1. Guidance-
Presented By-
Dr.Sadhana Jain
Prof. & Head
Dept. of Anaesthesiology,
Dr. Deepak Kumar
Post Graduate student
Dept. of Anaesthesiology
S.P. Medical College , Bikaner
1

2. ANAESTHESIA MACHINE
 Anaesthesia machine is a device which delivers
precisely known but variable gas mixture,
including anaesthetizing and life sustaining gases
ANAESTHESIA MACHINE- 2 types
1. Intermittent gas flow type
2. Continuous gas flow type

3. Intermittent gas flow type





1.
2.
–
They provide oxygen and
nitrous oxide.
They operate on demand.
Gas flow are drawn by
inhalation.
They are useful for short
surgical procedures .
Example –
Walton V machine
Modified Walton V
machine(Lucy Baldwin’s
apparatus)
3

4. 3. Entonox apparatus :Intermittent gas flow machine by
Rovenstein.
It has premixed cylinder of oxygen
(50%) with nitrous oxide (50%).
- Cylinder has body of French blue
with top white with pin index of 7.
- Pressure regulator.
- Pressure gauge (2000 psi).
- Demand valve.
- Key to open the cylinder.
- Circuit provided with facemask,
expiratory valve, corrugated tube &
metal hand piece to hold mask.
4

5. - Oxygen & nitrous oxide mixture available in gas form due
to Poynting effect. (At 2000 psi pressure & at room
temperature, oxygen has solvent action, keeps nitrous
oxide in gaseous form)
- The mixture separates into component parts, at -7 degree
celsius known as pseudocritical temperature, carries risk of
hypoxia due to nitrous oxide .
- This is prevented by:
 proper storing,
 avoiding excessive cooling
 rewarming of cylinder,
 shaking ,
 inverting several times before use.
5

6. - Used very effectively as analgesic for :
. Dressing of surgical wounds.
. Dressing of burns.
. Labour analgesia.
. Dentistry.
. Pain relief for trauma pts.
. Post-operative pain relief
. In ophthalmological examination.
. During cardiac catheterization.
6

7. - Other intermittent gas flow machines :
1) EMOTRIL – E.M.O. apparatus with trilene. Grey in colour.
Draw-over giving air+trilene (0.3 to 0.5 %).
2) TECOTA – Temperature compensated trilene apparatus
giving air+trilene .
3) CYPRANE INHALER - Giving air+ methoxyflurane(0.35
%) for labour analgesia.
4) CARDIFF INHALER - Giving air+ methoxyflurane(0.35
%) for labour analgesia. ( inhaled during painful uterine
contractions in first stage of delivery.
7

8. Continuous gas flow type-Gas flows both
during inspiration and expiration. Egs :
• Boyle Machine
• Forregar
• Dragger

9. History
 INVENTOR ?
Henry Edmund
Gaskin Boyle
1917
Modified machine
manufactured by
James Tayloe
Gwathmy

10.  ORIGINAL BOYLE’S MACHINE
Sight-feed water bottle and controls
mounted on a vertical rod
4 N2O cylinders
Reducing valves with spirit lamps
1 O2 cylinder
Rebreathing bag
Face piece/mask

11. MODIFICATIONS
 1920 : Addition of ether bottle
 1926 : Addition of chloroform bottle
 1927 : Back bar added
 1930 : Addition of plungers and cowls in ether
and chloroform bottles
 1933 : Dry bobbin flow meters replaced water
sight feed bottles
 1937 : Rotameter displaced dry bobbin
flowmeters
 1979 : Standards for anaesthesia machines

13. MODELS AVAILABLE IN INDIA
 Porta Boyle
 King Porta Boyle
 Boyle Cadet
 Boyle F
 Boyle major
 Boyle mark III (Boyle Basic)
 Boyle mark IIIS
 Boyle mark IV

14. “ the traditional pneumatic anesthesia machine has
evolved into a complex electrical, mechanical and
pneumatic multi component workstation”

