WO2011058371A1 - Dispositif d'humidification de gaz d'un respirateur - Google Patents

Dispositif d'humidification de gaz d'un respirateur Download PDF

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Publication number
WO2011058371A1
WO2011058371A1 PCT/GB2010/051893 GB2010051893W WO2011058371A1 WO 2011058371 A1 WO2011058371 A1 WO 2011058371A1 GB 2010051893 W GB2010051893 W GB 2010051893W WO 2011058371 A1 WO2011058371 A1 WO 2011058371A1
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WO
WIPO (PCT)
Prior art keywords
gas
moisture
patient
port
capture
Prior art date
Application number
PCT/GB2010/051893
Other languages
English (en)
Inventor
Keith Turner
Michael Andrew Beadman
Michael Roger Cane
Richard Thomas Brown
Stephen J. Lamb
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Inspired Medical Technologies Limited
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Publication date
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Publication of WO2011058371A1 publication Critical patent/WO2011058371A1/fr

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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. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/1045—Devices for humidifying or heating the inspired gas by using recovered moisture or heat from the expired gas
    • 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. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/08—Bellows; Connecting tubes ; Water traps; Patient circuits
    • A61M16/0808—Condensation traps
    • 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. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/105—Filters
    • A61M16/1055—Filters bacterial
    • 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. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/1075—Preparation of respiratory gases or vapours by influencing the temperature
    • 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. mouth-to-mouth respiration; 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
    • A61M16/16—Devices to humidify the respiration air
    • 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
    • A61M2205/00—General characteristics of the apparatus
    • A61M2205/33—Controlling, regulating or measuring
    • A61M2205/3368—Temperature
    • 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
    • A61M2205/00—General characteristics of the apparatus
    • A61M2205/36—General characteristics of the apparatus related to heating or cooling
    • A61M2205/3606—General characteristics of the apparatus related to heating or cooling cooled
    • 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
    • A61M2205/00—General characteristics of the apparatus
    • A61M2205/36—General characteristics of the apparatus related to heating or cooling
    • A61M2205/366—General characteristics of the apparatus related to heating or cooling by liquid heat exchangers

Definitions

  • the invention relates to a gas humidification device and a method of humidifying gas from a ventilator.
  • Respiratory humidifiers are used to condition breathing gases for patients breathing on a mechanical ventilator or CPAP.
  • the gas which can be air, oxygen, or a mixture, is pumped by the ventilator and transferred to the patient via a breathing circuit.
  • the circuit has a Y-shaped connector to separate inspiratory (inhaled) and expiratory (exhaled) gas flows close to the patient.
  • There are also a series of connecting components including a catheter mount to provide flexion, a swivel to enable the circuits to move without strain, and a suction catheter mount to allow secretions to be removed from the lungs. Finally, the gas passes into a delivery component.
  • this is typically an endotracheal tube which carries the gas past the patient's mouth and throat, down the trachea and into the lungs. In other settings it can be a mask which delivers gas to the mouth and nose. All components from the Y-shaped connector through to the patient create space in the circuit which is not cleared of exhaled gas before inhalation, generally known as dead space.
  • the gas is at room temperature and dry. It therefore has to be heated and humidified before being delivered to the patient.
  • a respiratory humidifier In the healthy human these functions are performed by the nose and upper airway. They are essential for normal breathing and gas exchange.
  • the first type is a heated humidifier.
  • gas passing along the inspiratory limb of the breathing circuit is passed over a chamber of water which is heated by a hotplate.
  • a heated humidifier can successfully deliver fully humidified gas at body temperature.
  • the gas cools and condensation forms on the circuit. This is undesirable because it makes the circuit difficult to manage, there is risk of draining liquid water into the lungs, and it can promote colonisation of microbes which can lead to infections such as Ventilator Associated Pneumonia (VAP).
  • VAP Ventilator Associated Pneumonia
  • the second type is a heat moisture exchanger (HME), usually combined with an antimicrobial filter and referred to as an HMEF.
  • HME heat moisture exchanger
  • An HME contains an exchange medium to capture moisture and energy from expired gas. This medium is often formed from a foamed material or a coil of corrugated paper or plastic, but can take other forms. As the gas passes over the medium, it cools and moisture is condensed onto the medium. In some cases, hygroscopic salts remove further moisture from the gas. During inspiration, cool dry gas is drawn over the exchange medium, collecting heat and moisture before then being delivered to the patient.
  • the antimicrobial filter When present, the antimicrobial filter is placed on the ventilator side of the HME, and prevents the spread of microbes to other parts of the breathing circuit and back into the lungs.
  • the advantages of this type of humidifier are that it produces less condensation, requires no power, can be less prone to colonisation by microbes and is inexpensive. However, it is considerably less than 100% efficient at returning expired moisture to the patient, and therefore cannot be used for long-term humidification.
