The document discusses various paediatric breathing circuits used in anaesthesia. It describes the key components and classifications of breathing circuits. The most commonly used circuits include the Mapleson A (Magill) system, which is best for spontaneous breathing but requires high fresh gas flows. The Mapleson D and Bain circuits are efferent reservoir systems that work efficiently for controlled ventilation. The Ayre's T-piece is a simple no-valve circuit designed for paediatric use. The document provides details on the construction, functioning and advantages of these different breathing circuit designs.

1. PAEDIATRIC
BREATHING CIRCUIT’s

2. DEFINITION:
Assembly of components which
connects the patient’s airway to the
anaesthetic machine creating an
artificial atmosphere, from and into
which the patient breathes.
A breathing system converts continuous
flow from the machine to a intermittent
flow.

3. INTRODUCTION
Any resemblance to a breathing system was
developed by Barth (1907)
 The Mapleson A (Magill) system was
designed by Sir Ivan Magill in the 1930's
 In 1926 , Brian Sword introduced the circle
system
 Ayre’s T-piece was introduced in 1937
 Bain Circuit was introduced in 1972 by Bain
and Spoerel.


4. CRITERIA FOR IDEAL SYSTEM
ESSENTIAL:1.Delivery of gas from machine to the
alveoli in same concentration as set
and in shortest possible time
2.Effective elimination of CO2
3.Minimal dead space
4.Minimal resistance

5. DESIRABLE:1.Economy of fresh gas
2.Conservation of heat
3. Adequate humidification
4. Efficient during spontaneous and
controlled ventilation
5. Efficient for adult, pediatrics and
with mechanical ventilators
6. Light weight
7. Less theater pollution
8. Convenient during use.

6. COMPONENTS
1.Bushings(mount)
2.Sleeves
3.Connectors & Adaptors
4.FGF inlet
5.Breathing tube
6.Reservoir Bag
7.Valve’s
8.Filters
9.CO2 absorber

7. CLASSIFICATION OF BREATHING
SYSTEMS

McMohan in 1951
Open
- no rebreathing
Semiclosed - partial rebreathing
Closed
- total rebreathing

Dripps et al have classified them as
Insufflation, Open, Semi-open,
Semi-closed and Closed

8. Conway suggested a functional
classification
1.
Breathing systems with CO2
absorber
2.
Breathing systems without CO2
absorber.

9. BREATHING SYSTEMS
WITHOUT CO2
ABSORPTION
BREATHING SYSTEMS
WITH CO2
ABSORPTION
Unidirectional flow
Unidirectional flow
A) Non rebreathing
systems.
B) Circle systems.
Circle system with
absorber.

10. BREATHING SYSTEMS BREATHING SYSTEMS
WITHOUT CO2
WITH CO2
ABSORPTION
ABSORPTION
Bi-directional flow
A) Afferent reservoir
systems.
- Mapleson A,B,C
- Lack’s system.
B) Enclosed afferent
reservoir systems
Miller’s (1988)
Bi-directional flow
To and Fro system.

11. BREATHING SYSTEMS
WITHOUT CO2
ABSORPTION
c) Efferent reservoir
systems
Mapleson D
Mapleson E
Mapleson F
Bain’s system
d) Combined systems
Humphrey ADE
Multi circuit system

12. NONREBREATHING SYSTEM(Uni-directional)
 Uses
non-rebreathing
valve
 No mixing of fresh gas
and expired gas
 Fresh gas flow =/> Minute
volume

13. Disadvantage:
FGF has to be constantly adjusted
so uneconomical
No humidification
No conservation of heat
Not convenient because of bulk of
valve
Valve malfunctioning due to
condensation of moisture

14. Bi-Directional Flow system
extensively used
 depend on the FGF for effective
elimination of CO2
FGF
- No FGF - suffocated
- Low FGF - does not eliminate CO2
- High FGF – wastage

FGF should be delivered as near the
patient’s airway as possible.