15. Functions of a WORKSTATION
 Safe provision, selection and delivery of anesthetics
 Provision of back up supplies of gases
 Respiratory support
 Monitoring of machine function
 Monitoring of patient
 Record Keeping
 Anesthetic Gas Scavenging System (AGSS)
 Suction regulator
 Supplemental oxygen
 Work surface and storage facility for “everyday items”
 Electricity sockets

16. SYSTEM
COMPONENTS
ELECTRICAL
COMPONENTS
PNEUMATIC
SYSTEM

17. Electrical Components
 Master Switch:
 Activates both electrical and pneumatic function
 Standby mode: Quicker power up

18. Electrical Components
 Power failure indicator:
 Visual or Audible indicator to alert provider of power
failure.

19. Reserve power:
Electricity is crucial – Backup necessary
Back up with Single power source
UPS may be added
Amount of charge left is displayed

20. Electrical Components
 Electrical outlets
 Convenience electrical outlets on the back of the
anesthesia machine. These should be used only for
anesthesia monitors and not for general operating
room use.
 Circuit breakers to protect from overload

21. Data communication ports :
Communication between anaesthesia
machine, monitors and data management
system.
View Figure

22. PNEUMATIC
SYSTEM

23. 100 kPa = 1000 mbar =
760 mm Hg = 1030 cm
H2O = 14.7 psi = 1 atm
1 psi = 6.8 kpa
Psig = pounds per square inch gauge

24. Pneumatic system
High
Pressure
system
Intermediate
Pressure
system
Low pressure
system

25. O2 = 2000 psig
N2O = 750 psig
Cylinder = 45- 50 psig
Pipeline= 50- 60 psig
just above atmospheric pressure
and variable
(5-8 psig)

26. BRIEF NOTE ON CYLINDERS
 Components:
 Body
 Valve – Port, stem
 Handle
 Pressure relief device
 Conical depression
 Pin index safety
system

27.  BODY
Alloy of molybdenum and
steel
MRI – ALUMINIUM
 VALVE
Filled and discharge
through valve
Port : Point of exit
Stem : stem against seat
arrangement to close
valve
 HANDLE
body

28.  CONICAL DEPRESSION
Receives retaining screw of the yoke
 PRESSURE RELIEF DEVICE
Venting of contents at dangerously
high pressures
TYPES :
 Rupture disc – copper
 Fusible Plug (Woods alloy) –
bismuth, lead tin, Cadmium
(Melts at 150-170 deg F)
 Combination of both
 Pressure relief valve (spring
loaded)

29. SIZE OF CYLINDERS
Cylinder classified using a letter code
A type cylinders are smallest
However AA (smaller than A) also available.
SIZE D & E is the cylinder most commonly used

31. TYPICAL MEDICAL GAS CYLINDRES,
VOLUMES, WEIGHT
cylinde
r size
Cylinder
Dimensions
(O.D. × Length
in Inches)
wt .(lb)
A
B
3X7
0.23
3 1/2 x 13
5
D
4 1/2 x 17
11
E
41/4 x 26
M
7
EMPTY
oxygn
(litres)
NITROUSO
XIDE
76
Air
CO2
(litres) (litre
s)
189
(litres)
370
200
375
940
400
14
625
1590 660
1590
x 43
63
2850
7570 3450
7570
G
8 1/2 x 51
97
5050
1230
0
13800
H
91/4 X 51
119
6550
6900
940
15800

32. COLOUR OF CYLINDER
GAS
USA
INTERNATIONAL
oxygen
Green
White Shoulder&
Black Body
Gray
Carbon dioxide Gray
Nitrous
oxide
helium
Blue
Blue
Brown
Brown
Nitrogen
Black
Black
Air
Yellow
Gray Body ,Shoulder
black/white quartered

33. CONTENT AND PRESURE
FIG:A nonliquefied gas such as oxygen will show a steady decline in pressure until
the cylinder is evacuated. Each cylinder, however, will show a steady decline in
weight as gas is discharged.