  • Another problem associated with HMEs is that they increase the dead space and therefore carbon dioxide content of inspired gas, increasing the work of breathing.
  • Some technologies have been developed which attempt to capitalise on the best aspects of both technologies by creating a hybrid design. These typically include an HMEF-like element to capture and release moisture, an external water supply, and an embedded heater.
  • the heater raises the temperature of inspired gas closer to body temperature, and the external water supply increases the humidity of gas supplied to the patient.
  • the extra overhead of the external water supply has to be managed, and in some cases the humidity of supplied gas is still not high enough for long term humidification. There are also difficulties with regulating temperature and dangers associated with overheating.
  • a gas humidification device for a ventilator comprising:
  • a machine gas port for connection to a ventilator
  • a patient gas port to provide a gas supply for a patient
  • a gas cooling system coupled in a gas flow path from said patient gas port to cool gas from said patient and condense water
  • a gas heating system coupled in a gas flow path between said machine gas port and said patient gas port to heat gas prior to delivery to said patient;
  • gas humidification means in said gas flow path between said machine gas port and said patient gas port to humidify said gas prior to delivery to said patient;
  • water transport means to transport said captured condensed water to said humidification means.
  • a device for humidifying gas in a patient breathing system comprising
  • a patient gas port through which the patient inhales or exhales
  • a moisture capture mechanism connected to the patient gas port which captures moisture in exhaled gas
  • a moisture transport mechanism for transporting captured moisture from said moisture capture mechanism to said moisture release mechanism.
  • the moisture capture mechanism gas cooling system
  • the moisture release mechanism gas heating system
  • one or more of these mechanisms may be termed active, rather than passive as in a standard HME.
  • the expired or exhaled gas passes over the moisture capture mechanism (gas cooling system), which condenses moisture out of the expired gas and holds it within the device.
  • the moisture capture mechanism gas cooling system
  • said moisture capture mechanism may comprise a moisture extraction system coupled in a gas flow path from said patient gas port whereby exhaled gas passes over said active moisture capture mechanism which condenses moisture out of the exhaled gas; and a first moisture store which stores said condensed moisture.
  • the moisture extraction system may be a gas cooling system which cools the exhaled gas to condense moisture.
  • said moisture extraction system may be a pressure reduction system which reduces the pressure of the exhaled gas to condense moisture out of the exhaled gas.
  • said moisture extraction system may use a chemical reactant (e.g. a hygroscopic salt).
  • said gas cooling system may comprise a fluid chamber having fluid inlet and outlet ports, said fluid chamber being thermally coupled to a plurality of heat transfer elements, wherein said heat transfer elements are thermally coupled to said first moisture store (said moisture capture means) and define a plurality of gas flow channels for a said gas flow path.
  • cooling may be achieved by flowing a cold fluid through a heat-exchange structure, in a similar way to that used in a car radiator.
  • said gas cooling system may comprise a thermoelectric cooler located inside the device to provide a cold element.
  • gas may be expanded through a nozzle inside the device to provide a cold element.
  • a heat pipe may be used to transfer heat.
  • said moisture release mechanism may comprise a second moisture store which stores captured moisture transferred from said moisture capture mechanism to said moisture release mechanism and an element coupled in an gas flow path between said gas supply and said patient gas port to evaporate said captured moisture into inhaled gas, i.e. into gas prior to delivery to said patient.
  • the element may incorporate features which assist the rate of evaporation of moisture into the gas.
  • Said element may be a heating system whereby the gas may be heated directly or indirectly to increase its capacity to hold moisture and thus the amount of moisture supplied to the patient may be maximised.
  • the heating system may heat any one of or a combination of the gas, the stored captured moisture, the first or second moisture store and the moisture transfer mechanism.
  • said gas heating system may comprise a fluid chamber having fluid inlet and outlet ports, said fluid chamber being thermally coupled to a plurality of heat transfer elements, wherein said heat transfer elements are thermally coupled to said second moisture store (said gas humidification means) and define a plurality of gas flow channels for a said gas flow path.
  • heating may be achieved by flowing a warm fluid through a heat-exchange structure, in a similar way to that used in a car radiator.
  • the heating system may be the warm side of a thermoelectric cooler, or other heat-pump technology such as a heat pipe.
  • the heating system may be a resistance wire. The wire may be embedded inside the heating system itself or another component of the device.
  • the wire may be embedded inside a moisture store which is formed from foam (e.g. foamed plastics), corrugated paper or corrugated plastic.
  • the wire may also be positioned so as to heat the gas which in turn transfers the energy to the moisture, causing evaporation.
  • Both the cooling and heating mechanisms can incorporate features, such as colour and surface finish, that provide desirable conditions for thermal transfer between the mechanism and the gas by radiation.
