anaesthesia breathing circuits. mapleson circuits. classification of circuits. functional analysia of circuits. draw over circuit. advantages and disadvantages of different circuits.

1. Breathing circuits
By:-
DR. PRATEEK GUPTA
PG ANESTHESIA (1ST YEAR)

2. WHAT IS IT
• 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

4. • In 1936, Brian Sword
introduced the circle
system
• Ayre’s T-piece was
introduced in 1937
• Bain Circuit was
introduced in 1972 by
Bain and Spoerel.

5. • Fresh gas entry port, through which
gases are delivered from machine to
system
• Port to connect it to the patient
• Reservoir for gas, to meet peak
inspiratory flow requirements
• Expiratory port through which expired
gas is vented to to atmosphere
• A CO2 absorber
• Corrugated tubes for connecting these
components

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. Criteria 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

8. DESIRABLE
1.Economy of fresh gas
2.Conservation of heat
3. Adequate humidification
4.Efficient during spontaneous
and controlled ventilation

9. CONTD..
5. Efficient for adult, pediatrics and with
mechanical ventilators
6. Light weight
7. Less theater pollution
8. Convenient during use.

10. CLASSIFICATION
• McMOHAN in 1951
• OPEN - no rebreathing
• SEMICLOSED - partial rebreathing
• CLOSED - total rebreathing

11. Dripps, eckenhoff and vandam
• Based on presence or absence of
-Reservoir bag
-Rebreathing
-CO2 absorption
-Directional valve
• Insufflation- gases are delivered directly
into patient’s ariway

12. TYPE INHALATION EXHALATI
ON
RESERVOIR REBREATHI
NG
CO2
ABSORPTN
EXAMPLE
OPEN AIR + AGENT Atmospher
e
- - - Open drop
T-Piece
SEMI-OPEN AIR + AGENT
FROM
MACHINE
Atmospher
e
SMALL MINIMAL
(on FGF)
- T-Piece
with small
reservoir
SEMI-
CLOSED
From
Machine
Atmospher
e+
Machine
large possible + Magill
attachment
Mapleson
systems
CLOSED From
Machine
Atmospher
e+machine
Large Possible + Circle
system

13. CONWAY
• Breathing systems with CO2
absorber
• Breathing systems without CO2
absorber.

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

15. BREATHING SYSTEMS
WITHOUT CO2
ABSORPTION
BREATHING SYSTEMS
WITH CO2
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.

16. 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

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

19. 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

20. Bi directional flow
• 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.

21. MAPLESON SYSTEM
• 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)

23. 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.

24. • 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

25. AR SYSTEMS
• SPONTANEOUS BREATHING
- the expiratory valve is separated from
the reservoir bag
- FGF should be atleast one MV
- Apparatus dead space is minimal.
• CONTROLLED VENTILATION
-Not efficient
• FGF close to the expiratory valve
(Mapleson B & C) , the system is
inefficient both during spontaneous and
controlled ventilation

26. MAPLESON A (Magill’s)
• PIC

27. 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.

28. • 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

30. • FGF requirements
-SPONTANEOUS
• FGF = Minute volume
FGF of 51-85ml/kg/min advised to
prevent re-breathing or 42-88% of
MV
-CONTROLLED
• FGF = 2.5 x MV

31. MAPLESON A
 Inspiration
• The valve closes
• Patient inspires FG from the reservoir
bar
• FG flushes the dead space gas towards
patient

32. 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

34. CONTROLLED
VENTILATION
• INEFFCIENT.
• Venting of gas occurs during the
inspiratory phase, and the alveolar gases
are retained in the tubing during
expiration phase

35. • 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

36. • 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

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

38. 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)

41. • Tube length 1.5 m
• Outer tube diameter – 30 mm
• Inner tube diameter - 14 mm
• Inspiratory capacity - 500 ml

42. 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

43. • 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.

44. Mapleson B
• Fresh gas inlet near pt and distal to
APL
• APL opens when pressure in the circuit
rises and an admixture 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

46. Mapleson C
• Also known as Water to and fro (Water’s
Circuit)
• Similar in construction to the Mapleson B but
main tubing shorter
• As efficient as Mapleson A if expiratory pause is
minimal
• FGF is equal to 2×MV to prevent rebreathing
• CO2 builds up slowly with this circuit, not
efficient

48. ENCLOSED AFFERENT
RESERVOIR SYSTEMS (EARS)

49. • UTILIZATION ??? 82?/93?74?

50. 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

51. 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

52. 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

58. FACTORS THAT TEND TO DEC
REBREATHING (SPONT)
• HIGH I:E RATIO
• SLOW RISE IN INSPIRATORY FLOW
RATE
• A LOW FLOW RATE IN LAST PART OF
EXPIRATION
• A LONG EXPIRATORY PAUSE (BEST)

59. Functional analysis
• pic

60. • 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

61. 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
•

62. Contd.
• 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

63. 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

64. Functional analysis
• During controlled ventilation
-when FGF is high, PaCO2 becomes
ventilatory dependent.
• -when MV exceeds FGF, PaCO2 becomes
dependent on FGF

65. testing
• 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) Pethik test
•  Close APL valve, Activate O2 flush
•  Observe the bag
•  Due to venturi effect , Bag will deflate .

66. 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.

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

69. 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

70. 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 (risk of
barotrauma)
• 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

72. 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

75. 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

76. • 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

77. • FGF requirements:-
• Spontaneous-
2-3 times MV
• Minimum flow 3L/min
• Controlled-
1000ml + 100ml/kg

78. ADVANTAGES
• Compact
• Cheap
• No valves
• Minimal dead space
• Minimal resistance to breathing/less
work of breathing
• Ventilator can be used

79. disadvantages
• The bag may become twisted and
impede breathing
• High gas flow requirements

80. 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

85. ADVANTAGES OF MAPLESON
• Simple, inexpensive & rugged
• Variation in MV effect ETCO2 less than
circle
• In Coaxial, Inspiratory limb heated by
warm exhaled gas
• Can be used to ventilate patient in MRI
unit
• Lightweight, no drag on mask or
tracheal tube

86. DISADVANTAGES OF
MAPLESON
• Requires high FGF
• Inspired heat and humidity is low (unless
device is used)
• In A, B, and C APL valve near patient,
hence inaccessible to the operator.
Scavenging is awkward
• Not suitable for malignant
hyperthermia, not possible to increase
FGF enough to remove increased CO2
load

87. 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

89. Draw-over anesthesia
• Non-rebreathing 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

91. 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

92. 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

93. Humphrey’s pic

94. Circle system
• ESSENTIAL CPMPONENT:
• Soda lime canister
• Two unidirectional valve
• FGF entry
• Y piece
• Reservoir bag
• Relief valve

95. 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

98. 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

99. 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
•

100. DISADVANTAGES
• Increased dead space
• Malfunctioning of unidirectional valve
• Exhausted soda lime; danger of
hypercarbia