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WO2004091708A2 - Vaporisateur pour anesthesie ameliore - Google Patents

Vaporisateur pour anesthesie ameliore Download PDF

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Publication number
WO2004091708A2
WO2004091708A2 PCT/GB2004/001649 GB2004001649W WO2004091708A2 WO 2004091708 A2 WO2004091708 A2 WO 2004091708A2 GB 2004001649 W GB2004001649 W GB 2004001649W WO 2004091708 A2 WO2004091708 A2 WO 2004091708A2
Authority
WO
WIPO (PCT)
Prior art keywords
liquid
agent
vaporizer
flow
carrier gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2004/001649
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English (en)
Other versions
WO2004091708A3 (fr
Inventor
Alan Green
Richard Kent
Paul Siow
Steve Heath
Norman Jones
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Penlon Ltd
Original Assignee
Penlon Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Penlon Ltd filed Critical Penlon Ltd
Publication of WO2004091708A2 publication Critical patent/WO2004091708A2/fr
Publication of WO2004091708A3 publication Critical patent/WO2004091708A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/14—Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase
    • A61M16/18—Vaporising devices for anaesthetic preparations
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/14—Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase
    • A61M16/147—Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase the respiratory gas not passing through the liquid container
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/1005—Preparation of respiratory gases or vapours with O2 features or with parameter measurement
    • A61M2016/102—Measuring a parameter of the content of the delivered gas
    • A61M2016/1035—Measuring a parameter of the content of the delivered gas the anaesthetic agent concentration

Definitions

  • the present invention relates to an apparatus for vaporizing a liquid and, more particularly, to a vaporizer that receives carrier gas, vaporizes a liquid anaesthetic agent and combines it with the carrier gas to produce a stream of carrier gas containing a known concentration of anaesthetic agent for introduction into a patient.
  • UK Patent No. 1 224 478 describes an anaesthetic vaporizer of the by-pass type in which a carrier gas, comprising a mixture of gases such as oxygen, air and nitrous oxide, is initially divided on entry to the vaporizer between a first stream which is directed towards the sump or vaporizing chamber of the vaporizer to entrain vapour from a volatile liquid anaesthetic contained therein; and a second by-pass stream, the first and second streams subsequently recombining prior to leaving the vaporizer for delivery to a patient.
  • a carrier gas comprising a mixture of gases such as oxygen, air and nitrous oxide
  • This known vaporizer has been used successfully over a number of years for delivery of anaesthetic agents such as halothane, trichlorethlene and ether derivatives including enflurane, fluoroxene, methoxyflurane and isoflurane. All the aforementioned anaesthetic agents have a boiling point at atmospheric pressure well above 40°C, but vaporization is achieved at ambient temperatures, typically using wicking materials to achieve a large vaporization surface.
  • anaesthetic agents such as halothane, trichlorethlene and ether derivatives including enflurane, fluoroxene, methoxyflurane and isoflurane.
  • All the aforementioned anaesthetic agents have a boiling point at atmospheric pressure well above 40°C, but vaporization is achieved at ambient temperatures, typically using wicking materials to achieve a large vaporization surface.
  • Desflurane 2-(difluoromethoxy)-l,l,l,2-tetrafluorethane
  • This physical characteristic of Desflurane renders by-pass type anaesthetic vaporizers unsuitable for delivering this agent to a patient.
  • By-pass type vaporizers are unsuitable for use with Desflurane because its boiling point is approximately in the middle of a conventional vaporizer's operating ambient temperature range of between 15°C and 35°C.
  • US patent US 5,146,915 discloses an alternative to a conventional by-pass type vaporizer for the new class of agent in which the liquid in a reservoir is deliberately heated in order to provide both a continuous source of anaesthetic vapour to blend with the carrier gas and the pressure to drive the vapour through a passive flow control device.
  • a gas pressure regulator is placed between the pressurized reservoir and the flow control device to limit the pressure drop across it so that the gas flow is independent of the pressure in the reservoir.
