ANESTHESIA MACHINE

1. Anaesthesia
machine
SPEAKER: DR. MANOJ KUMAR SHARMA
G.S.V.M. MEDICAL COLLEGE
KANPUR {U.P}

3. History
 W T G MORTON 1846
 Introduced by Henry edmund gaskin
boyle in 1917…..1918 royal london
 American Gwathmey 1912
 Geoffrey Marshal {1914- 1918} … 1919
 Addition of vapourizing bottle to
flowmeter in 1920
 Addition of second vapourizing bottle
and bypass control in 1926
 In 1933 dry bobbin
 1952 PISS, 1958 Bodock seal

4. Functioning
gas supply
gas inlet
pressure reduction
flowmeter
vapourizer
common gas outlet
breathing circuit
patient

5. FUNCTION OF ANESTHESIA MACHINE
 Provide o2
 Accurate mixture of anesthetics and
mixture
 Enable patient ventilation
 Minimise anesthesia related risk to
patient and staff

6. 45-55
PSI 12-16
PSI

7. PNEUMATIC SYSTEM
HIGH PRESSURE
• Cylinders
• Hanger Yoke
• Cylinder Pressure
Indicator(Gauge)
 Pressure Regulators
INTERMEDIATE
PRESSURE
Master Switch
Pipeline Inlet
Connections
Pipeline Pressure
Indicators
Piping
Gas Power Outlets
Oxygen Pressure Failure
Devices
Gas Selector Switch
Second stage Pressure
Regulator
Oxygen Flush
Flow Adjustment Control
LOW PRESSURE
Flowmeter
Unidirectional(Check)
Valves
Pressure Relief Device
Low Pressure Piping
Common (Fresh) Gas
Outlet

8. Components
 Cylinders- Pressurized container used for storage
and transport.
 Boyles machine consist of 2 oxygen ,2 nitrous
oxide
 Cylinders are made of chrome molybednum steel 3
mm, aluminium 6 mm .cylinders for m.r.i. room,
composite{al wrapped in carbon fibre}30% more
gas 70% more lighter.
 There are different size of cylinders specified as
A,B,C,D,and others,the size A is smallest, D and E
are in common use
 O2 ,N2,AIR in compressed form while N20,CO2
and cyclopropane in liquid form

9. COMPRESSED GAS CYLINDER
Body
 Components of a cylinder :
Shoulder Valve
Port
Stem
Fusible material {woods metal}
b/w cylinder and valve

10. International colour code of cylinder
O2-black with white shoulder
N20-blue
C02-grey
cyclopropane –orange
Air-grey with white /black quarters
Entonox-blue with white/blue quarters

11. COMPONENT OF CYLINDER
Valve: bronze/ brass
There are 2 main types of valves
1. diaphragm- valve stem with adjustable
screw,less likely to leak,expensive,
It can be fully opened using only one half to
three quarter turn
2.Packed or flush type –this noninterchangeble
flush type valve(with pin index system) is commonly
used in modern anaesthetic machine
CONICAL DEPRESSION

12. Pressure relief device.Pressure relief device.
(safety relief device, safety device)(safety relief device, safety device)
Purpose :to vent the cylinders contents to the atmosphere if thePurpose :to vent the cylinders contents to the atmosphere if the
pressure of the enclosed gas increases to a dangerous level.pressure of the enclosed gas increases to a dangerous level.
TYPES
1) Rupture Disc
2)Fusible Plug
3)COMBINATION
OF 1 & 2
4)Pressure Relief Valve

15. 02- 2,5
N20- 3,5
Cyclo-propane- 3,6
Nitrogen- 1,4
CO2<7. 5%- 2,6
>7.5%- 1,6
Air - 1,5
Entonox- 7

16. Pin index system
 It is introduced in1952
 Cylinders are locked to machine in yoke
with 2 pins and 2 corrosponding holes
 A line is drawn through the centre of
valve outlet at an angle of 30 deg. to
right face of valve.the central point of
position 1 pass through it, arc of radius
9/16 inch,other positions are passes
through intervals of 12 deg
 6 mm long 4 mm dia

