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56 Cards in this Set
- Front
- Back
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Name the two largest manufactrues
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North american drager
Ohmeda |
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What is the basic functon of an anesthesia machine?
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To recieve compressed gases adn to create a gas mixture of known composisiton and flow rate
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What are the most important features of the vent?
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to be able to supply 1000 ml per 2 sec (common to maintain rr 10 I:E ratio of 1:2 and peak inspiratory flow rate of 30 m/min
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What are the 5 tasks of oxygen
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1) powers the ventilator driving gas
2)Provides pressure at the oxygen flush valve 3) Activation fo the low pressure alarm 4) Proceeding thru the second stage regulator to the flowmeters |
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Both gases are transported via breathing circuit to:
task of nitrous task of air |
anesthetize patient
air-sustain life |
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Where are the cylinders located?
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Manifold room-code is 2,3,4
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The central supply system for NO2
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NO2 is delivered to the hospital from H cylinders which are connected to a manifold
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what is psi of hospital pipeline?
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50 psi
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what are pressures of gas cylinders?
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O2 200 psi
NO2-745 psi (regulated to about 45 psi after enters machine |
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How much gas is delivered with the oxygen flush?
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delivers 35-75 L/Min
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what not to do with O2 flush valve
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Dont flush with mask on face to fill up bag
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What is the DISS?
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Diameter Index Safety System
Pipeline inlets are connected with DISS and are non interchangeable (connections are gas specific) |
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What problems can arise from pipeline sources
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1) particles, bacteria, viral, moisture, inadequate pressure, excessive pressures, and accidental crossover (switch btw O2 and some other gas such as NO2)
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What do you do if you loose Oxygen pipeline pressure
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1) Open emergency Oxygen cylinder fully (not just the three or four turns used for checking)
2) Disconnect the pipeline connection at the wall 3) why? something is wrong at the pipeline 4) ventilate by hadn rather than with the mechanical vent |
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What is the PISS?
what does it do? |
Pin index safety system
-prevents misconnection of a cylinder at the wrong yoke -Keeps cylinders closed, except when checking machine, or while in use -Each cylinder has a unique arrangement of pins -These pins match holes in the yoke where it attaches to the machine |
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What do valves consist of (spindle valve) made of bronze or brass
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body, port where gas exits, stem (shaft) closes valve by sealing against the seat, handle or handwheel (to open the valve), safety relief device, conical depression (opposite the port, it accepts the tip of the screw shich secures the cylinder in the yoke)
PISS pins |
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What is the function of the hanger yoke?
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-it orients cylinders
-provides a gas tight seal -ensures unidirectional flow |
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What is the function of the Check valve located within the hanger yoke?
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-Reduces the chance of transfilling or leakage (if yoke is empty)
-Allows change of cylinders during a case |
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Name three dif types of pressure relief valves:
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Fusible plug
Frangible disc Safety relief valve |
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How is the pressure from the E cylinder thru the yoke (750-2000psi) reduced
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1) a cylinder pressure regulater (first stage regulator)
converts high, variable cylinder pressure to a constant pressure of approx 45 psi. (-This is intent slightly lower than pipeline which prevents silent de;letion of cylinder contents if a cylinder is accidentally left open after machine check) 2) O2 NO2, and air have their own cylnider pressure guage 3) if two cylinders open at same time, the cylinder pressure gauge indicates press in teh higher pressure cylinder only |
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Name the E cylinder char
color, psi, capacity (L), piss O2 NO2 Air |
O2 green, 2000, 660, 2-5
NO2, blue, 745, 1590, 3-5 Air, yellow, 1900, 625, 1-5 |
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describe Cylinder contents and pressure
non liq gas liq gas |
Non liq gas: as content is released, pressure declines linearly and steadily ads the gas is used
-=Liquefied: pressure depends upon the vapor pressure of the liquefied gas Pressure not an indicaor of amnt of gas remaining as long as contents are partly in a liq phase |
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Name the three prs systems within the machine
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1) high press system (parts which recieve gas at cylinder pressure)
2) intermediate press system (receives gases at low, relatively constant pressures 3) Low pressure system |
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Describe the components of the high pressure system
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) high press system (parts which recieve gas at cylinder pressure
2) parts include=hanger yoke, yoke block (with check valves), cylinder presssure gauge, cylinder pressure regulators |
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Describe components of the intermediate pressure system
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Recieves gases at low, relatively constant pressures (37-55 psi=pipeline pressure)
-Pipeline inlets and pressure guages -ventilator power inlet -Oxygen pressure-failure device (fail safe) and alarm -flowmeter valves -oxygen second-stage regulator -oxygen flush valve |
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Describe the oxygen pressure failure device
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-a fail safe valve is controlled by oxygen pressure
-it shuts off or proportionally decreases and'or interupts the supply of nitrous oxide or air if the oxygen supply press decreases below 12-30psi |
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where is the oxygen pressure failure device sensor placed?
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in-line between the NO2 supply and the NO2 flowmeter
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What are the differences btw ohmeda vs drager fail safe systems?
