This document defines key concepts related to vaporisers such as vapor, vapor pressure, boiling point, and defines a vaporiser as an instrument that facilitates the change of a liquid anaesthetic into a vapor and adds a controlled amount to gas flow. It discusses factors that affect vaporiser performance such as carrier gas composition, temperature, back pressure and flow rate. It also classified vaporisers based on methods of regulating concentration and vaporization, and location in the breathing system. Modifications to vaporisers to address issues related to back pressure are described.

1. VAPORISERSVAPORISERS
DR. ANJU BHALOTRADR. ANJU BHALOTRA
MAMCMAMC

2. PHYSICS RELATED TO
VAPORISERS
• WHAT IS VAPOR?
• WHAT IS VAPOR PRESSURE?
• WHAT IS A VAPORISER?

3. DEFINITIONS
• VAPOR IS THE GASEOUS PHASE OF A
SUBSTANCE WHICH IS NORMALLY A
LIQUID AT ROOM TEMP. AND
ATMOSPHERIC PRESSURE
• GAS IS A SUBSTANCE WHICH EXISTS
ONLY IN THE GASEOUS STATE AT
ROOM TEMP. AND ATMOSPHERIC
PRESSURE

4. WHAT IS CRITICAL TEMPERATURE?
• FOR ANY SUBSTANCE THERE IS A MAXIMUM TEMP AT
WHICH IT CAN BE COMPRESSED SO AS TO CONVERT
IT FROM A GAS TO A LIQUID. THIS IS KNOWN AS
THE CRITICAL TEMP AND ABOVE THIS TEMP. NO
AMOUNT OF COMPRESSION WILL LIQUEFY IT.
• Under these conditions the substance is a GAS.
• Below that critical temp it is a VAPOR.
• CRITICAL TEMPS ; O2 is -118.4 degrees C
N2O is 36.5 degrees C
CO2 is 31 degrees C
The pressure required to liquefy a gas at its critical temp. is
the CRITICAL PRESSURE.

5. What is Vapor pressure?
• When a volatile liquid is enclosed in a
container, molecules of the liquid
break away and enter the space
above to form a vapor.
• These molecules bombard the walls
of the container creating a pressure
called vapor pressure.

6. What is Saturated Vapour
Pressure?
• For a particular liquid at a particular
temperature there occurs an
equilibrium at which the number of
molecules leaving the liquid equals
the number reentering
• It is the maximum VP at a particular
temp.
• Depends only on TEMPERATURE and
is independent of pressure

7. What is Boiling point?
• The temperature at which the SVP
becomes equal to the atmospheric
pressure. At this temp. all the liquid starts
to change into the vapor phase.
• If ambient pressure is decreased, so is the
boiling point

8. Boiling Point . SVP at 20o
C
(degrees C) (mmHg)
Ether 36.5 440
Trilene 87.5 57
Halothane 50.2 243
Enflurane 56.5 175
Isoflurane 48.5 238
Desflurane 22.5 669
Sevoflurane 58.6 160

9. Some more definitions
• What is Latent heat of Vaporisation?
• Specific Heat?
• Thermal Conductivity?
• Thermal Capacity?

10. What is the Latent heat of
Vaporisation?
• It is the amount of heat/ calories required
to convert 1 ml of liquid into vapor.
• Removes the more energetic molecules SO
that the temp. of the remaining liquid falls.
It is inversely rel. to ambient temp.
• SO-as vaporisation proceeds there a is
decrease in the vapor concentration
UNLESS some form of
thermocompensation is provided.

11. What is Specific heat?
• IT IS THE AMOUNT OF HEAT REQUIRED TO
RAISE THE TEMP. OF 1 gm OR 1 ml OF A
SUBSTANCE THROUGH 1 degree C
Significance
• LIQUID ANAESTHETIC AGENT-should have a
low specific heat so as to facilitate vaporisation
• VAPORISER CONSTRUCTION MATERIAL-
should have high specific heat; acts as a heat
sink; provides a more stable temp.
• Sp. Heat of water -1cal./gm/degree C
Cu - 0.095 cal/gm /degree C

12. Thermal Conductivity?
• Measure of the speed with which heat flows through a
substance
• Amount of heat that flows through unit area of a plate of
unit thickness in unit time per degree of temp. gradient
Significance
Vap. constructor material should be able to conduct heat
from surroundings to contained liquid
Cu has a moderate sp.heat and high thermal conductivity –
used for construction of vaporisers
Glass is a bad conductor (thermal insulator)
More recently use bronze/ stainless steel

13. Thermal Capacity?
SPECIFIC HEAT X MASS
Amount of heat stored in the
vaporiser body

14. THERMOSTABILISATION
?
• Utilisation of some means to minimise
temp. changes
• Construct vaporisers of materials with
high thermal conductivity and specific
heat to minimise temp. changes when in use
• Heavy metal parts act as a heat reservoir
• Wicks to be in contact with the metal part
so that heat loss due to vaporisation is
quickly replaced
• Immerse vap. chamber in a large mass of
water

15. THERMOCOMPENSATION
?• Some means to maintain the vaporiser
output constant despite any temp. changes
• Alteration in the splitting ratio (automatic
compensation)
Eg. Bimetallic strip in tec vaporisers,
ether filled bellows in penlon vaporisers,
EMO
• Computer control - electronic vaps
• Manually adjust flow - measured flow,
drager Vapor (TILC)
• Supplied heat -tec 6 (electrically heated)

