NEWER VAPORIZERS
Presented by: Dr. manoj kumar
Moderated by: Dr. Aparna Sharma
• The Datex-Ohmeda Tec 4, Tec 5, and Tec 7, as
well as the North American Dräger Vapor 19.n
and 20.n vaporizers, are classified as variablebypass, flow-over, temperature-compensated,
agent-specific, out-of-breathing-circuit
vaporizers
• The SVP of most inhalation agents is MUCH more that
is required to produce anesthesia i.e. 32% vs 0.75 or
243 mm 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
• How much liquid agent does a vaporizer use per hour?
• Ehrenwerth and Eisenkraft (1993) give the formula:
• 3 x Fresh gas flow (FGF) (L/min) x volume % = mL
liquid used per hour
• Or one can determine the volume (mL) of saturated
vapor needed to provide 1% (ie 4000(flow) x 0.01 = 40
mL) Typically, 1 mL of liquid volatile agent yields about
200 mL vapor.
Ohmeda tec vaporizer
• Safety Features
• Newer generations of anesthesia vaporizers are
Agent-specific, keyed filling devices help prevent
filling a vaporizer with the wrong agent.
• Overfilling of these vaporizers is minimized because
the filler port is located at the maximum safe liquid
level.
• Finally, today's vaporizers are firmly secured to a
vaporizer manifold on the anesthesia workstation.
Thus, problems associated with vaporizer tipping
have become much less frequent.
• Interlock systems prevent the administration of
more than one inhaled anesthetic
• the wick systems are placed in direct contact
with the metal wall of the vaporizer to help
replace energy (heat) consumed during
vaporization.
• The materials that vaporizers are constructed
of are chosen because they have a relatively
high specific heat and high thermal
conductivity.
• These factors help minimize the effect of
cooling during vaporization
TEC VAPORIZERS
• CLASIFICATION (TEC I-7)
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
• for halothane, enflurane, isoflurane, and
sevoflurane
• filling devices: a funnel filler, the Quik-Fil, or
the Easy-Fil
• Capacity: 300 mL
• Temp: 18 to 35 degree celcius
• barometric changes are compensated
automatically. Fluctuating back pressure can
affect the vaporizer and increase the delivered
concentration
•
•
•
•
Vaporizing chamber circuit
The fresh gas flows from the flowmeter across the sump
cover where it is diverted through the central cavity of the
rotary valve and back through the IPPV compensating
assembly.
Gas now flows from the IPPV assembly down through the
tubular wick assembly where it picks up anesthetic vapor
and then flows across the base of the vaporizing chamber
above the liquid agent.
From the base of the vaporizing chamber the gas/agent
mixture flows through the sump cover to the proportional
radial drug control groove of the rotary valve and then
back into the sump cover where it combines with the
fresh gas from the bypass circuit.
The combined total flow then flows out from the
vaporizer and via the Selectatec circuitry to the anesthesia
gas delivery system.
1.Rotary valve
2.Enriched fresh gas out
3.Combined fresh gas
and enriched gas out
4.Fresh gas bypass
5.Fresh gas out
6.Thermostat
7.Vaporizing chamber
8.Wick assembly
9.IPPV compensating
assembly
10.Sump cover
11.Vapor control channel
12.Shown in ON position
• Earlier versions of the Selectatec Series Mounted
Manifold that provide mounting positions for three
vaporizers require that if only two vaporizers are fitted,
then the center position must be occupied.
• If the center position is not occupied, the interlock that
helps ensure that only one vaporizer at a time can be
turned ON is ineffective.
• Later versions of the Selectatec Series Mounted
Manifold that provide mounting positions for three
vaporizers incorporate an additional interlock that
helps ensure that only one vaporizer at a time can be
turned ON even if the center position is not occupied
•
•
•
•
Hazards
If inverted: rule of 5
Overfilling
Fluctuating back pressure may be imposed on
the vaporizer by downstream components
and/or assisted or controlled ventilation to the
patient.
• Pressures in excess of 400 mmHg may overcome
the internal pressure balance and cause a
variation in output.
• Mainteinance: drain
TEC 6
• CLASSIFICATION
• Conc calibrated
• Thermocompensation
by supplied heat
Or
Electrically heated dual
circuit gas-vapor blender
Capacity: 425ml
Dial: 1-18%
Filler port, power cord, battery
TEC 6
• Designed for the delivery of Desflurane
• Electronic vaporizer which heats Desflurane to
maintain constant temperature and vapor
pressure for consistent output
• It has an LED display which indicates vaporizer
status - no output, low agent, warm-up,
operational and alarm battery low
• Features several intrinsic vaporizer monitors and
alarms that constantly monitor vaporizer status.
Temperature compensation
Supplied Heat
• Maintains a constant temperature by electric heater.
