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Principles of Science BVetMed 3 > Anaesthetic equipment > Flashcards

Flashcards in Anaesthetic equipment Deck (63)
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What gas can be supplied? 3

Oxygen, NO and medical air


What is the 'PISS' system?

Pin-index safety system on E-sized cylinders (ensures safety of pressurised gas). There is a washer (the Bodok seal) between the cylinder and the yoke.


Describe an oxygen cylinder

(Black) or white cylinder
White top
137 bar (13700kPa)
guage pressure indicates volume left in cylinder


What is a blue cylinder?

NO gas
4.4 bar (4400kPa)
Guage pressure does NOT indicate volume left
Weigh cylinder
Gas present (L) = ((net-tare) weight (g) * 22.4)/44


Define MHRA

Medicines and Healthcare products Regulatory Agency


Describe a medical grade air cylinder

Grey cylinder
Black/white quarters on top
Supply pressure depends on use
Advanced surgeries
Mostly N, less O2.


Why use medical gas pipelines?

(Gas supplied from source outside building)
Safer and more economical


What are the terminal units of medical gas pipelines called?

Schrader valves. Terminal units are colour coded like the cylinders. These are non-interchangeable. Hoses connecting valves to the anaesthetic machine are colour coded.


What is an oxygen concentrator ?

extracts oxygen from the air but needs a source of electricity. Max. O2 concentration is 95%. Smaller practices usually.


What does an anaesthetic machine consist of?

Gas supply
Pressure gauges
Pressure regulators
Other features (emergency O2 flush, common gas outlet)


What does a pressure regulator do?

decreases pressure from the cylinder to be used in the patient.


Describe pressure guages

For O2 - this indicates amount left in cylinder
For NO - need to weigh cylinder


What do pressure regulators/reducing valves do?

Reduce cylinder pressure to a safer level (around 4 bar)
Keep pressure constant
Positioned between cylinder and machine


What do flowmeters do?

- Measure flow rates of gases (indicated by a bobbin or ball bearing floating in a transparent glass or plastic tube. Read flow rate on the top of the bobbin or the middle of the ball bearing)
- Calibrated for a single gas
- Flow controlled by turning a knob on front of flowmeter
- Knobs are colour-coded for each gas


What do low oxygen pressure alarms do?

whistle either powered by low pressure oxygen or NO cylinder


What does the emergency oxygen flush do?

The O2 flush valve enables high flow of O2, bypassing the 'back bar' (therefore usually bypassing the vaporiser)


What is a pressure relief valve for?

so that if something blocks the outlet, the pressure does not rise so far that the machine comes apart.


What do compressed oxygen outlets do?

drive the ventilator (not electricity)


What do vaporisers do?

vaporise liquid (volatile) anaesthetics
Deliver known concentrations of anaesthetic
Calibrated for one agent only
Accurate over a range of temperatures and flows


What affects administration through a vaporiser?

Flow through the vaporising chamber
Efficiency of vaporisation
Gas flow rate
Carrier gas composition


What is isoflurane TEC 3?

Agent specific filling (Fraser Sweatman pin safety system, prevents mixing of agents within the vaporiser)
Must not be tipped over (uncontrolled output of anaesthetic agent may result)


What is TEC4?

Similar to TEC3 but...has an anti-spill feature and an interlock facility (to prevent 2 vaporisers being used simultaneously)


What is a penlon vaporiser?

More modern. Currently manufactured for isoflurane/sevoflurane
- Temperature compensated
- High resistance
- Agent specific
- Flow compensated
- Back pressure compensated
- Wick: cartridge design for easy cleaning


Aims - Fraser Sweatman safety system - 2

To reduce spillage of volatile agents and prevent mixing of 2 agents inside a vaporiser.


What do sevoflurane bottles do?

They plug directly into the vaporiser and this eliminates spillage.


What is an APL valve?

Adjustable Pressure Limiting Valve - most breathing systems have this


List types of scavenging system - 3

Activated charcoal absorbers
Passive and active scavenging systems


Features - activated charcoal absorbers

Must be replaced every 12 hours
Don't absorb NO
Gas is adsorbed onto the charcoal


How do active and passive scavenging systems work?

waste gases ducted out of window, pipe or extractor fan to outside. Pollution of atmosphere. Active systems connect to vacuum. Air brake MUST be utilised.

ACTIVE: pumped away int the atmosphere, need an 'air brake' to limit suction.


How are anaesthetic breathing systems classified?

Usually classified by how they eliminate CO2 from expired gas:

NON-rebreathing system
Rebreathing system

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