  • European patent application EP 0911053 and United States Patent US 5,509,405 each disclose a vaporizer in which liquid anaesthetic agent is pumped to a vaporizing chamber where it is introduced into a carrier gas stream for delivery to a patient.
  • a drawback of these vaporizers however is that the use of a dispensing pump to deliver the correct amount of liquid to be introduced into the carrier gas stream has associated accuracy and reliability problems.
  • a peristaltic pump (as used in the vaporizer disclosed in US 5,509,405) generally does not provide the accuracy and reliability required for the delivery of controlled doses of anaesthetic to a patient.
  • European patent EP 0449 545B1 discloses a vaporizer which avoids the above problems by delivering liquid anaesthetic agent into a gas carrier stream by pressurization of the liquid agent.
  • the pressurization of the liquid agent is by means of a pressure differential purposely created in the carrier gas bypass passage. This pressure is limited by the characteristics of the gas supply system and cannot be sufficient to prevent the liquid anaesthetic agent boiling at the higher ambient temperatures.
  • European patent application EP 0983773 A2 discloses a vaporizer in which pressurized liquid anaesthetic agent is introduced into a carrier gas supply by controlling the flow rate of the carrier gas. Consequently the introduction of the liquid anaesthetic agent is not controlled independently of the carrier gas supply.
  • the present invention seeks to provide an improved anaesthetic vaporizer which controls, in a reliable and safe manner, the delivery of an independently pressurized liquid anaesthetic agent to a vaporizing chamber within, or connected directly to, the carrier gas flow path within the vaporizer.
  • a first aspect of the invention provides an anaesthetic vaporizer, comprising a reservoir for containing liquid anaesthetic agent, pressurizing means for pressurizing the liquid anaesthetic agent in the reservoir, a vaporizing device and a conduit for a carrier gas supply, the vaporizer being arranged such that in use liquid anaesthetic agent contained in the reservoir is pressurized by the pressurizing means and conveyed in liquid form by that pressurization to the vaporizing device where it is vaporized for delivery to a patient with the carrier gas, wherein both the pressurization and the conveyance of the liquid anaesthetic agent to the vaporizing device are controlled independently of the carrier gas supply.
  • the vaporizing device comprises a part of, or is in communication with, the conduit for the carrier gas supply.
  • the vaporizer according to the invention has several advantages. Firstly, because the anaesthetic agent is conveyed in liquid form to the carrier gas the invention avoids the need to heat a large mass of liquid agent in order to vaporize it. Because the liquid anaesthetic agent is pressurized the invention also avoids the need to cool it. The power consumption required by the vaporizer is thereby significantly reduced. This enables the use of a low voltage electrical power supply that has the benefit of safety due to the avoidance of high voltages and the possibility of a battery-powered backup in the event of a power failure.
  • the liquid agent is conveyed by means of pressurization of the liquid rather than by the use of a metering pump, it avoids the poor accuracy and reliability problems often associated with liquid metering pumps, particularly when low volumes of liquid are involved.
  • the pressurization of the liquid agent and the conveyance of the liquid agent to the vaporizing device are controlled independently of the carrier gas supply, the vaporizer provides better control and safety than hitherto.
  • the invention enables the possibility of accurate measurement and control of the supply of liquid agent to the vaporizer, and hence to the carrier gas, independently of the flow of the carrier gas. This, preferably coupled with independent measurement of the gas flow, provides for greater accuracy and a means of checking, preferably in real-time, that the vaporizer is in fact functioning as intended.
  • the vaporizer preferably includes a liquid flow sensor (for example a mass flow sensor) arranged to measure the rate at which the liquid agent is conveyed to the vaporizing device.
  • a liquid flow sensor for example a mass flow sensor
  • the vaporizer includes means for measuring the concentration of vaporized agent in the carrier gas.
  • Such means preferably comprise first and second gas flow sensors.
  • the first gas flow sensor preferably measures the rate of flow of the carrier gas prior to introduction of the agent therein.