16. PARTIAL PRESSURE
• DALTONS LAWS RELATING TO PARTIAL
PRESSURE-
(1)if several vapors/gases (having no chemical
action on each other) are confined in a space, the
total pressure P= P1+ P2+ P3 ( if seperately
confined in the same space)
(2)The maximum pressure exerted by a particular
vapor in a closed space depends only on NATURE
OF LIQUID and the TEMPERATURE and NOT on
ambient pressure
It is an absolute value which correlates with
anaesthetic depth

17. CONCENTRATION OF
VAPOR
May be expressed as
VOLUME %
OR
PARTIAL PRESSURE

18. VOLUME %
• Commonly used
• It is the number of units of volume of a gas in
relation to a total of 100 units of volume for the
total gas mixture
• Is a relative ratio of gas molecules in a mixture
vol % /100 = partial pressure/total pressure
OR
Vol % = pp/tp x 100
• Easy parameter to calculate

19. PARTIAL PRESSURE VOLUME %
Expresses an absolute
value
Is relative ratio of gas
in a mixture
Pp / tp is equal to Vol % / 100
Uptake / depth of
anaesthesia are directly
related to pp
Indirectly related
Given pp same
anaesthetic potency
under various
barometric pressures
Not so

20. What is MAC ?
• Typically expressed as vol% of
alveolar gas at 1 atm at 1 atm.
• Eg. MAC of halothane is 0.75
enflurane is 1.68
isoflurane is 1.15
desflurane is 6.0
sevoflurane is 2.1

21. What is MAPP ?
• Minimum alveolar partial pressure
(MAPP)
• Expresses MAC in terms of pp (P
mac1)
• MAC of hal is 0.75
pp of hal for 1 MAC is
0.75/100 x 760 = 5.7 mm Hg
• Pmac1 of des for is
6/100 x 760 = 45.6 mm Hg

22. What is a Vaporiser?
• A VAPORISER IS AN INSTRUMENT DESIGNED
TO FACILITATE THE CHANGE OF A LIQUID
ANAESTHETIC AGENT INTO A VAPOR
AND
ADD A CONTROLLED AMOUNT OF THIS
VAPOR TO THE FGF
• The SVP of most inhalation agents is MUCH more
than is required to produce anaesthesia i.e. 32%
vs 0.75 or 243mm Hg vs 5.7 mm Hg for halothane
• Need to dilute this vapor with the carrier gas and
deliver a controlled amount of this vapor to the
patient

23. Terminology for
Vaporisers
• PLENUM - FGF is pushed into the
vaporiser , high resistance
• DRAWOVER - gas is pulled into the
vaporiser by the patients own
inspiratory effort, low resistance eg.
Goldman, EMO, OMV, BSIU
• INHALER - a drawover vaporiser in
which the carrier gas is air

24. CLASSIFICATION OFCLASSIFICATION OF
VAPORIZERS.VAPORIZERS.

25. OLDEST
CLASSIFICATION.
METHOD OF REGULATING OUTPUT CONCENTRATION.
1. VARIABLE BYPASS
2. MEASURED FLOW
METHOD OF VAPORIZATION
1. FLOW OVER - WITH WICKS.
- WITHOUT WICKS.
2. BUBBLE THROUGH
3. FLOW OVER OR BUBBLE THROUGH
LOCATION
1. OUTSIDE THE BREATHING SYSTEM
2. INSIDE THE BREATHING SYSTEM
TEMPERATURE COMPENSATION
1. NONE
2. BY SUPPLIED HEAT
3. BY FLOW ALTERATION
SPECIFICITY
1. AGENT SPECIFIC
2. MULTIPLE AGENT

26. OLDER CLASSIFICATION.
METHOD OF REGULATING OUTPUT CONCENTRATION
1. CONCENTRATION CALIBRATED
2. MEASURED FLOW
METHOD OF VAPORIZATION
1. FLOW OVER
2. BUBBLE THROUGH
3. INJECTION
TEMPERATURE COMPENSATION
1. THERMOCOMPENSATION
2. SUPPLIED HEAT
SPECIFICITY
1. AGENT SPECIFIC
2. MULTIPLE AGENT
RESISTANCE
1. PLENUM
2. LOW RESISTANCE

27. NEWER CLASSIFICATION.
METHOD OF REGULATING OUTPUT
CONCENTRATION
(1) Conc. Calibrated
(2) Measured flow
METHOD OF VAPORISATION
(1) Flow over
(2) Bubble through
(3) Injection
TEMP. COMPENSATION
(1)Thermocompensation
(2) Supplied heat

28. MEASURED FLOW
VAPOURISER
• Use a measured
flow of carrier gas
to pick up agent
• (1) Vaporiser-
body, filler port
and thermometer
(2) flowmeter
assembly
(3) on/off valve

29. Calculations for output in
measured flow vaporisers
• Set 100ml/min flow of carrier gas (oxygen) from dedicated
flowmeter
• SVP of hal in vap. chamber is 243 mmHg
• Hal forms 243/760 x100= 32% of gas mixture
• Carrier gas will occupy the rest of the vol i.e. 100-32= 68%
• This 68% is occupied by 100 ml/min carrier gas
• And 32% hal will be = 100/68 x32 = 47 ml
• Gas exiting is 147ml with 47 ml hal vapor
• To get a mixture containing 1% hal this 47 ml should be
diluted in 4700ml.
• Required carrier gas is 4700-147= 4553 ml
• If set 100ml measured flow to vaporiser, usually set 5
L/min flow of carrier gas to get 1% halothane
• Ratio of gas through vaporiser:main gas flow is
100:4600=1:46

