Vaporizers 2015 spmc

VAPORIZERS
Dr. deepak kumar
Resident in Anaesthesia deptt
S.P.Medical College &
A.G.Hospitals, Bikaner

What is a Vaporizer?
A VAPORIZER 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.

Function of Vaporizers
• Produce vaporisation of volatile agent
• Mix vapour with fresh gas flow
• Control the mixture despite variables
►To deliver safe and accurate concentration of
inhalational agents to the patient.

Applied Physics
• Factors affecting vaporization of a liquid
1.Temperature
2.Volatility
3.Surface area
4.Removal of vapor from the vicinity
of the liquid.

Applied Physics
• Vapor
• Gas
• Critical temperature
• Vapor pressure
• Boiling point
• Partial pressure
• Heat of vaporization
• Specific heat
• Thermal conductivity
• Thermal capacity

Vapor
• Vapor is the gaseous phase of a substance which is
normally a liquid at room temp. and atm. pressure
Gas
• Gas is a substance which exists only in the gaseous
state at room temp. and atm.

Critical temperature
• It is the temperature, above which no amount
of pressure will convert a gas to a liquid.
02=-118.4°C; N2O= 36.5°C; CO2= 31°C.
• The pressure required to liquefy a gas at its
critical temp. is the CRITICAL PRESSURE .

Vapor pressure
• When enclosed in a container molecules of a
volatile liquid break away to form vapor.
• Vapor pressure is the pressure with which they
bombard the walls of the container.
• Vapor pressure depends only on temp and nature
of liquid.
• Vapor pressure of an agent determines how
much of vapour will be formed from 1 ml of the
liquid.
• Since diff anaesthetic agents have diff vapour
pressure so need separate vaporizers.

Boiling point
• Boiling point of a liquid is that temp at
which the vapor pressure is equal to the
atmospheric pressure.
• Lower the atmospheric pressure, lower
the boiling point.

Partial pressure
• The part of total pressure due to any one gas
in the mixture
• Depends on – Nature of liquid and Temp.
• Clinical significance-
Patient uptake and anaesthetic depth are
directly related to partial pressure.

• HEAT OF VAPORIZATION-
It is the number of calories needed to
convert 1gm or 1ml of liquid to vapor.
• SPECIFIC HEAT-
Quantity of heat required to raise the
temp of 1gm or 1ml of substance by 1*c .

• THERMAL CONDUCTIVITY-
A measure of speed with which heat
flow through a substance .
• THERMAL CAPACITY-
Amount of heat stored in vaporizer body
= specific heat x Mass

CLINICAL SIGNIFICANCE-
• liquid with low specific heat vaporize easier.
• Higher the thermal conductivity, better a
substance conduct heat
• Vaporizers construct of material with high
thermal conductivity and specific heat e.g.-
copper, bronze to minimise temp changes
when in use.

Related physics
THERMOSTABILISATION Methods :-
 Vaporizer constructed of metal with high thermal
conductivity.
 Heavy metal parts act as heat reservoir.
 Wicks to be in contact with the metal part so that
heat loss due to vaporization is quickly replaced.
 Immerse vaporizer chamber in a large mass of water.

Related physics
THERMOCOMPENSATION-
• Some means to maintain the vaporizer
output constant despite any temp changes
Methods -
1.Alteration in splitting ratio(automatic
compensation) e.g.- bimetallic strip in Tec
vaporizers, ether filled bellows in penlon
vaporizers, EMO(Epstein Macintosh Oxford)

Related physics
2.Computer control-electronic vaporizers.
3.Manually adjust flow- measured flow ,
drager vapor.
4.Supplied heat- Tec 6(electrically heated).

