Anaesthetic equipment Flashcards
What are the components to an aesthetic machine?
Oxygen supply Flow meter Vaporiser Breathing circuit Scavenging system
The flow meter has an emergency bypass valve. What is this for?
Bypass anaesthia
Deliver just O2
What does the vaporiser do?
Mix and vaporiser the correct ratio of O2:anaesthesia
What is the scavenging system for?
Removing exhaled gases (anaesthetic and vapour)
from the environment
Induction agents are usually IV. How long does this last? What does it give you time to do?
Short - 30 secs
Intubate and set up maintenance agent
What is the maintenance agent?
Gas
Volatile liquid
Maintains anaesthesia
Why are maintenance agents safer than IV agents?
IV require metabolism by liver to deactivate
Inhalation deactivate as soon as stop being delivered
What are the advantages and disadvantages of a rebreathing system?
Large patients (>25kg) as high resistance Economical as requires less gases
What do you have attached to a rebreathing circuit? What does it do?
Soda lime canister
Removes CO2
Goes pink to white, or white to pink - need replacing
What are the 5 main components to a breathing circuit?
Adapter Expiratory valve (adjusts pressure) Expired gas tube (white) Fresh gas tube (green) Reservoir bag (Soda lime canister)
What does the adapter do?
Connect ET tube to breathing circuit
What is the function of the reservoir bag?
Check patient is breathing
Do IPPV if needed
The rebreathing system only requires a small top up of O2. How much gas is expired per minute? How many litres are requsaired per minute until anaesthesia is stable, and for maintenance?
10-50mls/kg/min of expired gas
2-3 litres/min until stable
0.5-1 litres maintenance
Minute volume = volume of gas expired per minute. This is approximately…
200mls/kg/min
Gas flow rate must exceed minute volume to prevent rebreathing of expired gas. How efficient, and therefore how much does minute volume need to be multiplied for per circuit?
Mapleson A = high efficiency 1x minute volume
Mapleson D = medium efficiency, 2-2.5x minute volume
Mapleson E = low efficiency, 2.5-3x minute volume
What are the consequences of having a flow rate higher than needed?
Wasteful
Fresh gas expelled
What are the consequences of having a flow rate slightly lower than needed? Is this accpetable?
Acceptable
Warmer than fresh gas
What are the consequences of having a flow rate too low?
Dangerous!
Inhale CO2 –> hypercapnic
What is Mapleson A and the modification of Mapleson A called?
A = Magill Modification = parallel lack
Mapleson D doesn’t have an alternative name. What is the name of the Mapleson D modification?
Coaxial Bain
What is Mapleson E called? What does it lack? How does this affect E’s resistance?
Ayre’s T piece
No reservoir bag
Low resistance
What is Mapleson F?
What is the difference between Mapleson E and F?
Jackson-Rees
Same as E but with reservoir bag
The Magill breathing circuit only has what parts to the breathing circuit?
Expiratory valve Reservoir bag Fresh gas tube Adapter No expired tube
If wanting to do IPPV, what do you need to do first?
Shut off expiratory valve and turn anaesthetic off
Difficult if far away