34. CONTENTS AND PRESSURE
FIG:The relationship between cylinder weight, pressure, and contents. A gas stored partially in liquid
form, such as nitrous oxide, will show a constant pressure (assuming constant temperature) until all the
liquid has evaporated, at which time the pressure will drop in direct proportion to the rate at which gas is
withdrawn.

35. Cylinder marking1.Name of manufacturer and name of institute
2.Specific number
3.Name of the gas
4.Year of testing and name of the test like BT-bending test
5.Weight in kg
6.Capacity in liters
Name of tests1.BT-Bending test
2.Tensile test
3.Impact or flattening test
4.Pressure or Hydraulic test(Every 5 year)
35

36.  Critical Temperature is the temperature
above which any gas cannot be liquefied no
matter how much pressure is applied ( O2=-119°
C, N2O= 36.5 ° C)
 Critical pressure is the minimum pressure
that is required to liquefy a gas at critical
temperature.
 Service pressure is the maximum pressure to
which cylinder may be filled at 21.1 ° C
 Filling ratio (for liquefied gases) is the percent
ratio of the weight of the gas in the cylinder to
the weight of water a cylinder can hold at
60 ° F. (N2O = o.68 in tropical, 0.75 in
temperate)

37. Components of pressure systems

38. High Pressure System
 HIGH, VARIABLE
LOW, CONSTANT
 Components
Hanger yoke assembly
Cylinder Pressure Indicator
Pressure Regulators

39. HANGER YOKE
 Orients and supports the cylinder
 Gas tight seal, unidirectional flow

40.  BODY
BODY
 Threaded into frame of machine
 Supports cylinder
 Hinged Swinging gate
Swinging
gate

41.  RETAINING SCREW:
 Threaded into the distal end
of yoke
 Tightening the screw – gas tight
seal
 Conical point fits into conical
depression on cylinder
 NIPPLE:
 Projects from yoke and fits into
cylinder port
 Entry of gas
NIPPLE
RETAINING
SCREW

42.  INDEX PINS
 Component of pin index
safety system
 4mm in diameter and 6mm
long (except pin 7 which is
slightly thicker) .
 Pinhole are 4.8mm in
diameter . Diameter of
valve outlet is 7mm
 Fit into the corresponding
holes on the cylinder
 Holes are on the
circumference of a circle of
9/16th inch radius centered on
the port of a cylinder

43.  1, 3
 1, 4
 1, 5
 1, 6
 2, 4
 2, 5
 2, 6
 3, 5
 3, 6
 4, 6
7
Ethylene
Nitrogen
Air
CO2 or O2 (CO2 >7%)
Helium & O2 (He <80%)
Oxygen
CO2 or O2 (CO2 <7%)
Nitrous oxide
Cyclopropane
He & O2 (He >80%)
Entonox

44.  Swinging gate–type
Placing cylinder in yoke.
The cylinder is supported
by the foot and guided into
place manually
yoke. Note the washer
around the nipple and
the index pins below.

45.  FAILURE OF PIN INDEX SAFETY
SYSTEM?
Breakage of pins
Double washer
Pushing in of pins

46.  WASHER (BODOK SEAL)
 Seal between cylinder valve & yoke
 Fits over the nipple
 FILTER
 Between cylinder and check valve
 Particulate matter

47.  CHECK VALVE ASSEMBLY
 Plunger slides away from the side where pressure
is greater
 Unidirectional flow
 Prevents transfilling
 Prevents loss of gas when changing cylinders

48.  YOKE PLUG
 Check valve not designed to
function as seals
 Place yoke plug when no
cylinder present
 If cylinder present keep
valve closed

49. Pressure gauge2 common type- 1) Bourdon gauge
2) Aneroid gauge
Bourdon pressure
gauge
Bourdon gauge1.It is robust
2.Inexpensive
3.Able to withstand high pressure
4.Low precision
5.Used to indicate cylinders and
pipeline pressure
Aneroid gauge1.Delicate and sensitive
2.Comparatively expensive
3.Able to indicate low pressure
4.Used for airway & blood pressure
measurement
49