Properties Of Common Anaesthetic
Agents
Agent Boiling Point at
100 kPa
(degree Celsius)
Vapor Pressure
(at 20 deg C)
MAC value
(vol% ) in 100% O2
1) Ether 34.5 440 19
2) Halothane 50.2 243 0.75
3) Enflurane 56.5 175 1.68
4) Isoflurane 48.5 238 1.15
5) Desflurane 22.8 669 6.4
6) Sevoflurane 58.6 157 2.0
7) Trilene 87.5 57 0.17

Terminology for vaporizers
PLENUM- FGF is pushed in to the vaporizer(high
resistance).
DRAWOVER- Gas is pulled in to the vaporizer by
the patients own inspiratory effort(low
resistance) e.g.- Goldman,EMO,OMV
INHALER- A drawover vaporizer in which the
carrier is air.

SPLITTING RATIO
• The ratio of the bypass gas to the gas going to
the vaporizing chamber is called the splitting
ratio
• It depends on-
1.The resistance of the two pathways, which
inturn depends on the variable orifice of the
inlet/outlet.
2.Temp of the liquid/carrier gas
3. Flow rate of gases.

CLASSIFICATION
• Dorsch & Dorsch classification (1979)
1) Regulation of output concentration
2) Method of vaporization
3) Location of the vaporizer
4) Temperature compensation
5) Specific anaesthetic agent

CLASSIFICATION
• Dorsch & Dorsch classification
a) Variable Bypass type
b) Measured flow type

Flowmeter
Patient
VARIABLE BYPASS

MEASURED FLOW VAPORIZER
• Uses a measured flow of carrier gas to
pick up agent
• Consist of-
1.Vaporizer
2.flowmeter assembly
3.Vaporizer circuit control valve

Cont...
• Operator has to set the flow to the vaporizer
and bypass with separate flowmeters
• This means that respective flows have to be
calculated for a given temp and vapour
output.

Measured Flow Vaporizer
V V
C
L

CLASSIFICATION
a) Flow over
b) Bubble through

Flow over
• A stream of gas passes over liquid surface
• Efficiency depend on-
1. Gas-liquid interface e.g.- baffles, spiral
tracks, wicks.
2. Velocity of carrier gas flow
3. Height of gas

Bubble through
• Bubble the gas through the liquid
• efficiency depends on-
1. size of bubbles
2. depth of the liquid
3. velocity of carrier gas
E.g.- sintered diffuser
-cowl in Boyle’s bottle

CLASSIFICATION
a) VOC(Vaporizer outside the circuit)
b) VIC (vaporizer inside the circuit)

In system vaporizer(VIC)
• Should have standard male and female 22 mm
fittings or standard screw threaded
fittings,inlet and outlet ports should have
arrows.
• Should have low resistence.
• Vaporiser concentration and output vary
• Easy to wash and clean
• Drawover vaporizers eg- goldman,EMO,OMV

OUT OF SYSTEM VAPORIZERS(VOC)
• Usually on back bar – b/w flowmeter and FGF
outlet
• Most variable bypass vaporizers and all
measured flow vaporizers are VOC type.

CLASSIFICATION
a) Non compensated
b) Compensated

TEMP COMPENSATION
• To maintain a constant output from the
vaporizer,mechanisms to compensate for the
fluctuations in temp are to be employed.
• Method –
1. automatic- alteration in the splitting
ratio(bimetallic strip in tec vaporizer,ether
filled bellows in penlon vaporizers,EMO
2.Supplied heat- tec 6(electrically heated)
3.Computer control- electronic vaporizers

CLASSIFICATION
a) Agent specific
b) Multiple agent

CLASSIFICATION
• Gray & Nunn Classification (1971)
1) Plenum vaporizers
2) Draw over vaporizers
3) Vaporizers for use inside a circle anaesthetic
system

CLASSIFICATION
• Gray & Nunn Classification
1) Plenum vaporizers
Fresh gas flow is forced into a chamber
Unidirectional gas flow
Relatively high resistance to gas flow
e.g. Boyle vaporizer, copper kettle,
Tec series vaporizers

CLASSIFICATION
2) Draw over vaporizers/ Inhalers: Air or
anaesthetic gases drawn over or through the
vaporizer either by pt’s own respiratory efforts
or by a self inflating bag or manual bellows.
Very low resistance to gas flow
e.g. EMO vaporizer, Oxford
miniature inhaler, emotril, tecota
vaporizers.