  • said heat transfer elements may be in the form of a plurality of fins and the geometry of the fins may be chosen to optimise the ratio of heat transfer to volume and/or to optimise the ratio of heat transfer to weight.
  • the fins may be metal and have a length between 4 to 9mm.
  • the fins may be made from a polymer material and have a length between 0.5 to 3mm.
  • One or both of said gas cooling system and said gas heating system may alternatively comprise a coiled tube through which fluid flows, with a plurality of gas flow channels for a said gas flow path being defined by gaps between each coil.
  • Said coiled tube may comprise at least two layers of coils, each layer offset relative to the other layer whereby the coils of one layer fill the gaps of the other layer. In this way a convoluted passage is defined for the gas flow.
  • the gas cooling system and the moisture capture means may be mounted in an expiration path between said gas supply and said patient gas port and the gas heating system and the gas humidification means may be mounted in an inspiration flow path from said patient gas port to said gas supply.
  • the device may further comprise a valve controlling the gas flow in the device whereby exhaled gas is prevented from flowing into the inhalation path and through the gas cooling system and the moisture capture means and inhaled gas is prevented from flowing through the exhalation path and through the gas heating system and the gas humidification means.
  • said moisture transport mechanism or water transport means may be formed from a wicking material.
  • said moisture transfer mechanism or water transport means may use gravity, squeezing and/or mechanical translation to transport the moisture from the moisture capture element (moisture capture means) to the moisture release element (gas humidification means).
  • the moisture transfer mechanism may be integrally formed with one or both of the first and second moisture stores.
  • the moisture release mechanism (or gas humidification means) and moisture capture mechanism (or moisture capture means) may be arranged relative to one another so that moisture captured by the moisture capture mechanism falls under gravity to and collects in the moisture release mechanism.
  • the device may be designed to ensure the device is not sensitive to orientation.
  • moisture may be collected in a foam or corrugated paper or plastic arrangement that is in communication with the moisture capture element, and transported to the moisture release element by squeezing in a motion similar to that used in a peristaltic pump.
  • a rotating disc can be used to mechanically translate moisture from the moisture capture element to the moisture release element.
  • the device may comprise a wicking material.
  • Said moisture capture means, said water transport means and said gas humidification means each may comprise a portion of said wicking material.
  • One or both of said gas cooling system and said gas heating system may comprise a fluid chamber having fluid inlet and outlet ports, said fluid chamber being thermally coupled to a plurality of heat transfer elements, wherein said heat transfer elements are thermally coupled to said wicking material and define a plurality of gas flow channels for a said gas flow path.
  • the wicking material may have a capillary-like structure.
  • Said wicking material may be provided with a plurality of pleats whereby said wicking material has a large surface area.
  • An anti-microbial coating may also be incorporated into the surfaces of any component, the wicking material and other structures (e.g. foam moisture store).
  • the fins may define a plurality of slots which form the gas flow channels and wherein the slots are open to allow the wicking material to be removably inserted in the slots
  • the device may comprise two compatible and removably connectable components.
  • a first mouthpiece component may comprise said machine gas port, said patient gas port, said moisture capture means, said water transport means and said plurality of heat transfer elements for both said gas cooling system and said gas heating system.
  • a second umbilical component may comprise said fluid chamber of both said gas cooling system and said gas heating system. In this way, the second component may be a sealed system.
  • the mouthpiece may be a disposable component.
  • Each of said fluid chambers may be received in corresponding apertures in said mouthpiece component.
  • the fluid chambers are designed to mate with high force to ensure good thermal contact.
  • each of said fluid chambers may be generally wedge-shaped or otherwise designed to ensure good thermal transfer..
  • the device may incorporate an anti-microbial filter to reduce the chances of infection.
  • a filter may be similar to those used in an HMEF on the ventilator side of the device.
  • the device may incorporate a secondary moisture capture mechanism in the gas flow path adjacent the machine gas port.
  • the secondary moisture capture mechanism may be similar to the moisture capture mechanism in know HMEFs.
  • the device may be configured to fit within a tube forming part of the patient breathing system.
  • the tube may be internal or external to the patient. It will be appreciated that by placing the device within a patient, e.g. in the endotrachael tube, dead space is minimised. This may be achieved because of the increased efficiency of the proposed device when compared with known devices which allows the device to be miniaturised compared to the known devices.
  • the device may have a generally cylindrical configuration, e.g. by providing generally cylindrical key components.
  • at least one or all of the moisture capture mechanism, the moisture release mechanism and the moisture transport mechanism are generally cylindrical.
  • a method of humidifying a gas supply to a patient comprising:
  • the method may comprise capturing condensation by actively cooling gas.
  • the method may comprise humidifying said gas for inhalation by heating said gas.