50. Pressure gauge
1. The gauge is usually colour coded and name and symbol of
gas are written over the dial. Blue colour for nitrous oxide
and white for oxygen.
2. Cyclopropane and nitrous oxide does not need to carry
pressure gauge as weight is the only reliable guide to
detect the exact amount in the cylinder as they are in
liquid form.
3. The scale must be at least 33% greater than the maximum
filling pressure of the cylinders or the full indication
position.
4. Gauge is calibrated in (kilopascal)kPa or (pound per
square inch)psi
or Kg/cm2 .
50

52. Digital pressure indicator LEDs(light –emitting diodes ) indicate cylinder or
pipeline pressure.
 Green light- Pressure is adequate.
 Red light- Pressure is inadequate.
 Dark light- Either valve is not open or the cylinder or
pipeline are disconnected.
 The pipeline pressure indicator should be towards pipeline
side of check valve, not towards machine.
7 December 2009
Presented by Dr.Mukesh Kumar
52

53. PRESSURE REGULATORS
 3 main reasons:
 Pressure delivered is too high to be used safely
 Fine and accurate control of gas difficult at high Pr.
 As contents of cylinder exhausted Pr falls necessitating
continual adjustment to maintain flow rate
Reduced
PRESSURE
Constant

54.  BASIC PRINCIPLE
A larger pressure acting over a small area is balanced by a
smaller pressure acting over a large area.
a1XP1=A2Xp2

55.  SIMPLE PRESSURE REGULATOR
diaphragm
Adj. screw
Spring
Low pr
chamber
Valve
seating

56.  SIMPLE PRESSURE REGULATOR
 Diaphragm – rubber, neoprene, metal
 2000 psi to 60 psi

57.  ADAMS REGULATOR
 Lazy tongs toggle arrangement

58.  Adjustments to alter regulated pressure – only
by service engineers
 Modern pressure regulators are “universal”
 Required to withstand 30 mega pascals(4410
psig)
 Output should not vary more than 10% across
wide flow range (100 ml/min to 12L/min)
 Relief valves on Regulators:
Safety blow off valves on downstream side
Relief valve set at 70 psig-100psig

59. INTERMEDIATE PRESSURE SYSTEM
 COMPONENTS
 Pneumatic part of the master switch
 Pipeline inlet connections
 Pipeline pressure indicators
 Piping
 Gas power outlet
 Oxygen pressure failure devices
 Oxygen flush
 Additional pressure regulators
 Flow control valves

60.  Pneumatic part of the master switch
 Located downstream of the inlets for cylinder and
pipeline supply
 Oxygen flush usually independent
 Pipeline inlet connections
 Entry point for gases (O2, N2O, air)
 Unidirectional check valve
 Filter with pore size < 100 µm
 Threaded non interchangeable DISS
 Body, Nipple, Nut combinations
 Diameters on each part varies so that only properly
mated parts will fit together

61.  DISS

62.  Pipeline pressure
indicators
Indicates pipeline
pressure of each gas
50 – 60 psig
Pipeline side of check
valve



Will monitor pipeline
pressure only
If on machine side,
would monitor machine
pressure
If pipe line fails,
cylinder open – no
indication

63.  Piping
 Previously copper now high density nylon
 Connects individual components
 Withstand 4 times the intended service pressure
 Leak between inlet and flowmeter not more than 25
ml/min
 If yoke and pressure regulator are included leak not
more than 150 ml/min

64.  Gas power outlet (Auxiliary Gas)
 Driving gas for ventilator, gas for jet ventilator
 O2 or air

65. Oxygen Pressure Failure devices These includes-
 1.Oxygen Failure safety devices- (Oxygen Failure safety
valve,low pressure guardian system, Oxygen Failure
protection devices, pressure sensor shutoff system,fail
safe,nitrous oxide shutoff valve)
 This valve shuts off or proportionally decreases and
ultimately interrupts the supply of nitrous oxide if the
oxygen supply pressure decreases.
 The anaesthesia workstation standard requires that
whenever the oxygen supply pressure reduced below
the manufacturer-specified minimum,the delivered
oxygen concentration shall not decrease below 19% at
the common gas outlet.