CLASSIFICATION
3) Vaporizers for use inside a circle anaesthetic system
e.g.- Goldman vaporizer
Rawbotham vaporizer

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

Factors affecting vaporizer
performance
• Flow rate
• Temperature
• Barometric pressure
• Intermittent back pressure
• Gas direction
• Liquid levels
• Anaesthetic agents
• Carrier gas composition (N2O causes transient drop)

performance
• Flow rate
At high flows,the vaporizer delivers less
anaesthetic concentration than is set on
the dial
problem is solved by increase the surface
area of contact b/w the fresh gas and
anesthetic agent
Eg- WICKS

TEMPRATURE
• As anaesthetic molecule escape temp
decreases more difficult for the
remaining molecules to escape less
vaporisation.
• Thus at lower temp there is less
vaporization.
• Problem solving-
 Giving heat
 Giving flow

Giving heat
1.Vaporizer material
good conductor(high thermal conductivity)
act as a heat reservoir(high specific heat)
2.Supplied heat (tec-6 electrically heated)

Giving flow
• Giving flow (thermocompensation) by
alteration in splitting ratio
1. Mechanically
2. Compuer controlled

performance
• Intermittent back pressure
Pumping effect(hill and lowe effect)
Pressurizing effect(cole effect)

Pumping effect(Hill and lowe effect)
• The effect of changing pressure during IPPV
increasing the output of the vaporizer is called
the “pumping effect”
• During positive pressure ventilation, pressure
transmitted back results in compression of
gas.
• Since the vaporizing chamber volume is much
larger than the ‘by pass’ channel volume,
more fresh gas gets compressed in to it.

Cont…
• This extra fresh gas that enters the vaporizing
chamber collects anesthetic vapour
• Some of the rapidly expanding gas (containing
vapour) enter the inlet of the vaporizer and
cross over into the ‘bypass’ channel.
• The addition of the ‘bypass’ vapour to the
vaporising chamber raises the final
concentration of anesthetic delivered.

Modifications to reduce the
‘pumping effect’
• By pass channel made larger
• Inlet tube made longer
• Exclude wicks from inlet
• Increased resistance – a high internal
resistance to “resist” changes to flow.
• Check valve at outlet of the vaporizer -Fluotec
2
• Check valve upstream to junction with the
oxygen flush.
• Pressure relief valve.

Pressurising effect
• k/a ‘cole effect’ – decreased output of
anesthetic agent.
• An inreased in pressure causes an increased
pressure inside the vaporizer.The carrier gas is
compressed but the vapour pressure of the
volatile anesthetic is unaffected.Net result
decreased conentration of anesthetic
delivered.

Carrier gas composition
• Most vaporisers are calibrated using 100% o2
• Composition of carrier gas affects output in
many(vaporiser aberrance)
• If add N2O- decreased output(25% less with
100% N2O)due to solubility of N2O in agent
.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.

EFFECT OF BAROMETRIC PRESSURE
• Vaporizers are calibrated at std. atmospheric
pressure(at sea level)
• Low boiling point,high SVP anaesthetic volatile
agents- more susceptible to influence by
barometric pressure.
• Vapour pressure of agent is independent of
barometric pressure.
• Effect of low atm. Pressure- deliver HIGHER
concentration if measured in volume% but
deliver same partial pressure

Cont….
• Clinically effect unchanged
• Effect of high atm.pressure-
increased density of gas increased
resistance through vapourising chamber
decreased vapour output both in partial
pressure and volume%

Early methods
• OPEN DROP METHOD:-
Inhalational anaesthesia by
vaporization of a liquid anaesthetic placed
drop by drop on a gauze/ mask covering the
mouth and nose.
Devices- Schimmelbusch mask
other modification- Yankauers, Bellamy
gardner