  • the second gas flow sensor preferably measures the rate of flow of the carrier gas containing vaporized agent.
  • a second aspect of the invention provides an anaesthetic vaporizer comprising a reservoir for containing liquid anaesthetic agent, pressurizing means for pressurizing the liquid anaesthetic agent in the reservoir, a vaporizing device, a conduit for a carrier gas supply, a liquid flow sensor, a liquid flow control device and first and second gas flow sensors, the vaporizer being arranged such that in use liquid anaesthetic agent contained in the reservoir is pressurized by the pressurizing means and conveyed in liquid form by that pressurization to the vaporizing device where it is vaporized for delivery to a patient with the carrier gas, wherein the liquid flow sensor measures the rate at which the liquid agent is conveyed to the vaporizing device, the first gas flow sensor measures the rate of flow of carrier gas, the second gas flow sensor measures the rate of flow of carrier gas containing vaporized agent, and the rate of flow of the liquid agent conveyed to the vaporizing device is controlled by the liquid flow control device.
  • the vaporizer according to the first and/or the second aspect of the invention includes a system for pressurizing the liquid anaesthetic agent in the reservoir. This may be achieved, in a first embodiment of the invention, by heating the liquid in the reservoir such that the vapour pressure of the liquid pressurizes the liquid. In practice this normally requires the use of temperatures of the order of 30° C or more, which means that such an arrangement suffers from some of the limitations of some of the prior art using vapour flow control systems.
  • a second embodiment of the invention uses independent pressurization means.
  • a gas compressor may pressurize the liquid agent by applying gas pressure to the surface of the liquid, either directly, or indirectly, e.g. by such means as a diaphragm, or bellows, interface. If a pressure above approximately 1.0 bar is used then the liquid agent will not boil with the vaporizer operating at any normal ambient temperature; even without cooling the liquid. This means that the pressure can be maintained completely independently of ambient temperature.
  • a preferred method is to use gas pressure to pressurize the liquid to a minimum pressure that is required to adequately control the liquid flow but to use a flow control system that will not be affected if the vapour pressure rises to pressures above the gas pressure due to high ambient temperatures. This has the advantage that a smaller, lower powered compressor can be used.
  • a convenient method to do this is, prior to reducing its pressure, to reduce the temperature of the liquid to a level where the increased solubility offsets the decrease of solubility due to Henry's Law. This has been found to give the predicted result although it has to be recognised that within the core of an electrically operated control valve the temperatures may be higher than the external body temperature and that the reduced temperature must be effective at the hottest point in the liquid flow path.
  • the preferred solution to this conflict of requirements is to use a specially devised pressure-difference control device that maintains a substantially constant pressure difference, e.g. of the order of 0.1 bar , across the control device irrespective of the supply pressure of the liquid flow being controlled.
  • a preferred embodiment of this pressure- difference control device is shown in Fig 3, and is described in detail below.
  • the pressure-difference control device also substantially maintains the set pressure difference across the flow-control device irrespective of the downstream pressure; typically this will be the pressure of the carrier gas. This is important because, in practice, it can vary by an amount in excess of 0.1 bar, typically as an anaesthetic ventilator cycles between inspiration and expiration, and this would be sufficient to affect the liquid flow in an uncompensated system.
  • a third aspect of the invention provides an anaesthetic vaporizer comprising a reservoir for containing liquid anaesthetic agent, a vaporizing device, a conduit for a carrier gas supply, and a liquid flow control device, the vaporizer being arranged such that in use liquid anaesthetic agent contained in the reservoir is conveyed in liquid form to the vaporizing device where it is vaporized for delivery to a patient with the carrier gas, wherein the liquid flow control device is adapted to control the rate of flow of the liquid agent conveyed to the vaporizing device and to maintain a substantially constant pressure difference across itself.
