1. Breathing Systems
Tom Williams

2. Ideal Properties of Breathing Systems
Simple & Safe to use
Delivers the intended inspired gas mix
Permits SV & IPPV of all age groups
Efficient (low fresh gas flow)
Prevents barotrauma
Sturdy, compact & light
Easy removal of waste gases
Easy to maintain with minimal running costs

3. Components of Breathing systems
FGF
Tubing
Pressure Relief Valve / APL
Bag / Reservoir
Soda lime
One way valves
Connection to patient

4. Many Configurations No Soda Lime Soda Lime Uni Non-Rebreathing
Circle System Bi
a) Afferent reservoir systems.
Mapleson A, B & C
Lack’s system.
b) Enclosed afferent reservoir systems
Miller’s (1988)
c) Efferent reservoir systems
Mapleson D, E & F
Bain’s system
d) Combined systems
Humphrey ADE
Waters Canister

5. Mapleson Classification
Described by Mapleson in 1954
Review of systems in use at the time
Mapleson F more recently described

6. Mapleson A AKA Magill System Tube Volume > Tidal Volume (550mls)
Efficient for SV with FGF = AV
Inefficient for IPPV (3 x AV)
Lack System moves APL back towards bag (coaxial)

7. Mapleson B & C Not often used in current practice
Inefficient during SV & IPPV
B is more efficient than A during IPPV
Compact & light weight

8. Mapleson D AKA Bain System (coaxial)
Fresh gas flows through inner tube
Not efficient for SV (2 x MV)
More efficient with IPPV with long expiratory pause
Light at the patient end

9. Mapleson E & F AKA Ayre’s T-piece +/- Jackson-Rees Bag
Paediatric practice (weight < 20kg)
Not efficient (2 x MV)
Valveless, minimal resistance to SV

10. Enclosed afferent reservoir system
Mapleson A within a box
Efficient for both SV & IPPV
Complicated
Not often mentioned

11. Humphrey ADE circuit
Combines the Mapleson A, D & E systems with a switch to select the mode
Efficient in both SV & IPPV
Suitable for both adult & paeds
Increased complexity

12. Circle System
Requires unidirectional valves, APL valve, reservoir bag, gas analyzers & soda lime
Recycles exhaled gas - very efficient
Can be closed, normally semi-closed
Needs to be flushed prior to N2O use
High resistance to breathing during SV

13. Problems with Soda Lime
Corrosive
CO can be produced (enflurane/isoflurane & dry soda lime)
Compound A can be produced (sevoflurane and warm soda lime)
New designs of soda lime reduce problems

14. Waters Canister AKA to-and-fro system
Mapleson C with a soda lime canister between the APL valve and the reservoir
Increasing dead space as granules near the patient are exhausted first
Risk of inhaling soda lime
Not currently widely used

15. Non-Rebreathing Systems
No mixing of fresh and expired gas
Rely on unidirectional valves
Require a minimum of 1 x MV
Inspiratory & expiratory valves often coupled to allow IPPV
Risk of barotrauma at high gas flows

16. Any Questions? No Soda Lime Soda Lime Uni Non-Rebreathing
Circle System Bi
a) Afferent reservoir systems.
Mapleson A, B & C
Lack’s system.
b) Enclosed afferent reservoir systems
Miller’s (1988)
c) Efferent reservoir systems
Mapleson D, E & F
Bain’s system
d) Combined systems
Humphrey ADE
Waters Canister