Anaesthetic Breathing Systems Flashcards
What is a ‘Non-rebreathing system’? Can you give some examples?
Enough fresh gas flow is put in to prevent rebreathing, no expired gas is re-used. E.g. Lack, Magill, Bain, Ayre’s T-piece.
What is a ‘Rebreathing system’? Can you give some examples?
CO2 expired and removed usually by chemical means (usually soda-lime). If it has a cannister with granules its a REBEATHING. e.g. Circle, To and Fro.
What are the advantages of a non-rebreathing system?
Simple and cheap, Inspired gas composition known, low resistance to breathing, rapid anaesthesia depth change.
What are the disadvantages of a non-rebreathing systems?
High gas flow requried (if not enough, may rebreathe expired air), high volatile agent consumption, expired heat/moisture lost.
What are the advantages of a rebreathing system?
Lower fresh gas flows, don’t usually have to calculate just enough for metabolic needs, low volatile agent consumption, warm and humidified gas.
What are the disadvantages of a rebreathing system?
Exact composition of rebreathed gas unknown, expensive, slow depth change.
How do you calculate total gas flow needed?
Minute volume = Tidal volume (weight in kg x 10-15ml) x RR
Total fresh gas flow = MV x System Factor
What type of breathing system is a Magill? Where is the reservoir bag? What is the circuit factor of a Magill breathing system?
Non-rebreathing system, with reservoir on inspiratory limb. Circuit factor of 1-1.5 x
Is the Magill breathing system suitable for IPPV? What weight animals would you use a Magill system on?
Not a good choice for IPPV as it needs much higher flow rates. Suitable for animals >10kg.
What type of breathing system is a Lack? Where is the reservoir bag? What is the circuit factor of a Lack breathing system? What two types of lack can you get?
Non-rebreathing system, with reservoir on inspiratory limb. Circuit factor of 1-1.5 x. Can get coaxial (not used) or parallel lack.
Is the Lack breathing system suitable for IPPV? What weight animals would you use a Lack system on?
Not a good choice for IPPV as it needs much higher flow rates. Standard lack Suitable for animals >10kg, mini lack suitable for use on animals <10kg.
What type of breathing system is a Ayre’s T piece? Where is the reservoir bag? What is the circuit factor of a Ayre’s T piece breathing system? What variants can you get?
Non-rebreathing system, with reservoir on expiratory limb. Circuit factor of 2.5-3 x. Can get standard T piece, Jackson Ree’s T piece etc.
Is the Ayre’s T piece breathing system suitable for IPPV? What weight animals would you use a Ayre’s T piece breathing system on?
Good choice for IPPV as high flow rates. Low resistance so suitable for animals <10kg.
What type of breathing system is a Bain? Where is the reservoir bag? What is the circuit factor of a Bain breathing system? Is the bain parallel or coaxial?
Non-rebreathing system, with reservoir on expiratory limb. Circuit factor of 2.5-3 x. It is coaxial with the inspiratory tube on the inside.
Is the Bain breathing system suitable for IPPV? What weight animals would you use a Bain breathing system on?
Good choice for IPPV as high flow rates. Used on dogs over 10kg, however uneconomical in larger animals.