CONT..
• SEMI OPEN-
a frame added to “keep the ether in” in
an enclosed area- permitted some degree of
rebreathing.
e.g.- Ogston’s inhaler
Flagg’s can

Early devices- open drop
method(schimmelbusch mask,
yankaeur mask and bellamy
gardner wire mask)

Semi open drop method
Ogston mask with schimmelbusch
frame

OPEN ETHER ADMINISTRATION
• TECHNIQUE-
Volatile anaesthetic dripped on to a gauze:
1. ETHER- 16 layers gauze over mask
2. CHLOROFORM/ETHYL CHLORIDE- 12 layers of gauze/1
layer lint(chloroform dropped over half the area)
- gradually increased no. Of drops/min
- During inspiration air passed through the gauze and
vaporizes the liquid anaesthetic into high
concentration.

Open drop ether
• Bellamy gardner dropper
- amber coloured
- control on pouring
- capacity – 90 ml ether

INDUCTION
• WITH ETHER
• RATE OF DROPS
1ST
min = 12 drops = 1 %
2nd
3rd
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

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

Advantage of open drop
• Easy to administer
• Low dead space 40-60 ml
• Low resistence
• Wide margin of safety
• Relatively cheap

Disadvantage of open drop
• Significant rebreathing
• Hypoxic mixtures may occur
• Poor control of inspired gas concentration
• Inability to assist or control ventilation
• No conservation of heat or humidity
• Difficult airway management especially during
head and neck procedure
• Pollution of the operating room
• Hazardous especially with flammable agents.
• Skin burn.
• Eye injury

In system vaporizers(VIC)
• There are two ways that gas flows through a
vaporizer
- push through
-Drawover

Drawover anaesthesia
• Drawover system :
- provide anaesthesia without a supply of
compressed gases.
-Atmospheric air – main carrier gas
-drawn by the patient’s inspiratory efforts
- volatile agent (ether or halothane) added
to vaporizer
- Inhaled by the patient via a non-rebreathing
valve.

Drawover anaesthesia
• The component of a drawover circuit

EMO Vaporizer
Epstein, Macintosh, Oxford (EMO) introduced
in 1952
Classification-
• Variable bypass/conc. calibrated
• Flow over with wicks
• Temperature compensated by supplied heat and
altered flow.
• Agent specific-used for ether, halothane, chloroform
and trilene.
• Can be a part of a drawover system or used as a
plenum vaporizer
• Low resistance(<1.25cm water at 40 Lpm flow)

• 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)
• 1250ml water filled in
water chamber

A- Inlet
B- Outlet
C- Water compartment
D- Ether
E- Vaporizing chamber
F- Thermo compensating
valve
G- Off/on valve
H- Mixing chamber
I- Water drain

Ctd
• FILLER-depress to fill (control lever at 0-not
transit- for air to escape) springs back
automatically.
• 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

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 –
indicator should 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

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, useful in mass
casualties, no effect of altitude, easy maintenance, no need
for sterilisation

OXFORD INFLATING BELLOWS
• Self inflating bellows used with
spontaneous/controlled ventillation
• Bellows sit vertically,internal volume
maintained by a spring; 6 bellows- 150 ml
each
• 2 unidirectional flap valves
• Magnet to inactivate distal unidirectional
valve.

Oxford miniature vaporizer(OMV)
Introduced by Epstein, Macintosh and
Mendelssohn in 1941.
• Conc. Calibrated
• Draw over vaporizer (low resistance)
• Flow over with wicks
• Temperature regulated by means of calcium
chloride( supplied heat)
• Outside the circuit, can be used as plenum
vaporizer

OXFORD MINIATURE VAPORISER(OMV)
• Simple portable inhaler
• for less volatile agents – halo, trilene, chloroform
• Fairly 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

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 20 ml ; cannot mount on backbar

Goldman Vaporizer
• Classification
- concentration calibrated
- flow over without wick
- no temp compensation
- multiple agents –
halothane,trilene
- in or out of system

Goldman vaporizer
• Small glass bowl
• Capacity 20 ml
• Bowl attached to a head, which divide gas b/w
bypass and vaporizing chamber
• Control lever at top; max conc. Delivered at 3rd
mark of 2.21%
• Young modification- added a wick(increase to
4%)
• Halls modification – 2 in series

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.