  • vapour pressurization is employed to pressurize the liquid chamber there is no subsequent problem with gas being released from solution but this is replaced by the problem of boiling occurring during any pressure drop, such as must take place in any flow control device, unless there is also a reduction in the liquid temperature at that point. Also, unless the temperature of the relatively large mass of liquid in the reservoir is fairly accurately controlled, probably necessitating cooling as well as heating, then the supply pressure to the control device will vary. As in the previously described arrangement, the use of a pressure- difference control device will solve both of these problems.
  • This solution also opens the way to use a system that requires neither the higher temperatures necessary to drive a solely vapour- pressure energised system nor the higher pressures necessary to prevent local boiling. All that is required is for a gas-pressurization system that maintains a minimum overall supply pressure sufficient to allow accurate flow control to be achieved. Independently from this the vapour pressure is allowed to attain its own level according to the reservoir temperature with no need to specifically control this temperature. This results in a smaller, lower-power gas compressor requirement and avoids the higher electrical-power loads necessary to control the bulk temperature of the liquid in the supply reservoir.
  • the gas-pressurization pressure need be no more than about 0.3 bar but the system can still operate accurately if the liquid bulk temperature rises to 35° C with its corresponding vapour pressure of the order of 1 bar.
  • the pressure-difference control device will be substantially that of the carrier-gas pressure (typically, less than 0.1 bar). At these pressures any dissolved air will be released, unless the temperature is very low, and the liquid will start boiling at a rate determined by the heat flow into the liquid passage. In practice, it is found that by careful design of the flow passages the release of gas is sufficiently ordered that it presents no problem in achieving a regular delivery to the vaporizing device but that if boiling occurs the process is generally spasmodic and, although the average anaesthetic-agent delivery is accurate, excessive fluctuations are observed at the outlet of the vaporizer.
  • the vaporizing device comprises a part of, or is in communication with, the conduit for the carrier gas supply.
  • the vaporizer according to the present invention is not just an open-loop calibrated dispenser. It dispenses under closed-loop control using real-time feedback of liquid delivery flows. It preferably also confirms correct dispensation with real-time measured vapour concentration by the second gas sensor. It is a system which firstly independently measures, and controls by direct feedback, correct delivery of liquid agent, as necessary, according to the carrier gas volume flow, or any other requirement determined by the control algorithm, based on safety, accuracy or alternative control strategies, and secondly confirms the subsequent vapour concentration within the carrier gas after the liquid has vaporized, features not found in prior vaporizers.
  • These gas flow sensors preferably also use the same additional information to determine the composition of the carrier gas, and this information preferably is fed back to a processor, which adjusts the liquid agent flow rate and preferably maintains a constant agent vapour volume/volume concentration throughout the specified carrier gas composition ranges.
  • Figure 1 represents a schematic diagram of a vaporizer according to one embodiment of the present invention
  • Figure 2 shows a functional block diagram of the vaporizer shown in
  • Figure 1; and Figure 3 shows a preferred form of pressure-difference control device used in vaporizers according to embodiments of the invention.
  • Figures 1 and 2 a multi-agent vaporizer for the delivery of any chosen volatile liquid anaesthetic agent is illustrated.
  • the vaporizer may allow the operator to deliver a range of anaesthetic agents.
  • the agent reservoir 1 may be built into a removable cartridge allowing the delivery of the anaesthetic agents Desflurane, Sevoflurane, Isoflurane, and Enflurane, for example.
  • the different agents can be recognised by the use of a different indexing system on each agent-specific cartridge.
  • the software-controlled system then automatically recognises the agent to be delivered, the fresh-gas flow and the concentration to set.
  • the delivery system then delivers the correct liquid-agent flow through to the carrier gas.
  • the vaporizer reservoir is filled, at normal room temperature, with liquid agent through a proprietary filler system.
  • the filling system operates whether the reservoir is pressurized or not. When a liquid level sensor 3 indicates the level as full, the filling bottle is removed and the filler is sealed. If unpressurized, the reservoir is then pressurized, by pressurizing means 5, such as a gas compressor (that pumps air or another gas into the reservoir 1), to the predetermined operating pressure.