•Low boiling point 22.8C causes unpredictable
output Supplied Heat (Must be connected to
electrical outlet):
•Warms liquid Desflurane to 39C to
achieve a pressure of 1,500 mmHg
•Controls gas output by variable
resistance via a differential pressure
transducer
•2 heaters in base(sump) and 2 in the
upper part of vaporizer.
The Tec 6 vaporizer is an electrically heated,
thermostatically controlled, constant-temperature,
pressurized, electromechanically coupled dual-circuit, gasvapor blender.
 The pressure in the vapor circuit is electronically
regulated to equal the pressure in the fresh gas circuit.
 At a constant fresh gas flow rate, the operator regulates
vapor flow with a conventional concentration control dial.
 When the fresh gas flow rate increases, the working
pressure increases proportionally.
 For a given concentration setting even when varying the
fresh gas flow rate, the vaporizer output is constant
because the amount of flow through each circuit remains
proportional
• 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 setting x 760/ambient pressure
• Effect of carrier gas; addition of N2O – less viscosity –
decrease vapor output
• Mounting – for rt - side of machine
• Bottle; has a spring valve to prevent escape of agent
• Hazards
Checkout procedure
• Press and hold the mute button until all lights and alarms
activated.
• Turn on to at least 1% and unplug the electrical connection.
A "No Output" alarm should ring within seconds. This tests
battery power for the alarms.
• Safe T fill
• The bottle probe inserts directly into the filler
port.
• An "O" ring fitted on the spring-loaded bottle
cap helps engage and seal the opening before
liquid can flow, which aids in preventing
spillage and operating room contamination.
ALADIN CASSETTE VAPORIZER
• A fixed restrictor is located in the bypass chamber, and it
causes flow from the vaporizer inlet to split into two flow
streams .
• One stream passes through the bypass chamber, and the
other portion enters the inlet of the vaporizing chamber
and passes through a one-way check valve.
• The presence of this check valve is unique to the Aladin
system. This one-way valve prevents retrograde flow of
the anesthetic vapor back into the bypass chamber, and
its presence is crucial when delivering desflurane if room
temperature is higher than the boiling point of
desflurane (22.8°C).
• A precise amount of vapor-saturated carrier gas passes
through the flow control valve, which is regulated by the
CPU. This flow then joins the bypass flow and is directed
to the outlet of the vaporizer
• controlled vaporization of desflurane presents a unique challenge,
particularly when room temperature is greater than the boiling
point of desflurane.
• At higher temperatures, the pressure inside the vaporizer sump
increases, and the sump becomes pressurized. When sump
pressure exceeds pressure in the bypass chamber, the one-way
check valve located in the vaporizing chamber inlet closes to
prevent carrier gas from entering the vaporizing chamber.
• At this point the carrier gas passes straight through the bypass
chamber and its flow sensor.
• Under these conditions, the electronically regulated flow control
valve simply meters in the appropriate flow of pure desflurane
vapor needed to achieve the desired final concentration selected
by the user.
• ADU users should be cautious of this potential problem, especially
when desflurane is used.
• To offset cooling effect, the S/5 ADU is equipped with
a fan that forces warmed air from an “agent heating
resistor” across the cassette (vaporizer sump) to raise
its temperature when necessary(<18 C)
• The fan is activated during two common clinical
scenarios: (1) desflurane induction and maintenance
and (2) sevoflurane induction
• Liq. Level indicated on screen. if 10% - alarm message
• If the cassette pressure is higher than the pressure
distal to the cassette outflow, the vaporizer starts to
work as an injector
• If the temperature falls below 20°C or the fresh gas
flow is over 8 L/minute, the vaporizer may be unable to
produce high concentrations and the messages
insufficient agent and decreased flow will appear on
the machine.
• Hazards
• The cassette is fitted with an overfill protection
mechanism. If air is allowed into the agent bottle, this
mechanism is deactivated. This may result in overfilling
and anesthetic overdose.
• Turning the vaporizer ON while filling may pressurize
the cassette and cause liquid to leak at the filling port
• When the fresh gas flow is lowered, the one-way valve
that prevents backflow of saturated vapor from the
cassette toward the bypass channel may fail to close,
resulting in high delivered concentrations.
• This problem may be more significant when desflurane
is used.
Funnel fill
At »T« setting Vapor may be moved in any
position.
If not at »T« setting, risk of incorrect output
concentration,
or of anaesthetic agent escaping otherwise
When control dial is set at »0« or above »0«,
do not use
Vapor at an angle of more than 30°.
Risk of incorrect output concentration or
anaesthetic
agent escaping otherwise.
Off position vs T position
On position
• Hazards
• Cellular phones should not be used within 10 m of the
vaporizer.
• The D-Vapor is not designed to be used at an angle of
more than 10 degrees. At greater angles, an
uncontrolled concentration of vapor may result
• The output is not defined in the area between 0% and
0.2%. The handwheel should not be set in this area.
• The Vapor is not suitable for use with a breathing
system due to high pneumatic resistance.