30. Conc. Calibrated vaporiser
• Total FGF goes through the
vaporiser
• Picks up a predictable conc. of
vapor & flows to CGO
• Ratio of bypass gas to gas going
to vc is called Splitting Ratio
(for 1% hal is 1:46)
• Depends on res. of the 2
pathways (controlled by conc.
Control dial & thermocomp.
valve)
• Agent conc. is controlled by a
single calibrated dial
• Machine std

31. Method of Vaporisation
• Flow over; a stream of gas passes over
liquid surface. Enhance vaporisation by
increasing gas-liquid interface e.g. baffles,
spiral tracks, wicks
• Bubble through; break gas up into small
bubbles e.g. sintered diffuser, cowl in
Boyles Bottle (depth of liquid, size of
bubbles)
Attempt is to fully saturate the gas leaving
the vaporising chamber

32. Factors affecting rate of
vaporisation
• Volatility of the agent
• Surface area of contact between gas &
liquid
• Flow rate of gases over the liquid
• Temperature of the liquid
• Height of gas flow above liquid

33. Injection technique
• Inject a known amount of liquid –from a reservoir in the
vaporiser or from an agent bottle into a known volume of gas
• 1 ml of halothane = ? ml hal vapor
• Avogadros hypothesis
197.4 g of halothane occupies 22.4 l at STP
At 20 degrees C (293 K)
Charles Law- V1/T1 = V2/T2 = 22.4/273 = V2 /293
= 24.04 L
1 gm will give 24.04/197.4 L
Density of hal is 1.86 so 1 ml weighs 1.86 gm
1 ml will give 24.04/197.4 x 1.86 = 0.226 L = 226 ml
If FGF is 6000 ml/min for a 1% conc need 60 ml vapor or 0.25 ml
liquid halothane / min
How much liquid agent does a vaporiser use per hour?
Ehrenworth & Eisenkraft (1993) gave formula
3 x FGF (L/min) x vol % = ml liquid used per hr

34. VOC/VIC
• All contemporary vaporisers are for use
outside the circuit as they all offer high
resistance to gas flow
• If situated within the circle (VIC) should have
negligible resistance
• In VIC pts expired air passes through the
vaporiser- conc. of volatile agents will be
increased by rptd passage of gases through
the vaporiser- vap should be inherently
inefficient
• Should not have cloth wicks (sodden with
water vapor)
• E.g. of low res. Vaps ; Goldman, Mckesson,
Rowbotham

35. Factors affecting
Vaporiser performance
• Pumping /pressurising effect
• Carrier gas composition and rate
• Extremes of temp.
• Barometric pressure
• Gas direction
• Anaesthetic agent

36. EFFECTS OF BACK
PRESSURE
• PUMPING EFFECT ( Hill & Lowe
effect)
• PRESSURISING EFFECT ( Cole
effect)
INTERPLAY

37. EFFECT OF BACK PRESSURE.
PUMPING EFFECT
 HIGHER CONC. THAN
INDICATED ON
DIAL DELIVERED.
- LARGE PRESSURE
FLUCTUATIONS
- LOW DIAL SETTING
- LOW FLOW RATE
PRESSURISiNG
EFFECT
 LOWER CONC. THAN
INDICATED ON
DIAL DELIVERED.
- LARGE PRESSURE
FLUCTUATIONS
- LOW DIAL SETTING
- HIGH FLOW RATE

38. Mechanism of Pumping
effect

39. Mechanism of
Pressurising effect

40. MODIFICATIONS
• CONC. CALIBRATED VAPORISERS
• Decrease size of v.c.
• Increase size of bypass
• Increase overall resistance to airflow through the
vaporiser
• Long spiral tube leading to the v.c.
• Incorporate an expansion chamber
• Exclude wicks from the inlet
• Pressurise the vaporising chamber-Drager 19.1
Vapor-release of upto 200 mbar

41. MODIFICATIONS(ctd)
• MEASURED FLOW VAPORISERS
• Decrease size of the vaporising
chamber
• Longer outlet tube
• Check valve to prevent backward flow
• Relief valve to limit maximum
pressure

42. MODIFICATIONS (ctd)
• ANAESTHESIA MACHINE
• Pressure relief valve
• Check valve at outlet of the
vaporiser –Fluotec 2
• Check valve upstream to junction
with the oxygen flush

43. Carrier gas composition
• Most vaporisers are calibrated using 100% O2
• Addition of air – little change
• Comp.of carrier gas affects output in many
(vaporiser aberrance)
• If add N2O
Temporary effect –decreased output (25% less
with 100% N20) due to solubility of N2O in agent
(about 4.5 ml in 1 ml). As N2O dissolves in liquid
anaesthetic ,flow of gases exiting vaporiser
decreases
Once saturated with N2O, output gradually
increases but is less than before (10% less with
100% N2O)

44. FGF rate
• At high dial concentrations and high flow
rates, output may be less
-due to high flows ,saturation may be
incomplete
-also due to high demand, may cause a fall
in temp. and hence vaporisation rate
-incomplete mixing in vap. Chamber
At low flow rates(<250 ml/min) output
less due to inability of FGF to push heavy
vapor