  • pressurizing means 5 such as a gas compressor (that pumps air or another gas into the reservoir 1), to the predetermined operating pressure.
  • a pressure is selected that is above the minimum pressure at which the flow-control system will operate in a manner that gives stable flow control independent of any changes of pressure of the carrier gas.
  • the pressure generated in the reservoir by the compressor will typically be 0.2 bar, or more, but vapour pressure of the liquid agent at the maximum specified ambient operating temperature may typically raise this up to 1.0 bar.
  • Fresh gas inlet and outlet flows are measured with flow- measuring sensors 6 and 14 and the flow rate is registered in the control processor 8. With no anaesthetic agent being delivered the inlet and outlet flow sensors will provide similar flow readings to each other irrespective of the fresh gas composition, and only by the addition of the agent will there be a difference between the inlet and outlet flow sensor ' readings. From this difference the concentration of anaesthetic agent can be determined and checked with that set on a concentration selection dial 18 (or other anaesthetic concentration control) by the operator of the vaporizer. The sensors preferably also detect the presence of N 2 0 in the carrier gas, and calculate the concentrations of IM 2 0 and 0 2 .
  • the flow of liquid anaesthetic agent from the pressurized reservoir chamber is measured with a micro-flow sensor 9.
  • the preferred form of this sensor incorporates a low-power heating device which may cause a small local rise of temperature of the liquid flowing through it. If the reservoir has been pressurized by means of vapour pressure then local boiling could occur at the sensing element and so with this arrangement the liquid may need to be cooled by the amount necessary to counteract the heating effect before it enters the sensing element.
  • the central processor checks the actual flow of anaesthetic agent against that expected for the set concentration and the carrier gas flow.
  • the proportional flow-control valve 10 is then controlled via a closed loop with the sensor, to deliver the required amount of agent. Extremely low flows, below that which can be continuously controlled by the flow- control valve, can be achieved through pulsed operation, and specifically pulse-width modulation, of the control valve. Measured flows of liquid are integrated over time to confirm correct delivery.
  • thermoelectric solid-state cooling device operating on the reversed thermocouple principle.
  • Such devices are extremely compact and pump heat from a 'cool' surface to a 'hot' surface. They are widely available commercially as standard components.
  • the 'cool' surface of such a heat pump can be connected to a thermally-connected assembly containing the liquid flow sensor 9, the proportional flow control valve 10, the pressure-difference control device 7 and the shut-off valve 11.
  • This assembly can, in turn, be thermally insulated from the rest of the vaporizer.
  • the 'hot' surface of the heat pump can be connected to the main body of the vaporizer at a point where any heat flow can be readily conducted away so as to result in a minimum temperature rise at the 'hot' surface.
  • a second cooling device could be installed in parallel to ensure that cooling can be maintained even if one of the two devices fails.
  • the liquid agent then flows through the pressure-difference control device 7, across which a substantially constant pressure difference is maintained irrespective of the flow or supply pressure of the liquid agent being delivered.
  • the liquid agent On exiting the pressure-difference control device 7 the liquid agent is delivered, via a safety shut-off valve 11, into a heated vaporizing device 12.
  • liquid in the liquid supply passage will be kept below its boiling point to prevent irregular vapour-bubble formation but that there may well be slug flow due the steady release of dissolved air which collects into air bubbles regularly spaced in the flow. If the liquid supply passage is of a constant, small diameter, typically of the order of 1.0 mm, and with no discontinuities, or pockets where air can collect, then the flow to the vaporizer has been found to be sufficiently regular to provide a substantially constant vaporization rate.
  • a normally-closed, electrically- operated shut-off valve 11 is placed in the passage to the vaporizing device. With the design used here for illustration, care is taken in the selection and positioning of this valve to ensure that it does not present any air collection points that might cause air to collect and build up into larger and more randomly released bubbles. It is also arranged that any temperature rise that may occur as the liquid passes through this valve does not raise the liquid to its boiling point so as to form the more irregular vapour bubbles.