15. Mapleson systems

1954 by Professor W W Mapleson
- Maplesons A-(magills )
- Maplesons B
- Maplesons C
- Maplesons D
- Maplesons E (T-piece)
- Maplesons F (Jackson-Rees modification of
the T-piece)

16. MAPLESON SYSTEM

17. Functional classification
Afferent reservoir system (ARS).
 Enclosed afferent reservoir systems
(EARS).
 Efferent reservoir systems (ERS).
 Combined systems.

Enclosed afferent reservoir system has
been described by Miller and Miller.

18. 
afferent limb - delivers the fresh gas from
the machine to the patient.

efferent limb - expired gas from the patient
and vents it to the atmosphere through the
expiratory valve/port

19. AFFERENT RESERVOIR (AR)
SYSTEMS
- Mapleson A, B and C systems have the
reservoir in the afferent limb

20. 
AR systems - spontaneous breathing
- the expiratory valve is separated from the
reservoir bag
- FGF should be atleast one MV
- apparatus dead space is minimal.

Not efficient - controlled ventilation
FGF close to the expiratory valve (Mapleson
B & C) , the system is inefficient both during
spontaneous and controlled ventilation

21. Mapleson A (Magill’s)

22. MAPLESON A

Also known as “MAGILLS SYSTEM”

Best for spontaneous ventilation

Depend on FGF for CO2 washout so also
known as “FLOW CONTROLLED
BREATHING SYSTEM”

No rebreathing if FGF=minute volume

No separation of inspired and expired gases

Monitoring of ETCO2 is must.

23. 




APL valve at patient end.
FGF and RB at other end of system
Only one tubing so mixing of gases
Work of breathing is less
Length of corrugated tube 110cm /
volume=550ml

24. FGF requirements
Spontaneous
FGF = Minute volume
FGF of 51-85ml/kg/min advised to
prevent re-breathing
Controlled
FGF = 2.5 x MV

25. Mapleson A


Inspiration
 The valve closes
 Patient inspires FG from
the reservoir bar
 FG flushes the dead
space gas towards
patient
Expiration
 The pt expires into the
reservoir bag
 The initial part of the
expired gas is the dead
space followed by
alveolar gas
 Meets up with
FG,pressure in the circuit
increases forces the APL
open

26. Mapleson A

Controlled Ventilation
 The Mapleson A is inefficient during controlled
ventilation.
 Venting of gas in the circuit occurs during the
inspiratory phase, and the alveolar gases are
retained in the tubing during expiration phase
 Hence the alveolar gas is rebreathed before the
pressure in the system increases sufficiently
enough to force the expiratory valve open
 A Fresh gas flow of >20l/min is required to
prevent rebreathing during controlled ventilation

27. This system differs from other circuits in that
the fresh gas does not enter the system near
the patient but near the reservoir bag.
Hazard:- should not be used with mechanical
ventilator coz entire system becomes dead
space

28. Test for Mapelson “A”
Occlude patient end, close APL valve,
pressurize system – maintaining
pressure confirms integritiy

29. LACK’S MODIFICATION






In 1976; Lack modified the mapelson A.
APL valve at other end
Added expiratory limb so no mixing of gas
Two arrangement;
Dual arrangement(parellel)
Tube within tube(co-axial)

30. Tube length 1.5m
Outer tube diameter; 30mm
Inner tube diameter ; 14mm
Inspiratory capacity ; 500ml

31. TESTING

1)Attach tracheal tube to inner tube at
patient end ; blowing down the tube with
APL valve closed will produce bag
movement if there is leak between two
tubes

2) Occlude both limbs at patient end with
APL valve open; squeeze the bag; if there
is leak in inner tube; gas will escape from
APL valve and bag will collapse

32. Advantages:Location of APL valve- facilitates IPPV / scavenging.
Disadvantages:Slight increase in work of breathing.
Break / disconnection of inner tube- entire reservoir
tube becomes dead pace.