45. Extremes of temp.
• In spite of methods of
thermostabilisation and
thermocompensation, there are still
limitations as the function of all the
temp. compensating devices vary
linearly with temp. while SVPs of
volatile agents vary nonlinearly with
temp.
• With rise in temp-decrease viscosity
of fluids and increase viscosity of
gases

46. EFFECT OF BAROMETRIC PRESSURE
VAPORIZERS ARE CALIBRATED AT
STANDARD (SEA LEVEL) ATMOSPHERIC
PRESSURE
LOW BOILING POINT , HIGH SVP AGENTS
ARE MORE SUSCEPTIBLE TO INFLUENCE
BY BARO. PRESSURE.
VP of agents is independent of barometric
pressure
Anaesthetic potency depends on pp

47. LOW ATMOSPHERIC PRESSURE.
CONC. CALIBRATED VAPORISERS.
DELIVER HIGHER CONC. IF MEASURED IN VOLUME %
BUT DELIVER SAME PARTIAL PRESSURE SO CLINICAL
EFFECT UNCHANGED
c’p’=cp or c’= cp/p’
At 0.5 atm, c’= c x 1/0.5= 2%
SMALL DEVIATIONS IN PERFORMANCE DUE TO
ALTERED SPLITTING RATIO ( less gas density so
increased flow through the vaporisng chamber)
MEASURED FLOW VAPORIZERS
.
DELIVER INCREASED P.P & VOLUME % INCREASED EVEN
MORE

48. HIGH ATMOSPHERIC PRESSURE.
• CONC. CALIBRATED VAPORISERS.
AT 2 ATM.- CONC. IN VOL. % IS HALF
- EFFECT ON PP. IS LESS
INCREASED DENSITY OF GAS  INCREASED
RESISTANCE THROUGH VAP. CHAMBER 
DECREASED VAP. OUTPUT (IN BOTH PP. AND
VOL. %)
.
• MEASURED FLOW VAPORISERS.
DECREASED CONC. IN BOTH PP. AND VOL. %

49. IDEAL VAPORISERIDEAL VAPORISER
• DELIVER A FIXED DESIRED CONC. (EQUALDELIVER A FIXED DESIRED CONC. (EQUAL
TO CONC. ON DIAL SETTING)TO CONC. ON DIAL SETTING)
• INDEPENDENT OF TEMPERATURE , FLOWINDEPENDENT OF TEMPERATURE , FLOW
RATE AND CARRIER GASRATE AND CARRIER GAS
• NO EFFECT OF BACK PRESSURENO EFFECT OF BACK PRESSURE
• EASY TO MAINTAIN AND CLEANEASY TO MAINTAIN AND CLEAN
• AGENT SPECIFICAGENT SPECIFIC

50. ASTM Standards
• (1) Vap must be capable of accepting 15L/min and
deliver predictable vapor conc.
• (2) effects of condns of use in manual
• (3) influence of temp/inflow rates to be stated
• (4) must be a system to isolate vaps from each
other
• (5) controls to limit escape of vapor from vc so
less than 0.1% is delivered in off
• (6) knobs to turn counterclockwise to increase
• (7) must have liquid level indicator visible from
front
• (8) cannot be overfilled

51. ctd
• (9) must allow calibrated flows of O2 &
N2O in ON & OFF and not discharge liquid
through outlet when mounted
• (10) if unsuitable for use in breathing
system, noninterchangeable 23 mm
fittings; inlet to be male, outlet to be
female, direction of gas flow to be marked
• (11) if suitable for use in breathing system,
standard 22 mm fittings ; inlet to be
female, outlet male and direction to be
marked.

52. Specific vaporisersSpecific vaporisers

55. OPEN DROP METHOD
• Vaporisation in air (1847-Simpson)
• Schimmelbusch mask
• Other modifications –Yankauers, Chadbourne, etc
• Bottle to pour- Bellamy Gardner
amber coloured
control on pouring
capacity -90 ml ether
• Gamgee with central hole/cover face
• Eye ointment
• 16 layers gauze for ether
• Drop ether evenly over whole area
• Gradually increase no. of drops/ min.
• (for chloroform/ethyl chloride use 12 layers
of gauze/1 layer lint and drop chloroform over
only half the area)

56. INDUCTION
• WITH ETHER
• RATE OF DROPS
1ST
min = 12 drops = 1 %
2nd
min = 25 drops = 3 %
3rd
min = 50 drops = 6 %
4th
min = 100 drops = 10-12 %
• ETHYL CHLORIDE - 3 to 5 ml - 3 to 5 %
• Rate of drops
1st
min = 30 drops
2nd
min = 60 drops
3rd
min = 90 drops

57. MAINTENANCE
• Conc.for maint. with ether is 6 -8 %
• Heat loss = 200-300 cal/min
• Temp. above and below mask = 2-3 degrees < room
temp.
• Temp. at mask = 0 – 1 degrees C
• Gas comp.under mask
0% ether = 80% N2 + 20% O2
5% ether = 76% N2 + 18% O2
10% ether = 72% N2 + 16% O2
Add O2 – risk of explosion
Rise in CO2

58. ADVANTAGES
• EASY ADMINISTRATION
• LOW DEAD SPACE-40-60 ml
• LOW RESISTANCE
• WIDE MARGIN OF SAFETY
• FOR RURAL AREAS
• CHEAP