  • the liquid agent vaporized In the illustrative design described here only on reaching the vaporizing device is the liquid agent vaporized. As explained earlier, the vaporization process can be very unstable because of the large heat flows as vaporization bubbles are formed. It has been found by the present inventors that in the configurations that have been tested the best results are achieved by introducing the liquid as a continuous stream, or with regularly dispersed bubbles, and to drop this flow onto a solid, good-heat-conducting surface connected directly to a heater element. This arrangement maximises the flow of heat back into the surface following any local drop of temperature due to the formation of a vaporization bubble on the surface. If a local cool spot does temporarily occur any liquid that does not vaporize just flows on to another part of the surface and is evaporated there.
  • a smoother vaporization rate is achieved if at least part of the vaporizing surface is inclined to the horizontal, e.g. by 45° or more, and in such a manner that any liquid that meets a temporary cool spot quickly flows on to another part of the vaporizing surface.
  • the bulk temperature of the vaporizing device is maintained at a predetermined temperature by means of control loop with a temperature sensor and a heating element. As the liquid flow into the device increases it spreads over a larger area and more is evaporated. The latent heat of vaporization takes heat from the surface, reducing the temperature and hence causing the control system to deliver more power to the heater. As the vaporization increases there is an inevitable increase in the thermal gradient between the heating element and the vaporization surface and so it may be beneficial to increase the required operating temperature as the liquid flow increases.
  • the vaporizing device may be either in a side passage but connected to the carrier-gas flow conduit or may be situated within this conduit. If in a side passage the vapour will flow into the carrier gas conduit at the rate at which it is generated and the temperature of the carrier gas will be largely unchanged. If the carrier gas flows through the vaporizing device the heat within the carrier gas can be used to vaporize some of the liquid, which may economise on heater power consumption but will result in a corresponding cooling of the carrier gas. If the vaporizing device is insulated, heat flow back into the body of the vaporizer can be minimised which has the advantage of both reducing the electrical power requirement of the vaporizing device and of minimising the cooling power required to maintain the outlet flow from the pressure-difference control device below its boiling point.
  • a heater of no greater than 15 Watts is adequate to both maintain the vaporizing surface temperature and to give sufficient margin to provide a thermal time-constant more than adequate to respond to the most rapid changes in liquid flow.
  • the vaporizing surface temperature will be maintained at between 25° C and 35° C. If the temperature is too low a larger surface area for vaporization is required and if it is too large more heat will be lost to the body of the vaporizer and the vaporization process will become more violent and hence potentially less regular.
  • the vaporizing device 12 is in communication with the conduit for the carrier gas supply.
  • the anaesthetic agent that is transformed into the vapour phase in the vaporizing device passes at substantially constant pressure through a port connected directly to the carrier-gas supply conduit.
  • the vaporizing device could be located in (or comprise part of) the carrier gas supply conduit.
  • the vaporized agent may then pass through a mixing device 13 ensuring a complete mixing of the fresh gas and vapour.
  • the mixture subsequently passes through a second flow-measuring device 14 which independently monitors the increased output flow due to addition of vapour and provides for additional confirmation of correct vaporizer performance.
  • the control system is a software-controlled device using a safety- critical high-level language.
  • the software also monitors the controlled hardware and all of the feedback signals. In the event of a device failure the system closes off the delivery of all anaesthetic agent, failing into a safe mode and generating a visual and audible alarm.
  • the use of electronics for the independent control of the liquid- anaesthetic-agent flow also means that the set concentration on the vaporizer can be overridden by other inputs making the vaporizer suitable for incorporation into an external control loop as, for example, may be used in a system that monitors and automatically controls the depth of patient anaesthesia.
  • liquid anaesthetic agent flow sensor has the additional benefit that the signal output from the sensor can be integrated to measure the amount of agent dispensed in a given period.
  • the display of this quantity is useful to users, not least for keeping records of costs when using very expensive agents.
  • the vaporizer is powered by mains electrical supply transformed down to a low voltage, thereby increasing safety.