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Ohmeda=all or none priciple, when oxygen supply pressure falls below 20-25 pse, flow of all other gases to their flowmeters is interrupted
Drager=called an oxygen falure protection device OFPD as oxygen supply pressure falls, OFPD proportrionaltey reduces supply press of all other gases. If O2 falls completely, the nitrious flow stops |
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Name and describe a secondary fail safe system in the Ohmeda machine
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second-stage O2 pressure regulator
regulates flow to flowmeters at 14 psi (ensures O2 flow until supply press less than 12-16 psi (all other gas flows stop at 20-25 psi |
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Name and describe a secondary fail safe system in the Drager machine
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Drager uses the oxygen ratio monitor controller (ORMC)
=OFPD proportional decreaes prsure of all other gases, then the ORMC shuts off teh NO2 control valve when O2 pressure decreases below 10 psi |
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Does the fail safe system prevent hypoxic mixtures?
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no, because it detects pressure not flow so it doesnt know which gas it is.
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What does prevent hypoxic mixture
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they hypoxic guard system
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In which cases does the hypoxic guard system prevent Hypoxic mixtures?
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-disconnects
-low O2 pressure in the pipeline -depletion of O2 cylinders |
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What detects O2 flow and where is it positioned?
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The oxygen analyzer is always positioned at the inspiratory limb
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Describe the oxygen flush valve
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-can be used when machine is off
-delivers 100%O2 at 35-75 L/min -Button is recessed and protected by a rim -Bypasses the vaporizers -dilutes inhaled agents |
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What makes up the low pressure system?
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-anything downstream of teh flowmeters
(vaporizers, common gas outlet, flowmeters) |
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Describe the flowmeters
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thorpe tubes-variable orifice (flow tube is tapered)
-Constant pressure -specifice for each gas -contains a ball or bobbin -at low flows, the gas viscosity is used to measure flows (poiseulles law) -at high flows, gas density is used (grahms law) |
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List the four flowmeter safety devices
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1) flowmeter sequence
2) minimum flow rate 3) characteristics of flow control knobs 4) mimimum oxygen ratio divice can turn o2 off and you will still have 0.15 flow |
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Describe the normal flowmeter sequence
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Normal gas flow is from left to right with oxygen located downstream of all other gases
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why is O2 downstream
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because if there is a leak in the system, upstream, it will result in the loss of NO2 instead of O2
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Name some other safety devices related to flowmeters
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Minimum flow rate: an oxygen flow cannot be completely discontinued, it is pre-set by manufacturer
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Safety devices on teh Ohmeda related to flowmeter
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valve stop that ensures a minimum flow of 200-300 ml/min
(drager we see .15L/min |
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Describe the Ohmeda hypoxic guard system
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(minimim oxygen ratio device) link-25-proportion limiting control system
-mechanically integrating of O2 and NO2 control valves -14 tooth sprocket is attached to the NO2 flow control valve -28 tooth sprocket attached to the O2 flow control vavle -a chain physically links the sprockets -when you increase the NO2 flow, you automatically increase the O2 flow also maintains at least 25% O2 conc or 3:1 flow |
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what is the difference between the drager and the Ohmeda hypoxic guard systems?
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Drager limits nitrous flow whereas teh Ohmeda increases O2 flow
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Describe the Drager hypoxic guard system
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ORMC-Oxygen ratio monitor controller
=pneumatic O2 and NO2 interlocking system maintains O2 conc of at least 25%, limits NO2 flow |
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When would hypoxic guard systems allow for hypoxic breathing?
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-wrong supply gas in O2 pipeline or cylinder
-defective pneumatic or mechanical components -leaks exist downstream of flow control valves -if third inert gas (such as helium) is used. |
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WHAT WILL INFORM YOU OF A CROSSOVER OR A NONOXYGEN GAS IN THE OXYGEN PIPELINE?
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THE O2 ANALYZER!!!
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Define a vapor
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gas phase of a substance that is liquid at room temp and atmospheric pressure
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Define vaporizaton
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conversion of a liquid to a gas (inside the vaporizer)
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What determines vaporization?
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-vapor pressure of the agent
-Temperature of the environment -Amount of carrier gas (NO2, & O2) used |
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What is the definition of a vaporizer?
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=the anesthetic vaporizer changes stored liquid anesthetic into anesthetic vapor. Thwe gas leaving the vaporizer contains a carefully controlled quantitiy of the anesthetic vapor
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List and define the 5 characteristics of vaporizers
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1) agent specific=calibrated for a single agent uses keyed fillers that decrease the likelihood of filling with the wrong agent
2) variable bypass=fresh gas flow consists of a carrier(flows over the liq agent) and a bypass gas (does not enter chamber) 3) flow-over= carrier gas flows over the surface of the liq volatile agent in the vaporizing chamber 4) Temp compensated=equipped with an automatic device that ensures a steady vaporizer output over a wide range of ambient temperatures 5) Out of circuit=vaporizers are located out of the system, own flowmeter, own connections to the system |
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Define thermocompensation
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Vaporization causes heat to be lost
-decreased temp decreases vapor pressure -To prevent fluctuations n vaporizor output owing to temp changes, compensatory mech built in -use of a valve that changes flow through vaporizer based on temp (temp compensating bypass) |
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What characteristics increase area that carrier gas flows over (gas-liq interface)
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baffles or wicks
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What allows only one vaporizer at a time to be open
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Vaporizer interlocking system
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Describe the Des vaporizer
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Tec 6
-differs in that it actively heats (39C) and pressurizes the liq agent -the vaporizer is a gas/vapor blender rather than a variable bypass. (heat produces vapor which is injected into the fresh gas flow) Des VP is 680 torr at room temp which is close to ATM -there are electronic alarms for low agent, no agent, and low batt |
