Term
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Definition
-pure gas under P -volume and P related i.e. contents of cylinder proportional gas P ~135atm |
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Term
Nitrous oxide (N2O) cylinders |
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Definition
-gas compressed to liquid -requires E for liquid to boil to produce gas -contents of cylinder NOT proportional to gas P ~44atm |
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Term
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Definition
indicate P and so content of cylinders of compressed gas NB: not N2O! |
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Term
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Definition
only way to accurate idea of contents is to turn it off and wigh the cylinder |
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Term
How are cylinders connected to the anaesthetic machine? |
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Definition
valve of cylinder
yoke of anaesthetic machine |
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Term
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Definition
Ensures incorrect gas cylinder can not be placed in yoke of anaesthetic machine indents/ holes in neck of valve of cylinder ... correspond with... pins of yolk of anaesthetic machine |
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Term
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Definition
prevents leaks between cylinder valve and yoke |
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Term
Oil or grease use as a seal |
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Definition
NEVER use oil or grease as a seal - if there is a leak between the cylinder and the yoke a fire will occur |
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Term
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Definition
provides a constant pressure to ensure a steady flow of gas is delivered to the patient (until the cylinder P falls below the output P) -connected to yoke of anaesthetic machine |
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Term
How does pressure regulator work? |
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Definition
-uses an internal "diaphragm" -has a safety valve which releases gas into the environment in case the diaphragm fails (which would result in high P gas being delievered to the patient) |
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Term
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Definition
gas from the regulator to the patient passes over a one-way check valve -prevents the reverse flow of gas back through the regulator -important im preventing loss of gas when cylinders are changed on the anaesthetic machine |
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Term
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Definition
aka needle valve -controls the flow of gas passing through the rotameter/flowmeter and hence to the vaporiser and patient -gas from the cylinder passes through this after the check valve |
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Term
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Definition
measures the flow rate of gas in a closed tube
-bobbin within the tube rotates - measure flow of gas from the top of the bobbin |
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Term
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Definition
for the admin of volatile agent (e.g. isoflurane) to the gas |
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Term
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Definition
indicates the percentage of FGF that is diverted to "pick up" saturated vapour e.g. 1% isoflurane = 1% of FGF to be delivered to the patient is saturated w. iso. vapour |
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Term
why must vaporisers be kept upright? |
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Definition
-if tipped the volatile agent may get into the mixing chamber and may result in a lethal conc. of anaesthetic agent being delieverd to the patient |
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Term
high pressure relief valve |
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Definition
gas passes through this after the vaporiser -protects the anaesthetic machine from excess P which may occur is the flow of gas from the machine is restricted NB: not to protect the patient! |
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Term
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Definition
the connection between the anaesthetic machine and the patient |
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Term
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Definition
-ratio regulator -nitrous oxide cut off -alarm whistles NB: not all devices are fitted to all machines |
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Term
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Definition
ensures the proportion of oxygen delivered to the patient is greater than the minimum conc. set (usually 28-35%)
e.g. N2O turned on before O2 flow - O2 flow will automatically be turned on at set min. conc.
-provides a hypoxic guard so patients always receive O2 at safe conc. and so prevent hypoxia |
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Term
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Definition
stope the flow of N2O to the flow control valve in the event of lost supply of O2 to the anaes. machine NB: does not prevent patient receiving hypoxic mixture |
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Term
How does the nitrous oxide cut off system work? |
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Definition
-normally the O2 P pushes a plunger up and out of the flow of N2O so the N2O flow can pass -w/o O2 flow, the plunger is released and blocks the passages of N2O flow |
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Term
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Definition
-activated when P of O2 pipes of anaes. machine reaches a certian preset P -usually powered by a small cylinder of O2 that is charged when the main cylinder is turned on or the pipeline is connected - when activated the gas in the alarm cylinder is released through a whistle |
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Term
Sequence of components of anaesthetic machine |
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Definition
Both O2 and N20: gas cylinder -->pressure regulator --> check valve (O2 cylinder has whistle alarm system attached) (N2O then passes through nitrous cut off valve) Both independently--> flow meter control valve and flowmeter Flow lines combine -->vaporiser --> high P relief valve -->common gas outlet |
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