  • a low voltage supply (for example 12V) is possible because the vaporizer avoids the need to heat or cool a large mass of anaesthetic agent; instead, only the required small mass of agent required to be mixed with the carrier gas is heated or cooled at any time.
  • the use of a low voltage supply also means that a battery back-up 16 may be present in case of mains supply failure.
  • FIG. 3 A preferred form of pressure-difference control device used in vaporizers according to embodiments of the invention is shown in Figure 3.
  • the device 7 comprises a diaphragm 21, a low force bias spring 22, a needle valve 23, a control seat 24, and a diaphragm support 25.
  • the functional components are retained in a suitable housing.
  • control valve 10 opens, fluid from the anaesthetic agent reservoir is allowed to flow through the control valve onto the upper side of the diaphragm 21. Pressure will rise on the upper side of the diaphragm 21 until the pressure coupled with the addition of the spring force 22 balances the force due to the reservoir pressure on the lower side of the diaphragm, and the diaphragm with its needle valve 23 will move downward and open the needle valve allowing the fluid to flow.
  • the pressure on the upper surface of the diaphragm 21 will increase, however as the force increases the diaphragm will move downward to increase the opening of the needle valve 23 further, maintaining a constant pressure differential across the valve assembly (i.e. the pressure-difference flow control device) for the range of specified flows.
  • the pressure on the upper side of the diaphragm 21 will decrease, the diaphragm will move upward and close the needle valve 23, thus maintaining the same pressure differential.

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  • Health & Medical Sciences (AREA)
  • Anesthesiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Pulmonology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Emergency Medicine (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
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Abstract

L'invention a trait à un vaporisateur pour anesthésie, qui comprend un réservoir (1) destiné à contenir un agent anesthésique liquide, des moyens de pressurisation (5) destinés à mettre l'agent anesthésique liquide sous pression dans le réservoir, un dispositif de vaporisation (12), et un conduit destiné à l'apport de gaz vecteur. Le vaporisateur selon l'invention est adapté de manière que, en cours d'utilisation, l'agent anesthésique liquide contenu dans le réservoir soit mis sous pression par le moyen de pressurisation, et acheminé sous forme liquide, sous l'effet de ladite mise sous pression, vers le dispositif de vaporisation, où il est vaporisé pour être administré à un patient avec le gaz vecteur, la mise sous pression de l'agent anesthésique liquide et son acheminement vers le dispositif de vaporisation étant tous deux commandés indépendamment de l'apport de gaz vecteur.
PCT/GB2004/001649 2003-04-15 2004-04-15 Vaporisateur pour anesthesie ameliore Ceased WO2004091708A2 (fr)

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Application Number Priority Date Filing Date Title
GB0308661.8 2003-04-15
GBGB0308661.8A GB0308661D0 (en) 2003-04-15 2003-04-15 Improved anaesthetic vaporizer

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WO2004091708A2 true WO2004091708A2 (fr) 2004-10-28
WO2004091708A3 WO2004091708A3 (fr) 2004-12-09

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005005349B3 (de) * 2005-02-05 2006-06-01 Dräger Medical AG & Co. KG Elektrisch beheizter Anästhesiemitteldosierer