66. SPRING LOADED VALVE
 O2 Failure Safety Device
(Valve)
 Located in the
intermediate pressure
system upstream of the
flow control valves of all
gases except O2
 Shuts off or proportionally
decreases N2O

67. GAS LOADED VALVE

68. 2.Oxygen Supply Failure AlarmThe anaesthesia workstation standard specifies that
whenever the oxygen supply pressure falls below the
manufacturer-specified threshold {usually 30psi (205kP)}.
- Alarm shall be enunciated within 5 sec.
- Alarm shall be of at least 7 sec. duration and shall have a
noise level of at least 60dB measured at 1m from the front of
the anaesthetic machine.
- They add in preventing hypoxia caused by problems
occurring in the machine circuit.
- Equipment problems(leaks) or operators error (closed or
partially closed flow control valve) occur downstream are
not prevented by these devices.
68

69.  O2 Supply Failure Alarm
 The Ritchie whistle : Normal operation

70.  The Ritchie whistle : During O2 failure

71.  Secondary Pressure
Regulators:
 Machine working pressure
may fluctuate. Eg: At times of
Peak demand.
 Parallel fluctuations in
flowmeter performance
 Pressure regulator set below
the anticipated pressure drop
smoothes out the supply.
 Mechanically linked anti
hypoxia device assume oxygen
pressure to be constant
 26 psig for N2O
 14 psig for O2

74. Flow Adjustment Control
 The flow adjustment controls regulate the flow of
oxygen, air, and other gases to the flow indicators.
 There are two types of flow adjustment controls:
mechanical and electronic.
 The anesthesia workstation standard requires that
there be only one flow control for each gas. It must be
adjacent to or identifiable with its associated
flowmeter.

75. Mechanical flow control valve
 The mechanical flow control valve (needle valve, pin valve,
fine adjustment valve) controls the rate of gas flow through its
associated flowmeter
 Some also have an ON-OFF function. On some machines, the
ON-OFF function is controlled by the master switch.
 Mechanical flow control valves are used with both
mechanical and electronic flowmeters

76. Mechanical Flow Control Valve
 COMPONENTS
 Body. The flow control valve body screws into the
anesthesia machine.
 Stem and Seat.
 The stem and seat have fine threads so that the stem
moves only a short distance when a complete turn is
made.
 When the valve is closed, the pin at the end of the stem
fits into the seat, occluding the orifice so that no gas can
pass through the valve. When the stem is turned
outward, an opening between the pin and the seat is
created, allowing gas to flow through the valve. The
greater the space between the pin and the seat, the
greater the volume of gas that can flow.

77.  To eliminate any looseness in the threads, the
valve may be spring loaded. This also minimizes
flow fluctuations from lateral or axial pressure
applied to the flow control knob.

78. Contd
 It is advantageous to have stops for the OFF and
MAXIMUM flow positions. A stop for the OFF position
avoids damage to the valve seat. A stop for the MAXIMUM
flow position prevents the stem from becoming disengaged
from the body.
 Control Knob :
The control knob is joined to the stem. If it is a rotary style
knob, the oxygen flow control knob must have a fluted
profile and be as large as or larger than that for any other
gas. All other flow control knobs must be round. The knob
is turned counterclockwise to increase flow. If Other types
of flow control valves are present, the oxygen control must
look and feel different from the other controls.

79. Flow Control Knobs

80. Contd…..
 When a machine is not being used, the gas source (cylinder or
pipeline) should be closed or disconnected.
 The flow control valves should be opened until the gas pressure
is reduced to zero and then closed.
 If the gas source is not disconnected, the flow control valve
should be turned OFF to avoid the fresh gas desiccating the
carbon dioxide absorbent and to conserve gas.
 Before machine use is resumed, the control valves should be
checked to make certain that they are closed.
 Sometimes, a flow control valve remains open after the gas is
bled out or opened when the machine is cleaned or moved.
 If the gas supply to an open flow control valve is restored and the
associated flow indicator is not observed, the indicator may rise
to the top of the tube where its presence may not be noticed.
 Even if no harm to the patient results, the sudden rise may
damage it and impair the flow meter accuracy.

