What are the first 3 suggestions for safe handling of E cylinders? 1. never stand cylinders upright without support 2. never leave empty cylinders on the machine 3. never leave the plastic cover on the port while installing the cylinder
Whare are the last 3 suggestions for safe handling of E cylinders? 4. never rely on cylinder color 5. never oil the valves 6. never remove the cylinder from the yoke without filling the space with a yoke plug if available
What purpose does a yoke plug serve? Backup strategy if the yoke check valve fails
What are the first 4 steps to install an E cylinder? 1)check the label 2)crack the valve 3)check for both PISS pins 4)check for only 1 washer
What are the last 3 steps to install an E cylinder? 5)place the cylinder in the hanger yoke 6)listen for an audible leak 7)check the pressure gauge
What is the purpose of cracking a cylinder valve prior to placement into the yoke? Removes dirt from the port
The port should always be pointed in what direction when cracked? Away from the operator and other personnel
What is the equation used to determine how much gas left in a used E cylinder? [Capacity(L)]/[Service pressure(psi)] = [Remaining capacity(L)]/[Gauge pressure(psi)]
How do you calculate how much time it will take to empty an E-cylinder when using manual ventilation with cylinder gas? Divide the remaining capacity in the cylinder by the flow rate at which you are running your case (L/min)
The purity of medical grade gases is set by what two regulating bodies? U.S. Pharmacopeia (USP) and FDA
What is significant about the service pressure of N2O? It will remain at 745 psi until the contents are almost completely empty
How much N2O has been used when the service pressure drops below 745 psi? Over 3/4
Removal of N2O above what flow rate is considered rapid removal? > 4L/min
What can happen with rapid removal of nitrous oxide from the cylinder? Formation of frost on the wall or cylinder valve freezing
Nitrous oxide (is/is not) flammable. is not
Nitrous oxide (does/does not) support combustion. does
What is the constituent breakdown of air? 78% nitrogen, 21% oxygen, 1% argon, 0.03% CO2, trace amounts other gases
Created by: philip.truong