59. DISADVANTAGES
• WASTEFUL
• OT POLLUTION
• UNKNOWN CONCENTRATION DELIVERED
• COOLING OF MASK/ ICE CRYSTALS – RES.
TO BREATHING, NEED SPARE MASK
• FACE/ EYE BURNS
• EXPLOSION(SPECIALLY WITH O2)
• CO2 ACUMULATION UNDER MASK
• MORE SKILL REQUIRED
• CANNOT GIVE IPPV

60. Others
• Add frame to “keep the ether in “ in
an enclosed area – permitted some
degree of rebreathing -SEMIOPEN
• Eg. Ogston inhaler
• Junkers chloroform apparatus
• Flagg can
• Boultons jar

61. EMO VAPORISER

62. EMO
1941 –Mendedelsson-Oxford vaporiser
1952- Epstein, Macintosh, Oxford Vaporiser
CLASSIFICATION
1. Concentration calibrated
2. Flow over with wick
3.Temperature compensation by supplied heat &
flow alteration
4. Agent specific (hal, ether, chloroform, trilene,
hal/ether azeotrope)
5. Low resistance(<1.25cm water at 40 Lpm flow)
6. Inhaler

63. • Wt- 6.5 kg ; ht
24cm ;dia 23cm
• TRANSIT position-
seals ether chamber
• CONTROL lever-upto
20%
• INLET/OUTLET – R
to L
• TAP for filling
/draining water
chamber at bottom
• Outlet(male)
inlet(female)

64. Ctd
• FILLER-depress to fill (control lever at 0-
not transit- for air to escape) springs back
automatically except Mk 1 (hazard-if leave
open pt will draw in ether –increase
output)
• LEVEL INDICATOR- moves only after
150 ml ; add 300ml for full (fill with
control at 0 –not at ‘in transit’
• TEMP.INDICATOR-rod with black & red
bands and metal top
20-25 degrees-black line with metal top
>32 degrees – red band- temp above
working range

65. Int. structure
• CLASSIFICATION • Air enters inlet (oxygen
added here)
• Mixing chamber (air from
inlet and carrying vapor
from v.c. mix here)
• Vaporising chamber-
donutshaped, wicks
• Control lever, on-off valve
at inlet of v. c
• Inlet relief valve- opens if
inlet blocked
• Water reservoir-
1250cc,
(Al in Mark I, stainless
steel in MarkII, III)

66. EMO(ctd)
• Thermocompensation mechanism at outlet
of v.c.
– metal bellows with liquid Ether[ether capsule]
& connected to plunger
– temp. range; 15-29 degree Celsius
• Water jacket serves as heat reservoir
Checks
(1) check level indicator-put “in transit”-invert –
chould fall to full
(2) close outlet- connect OIB to inlet- put”in
transit”- press bellows- open filler –no air
should escape
(3) release filler-set at 10% -rpt above
(4) attach bellows to outlet-block inlet –set at 2
% -suck air – should hear a hissing if safety
release valve is working

67. EMO(ctd)
• Care-Mark I--empty Al water jacket every 3 months,
Mark II & III- yearly water check
EVALUATION
1. Calibration of EMO is accurate only for
intermittent gas flows; maintains output at 5-13L/min
flows.Highest conc. delivered 16%. If use as plenum
i.e. blow air into it –increase output
2. Climate; Cool-add antifreeze (2% glycol)
Warm- cool by allowing agent to vaporise
-refrigerate
-air will deposit water in cooler vc
3. Splashing during transit if in ON position.
4. Sticking of rotor-PTFE coating in Mk4 (Stetson)
5. Advantage- compact, low cost, portable, mass
casualties, no effect of altitude,easy maintenance, no
need for sterilisation

68. Oxford inflating bellows
• Spring loaded
concertina bellows
• 6 bellows -150 ml
each
• 2 unidirectional
flap valves
• Ramaraos modifn
(for O2)
• Magnet to
inactivate distal
unidirectional valve

69. Spontaneous ventilation

70. Assisted ventilation

71. Assisted ventilation

72. EMO and paediatric
• Dead space too high
for babies
• Use paed entrainer
for O2 at inlet
• Use 50% N2O in O2
• EMO is used as a
plenum/constant flow-
needs about 10 Lpm
flow
• Use bellows in closed
position & attach T
piece circuit
• NO MAGNET

73. BSIU
• Facilitates induction
of ether anaesthesia
with halothane.
• Connected to outlet of
EMO; no controls
• Weight 450gms,
5.7cm in dia, 12cm ht
• annular well at top
holds 4ml of halo
• brushed nylon wick
absorbs 3ml of halo
• large baffle deflects
air down onto the wick
• delivers 2-4% halo for
3-4 min
• Low res-2-3 mm H2O

75. CLASSIFICATION(OMV)
• 1966(Macintosh and Epstein of Oxford)
• Conc calibrated
• Flow over with wick
• Temp compensation by supplied heat
• Low resistance
• Multiple agent

76. OXFORD MINIATURE VAPORISER(OMV)
• Simple portable inhaler
• for less volatile agents - halo,trilene, mf, chloroform
• Farly accurate over a short period of time
• 13.5 cm high,1060 gms with full water jacket.
• Control lever, alternative scales for halo(0-4%),tri(0-
1.5%), methoxy (0-0.6%)
• water jacket at base with 25% glycol
• Body stainless steel/wicks of stainless steel gauze
• Plugged into outlet of EMO-performance unaffected by
IPPV- can place on pt side of bellows
• Highest conc delivered 3.5% hal