17.  The diameter of valve outlet is 7mm.
 Various pin index-
02- 2,5
N20- 3,5
Cyclo-propane- 3,6
Nitrogen- 1,4
CO2<7. 5%- 2,6
>7.5%- 1,6
Air - 1,5
Entonox- 7

18. PRESSURE & FILLING
Filling ratio- it is the percentage of weight of gas in a
container to weight of water it can hold at 60 f. this is used
to prevent overfilling,N20-0.68,cyclo-0.55
Service pressure-each cylinder contains a gas under
specified pressure,which is known as service pressure.it is
the maximum pressure at 70 f
But able to withstand 1.66 time of the service pressure
Units of pressure( 100kPa = 760mmHg = 14.7psi =1atms)

19. cylindercylinder
sizesize
Dimensions(Dimensions(
OD*Length inOD*Length in
inchinch))
WeightWeight
(pounds)(pounds)
of emptyof empty
cy.cy.
OxygenOxygen N2ON2O CO2CO2 AirAir
BB 3.5 *133.5 *13 55 200L200L
19001900
psigpsig
370L370L
838838
psigpsig
DD 4.5*174.5*17 1111 400L400L
19001900
940L940L
745745
940L940L
838838
375L375L
19001900
EE 4.25*264.25*26 1414 660L660L
19001900
1590L1590L
745745
1590L1590L
838838
625L625L
19001900
MM 7*437*43 6363 3450L3450L
22002200
7570L7570L
745745
7570L7570L
838838
2850L2850L
19001900
GG 8.5*518.5*51 9797 13800L13800L
745745
12300L12300L
838838
5050L5050L
19001900
HH 9.25*519.25*51 119119 6900L6900L
22002200
15800L,715800L,7
4545
6550L6550L
22002200

20. ARLAS
 Approx remaining in hour = (o2
cylinder in pressure in psig / 200 ×
o2 flow rate per minute

22. Cylinder identification
 Should have a label
a. Name and chemical symbol of gas.
b. Product specification.
c. Hazard warning diamond shaped figuredenoting hazard
class contained gas.
d. Name and address of cylinder manufacturer.
e. Cylinder contents in liters.
f. Tare weight (weight when empty).
g. Maximum cylinder pressure.
h. Cylinder size code.
i. Directions for use.

23. PERIODIC TESTING
 Hydraulic test Is a measure of cylinder’s elasticity
cylinder pressurized to 240 atmospheres.The cylinder
should stretch less than 0.02%.
 Tensile test Done in one out of 100 cylinders. The
yield point should not be less than 15 tons per square
inch.
 Flattening test The cylinder is kept between two
compression blocks and pressure is applied from both
sides until the distance between blocks remains 6
times the thickness of the wall of cylinder. The walls
should not crack.

24. Impact test
Mean energy to produce the crack
should not be less than 5 and 10 lb/ft for transverse
and longitudinal strips, respectively.
Bend test
A ring of 25 mm width is cut from the cylinder and
divided into strips. Each strip is bent inward until
inner edges are a part, not greater than the diameter
of strip

25. Entonox

26. Entonox
This is 50.50 mixtures of nitrous oxide and
oxygen . The premixed contents remain in
gaseous phase at pressures and temperature at
which N2O by itself would normally be a liquid
(pointing effect) If Entonox cylinder is stored at
cold temperature (−7°C), some N2O separates as
liquid and may lead to delivery of uneven
mixtures, too much O2 at the beginning and too
much N2O later as the cylinder empties. Danger
of separation can be avoided by storing the
cylinders above 0°C, immersing the cylinder in
water at 52°C, inverting it thrice or keeping it
above a temperature of 10°C for 2 hours before
use.

