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NEWER VAPORIZERS

NEWER VAPORIZERS. Presented by: Dr. manoj kumar Moderated by: Dr. Aparna Sharma.

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NEWER VAPORIZERS

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  1. NEWER VAPORIZERS Presented by: Dr. manojkumar Moderated by: Dr. Aparna Sharma

  2. 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 variable-bypass, flow-over, temperature-compensated, agent-specific, out-of-breathing-circuit vaporizers

  3. 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.

  4. Ohmedatec vaporizer

  5. 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

  6. 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

  7. TEC VAPORIZERS • CLASIFICATION (TEC I-7) • Variable bypass • Flow over with wick • Out of system • Temp. compensated by automatic flow alteration • Conc. calibrated. • Agent specific

  8. 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

  9. 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 Selectateccircuitry to the anesthesia gas delivery system.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. The Tec 6 vaporizer is an electrically heated, thermostatically controlled, constant-temperature, pressurized, electromechanically coupled dual-circuit, gas-vapor 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

  17. 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.

  18. 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.

  19. ALADIN CASSETTE VAPORIZER

  20. 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

  21. 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.

  22. 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) sevofluraneinduction • 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.

  23. 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.

  24. Funnel fill

  25. 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.

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