77. OMV (ctd)
• Special filler with 2 springs
light pressure-air relief
more pressure-opens filler
• Funnel around filler has capacity of 10ml, covers 1/8th
of level indicator. A second 10ml can be added
• cleaning-drain by tipping after pressing filler lever,
wash out with alcohol or Ether.
• If used with EMO flow is R to L
• Another version for use with continuous flow machine
then flow is L to R
direction of gas flow marked with an arrow
Disadvantage of OMV-only 30 ml ;cannot mount on
backbar

78. OMV 50
• OMV 50- body deepened-hold 50 ml (3 hr
anaesthetic)
-Clamp for mounting on the back bar
- combined sight glass and filler
-some changes in int. gas passages
-suitable for use in system and as inhaler
-max. conc. delivered 3 %

79. Copper Kettle
• Classification
• Measured flow
• Bubble through
• Out of system
• Temp. compensation
by supplied heat and
manual flow alteration
• Multiple agent
• 2 models -400ml/ 160
ml

80. COPPER KETTLE
• Constructed of Cu
• Measured gas-centre tube-
surge chamber –passes
down around centre tube –
enters diffuser- sintered
bronze disc- bubbles –
vapor laden gas rises –
discharge tube
• 2 models – 400ml/ 160 ml

82. BOYLES BOTTLE
CLASSIFICATION
1. Concentration calibrated
2. Flow over or bubble through
3. No temp. compensation
4. Multiple agent(ether, hal,
trilene)
5. Out of system

83. – ETHER BOTTLE

85. Boyle Bottles
• Ether Bottle
• Larger vc-300 ml filled fully
• U tube & hood of Cu
• Has 4 lines between off & on-begins to
operate at 2nd
mk
• Trilene bottle -100ml for ½ inch liquid
depth
• Chrome plated U tube& hood; cowl
adjusted by stainless steel plunger
• Delivers 0.5-2 %
•

86. Boyle Bottles
• Halothane bottle
• Uses only control tap –no
plunger/hood
• Control lever marked 1-10 (8%)
starts at 3 , at 4 about 1%
• Inlet tube plugged at end; hole on
side 1 cm above

87. BOYLES BOTTLE
• FACTORS AFFECTING OUTPUT
1. Temp. of liquid
2. Plunger level
3. Control lever position
4. Level of liquid
5. Eccentricity of hood
6. Agitation of vaporiser as during
pouring of liquid in bottle(>5%x 15
secs)

88. BOYLES BOTTLE
• CARE & CLEANING
• Empty after use/allow to dry
• special grease for free rotation of drum
• Plunger loose-tighten the gland nut
• replace packing in gland nut-cotton,
neoprene, nylon
• bottle may chip off leading to leakage
• bottle washer may get damaged
• pressure build up in unused ether bottle
• static charges on cork-chain

89. Boyle bottles
• PRECAUTIONS
• While filling?
• When putting on –ether surge?
• To increase vaporisation?
• What is risk if cork chain is broken?
• Prevent agitation when moving?

91. Low resistance vaporisers
• Goldman, Mackesson
• CLASSIFICATION
• 1. Concentration
calibrated
• 2.Flow over without
wick
3.No temperature
compensation
4. Multiple agents-
Halothane , trilene
5. In or out of system

92. GOLDMAN VAPORISER
• Small glass bowl
• Capacity 20 cc
• Bowl attached to a head, which
divides gas between bypass and
vaporising chamber
• Control lever at top; max. conc
delivered at 3rd
mark of 2.21%
• Young modification -Added a wick
• Halls modification-2 in series

93. GOLDMAN VAPORIZER
MARK I MARK II MARK III
1. Self locks Click stops No locking
in off position in each setting
2. DIVISIONS Off-1-2-3-ON Off-1-2- ON
Off -1-2-3-ON
3. Max conc Max conc Max conc
delivered at delivered at delivered at
3 position. 3 position. On.

94. ROWBOTHAM
VAPORISER
• Has a wire gauze
wick
• 2marks to fill till
• Top mark/ blue
mark
• Max. at full on
3.10%

95. ADVANTAGES
• Portable
• Easy to operate
• Low resistance-used as VIC
• Calibrated at high flows of 30 Lpm so
safely use with O2 flush
• Small, inexpensive
• Safe- cannot deliver high conc.’s

96. DISADVANTAGES
• No temperature compensation- Level
of halothane kept at full mark
• Tilting - pouring of liquid in
respiratory tract
• Back pressure or pumping effect
• Small capacity vaporising chamber -
so delivers low halothane
concentration.
• agitation/splashing -5%

97. LOOSCO
• Improved plenum
vaporiser
• TILC vaporiser
• Single rotatory control
tap fitted with a
bimetallic strip
thermometer
• Output is read from a
calibration chart
• Bronze plunger fitted
with nylon liners

98. Precision vaporisers
• Include Ohmeda Tec series, Drager
Vapor 900 series, Forreger, Penlon,
Ohio
• Vc has network of wicks/channels to
ensure emerging gas is saturated
with vapor

99. TEC VAPORISERS

100. TEC 2

101. TEC 2 VAPORISER
• CLASSIFICATION
• Concentration calibrated
• Flow over with wick
• Temp. compensation by automatic
flow alteration
• Agent specific (halo, methoxy)
• Out of system
• plenum resistance