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

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

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%

Boyle’s bottle vaporizer
• Classification
• 1.Variable bypass
• 2.Flow over or bubble through
• 3.Not temperature
compensated
• 4. Agent specific
(ether,halothane,trilene)
• 5.Outside the circuit

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 %

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

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)

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

Copper Kettle vaporizer
Described by Lucein Morris in 1952.
Classification-
• Measured flow
• Bubble through
• Temperature compensated by supplied heat
and manual flow alteration.
• Multiple agent ( chloroform, ether,halothane)
• Outside the circuit
• 2 models 160ml/400ml

Copper kettle vaporizer
• Constructed of copper
-High heat capacity
- high thermal conductivity
-High degree of accuracy

• A- Filling funnel
• B- Drain
• C- Inlet
• D- Sintered bronze
porex disc
• E- Outlet

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

TEC VAPORIZERS
• CLASSIFICATION (TEC 1 to 5)
1.Variable bypass
2.Flow over with wick
3.Out of system
4.Temp. Compensated by automatic flow
alteration
5.Conc. Calibrated
6.Agent specific

TEC 2
• Used only for Halothane &
methoxyflurane
• Capacity 150 ml
• Calibrated upto 4% (in increments
of 0.5% )
•Temp. compensation by bimetallic
strip
• Filling tap at side, draining at
bottom
•Level indicator on side
•Conc. Dial in front, attached with a
spindle

TEC 2• Not accurate below
4L/min
• <2L/min flow and <2%
dial setting->delivers less
• >2% dial setting ->
deliver more
• With N2O it gives
greater output at lower
setting and less output
at higher setting
• Prone to pressure
changes:
 pumping effect at low
flows
 pressurizing effect at
high flows .

• Care and cleaning
Drain halothane every 2 week and discard as
THYMOL accumulates sticking of spindle and
bimetallic strip.
HAZARDS-
1. Tipping
2. Agitation  high output
3. Reverse flow:->back pressure changes
4. Sticking of control dial due to thymol
5. Between off and 0.5% some output can occur varying
with FGF.
6. Small leak in off position.

TEC 3
Construction:-
1.Conc. Control dial is on top
2.Calibrated from off to 5% in 0.5% gradations
3.Locking lever to be depressed before dial can
be turned
4.Screw cap filler with drain at bottom
5.Optional pin safety system for filling
6.Sight window for liquid level on left

TEC 3
•Used for Halothane, enflurane, isoflurane
& sevoflurane
•Capacity : 135ml (with dry wicks)
100ml ( with wet wicks)
•A bimetallic strip increases flow through
the bypass chamber when temperature
increases.
•Negligible back pressure changes
•No non return valve
•Less affected by fresh gas flow and
composition of carrier gas
•Control knob less likely to stick

Cont...
Internal structure:
• Completely redesigned
• Has 2 sections- lower vaporizing chamber and upper
duct and valve system
• 2 bypass channels- one direct 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 vaporizing
chamber.

TEC 3
• Accur. falls off at high
flow rates & dial
settings
• All are accurate with
low dial settings

TEC 3
EVALUATION
• Sudden increase or decrease in carrier gas flow,
intermittent back pressure and upstream O2
flush has negligible effect on vapor output.
• N2O has got little effect on output
• Performance in 0-0.5 % range governed mainly
by conc. dial & less by FGF.
• Upto 90° tipping has no effect
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.