81. LOW PRESSURE SYSTEM
 Downstream of flow control device
 Pressure only slightly above atmospheric, variable
COMPONENTS :
 Flowmeters
 Anti Hypoxia Devices
 Unidirectional valves
 Pressure relief devices
 Vaporisers – (another class not today)
 CGO (Common Gas Outlet)

82.  Flowmeters
 Mechanical flowmeter
 Thorpe tube : Transparent tapered with float
 Variable orifice
 Smallest diameter at bottom
 Gas enters from below
 Float moves with the flow of gas
 Rests at seat when no flow

83.  Flowmeters
 Rate of flow depends on
Pressure drop across constriction
Size of annular opening
Physical properties of the gas

84.  Flowmeters
 Pressure drop across constriction
Friction b/w indicator and tube wall
Loss of energy
Pressure drop constant
Weight / cross sectional area

85.  Flowmeters
 Size of annular
opening
Increase in flow
causes an
increase in the
size of the
opening

86.  Flowmeters
 Physical characteristics of the
gas:
 Low flow :Longer & narrow
constriction
Laminar flow
Viscosity (Hagen
Poiseulle law)
 High flow: Shorter and
wider constriction
Turbulent flow
Density(Graham’s
law)

87.  Flowmeters
Temperature and pressure effects
 Calibrated at 760 mmHg, 20 C
 Temp, pressure affect viscosity & density

Accuracy of flow can be affected
 Temperature changes are minor

Insignificant change in flow
 Low barometric pressure, high altitude

Low flow setting, laminar flow, depends on viscosity



Independent of altitude
High flow setting, turbulent flow, depends on density
↓ density due to high altitude – flow more than
indicated

88.  Flowmeter Assembly
 Tube, indicator, stop,
scale,
 Empties into a
common manifold

89.  Tube
 Glass (pyrex)
 Single / Double
taper
 Rib guides for
ball indicator
SINGLE TAPER
DUAL TAPER

90.  Indicator
 Free moving
device
 Made of
aluminium
 Nonrotating
 Rotating –
grooves, colored
dot.
 Ball – rib guides,
rotates.

91.  Scale
 Marked on/adjacent to tube
 Calibrated at in L/min
 Flow < 1L – ml/min, decimal fraction
 Lights

92.  Flowmeter tube arrangement
SAFE

93.  An oxygen leak from the flow tube can produce a
hypoxic mixture, regardless of the arrangement of
the flow tubes

94.  PROBLEMS WITH FLOWMETERS
Inaccuracy
 Improper assembly

May occur after service
 Improper calibration
 Dirt


Bobbin can get stuck, may not rotate, even if afloat
Flow meter indicates higher than actual flow
 Back pressure

Standards require back pressure compensation
 Improper alignment

If not vertical, annular opening asymmetrical, inaccurate
 Static electricity

If bobbin rotates normally, no inaccuracy

95.  PROBLEMS WITH FLOWMETERS
 Float damage

Float hitting the top when cylinder opened
 Bobbin stuck at the top
 Blocked outflow of the tube
 Flow control knob loose
 Inadvertent change of set flow

96.  ANTI HYPOXIA DEVICES
 “The anesthesia workstation standard
requires that an anesthesia machine be
provided with a device to protect
against an operator -selected delivery of
a mixture of oxygen and nitrous oxide
having an oxygen concentration below
21% oxygen(V/V) in the fresh gas or
the inspiratory gas”

97.  ANTI HYPOXIA DEVICES
 Mechanical device : Link 25 system
 Pneumatic device : Oxygen Ratio Monitor
Controller (ORMC)
 Electronically controlled : Penlon Ltd

98.  Mechanical device : Link 25 system
28 gears
14 gears

99. Mechanical device : Link 25 system
 N2O and O2 flow control valves are identical. A 14-tooth
sprocket is attached to the N2O flow control valve, and a
28-tooth sprocket is attached to the O2 flow control valve.
A chain links the sprockets. The combination of the
mechanical and pneumatic aspects of the system yields the
final oxygen concentration.