33. Mapleson B
Fresh gas inlet near pt and
distal to APL
 APL opens when pressure
in the circuit rises and an
admixure of alveolar gas
and FG is discharged
 During Inspiration,a
mixture of alveolar gas
and FG is inhaled
 Avoid rebreathing with
FGF>2×MV,not very
efficient

www.anesthesiauk.com

34. Mapleson C




Also known as Water
to and fro(Water’s
Circuit)
Similar in construction
to the Mapleson B but
main tubing shorter
FGF is equal to 2×MV
to prevent rebreathing
CO2 builds up slowly
with this circuit,not
efficient
www.anesthesiauk.com

35. EFFERENT RESERVOIR (ER)
SYSTEMs
Mapleson’s D, E ,F and bain circuits
 6 mm tube as the afferent limb that
supplies the FG from the machine
 ER systems are modifications of Ayre’s
T-piece
 work efficiently and
economically for
controlled ventilation


36. MAPELSON D

Incorporates T piece at
patient

RB and APL valve at other
end

FGF enters the system
through side arm of T
piece

FGF required to prevent
rebreathing is 1.5-2 times
minute volume

Used for spontaneous and
controlled ventilation

37. FUNCTIONAL ANALYSIS

38. BAIN’S SYSTEM

Described by Bain & Spoerel in 1972

Modification of Mapelson D system

Added one more tube; arranged coaxially
Inner tube inspiratory;
outer tube expiratory+inspiratory

Length of tube: 1.8m

Outer tube diameter: 22mm

Inner tube diameter :7mm

39. Fresh Gas Flow required:
SPONTANEOUS:
150 – 200 ml/kg/min
CONTROLLED :
70 ml/kg/min adult >60kgs
3.5 L/min for 10 – 50 kgs
2L/min for infants < 10kgs

40. ADVANTAGE:








Useful for pediatric as will as adult patient
Allows warming & humidification of gases
useful for spontaneous as will as controlled
ventilation
Easily dismantled; sterilised; so useful in infected
cases
Facilitates scavenging
Length of tubing is long so machine can be taken
away from patient ; useful in head & neck &
Neurosurgery.
Light weight
Can be used with ventilator

41. DISADVANTAGE:

High fresh gas flow requirements

Cannot be used with intermittent flow
machine.

Disconnection ,kink ,break, leak, at
inner tube may go unnoticed – entire
exhalation limb becomes dead space

42. Functional Analysis:During controlled ventilation
-when FGF is high, PaCO2 becomes ventilatory
dependent.
-when MV exceeds FGF , PaCO2 becomes
dependent on FGF

43. TESTING
(For inner tube)
A) Foex-Crempton Smith test
 Set low flow of O2 on flow meter , close APL valve
 Occlude the inner tube with a finger or barrel of
syringe at pt end .

Observe flow meter indicator
 If inner tube is intact and correctly connected flow
meter will fall
B) Pathik test
 Close APL valve, Activate O2 flush
 Observe the bag
 Due to venturi effect , Bag will deflate .

44. TESTING (for outer tube)
Close APL valve, occlude the patient end &
pressurize the system. If no leak pressure will be
maintained.
When APL valve is opened the bag will deflate
easily.

45. Ayre's T-piece Designed as a no valve circuit for
paediatrics in 1937 by Philip Ayre. (Later classified as
Mapleson E).

46. Mapleson E (Ayers T-Piece)
Length = 5cm
Diameter = 1cm
Side arms = 6mm

47. T-Piece System
The Mapleson E (T-Piece),has a length
of tubing attached to the T-piece to form
a reservoir
 Uses have decreased because of
difficulties in scavenging
 Still commonly used to administer
oxygen or humidified gas to intubated
patients breathing spontaneously
 There are numerous modifications


48. Mapleson E
For spontaneous ventilation,the
expiratory limb is left open
 For controlled ventilation,the expiratory
linmb is intermittently occulded and
fresh gas flow inflate the lungs
 Rebreathing will depend on the FGF,the
volume of the expiratory limb,the
patient’s minute vent. And the type of
ventilation,i.e. spont versus controlled


49. Our T-Piece

50. Mapleson F(Jackson-Rees System)
This is a modification of
the T-piece with a bag
that has a venting
mechanism-usually a
hole
 Adjustable pop-off valve
can even be included to
prevent over pressuring
 Scavenging can be
done


51. Mapleson F(Jackson Rees)

For spontaneous ventilation the relief mechanism is
usually left open

For assisted of controlled ventilation, the relief
mechanism is occluded sufficient enough to distend
the bag, respiration can then be controlled by
squeezing the bag