27. Heliox
Heliox is a mixture of oxygen and helium. The
latter is 86% less dense (0.179 g/L) than air
(1.293 g/L).
A mixture of 21% oxygen and 79% of helium
named as Heliox 21 is used to improve gaseous
exchange in acute exacerbation of asthma and
COPD {REYNOLD NO}

28. Safety system
 Colour coding
 Label on cylinder
 Valve system
 Pin index system

29. Yoke assembly

30. Yoke assembly
 It is the portion of machine at which the cylinders are
fitted
The hanger yoke consists of:
(1) The body, which is the
principle framework and supporting structure,
(2) The retaining screw, which tightens the cylinder in the
yoke,
(3) the nipple, through which gas enters the machine,
(4) the index pins, which prevent attaching an incorrect
cylinder,
(5) the Bodok seal,

32. Bourdon’s pressure gauge

33. Bourdon’s pressure gauge
 Indication of incoming gas supply
 In O2 cylinder – indicates amount of gas
 N2O cylinder – pressure is not indicative of
amount b’cos N2O is stored in liquified
form.
 Curved tube can rupture with high
pressure and the gauge has a vent on its
back which can release the gas in the
event of rupture.
 Safety system

34. Pressure reducing valve

35. PHYSICAL PRINCIPLE
A
P
a
p

36. Pressure reducing valve
 Converts high variable pressure in
cylinders to constant working
pressure suitable for anaesthesia
machine
 The pressure regulators reduce the
pressure of the O2 cylinders from
1900 PSIG to 45 60 PSIG and the‑
N2O cylinders from 760 PSIG 45 60‑
PSI

38. 38
Intermediate Pressure SystemIntermediate Pressure System
 Receives gasses from the
regulator or the hospital
pipeline at pressures of 40-55
psig
 Consists of:
 Pipeline inlet connections
 Pipeline pressure indicators
 Piping
 Gas power outlet
 Master switch
 Oxygen pressure failure devices
 Oxygen flush
 Additional reducing devices
 Flow control valves

39. Intermediate system
 Pipeline –
- Gas hoses are named and color coded
- Non interchangeable quick
couplers[shrader’s valve-gas specific]
- NIST
- Diameter index safety system[DISS]
- Pipeline pressure indicators

40. NIST
SCHRADER

41. DISS

42. NIST

43. 43
Second-Stage PressureSecond-Stage Pressure
RegulatorRegulator
 Located just upstream of the flow control
valves
 Receives gas from the pipeline inlet or the
pressure regulator and reduces it further to 26
psig for N2O and 14 psig for O2
 Purpose is to eliminate fluctuations in pressure
supplied to the flow indicators caused by
fluctuations in pipeline pressure

44. O2 FLUSH
 There is a direct tubing connecting the O2 pressure
regulator to the O2 flush. It gives 35 70 L/min of flow‑
with a pressure of 45 60 PSIG.‑
 Disadvantage: Barotrauma
Awareness

46. Oxygen SupplyOxygen Supply
Failure AlarmFailure Alarm

47. THE FLOW METER ASSEMBLY
The flow meter assembly controls, measures and indicates
the rate of flow of gas passing through it

49. Flow control valves
 Flow control valve or needle valves is used at lower end
of flowmeter
 It controls the rate of flow of gas through its associated
flow indicator by manual adjustment of a variable
orifice
 Gas flow is started, controlled and terminated by
unscrewing and screwing of pin valve

50. Low pressure system
 The low pressure system is downstream of the flow
control valves
 Pressure in this section is only slightly above
atmospheric
 Components found in this section includes flow
indicator vapourizer and common gas outlet

51. 51
Flowmeter

52. 52
Flowmeter PhysicsFlowmeter Physics
The rate of flow through the
flowmeter tube depends on 3 things
Pressure drop across the constriction:
As gas flows around the indicator it
encounters frictional resistance
between the indicator and tube
wall.there is loss of energy reflected in
a pressure drop. This pressure drop is
given by:
weight of float/cross sectional area

53. Size of annular opening: The
annular area varies while the
pressure drop across the
indicator remains constant for
all positions in the tube.
Physical characteristics of the
gas:
Low Flow: Small annular
space, therefore flow is
laminar, therefore flow is a
function of gas viscosity .
(Hagen-poiseuille equation)

54. High Flow: Large annular
space, therefore flow is
turbulent, therefore the flow
is a function of gas density .
(Graham,s law)

57.  Flowmeters are calibrated at atmospheric
pressure (760 torr) and room temp( 20 deg C).
 Changes in temp & pressure will affect density
and viscosity of a gas and affect flowmeter
accuracy.
 In a hyperbaric chamber flowmeter will deliver
less gas than indicated .
 With decreased barometric pressure (increased
altitude), the actual flow rate will be greater
than that indicated.