103. TEC 2
• Spindle pulled out & rotated
anticlockwise, concentration 0-4%
• Sight window on side for liquid
• Filling tap at side, drain at bottom
• V.c round, capacity 135 ml with series
of concentric, circular wicks
• Bimetallic strip at outlet of v.c.-Ni-
Cu

104. TEMP. COMPENSATION
(TEC 2)

105. TEC 2
• Evaluation of
performance -V.
inaccurate at low flows
below 4 l/min
• < 1 Lpm flow & < 3%-
delivers less
• >3% & flows 2 Lpm –
delivers more
• V. little change in
output <0.5%

106. TEC 2 evaluation
• Not accurate at flows below 4 l/min
• Addition of N2O increases vapor output at dial set below 1%
• Back pressure plays a significant role at flows < 2 Lpm
• CARE
• Drain every 2 weeks ,discard as THYMOL accumulates
• Sticking of spindle and bimetallic strip occurs
• HAZARDS
• Tipping
• Agitation
• Reverse flow

107. TEC 3

108. Classification
• Conc. Calibrated
• Flow over with wick
• Out of system
• Temp. compensation by flow
alteration
• Agent specific

110. Construction
• Conc. Control dial is on top with +ve
catch at OFF
• Calibrated from off to 5% in 0.5%
gradations
• Locking lever to be depressed before
dial can be turned
• Screw cap filler with drain at bottom
• Optional pin safety system for filling
• Sight window for liquid level on left

111. Int. structure
• Completely redesigned
• Has 2 sections-lower v.c and upper duct
and valve system
• 2 bypass channels-one directs gas stream
over bimetallic strip
• Bimetallic strip at inlet of 2nd
bypass
• Gas exits vc by way of the control channel
and joins gas coming from the bypass
• Bypass is located concentrically within the
vc

113. TEMP. COMPENSATION
(TEC 3)

114. TEC 3
• METHODS TO REDUCE EFFECT OF
INTERMITTENT BACK PRESSURE
• LARGER BYPASS
• VOL OF VC IS REDUCED
• TUBE LEADING TO VC LONGER
• EXPANSION AREA IN THE INLET TUBE
• WICKS EXCLUDED FROM AREA OF VC
NEAR THE INLET

115. TEC 3
• Accur.
falls off
at high
flow
rates &
dial
settings

116. TEC 3
• EVALUATION
• accurate at lower gas flows, improved
vap. Due to increased area of wicks, less
effect of carrier gas, pumping effect, flow
rates
• Performance in 0-0.5 % range governed
mainly by conc. dial & less by FGF
• HAZARDS:
• FAULTY LOCKING LEVER,
• TIPPING TO 180 DEGREE INCREASES
CONCENTRATION DELIVERED TO > 12%
• LEAKS SMALL AMOUNT OF VAPOUR IN OFF
POSITION
• REVERSE FLOW INCREASES OUTPUT

117. TEC 4

118. TEC 4
• CLASSIFICATION
• CONSTRUCTION
• Entire new look-CONTROL DIAL AT TOP –
release button to the left which must be
depressed to turn on
• LOCKING LEVER AT THE REAR-connected
to control dial so vap. can only be turned
on once locked on the manifold
• TWO FILLING MECHANISMS
• SCREW CAP WITH A DRAIN PLUG
• KEYED FILLING DEVICE

119. Int structure
• OFF-gas-inlet-bypass-outlet
• ON-gas stream split-bypass
vc (surrounds bypass)
before vc gas flows along the sides
along 2 concentric wicks surrounding
a copper helix – vc –flow past rotary
valve -outlet

121. TEC 4
• EVALUATION
• LESS PRECISE AT LOWER & VERY HIGH FLOW
RATES
• ACCURATE IN PROXIMITY OF MRI MAGNET
• N2O DECREASES OUTPUT
• SURGE IN OUTPUT ON OPENING
• TIPPING UPTO 180 DEGREES HAS NO EFFECT
• INABILITY TO TURN ON 2 VAP’S AT SAME TIME
ON BACK BAR
HAZARDS
REVERSE FLOW INCREASES OUTPUT
LEAKAGE OF AGENT IF INADVERTENT LOOSENING
OF DRAIN PLUG
OVERFILLING OF KEYED FILLING VAPORISER IF
VAPORISER IS IN ON POSITION OR BOTTLE
ADAPTOR IS LOOSE

123. TEC 5
• CLASSIFICATION
• CONSTRUCTION
– TOP CONTROL DIAL
– LOCKING LEVER AND RELEASE BUTTON
– SIGHT GLASS-BOTTOM RIGHT
– KEYED FILLING DEVICE
• FILLING DRAINING PORT
• LOCKING LEVER TO SECURE FILLER BLOCK
• SMALL LEVER AT BASE ALOWS LIQUID TO
BE ADDED OR DRAINED
-SCREW CAP WITH DRAIN PLUG

124. TEC5
• INTERNAL BAFFLE SYSTEM
• EVALUATION
– GREATER ACCURACY AT FGF OF
5L/MIN AND DIAL SET<3%
– MORE PUMPING EFFECT THAN TEC 4
– ACCURACY MAX 15-35 DEGREE
CELSIUS

125. TEC 5 INT. STRUCTURE
• INTERNAL
BAFFLE SYSTEM
• Vc lies within the
bypass which lies
along side of the
vaporiser
• Bimetallic strip in
the base
• Before reaching vc
–helical IPPV
assembly-spiral
wick