The volume of the reservoir bag should be
approximately the patient’s tidal volume, if the
volume is too large re-breathing may occur and if
too small ambient air may be entrained

To prevent rebreathing the system requires an FGF
of 2.5-3 × the patients Minute volume

52. FGF requirements:Spontaneous2-3 times MV
Minimum flow 3L/min
Controlled1000ml + 100ml/kg

53. Advantages






Compact
Cheap
No valves
Minimal dead space
Minimal resistance
to breathing.
Ventilator can be
used
Disadvantages


The bag may
become twisted and
impede breathing
High gas flow
requirements

54. What FGF’s are needed?
Mapleson
Systems
A
Magill
Lack
Uses
Spontaneous
Gen Anaesthesia
B
70-100 ml/kg/min
Resuscitation
Bagging
FGF IPPV
Min 3 x MV
Very uncommon,
not in use today
C
FGF SV
D
Bain
Spontaneous
IPPV, Gen. Anaes
E
Ayres T Piece
Very uncommon,
not in use today
F
Jackson Rees
Paediatric
<25 Kg
Min 15 lpm
150-200 ml/kg/min
2.5 – 3 x MV
Min 4 lpm
70-100 ml/kg/min

55. Relative Efficiency of rebreathing among
various Mapleson circuits

Spontaneous Ventilation-A>DFE>CB

Controlled Ventilation-DFE>BC>A

Mapleson A is most efficient during spontaneous
ventilation,but it is the worst for controlled
ventilation

Mapleson D is most efficient during controlled
ventilation

56. Insufflation





The blowing of anesthetic gases
across a patient’s face
Avoids direct connection between a
breathing circuit and a patient’s
airway
Because children resist the
placement of a face mask or an IV
line, insufflation is valuable
CO2 accumulation is avoided with
insufflation of oxygen & air at high
flow rate(>10 L/m) under H & N
draping at ophthalmic surgery
Maintain arterial oxygenation during
brief periods of apnea

57. Draw-over anesthesia

58. Draw-over anestheaia
Nonrebreathing circuits
 Use ambient air as the carrier gas
 Inspired vapor and oxygen
concentrations are predictable &
controllable
 Advantage; simplicity, portability
 Disadvantage; absence of reservoir bag
-> not well appreciating the depth of TV
during spontaneous ventilation


59. Disadvantages of the
insufflation & draw-over
systems
Poor control of inspired gas
concentration & depth of anesthesia
 Inability to assist or control ventilation
 No conservation of exhaled heat or
humidity
 Difficult airway management during
head & neck surgery
 Pollution of the operating room with
large volumes of waste gas


60. COMBINED SYSTEM
HUMPHREY’S ADE system:

To overcome the difficulties of changing breathing
system for different modes of ventilation this system
is developed

Two reservoir bag; one in afferent limb; other in
efferent limb; only one is in use at a time

System can be changed from ARS to ERS by
changing the position of lever

Used for adults as will as children

Functional Analysis same as MAP-A in ARS& as
BAIN in ERS

61. HUMPHREY’S ADE
MAP-A
Map-D

62. CIRCLE SYSTEM
ESSENTIAL CPMPONENT:
 Soda lime canister
 Two unidirectional valve
 FGF entry
 Y piece
 Reservoir bag
 Relief valve
CRITERIA FOR EFFICIENT
FUNCTIONING:
 Two unidirectional valve on
either side of RB
 Relief valve on expiratory
limb
 FGF should enter proximal
to inspiratory unidirectional
valve

63. TESTING






Set all the gas flows to zero.
Close APL valve
Occlude Y piece
Pressurize system to 30cm of with Oxygen
flush
Pressure should remain fixed for at least
10 sec.
Open APL valve and ensure pressure
decrease

64. CIRCLE SYSTEM ctd.
ADVANTAGES







Exhaled gas –co2 used again and again
Constant inspired concentration
Conservation of heat & humidity
Useful for all ages
Useful for low flow ;reduces cost of Anaesthesia
Low resistance
Less OT pollution
DISADVANTAGES:
Increased dead space
 Malfunctioning of unidirectional valve
 Exhausted soda lime; danger of hypercarbia