58. Arrangement
of flowmeter

59.  Other types of flow meter-
1.Heidbrink flow meter-contains a
tapered metal tube projected into
glass tube, float is black, inverted and
tapered, gives acc. Reading for low
and high flow
2.Connel flow meter-it is a ball float
flow meter, it is set an inclined plane
and provided with two ball floats
3.Foreggar flow meter-

60. AUXILIARY OXYGENAUXILIARY OXYGEN
FLOWMETERFLOWMETER
 Self contained flowmeter with its
own flow control valve,flow
indicator,& outlet
 Short tube with maximum flow of
10L/min
 Usually on the left side of the
machine
 Can be used to supply O2 to patient
without turning ON the machine
 Older machines – works on pipeline
supply,in newer ,works on cylinder
& pipeline supply both.

61. PROBLEMS WITH FLOWMETERSPROBLEMS WITH FLOWMETERS
 Inaccuracy- if mixing of components
occur
 Indicator problems – damage due to
sudden projection to top of the tube.
- worn or distorted
 Leaks – if flow control valve is left
open, there is no cylinder or yoke plug
in the yoke
 Using the wrong flowmeter – when
flowmeter sequence is altered

62. 62
Oxygen Supply FailureOxygen Supply Failure
AlarmAlarm The machine standard specifies that whenever the
oxygen supply pressure falls below a manufacturer-
specified threshold (usually 30 psig) a medium priority
alarm shall blow within 5 seconds.
 Electronic alarms: A pressure operated electric switch
operates this alarm
 Ohmeda: 28 psig
 Drager: 30-37 psig
 Pneumatic alarms (aka Bowman’s Whistle): Uses a
pressurized canister that is filled with oxygen when the
anesthesia machine is turned on. When the oxygen
pressure falls below a certain value, the alarm directs a
stream of oxygen through a whistle

63. Bowman’s Whistle

64. OFPD
datex
ohmeda

65. OFPD
DRAGER

66. HYPOXIA PREVENTION SAFETYHYPOXIA PREVENTION SAFETY
DEVICESDEVICES
MANDATORY MINIMUM OXYGEN FLOW:
 Some machines require a minimum ( 50-
250ml/min) flow of O2 before other gas will flow
 Some machines activate an alarm if O2 flow goes
beyond a certain minimum.
MINIMUM OXYGEN RATIO:
 Device to protect against operator selected
delivery of a mixture of O2 & N2O having O2 conc
below 21% O2 .

67. Hypoxia prevention safety
devices:
 Proportionating devices –
- link 25 in datex
ohmeda[mechanical,pneumatic
and electronic linkage]
- S-ORC in draeger,
- Mandatory minimum oxygen
flow

68. Mechanical
linkage

69. LINK 25

70.  Flow control valves are adjusted so that when 25%
O2 conc is reached ,a pin on O2 sprocket engages a
pin on O2 flow control knob.This causes O2& N2O
flow control valves to turn together to maintain
minimum O2 of 25%.
 If attempt is made to increase the N2O flow beyond
that ratio, the O2 flow is automatically increased.
 If O2 flow is lowered too much the N2O flow is
decreased proportionally
 An electronic system can be used to provide a
minimum ratio of O2 to N2O flow
ALARMS:
 Available to alert the operator that O2-N2O flow
ratio has fallen below a preset value

