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NU 568
Exam 2 - Anesthesia Machine - Lecture 1
| Question | Answer |
|---|---|
| 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
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