126. TEC 5
• EVALUATION
• ACCURATE AT FGF 5 Lpm & dial settings
< 3 %
• Improved key filler
• Easier mech. to switch on rotary valve
&lock with one hand
• HAZARDS
- more prone to pumping effect than tec 4
- large liquid loss if filling port is opened
- overfilling-bottle adaptor loose,
vaporiser ON
-reverse flow increases output

127. TEC 6

128. TEC 6 FOR
DESFLURANE
• CLASSIFICATION
• Conc calibrated
• Injection
• Thermocompensation
by supplied heat
or
Electrically heated,
dual circuit Gas /
Vapor blender

129. INT. STRUCTURE
• Electronically powered and controlled
• Des heated to 39 degrees by H
• VP 1300mmHg in sump
• FGF restricted at O; sensed by
differential pressure transducer P
and adjusts resistor R1
• Control dial adjusts 2nd
resistor R2

130. TEC 6
• H-heater
• O-fixed orifice
• P-differential
pressure
transducer
• R1-adjusted by P
• R2-adjusted by
control dial

131. Effect of barometric
pressure
• Works at absolute pressure- It maintains a
constant output in terms of vol % but pp varies
• If atm pr decreases-output in pp is also
decreased
reqd dial setting=dial settingx760/ambient
pressure
Effect of carrier gas; addition of N2O-less
viscosity-decrease vapor output
Mounting
Far rt side of machine
Bottle
Has a spring valve to prevent escape of agent

132. TEC 7

133. Tec 7
• Accurate through clinical flow range
• Easy turning dial to allow lt or rt hand
operation
• Smaller graduations for accuracy
• 3 filling options
Datex Ohmeda Easy Fil (patent pending)
funnel fill
Easy Fil (for sevoflurane)
Non spill system
prismatic sight glass

134. DRAGER VAPOR
• Most accurate
• Classification
• Conc calibrated
• Flow over with wick
• Out of system
• Temp. compensation
by manual flow
alteration
• Agent specific

135. TEMP. COMPENSATION
(DRAG)
• Annular valve
formed of 2
dissimilar metals
increases flow thru
bypass when temp.
rises

136. DRAGER FLOW
• V. accurate at all
dial settings over a
wide range of flow
rates

137. SIEMENS
Classification
• Conc calibrated
• Injection
• No thermocompensation

138. ALADIN CASSETTE
• classification
• Conc calibrated
• Flowover
• Automatic
thermocompensation
• Use with datex-
Engstrom AS/3 ADU

139. Obstetric inhalers
• Emotril
• Cyprane
• Provide TV 250-1000
ml; work over RR’s of
12-30/min; res of
breathing to be <1.25
cm H2O at 30 LPM

140. Agent specific filling device
• Keyed bottle collar
– Two projections -- one thick & one thin
to mate with corresponding indentation
on bottle cap of adaptor tube
• Adaptor tube -- one end bottle cap,
the other end of the tube called
filler block which fits into vaporiser
receptacle

141. TEC 4 (KEY FILLER)

142. TEC 4 (KEY FILLER)

144. TEC 4 (FUNNEL FILLER)

145. TEC 4 (FUNNEL FILLER)

150. KEY FILLERS

151. KEY FILLER

152. KEY FILLER

153. Interlock Devices
• Applied to control dial of vaporiser so that
only one vaporiser can be turned on at a
time.
• Ensure that
-only 1 vap. is turned on at a time
-gas only enters that which is on at that
time
-trace vapor output is minimised when
OFF
-vap.’s are locked onto gas circuit, hence
correctly seated

154. Selector valve
• Directs flow to only one vaporiser
while isolating other vaporisers from
machine circuitry
• unless selector device is combined
with an interlock device operator may
dial a concentration on a vaporiser
which is not connected to fresh gas
line and expected concentration not
delivered

155. Selectatec system
• Pair of port valves
for each vap
• Vap is mounted and
locked
• When ON 2 plungers
open the valve ports
& activate extension
rods that prevent
other vaps

156. BACK BAR DEVICES
• Ohmeda selectatec –has
pins in manifold linked
to control dial
• If one on –extend to
prevent other

157. OHIO SWITCH
• Allows lt, centre,
rt to be used
• Slots in selector
line up with flanges
on vap control dial

158. DRAGER LOCK
• For Drager 19.2
has rotating bar
on manifold with
teeth that fit
into a cut out on
the control dial

159. Order of Vap.
Less potent – upstream
More potent – downstream
If equipotent
low VP – upstream
high VP – downstream
ALSO if explosive – downstream
trilene – downstream
easy to clean - downstream

160. ORDER OF VAPORISERS

161. Hazards
• Incorrect filling
• Vaporisation of mixed anaesthetic liquids-
hal. facilitates vap. of iso and enfl.
• Tipping –only tippable are Vapor 2000 and
Aladin cassettes(have T setting )
• Overfilling-filler port to be below max.
safe level of liquid in sump
• Reversed flow
• Conc dial set wrong

162. Hazards
• Leaks- loose filler cap, at O ring
junction on the manifold
• Vapor leak into FGF
• Contaminants in vap. Chamber
thymol accumulates (has a v high
B.P,-233 degrees C)
hal turns brown
discoloration of enf, iso.-residual
HC’s

163. THANK YOU