2. INTRODUCTION
Breathing systems provide the final conduit for the
delivery of anaesthetic gases to the patient.
They link a patient to an anaesthesia machine
Traditional attempts to classify breathing systems
artificially consolidate functional aspects( e.g the extent of
rebreathing) with physical characteristics (e.g the
presence of unidirectional valves)
Terms like open, semiopen , semiclosed tend to result in
confusion rather than understanding.
3. Components include
Breathing tubes
Fresh gas inlet
Adjustable pressure limiting valve (APL)
Reservoir bag (Breathing bag)
Classified into
A
B
C
D
E
F
4. Mapleson
class
OTHER NAMES SPONTANOUS FGF
rate
CONTROLLED
FGF rate
A Magill
attachment
Equal to minute
ventilation(
80ml/kg/min)
Very high and
difficult to predict
B 2× minute ventilation 2-21/2 × minute
ventilation
C Waters’ to and
fro
2x minute ventilation 2-21/2 x minute
ventilation
D Bain circuit 2-3x minute ventilation 1-2 x minute vent.
E Ayre’s T –piece 2-3x minute ventilation 3x minute vent.
F Jackson- Rees
modification
2-3x minute ventilation 2x minute vent.
5. It combines mapleson A: efficient for
spontaneous ventilation with
Mapleson D: efficient for controlled ventilation
If no ventilator is attached to it and the port is
left open, the system will function as an Ayre’s
T piece
It work by movement of a lever on a metallic or
glass block called Humphrey block.
6. INSPIRATORY AND EXPIRATORY CORRUGATED
TUBES.
A Y-PIECE CONNECTOR.
AN OVERFLOW OR POP-OFF VALVE, REFERRED TO AS
THE ADJUSTABLE PRESSURE LIMITING (APL) VALVE.
A RESERVOIR BAG.
UNIDIRECTIONAL VALVES.
A CANNISTER CONTAINING A CARBONDIOXIDE
ABSORBENT