71. S- ORC

72.  Wrong Supply Gas
 Defective Pneumatics or
Mechanics
 Leaks Downstream
 Inert Gas Administration
LIMITATION

73. UNIDIRECTIONAL (CHECK )UNIDIRECTIONAL (CHECK )
VALVEVALVE
 During controlled ventilation a positive
pressure from breathing circuit can be
transmitted back to the machine
 Using O2 flush valve may also cause this
 Unidirectional check valves are present to
minimize these effects
 Valve is located between vaporizers and
common gas outlet ,upstream of where O2
flush flow joins fresh gas flow

74. PRESSURE RELIEF VALVEPRESSURE RELIEF VALVE
 May be attached downstream of
vaporizers on the back bar itself
or near common gas outlet
 Prevents high pressure being
transmitted to the machine
 Whenever preset pressure is
exceeded valve opens to
atmosphere and gas is vented
outside
 Usually opens when pressure in
the back bar 5 PSIG (300 cm of
H2O) This valve limits the
machine to provide jet
ventilation
 Also known as the pop-off valvepop-off valve.

75. COMMON ( FRESH ) GASCOMMON ( FRESH ) GAS
OUTLETOUTLET
 Receives all the gases and vapors
from the machine and delivers the
mixture to breathing system
 Machine standard mandates that it
be difficult to accidentally
disengage the delivery hose from
the outlet
 The pressure delivered at the outlet
is 5 -8 psi

76. BACK BARBACK BAR
 Part of frame of the Boyle’s machine which supports
the rotameter,vaporizers and other accessories
 There are 2 metal rods in back bar
 Flowmeters and vaporizers are connected with each
other and then bolted with the back bar.

77. VAPORIZER
 A vapor is the gaseous phase of
substance that is liquid at room temp.
and atm. pressure
 A vaporizer is an instrument designed
to change a liquid anaesthetic agent
into its vapor and add a controlled
amount of this vapor to fresh gas flow
 As many as three vaporizer can be
attached to anaesthesia machine

78. Safety features
 Antistatic tyre
 Pressure reducing valve
 02 failure alarm
 02,N20 lock
 Florescent back panel of
rotameter
 02 flush

79. Essential Features Purpose
Noninterchangeable gas-specific
connections to pipeline inlets (DISS)1
with pressure gauges, filter, and check
valve
Prevent incorrect pipeline attachments;
detect failure, depletion, or fluctuation
Pin index safety system for cylinders
with pressure gauges, and at least one
oxygen cylinder
Prevent incorrect cylinder attachments;
provide backup gas supply; detect
depletion
Low oxygen pressure alarm Detect oxygen supply failure at the
common gas inlet
Minimum oxygen/nitrous oxide ratio
controller device (hypoxic guard)
Prevent delivery of less than 21%
oxygen

80. Oxygen failure safety device (shut-off or
proportioning device)
Prevent administration of nitrous
oxide or other gases when the
oxygen supply fails
Oxygen must enter the common manifold
downstream to other gases
Prevent hypoxia in event of
proximal gas leak
Oxygen concentration monitor and alarm Prevent administration of hypoxic
gas mixtures in event of a low-
pressure system leak; precisely
regulate oxygen concentration
Automatically enabled essential alarms and
monitors (eg, oxygen concentration)
Prevent use of the machine without
essential monitors
Vaporizer interlock device Prevent simultaneous administration
of more than one volatile agent

82. Capnography and anesthetic gas
measurement
Guide ventilation; prevent anesthetic
overdose; help reduce awareness
Oxygen flush mechanism that does not
pass through vaporizers
Rapidly refill or flush the breathing
circuit
Breathing circuit pressure monitor and
alarm
Prevent pulmonary barotrauma and
detect sustained positive, high peak, and
negative airway pressures
Exhaled volume monitor Assess ventilation and prevent hypo- or
hyperventilation
Pulse oximetry, blood pressure, and
ECG monitoring
Provide minimal standard monitoring

83. Mechanical ventilator Control alveolar ventilation more
accurately and during muscle paralysis for
prolonged periods
Backup battery Provide temporary electrical power (> 30
min) to monitors and alarms in event of
power failure
Scavenger system Prevent contamination of the operating
room with waste anesthetic gases

84. THANKS