WO2009120057A1 (fr) * 2008-03-28 2009-10-01 Innovamédica S.A.P.I. De C.V. Cartouches d'anesthésique liquide et vaporisateur
CN102688546A (zh) * 2011-03-21 2012-09-26 通用电气公司 医用喷雾器和监视医用喷雾器的方法
WO2015017342A1 (fr) * 2013-07-29 2015-02-05 Oregon Health & Science University Vaporisateur d'anesthésique
DE102014008625A1 (de) 2014-06-17 2015-12-17 Drägerwerk AG & Co. KGaA Vorrichtung und Verfahren zur Dosierung eines Narkosemittels in einen Gasstrom
DE102016001383A1 (de) 2016-02-08 2017-08-10 Drägerwerk AG & Co. KGaA Vorrichtung zur Bereitstellung eines mit Narkosemittel angereicherten Atemgasstroms
CN108585534A (zh) * 2018-07-25 2018-09-28 湖北鸿创科技有限公司 一种玻璃蚀刻用鼓泡装置
US10610659B2 (en) 2017-03-23 2020-04-07 General Electric Company Gas mixer incorporating sensors for measuring flow and concentration
US10946160B2 (en) 2017-03-23 2021-03-16 General Electric Company Medical vaporizer with carrier gas characterization, measurement, and/or compensation
CN113350811A (zh) * 2021-07-08 2021-09-07 深圳市普博医疗科技股份有限公司 一种可自动液位检测的地氟醚蒸发罐

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DE102005005349B3 (de) * 2005-02-05 2006-06-01 Dräger Medical AG & Co. KG Elektrisch beheizter Anästhesiemitteldosierer
WO2009120057A1 (fr) * 2008-03-28 2009-10-01 Innovamédica S.A.P.I. De C.V. Cartouches d'anesthésique liquide et vaporisateur
CN105214189A (zh) * 2011-03-21 2016-01-06 通用电气公司 医用喷雾器和监视医用喷雾器的方法
US9586020B2 (en) 2011-03-21 2017-03-07 General Electric Company Medical vaporizer and method of monitoring of a medical vaporizer
EP2517748A1 (fr) * 2011-03-21 2012-10-31 General Electric Company Vaporisateur médical
US8752544B2 (en) 2011-03-21 2014-06-17 General Electric Company Medical vaporizer and method of monitoring of a medical vaporizer
US20120240928A1 (en) * 2011-03-21 2012-09-27 General Electric Company Medical Vaporizer and Method of Monitoring of a Medical Vaporizer
CN102688546B (zh) * 2011-03-21 2015-11-25 通用电气公司 医用喷雾器和监视医用喷雾器的方法
CN102688546A (zh) * 2011-03-21 2012-09-26 通用电气公司 医用喷雾器和监视医用喷雾器的方法
WO2015017342A1 (fr) * 2013-07-29 2015-02-05 Oregon Health & Science University Vaporisateur d'anesthésique
WO2015192946A1 (fr) 2014-06-17 2015-12-23 Drägerwerk AG & Co. KGaA Dispositif et procédé de dosage d'un anesthésiant dans un flux de gaz
DE102014008625A1 (de) 2014-06-17 2015-12-17 Drägerwerk AG & Co. KGaA Vorrichtung und Verfahren zur Dosierung eines Narkosemittels in einen Gasstrom
US11383060B2 (en) 2014-06-17 2022-07-12 Drägerwerk AG & Co. KGaA Device and method for dispensing an anesthetic into a gas stream
DE102016001383A1 (de) 2016-02-08 2017-08-10 Drägerwerk AG & Co. KGaA Vorrichtung zur Bereitstellung eines mit Narkosemittel angereicherten Atemgasstroms
FR3047418A1 (fr) 2016-02-08 2017-08-11 Draegerwerk Ag & Co Kgaa Dispositif pour la mise a disposition d'un flux de gaz respiratoire enrichi avec un agent anesthesiant
US10821256B2 (en) 2016-02-08 2020-11-03 Drägerwerk AG & Co. KGaA Device for providing a breathing gas flow enriched with anesthetic
US10610659B2 (en) 2017-03-23 2020-04-07 General Electric Company Gas mixer incorporating sensors for measuring flow and concentration
US10946160B2 (en) 2017-03-23 2021-03-16 General Electric Company Medical vaporizer with carrier gas characterization, measurement, and/or compensation
CN108585534A (zh) * 2018-07-25 2018-09-28 湖北鸿创科技有限公司 一种玻璃蚀刻用鼓泡装置
CN113350811A (zh) * 2021-07-08 2021-09-07 深圳市普博医疗科技股份有限公司 一种可自动液位检测的地氟醚蒸发罐

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WO2004091708A3 (fr) 2004-12-09

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