100.  Mechanical device : Link 25 system
 Not possible to deliver less than 25% O2
 Further safety feature : 25-250 ml/min basal flow of O2
 Limitations:
 Takes no account of gases other than nitrous (eg: air, He)
 Variations in gas supply pressure
 Low flow anesthesia– 25% may not be enough.

101.  Pneumatic devices
 Oxygen Ratio Monitor Controller (ORMC) (Drager)
 Depend on the balance of pressure exerted by O2 &
N2O on a coupled diaphragm
 Nitrous oxide slave control valve

102.  ORMC
An O2 chamber, a N2O
chamber, and a
N2Oslave control valve.
mobile horizontal shaft
The pneumatic input
into the device is from
the O2 and the N2O
flow meters
Resistorbackpressure
Movement of the shaft
regulates the N2O slave
control valve

104.  Electronically controlled anti hypoxia
device
 Paramagnetic O2 Analyzer
 N2O cut off when O2 < 25%

105.  BACK BAR
“describes the horizontal part of the frame of the
machine, which supports the flowmeter block,
the vaporizers and some other components”
 Flowmeter outflow to pop off valve
 Vaporiser heads are mounted
 Selectatec arrangement
 Common gas outflow
 Ends in non-return pop-off valve (30 -40 kPa=345
cm H2O)

106. BACK BAR
POP OFF
VALVE

107.  Uni directional check valve
 Positive pressure from
breathing system transmitted
of back
 Affects flowmeter readings
and vaporizer delivery
 Check valves incorporated
upstream of where O2 flush
joins FGF
 Great importance when
checking for leaks in machine

108.  COMMON GAS OUTLET (CGO)
 FGF into breathing system
 15 mm female slip in
 Coaxail 22 mm male connector
 Pressure delivered at outlet is 5-8 psig
 Not to be used to administer supplemental oxygen-
“inadvertant anesthesia”

109. PATHWAYS OF O2
Auxiliary

110. SAFETY FEATURES
Antistatic large castor wheels: 360
rotation
Front wheel locking bar
Small floor space 83 cm X 67 cm
Colour coded cylinders
Provision to accommodate 2 type E
cylinders
High pressure gas conduit tubing

111. SAFETY FEATURES
Pin index system
Pressure gauges
Pressure reducing valves
Oxygen fail safe device
Low pressure alarms
2 auxillary oxygen outlets

112. SAFETY FEATURES
 Flow meters:








Flow control valves, colour and touch coded
Oxygen knob; large, stands out
Minimium distance between knobs 25 mm
Recessed, guarded, bar protected knobs
Minimum 90 rotation required to change setting
Base rest for the bobbin
Rotating bobbin (slanted grooves/cuts at the top)
Long tubes, easy and accurate setting of flow

113. SAFETY FEATURES
 Flow meters:







Gas specific colour coded bobbin
Flouroscent dot on the bobbin
Position of the tubing
Top stop spring loaded
Arrangement of flowmeters, O2 flowmeter
downstream
Antistatic lumen of the tubes (tin oxide coating)
Back plate flouroscent

114. SAFETY FEATURES
 Non-return pop-off valve
 Trilene lock (Boyle F)
 Antistatic tubing, bag and mask
 Oxygen flush device
 Vaporiser arrangement (boiling pt, potency)
 Colour coded vaporisers
 Keyed filling ports of vaporisers

115. Places at which static electricity
charges can develop :1.At the wheels(eliminated with antistatic rubber).
2.At the yoke(use nonexplosive grease,Castro-sphirol).
3.At the flow meter (eliminated with antistatic spray like
Croxtene or Sphirol H).
4.At the junction of metal & rubber (use antistatic black
rubber).
5.At the red rubber E.T.tube & it’s connector(eliminated by
exhaled moisture)
6.At the sodalime canister(eliminated by exhaled moisture).
7.At the chain of cork in vaporizing bottle.(If the chain
breaks, a touch by someone carrying static charge can
cause spark).
115

116. PRE-ANESTHESIA CHECKLIST
First checklist – 1987
Revised in 1993.
Latest revision in 2008
Principle based as no one checklist
applies to all modern machine
models

117. 1.
Verify backup ventilation equipment is available &
functioning.