Penlon vaporizers
• gas passes through a spiral tube into the
vaporizing chamber, which contains a
stainless-steel wick
• Temperature compensation is provided by a
liquid-filled expansion bellows controlling a
variable resistance valve in the bypass.
• The vaporizer should be calibrated every 3 to
6 months
Penlon sigma alpha
•
•
•
•
•
For desflurane
Filling capacity- 330 ml
Temp- 15 to 30
Flow range : 0.5-12 L/min
Hazards: Electromagnetic interference
Penlon sigma delta
•
•
•
•
•
•
•
•
Mounting: Selectatec, Drager Plug-In, Cagemount
Specifications:
Weight: 5 kg approx.
Cagemount Dimensions: (mm) 133 wide x 158 deep x 219 high
Selectatec Compatible: with Interlock Dimensions (mm) 120 wide
x 190 deep x 242 high
Drager Plug-In Compatible: Dimensions (mm) 100 wide x 190
deep x 242 high
Capacity Volume: at MAX mark 250 mL nominal Volume at MIN
mark: 35 ±10 mL -- After draining, approximately 60 ±10 mL of
liquid is retained by the wick
Flow Range: Operating flow range 0.2 to 15 litres/min
Temperature Range: Operating temperature range 15° to 35°C
• temperature decreases with altitude;
• this is known as the ‘lapse rate’ and varies according to the
moisture content of the air and has an international standard of
6.498C per 1000 m from sea level to 11 000 m.
• Safety features
• Important safety features include:
• Keyed fillers
• Low filling port
• Secured vaporizers (less ability to move them about minimizes
tipping)
• Interlocks
• Concentration dial increases output in all when rotated
counterclockwise
Disadvantages
• heavy, expensive and require regular servicing
if their accuracy is to be maintained.
• built for use with a specific agent and can be
lethal if the wrong agent is used
• Their high internal resistance prevents them
from being used in the breathing circuit.
• Future ; closed sys where vaporizer control
may be linked directly to patient parameter
via feedback mech.
• Fillers
• Vaporizers may be filled by a conventional funnel-fill
mechanism, in which the liquid anesthetic is simply
poured into a funnel in the vaporizer.
• The problem with this method is that, if more than
one anesthetic is used in a facility, there is nothing to
prevent the vaporizer being filled with the wrong
agent. This may be prevented with the use of a keyfiller system
• an agent-specific filler tube is used, one end of which
slots into a fitting on the vaporizer, and the other end
slots into a collar on the bottle of anesthetic.
• The fitting on the vaporizer and the collar on the
bottle are specific to each agent, making it impossible
(or, at least, extremely difficult) to fill the vaporizer
with the wrong agent.
ASTM Standards
• Vaporizers suitable for use in the breathing system
must have standard 22-mm fittings or screw-threaded,
weight-bearing fittings with the inlet female and the
outlet male. The direction of gas flow must be
indicated
• The output of the vaporizer shall be less than 0.05% in
the “OFF” or “zero
• The average delivered concentration from the
vaporizer shall not deviate from the set value by more
than ±20% or ±5% of the maximum setting, whichever
is greater, without back pressure
• The effects of variations in ambient temperature and
pressure, tilting, back pressure, and input flow rate and
gas mixture composition on vaporizer performance
must be stated
MEASURED FLOW VAPORIZERS
• The vaporizer heats the anesthetic agent to a
temperature above its boiling point (so it behaves as
gas) and this is then metered into the fresh gas flow.
• A measured flow is sent by a separate oxygen flow
meter to pass to the vaporizer with the output being
at SVP for the anesthetic agent.
• In order to dilute this otherwise lethal
concentration, outpur from that flowmeter is
combined with gas passing form the main flowmeter
MEASURED FLOW VAPORIZERS
• Operator has to set the flow to the vaporizer and bypass
with separate flowmeters
• This means that respective flows have to be calculated
for each agent for a given temp and vapour output
• To calculate the vaporizer output, one must know the Vapor pressure of the agent
- The atmospheric pressure
- The total flow of gases
- The flow of the vaporizer
CALCULATIONS FOR OUTPUT IN MEASURED
FOW VAPORISERS
• Set 100 ml/min flow of carrier gas (oxygen)
from dedicated flowmeter
• SVP of hal in vap. Chamber is 243 mmHg
• Hal forms 243/760 x 100 = 32% of gas mixture
• Carrier gas will occupy the rest of the vol. i.e.
100-32=68%
• This 68% is occupied by 100ml/min carrier gas
• And 32% hal will be = 100/68x32=47 ml
CALCULATIONS FOR OUTPUT IN MEASURED
FOW VAPORISERS
• Gas exiting is 147 ml with 47 ml hal vapor
• To get a mixture containing 1% hal this 47 ml
should be diluted in 4700 ml
• Required carrier gas is 4700-147=4553 ml
• If set 100 ml 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
• % concentration of agent = 100 x vaporizer
output of anaesthetic/total flow