Anaesthetic Equipment

Question 1

What colour were/are oxygen cylinders?

Answer 1

past - black bodies white shoulders

now - white with name on side

Question 2

Which gas canisters will always read “full” on the guage unless empty? ie.no midway. How can you tell how much gas is left?

Answer 2

Nitrous Oxide

- weigh cylinder

Question 3

What does medical grade air consist of? What colour is the cylinder?

Answer 3

Nitrogen mainly

- grey cylinder, black white quarters on top

Question 4

What are the ends of pipelines called?

Answer 4

Schrader valves (colour coded like cylinders)

Question 5

What are the disadvantages of oxygen concentrators?

Answer 5

• also produce water, mix with anaesthetic agent and can cause probems
• need a source of electricity
• max o2 conc 95%

Question 6

What is the purpose of pressure regulators?

Answer 6

reduce cylinder pressure to safer level (4 bar) that wont explode animals lungs!

Question 7

What are flowmeters calibrated for?

Answer 7

Individual gases

Question 8

Which part of the bobbin or ball bearing is the flow rate read from?

Answer 8

centre of sphere, top of bullet

Question 9

What units are flowmeters measuring in?

Answer 9

l/min

Question 10

What does the emergency oxygen flush do?

Answer 10

Bypasses all pressureregulators etc. to purge system.. be careful!!

Question 11

What warning system is often in pace to prevent inadequate oxygen delivery?

Answer 11

Pressure alarm whistles - if pressure drops below a threshold then air will escape the storage area and whistle
- the storage area must be filled when anaesthetic machine turned on so will whistle at start too

Question 12

What are compressed O2 outlets for?

Answer 12

driving O2 powered ventilators at pressure

Question 13

What are the 2 types of vaporisers?

Answer 13

TEC 3 and TEC 4 (anti spill feature)

- calibrated for one agent only

Question 14

What environmental conditions must vaporisers account for?

Answer 14

temperature

- bimetallic strip regulates flow

Question 15

What scavenging systems are available?

Answer 15

> Passive
- dump outside window
- charcoal absorber (replace every 12 hours, doesnt do NO)
> Active
- Vacuum systems
- Need an air break to limit suction

Question 16

What are the 2 main types of breathing systmes?

Answer 16

> Non- rebreathing systems
- Magill, Lack, Bain, Ayre, Humphrey
Rebreathing systems
- circle, to and fro

Question 17

What is the Mapleson classifciation of breathing systems?

Answer 17

> functional classifcation A-E
- theoretical efficiency in fresh gas use
- fresh gas flow needed to prevent rebreathing expressed as a multiple of animals MINUTE VOLUME (tidal volume x resp rate)
= “circuit factor”

Question 18

Calculating minute volume? Estimating in practice? How is total gas flow calculated from this?

Answer 18

• 10-15ml/kg (higher in small animals) x RR
• 200ml/kg/min for all domestic animals
• gas flow = CF x MV

Question 19

What circuit factor does Magill have? What animals is this suitable for?

Answer 19

• 1-1.5 CF

- animals >10kg

Question 20

What type of circuit is the coaxial lack basically the same as? What animals is it suitable for? CF?

Answer 20

• Magill
• > 10kg
• 1-1.5

Question 21

What forms of parallell lack are available?

Answer 21

Standard animals >10kg

Mini animlas <10kg

Question 22

Which patients is a T piece best for? CF?

Answer 22

Small (no valves, low resistance)

CF 2.5-3

Question 23

What animals is a Bain suitable for? CF?

Answer 23

Animals >10kg (but uneconomical)
CF 2.5-3
- good for ventilating

Question 24

How is the breathing system tested before use?

Answer 24

• connect machine
• close APL valve
• cover pateint end iwth thumb
• oxygen flush to inflate reservoir bag
• watch for leaks
• open APL valve

Question 25

How are coaxial breathing systems checked?

Answer 25

• switch on O2 flow rate
• red stopper inserted
• if inner tube sealed, flow metre will drop
• if leaking, flow will remain constant

Question 26

What is a Humphrey ADE?

Answer 26

Mapleson A, D and E in one device

• lever up = parallell lack or magill
• lever down = bain

Question 27

Which machine have the vapouriser in circuit? Which are outside of circuit?

Answer 27

> in
- komersaroff
- stephens 
> out
- circle
- humphrey ADE
- to and fro

Question 28

What animals is a circle used for?

Answer 28

> 10kg

Question 29

How does use of rebreathing circuits differ to non-rebreating circuits?

Answer 29

• when connecting animal to system, use higher fresh gas flow initially for 10 mins (2-4l/min or 100ml/kg/min)
• flushes air out of system to prevent silution of anaesthetic

Question 30

What ratio of N2O:O2 should not be exceeded?

Answer 30

50:50

Question 31

When should CO2 absorbant be changed?

Answer 31

When half of it has changed colour

- be aware colour may change back over night - does NOT mean it is safe to use again!

Question 32

What may be produced by CO2 abdorbers?

Answer 32

carbon monoxide and compound a

Question 33

What basis do in circuit vapourisers work on?

Answer 33

Patient regulates own level of anaesthtic gas
- if get light, breathing ^, more gas inhaled, gets deeper
- if get deep, breathing v, less gas inhaled, gets lighter
> very economical!