TEC 4
Used for halothane, enflurane and
isoflurane
Entire new look-> Select-a-Tec manifold
Capacity 135ml (with dry wicks)
100 ml ( with wet wicks)
Graduation from 0-5% ( in 0.25%
increments from 0 -1%, and 0.5%
increments thereafter)
Depress release button on left of control
dial to turn on the vaporizer
Locking lever on rear- Vaporizer can be
turned on only if locked on manifold.
Two filling mechanism
1. screw cap with drain plug
2.keyed filling device

Improvement over tec 3
• Output unaffected by back pressure changes under
clinical conditions
• Unaffected by tipping even upto 180°
Limitations-
1. Excess pressure(>400 mmHg) cause decrease in
output.
2.Not so accurate at low flow rates, low dial settings
and larger pressure fluctuations.
3.Overfilling possible.
4.Use of N2O decreases output.
5. Difficulty in operation one handed.

TEC 5
Used for Halothane, isoflurane , enflurane
& sevoflurane
Capacity 300ml ( with dry wicks)
225ml (with wet wicks)
Graduation 0-5% ( 0.2% increments from
0-1% and 0.5% increments thereafter)
Features-
1.Top control dial
2.Locking lever
3. Release button at rear of dial
4.Sight glass – bottom right
5.Keyed filling device:
-FILLING DRAINING PORT
-LOCKING LEVER TO SECURE FILLER BLOCK
-SMALL LEVER AT BASE ALOWS LIQUID TO BE ADDED
OR DRAINED

Tec 5
Features :
• Internal baffle system
• VC lies within the
bypass, which lies along
side of the vaporizer.
• Bimetallic strip at the
base in bypass.
• Before reaching VC –
helical IPPV assembly--
spiral wick.

TEC 5
• Introduced in 1989 responding to criticism of the Tec 4.
Improved features of TEC 5:-
1. Bypass chamber at the base; an improved bimetallic strip.
2. Improved safety interlock.
3. Agent capacity increased from 125 ml to 300 ml.
4. Helical IPPV assembly to minimize effects of PPV.
5. One handed dial control and more obvious “off” position.
6. Service interval now three years.
7. Improved characteristics with tubular woven cotton wicks
8. Accurate with gas flow 5Lpm, dial settings < 3 %.
9. Greatest accuracy between 15-35 degree celcius

Hazards of TEC 5
• More prone to pumping effect then Tec 4.
• Large liquid loss if filling port is opened.
• Overfilling – bottle adaptor loose, vaporizer
on
• Reverse flow increases output.
• Carrier gas composition affects output.

TEC 6
• Classification –
1.Conc. Calibrated
2.Injection vaporizer
3.Thermocompensated by supplied heat or electrically
heated.
4.Electromechanically controlled dual circuit.
5.Gas-vapour blender.
6.pressurized
7.Single agent – Desflurane

• Used only for desflurane.
• Capacity 390ml
• Graduation 1-18% ( 1% increments from 1-
10 and 2% increments thereafter)
• Maximum permissible flow 20L/min
• Since VC is sealed from atm. special filler
system is required.
• Various LEDs in front pannel:-
Amber : without alarm- warm up
Amber : with alarm- agent level below 50 ml
Green : operational
Red :no output due to:--
1. Low agent level <20ml
2. Power failure
3. Malfunction
4. Tilted vaporizer beyond 20 degree

TEC 6
•Desflurane heated to 39 deg
celcius in a sealed chamber,
adjusted by H.
•VP 1300mmHg in sump.
•Carrier gas flow restricted by O,
so that pressure is ~ to flow.
•Pressure sensed by P , which
readjusts R1 so that desflurane
flow is ~ to FGF.
•Control dial adjusts R2, and thus
the output conc.
• H-heater
• O-fixed orifice
• P-differential pressure
transducer
• R1-adjusted by P
• R2-adjusted by control
dial

EVALUATION:-
• Output almost linear at 3%,5%, 7%.
• Slightly low output at <5l/min
• Ideal temp 18-30 deg celcius
• Tilting resistant
• Pumping effect insignificant
• Carrier gas effect minimal.