Contaminated oxygen supply,
Loss of oxygen supply pressure
Obstruction of the breathing system


So check for that Ambu!

118. 2. Check oxygen cylinder supply
 1 cylinder atleast half full (1000 psi)
 Not necessary to check N2O
 Close cylinder after checking

119. 3. Check central pipeline supplies.
 Check for proper connection at wall
 Check the pipeline pressure gauge- should read
approximately 50 psi.

120. 4. Check initial status of low pressure system.
 Check liquid level and fill vaporizers if necessary
 Fill ports tightly capped.
 Check vaporizer interlock.

121. 5. Perform leak check of low pressure system.
 Leaks as low as 100 mL/min may lead to critical
decrease in the concentration of volatile anesthetic
(creating a risk for intraoperative awareness), or
permit hypoxic mixtures under certain circumstances.
 Negative pressure leak test (10 sec.) is
recommended.
 Repeat for each vaporizer.

122. 6. Turn master switch on.
7. Test flowmeters.
 Damage
 Full range
 Hypoxic guard.

123. 8. Calibrate oxygen monitor
 Final line of defense against hypoxic mixtures.
 Calibrate/daily check: Expose to room air and allow to
equilibrate (2 min). Then expose to oxygen source and
ensure it reads near 100%

124. 9. Check initial status of breathing system
 Set the selector switch to Bag mode
 Check that the breathing circuit is
complete, undamaged, and unobstructed.
 Verify that the carbon dioxide absorbent is
adequate
 Install the breathing circuit accessory
equipment (e.g., humidifier, PEEP valve)
to be used during the case

125. 10. Test Ventilation systems and unidirectional valves
 Test ventilator – Bag on Y piece- look for adequate
tidal volume, filling of bellows at minimal flows.
 Check proper action of unidirectional valves.

126. 11. Perform leak test of breathing system
 High pressure leak test : Pressurise breathing system
to 30 cm H2O  10 seconds
 Open APL  pressure must decrease
 Bains : Inspection
Inner tube occlusion test
O2 flush test – Venturi effect

127. 12. Adjust and check scavenging system.
 Ensure proper connections between the scavenging




system and both the adjustable pressure limiting APL
pop-off valve and the ventilator's relief valve
Adjust the waste gas vacuum (if possible).
Fully open the APL valve and occlude the Y-piece
With minimum O2 flow, allow the scavenger reservoir
bag to collapse completely, and verify that the absorber
pressure gauge reads about zero.
With the O flush activated, allow the scavenger
reservoir bag to distend fully, and then verify that
absorber pressure gauge reads <10 cm H O

128. 13. Check, calibrate, set alarm limits of all monitors
 Capnometer
 Oxygen analyzer
 Pressure monitor with alarms for high and low airway
pressure
 Pulse oximeter
 Respiratory volume monitor i e , spirometer

129. 14. Check final status of machine
 Vaporizers off
 Bag/Vent switch to "bag" mode
 APL open
 Zero flows on flowmeters
 Suction adequate
 Breathing system ready

130. 15. “Anesthesia Time Out” – To be checked
immediately before induction :
 All monitors attached, functional?
 Capnogram, SpO2 waveforms?
 Flowmeter, vent settings proper?
 Manual/vent switch to manual and APL open?
 Vaporizers filled?

131. Repeat Check before each patient:
Suction
 Absorbent
 Vaporizers
 Breathing
circuit
Monitors/alarms
Anesthesia time out

132.  Minimum test under life-threatening conditions
1. High pressure test of the breathing circuit
2. Check patient suction
3. Observe and/or palpate breathing bag during
preoxygenation.
 This ensures adequate flow of oxygen
 Good mask fit (very important)
 The patient is breathing
 The Bag/Vent switch is on "Bag" not "Vent"
Checklist can be bypassed only a limited number of times

133. Thanks for your
attention