TEC 7
•Similar to TEC 5
•Used for isoflurane, enflurane , sevoflurane
•Capacity 300ml (with dry wicks)
225ml (with wet wicks)
•Graduation 0-5% ( 0.2% increments from 0-
1 and 0.5% increments thereafter)
•Available with 3 filling devices– funnel filler,
Quikfil, Easyfil.
•New ergonomics and design.
•Soldered sump assembly eliminating seals
•Improved sight glass design
•Clear agent color identification

Characteristics of
Drager Vaporizers
MOST ACCURATE
CLASSIFICATION-
• Conc. calibrated
• Flow over
• Temperature compensated
• Agent specific
• Out of circuit

Drager Vapor 19.1
Used for Halothane, isoflurane,
enflurane and sevoflurane
Capacity 200ml
Calibrated from 0-5% (o.2%
increments in between 0-1 and
1% thereafter)

Penlon sigma delta vaporizer
• Specifications-
• wt :5 kg approx
• Capacity volume : at MAX mark 250 ml
• Flow range: operating flow range .2 to 15 lt/min
SAFETY FEATURE-
1. Keyed filler
2. low filling port
3. Interlocks
4. Secured vaporizers

ALADIN CASSETTE VAPORIZER
Classification-
1.Conc. Calibrated
2.Flow over
3.Automatic thermocompensation
4. Agent specific
Features-
1.Cassettes containing liquid anaesthetic inserted into a port
2.Agent recognized and dispensed into the stream of FGF
3.Tipping resistant and maintenance free
4.Power battery backup and adequate O2 pressure mandatory
5.Fixed output irrespective of fresh gas mixture
6.Extremely light and can be removed with one hand.

Use with datex-Engstrom AS/3 ADU

SIEMENS
Classification
• Conc calibrated
• Injection
• No thermocompensation
• A caliberated throttlevalve is opened
and closed by user and thus regulate
the pressure exerted by FGF on
surface of liquid anaesthetic agent
• This pressure tends to force liquid to
atomize at the injector nozzle
• The liquid droplets vaporize in the
flowing FGF.

Agent specific filling system
• A vaporizer designed for a single agent be
fitted with a permanently attached agent
specific device to prevent accidental filling
with wrong agent.
• Reduce air pollution
TYPES-
1.Keyed filling system
2.Screw capped filling system
3.Pin safety system

Vaporizer mounting system
If >1 vaporizer can be switched on at a time:-
• The patient exposed to a overdose of
anaesthetic agent
• The downstream vaporizer is contaminated.
TYPES-
1.Select a tec back bar- a switch on the back bar
may be used to direct gas flow through only
one vaporizer at a time.
2.A mechanical locking system
3.A mechanical interconnector

Selectatec system
• Pair of port valves for
each vaporizer
• Vaporizer is mounted
and locked on back bar
• When ON 2 plungers
open the valve ports &
activate extension rods
that prevent other
vaporizer.

Vaporizer Mounting Systems
• Only one vaporizer can be turned on
• Gas enters only the “on” vaporizer
• Leak of trace gas is minimized.

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

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

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

ORDER OF VAPORISERS
UP STREAM    DOWN
STREAM
SEVOFLURANE ENFLURANE ISOFLURANE HALOTHANE DESFLURANE
VP-157 175 238 243 669

Hazards of contemporary vaporizers
Incorrect agent/ Misfilling
Tipping
Overfilling
Reversed flow
Simultaneous inhaled agent administration
Leaks
Electronic failure

IDEAL VAPORIZER
• Deliver fixed desired conc.
• Independent of-
temp
flow rate
carrier gas alteration
• No effect of back pressure
• easy to maintain and clean
• Agent specific

Vaporizers 2015 spmc

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