  • a method of conditioning temperature and humidity of a gas supply to a patient comprising:
  • the method may further comprise transporting said condensation away from a position of said capturing either:
  • said transporting may comprise wicking.
  • apparatus comprising means for implementing the above described methods.
  • the aspects above provide a humidifier which is more efficient than a HME and which supplies gas of sufficient humidity for long term ventilation, while also keeping both condensation and the risk of infection to a minimum.
  • the humidifier will have a small dead space, will be located close to the patient and will operate using low cost disposable components and be highly efficient.
  • Fig. 1 is a schematic drawing of a first gas humidifier for a ventilator
  • Fig. 2 is a schematic drawing of a second gas humidifier for a ventilator
  • Fig. 3 is a perspective view of a cooling or heating element for use in the humidifier of Fig. 1 or Fig. 2;
  • Fig. 4 is an exploded perspective view showing how the element of Fig. 3 is coupled to a moisture transport element
  • Fig. 5 is a cutaway view of a variation of the gas humidifier of Fig. 1 incorporating both a cooling element, a heating element and the moisture transport element of Fig. 4;
  • Fig. 6 is a generally cylindrical variation of the gas humidifier of Fig. 5;
  • Fig. 7 is a variation of the gas humidifier of Fig. 6;
  • Figs 8a and 8b are alternative generally cylindrical gas humidifiers
  • Fig 9 is a variation of the gas humidifier of Fig 8b;
  • Fig 10 is an alternative gas humidifier.
  • Figure 1 describes a humidifier in which breathing gas passes over both capture and release elements during both inspiration (inhalation) and expiration (exhalation).
  • gas at close to 100% relative humidity and close to body temperature 37°C passes from the patient 1 , over the moisture release mechanism (gas humidification means) 2.
  • the gas then passes over the moisture capture mechanism (moisture capture means) 3 which removes moisture from the gas.
  • the dry gas continues along the expiratory limb of the breathing circuit over an (optional) anti-microbial filter 6 to the ventilator 4.
  • the moisture enters the moisture transport means (moisture transfer mechanism) 5 and is carried in the direction of the arrows shown to the moisture release mechanism.
  • gas from the ventilator 4 travels along the inspiratory limb of the breathing circuit, over the moisture capture mechanism 3.
  • the dry gas then passes over the moisture release mechanism 2 which releases the moisture into the gas stream, and warms it to the desired temperature, which is likely to be close to 37°C.
  • the humidified gas is the delivered to the patient 1 .
  • Figure 2 describes a humidifier in which breathing gas passes over only one of the moisture capture element 13 or the moisture release element 16, depending on its direction of travel.
  • gas at close to 100% relative humidity and close to body temperature 37 ⁇ ⁇ passes from the patient 1 1 to a junction in the breathing circuit.
  • the one-way valves 12 then direct the gas towards the moisture capture element 13 which removes moisture from the gas.
  • the dry gas continues along the expiratory limb of the breathing circuit to the ventilator 14.
  • the moisture enters the moisture transport mechanism 15 and is carried in the direction of the arrow shown to the moisture release element 16.
  • gas from the ventilator 14 travels along the inspiratory limb of the breathing circuit, and is directed by the one-way valves 12 towards the moisture release element 16 which releases the moisture into the gas stream, and warms it to the desired temperature, which is likely to be close to 37°C.
  • the humidified gas is delivered to the patient 1 1 .
  • Figure 2 by placing the capture and release elements in separate flow paths, the overall length of the humidifier is reduced and thus the dead space is reduced.
  • FIG. 3 shows a moisture capture mechanism comprising a cooling system to cool the gas to condense out moisture.
  • the cooling system comprises an external temperature-controlled fluid bath 21 , a fluid transfer conduit 22, and a heat-exchange structure 23.
  • the external bath 21 is filled with a heat-transfer fluid and stabilised at a low temperature.
  • the cold fluid is then pumped along the transfer conduit 22 and flows through a cavity inside the heat exchange structure 23, cooling it down.
  • the heat exchange structure comprises a plurality of heat transfer elements in the form of fins 24.
  • the fins 24 provide the heat exchange structure with a large surface area which enable it to cool the incoming gas, condensing out the moisture.
  • Other ways could also be used to give the heat exchange structure a large surface area. For example, it may contain a convoluted path, narrow channels, or features to promote turbulence.
  • the moisture capture mechanism of Figure 3 may also be used as the moisture release mechanism by flowing a warm transfer fluid through the structure 23.
  • FIG 4 is shown as an exploded view to assist clarity.
  • Two heat-exchange structures 23, 25 of the type described in Figure 3 are connected together so that the fins define a plurality of gas flow channels through which gas can pass.
  • the gas path is designed so as to ensure efficient cooling of the gas while also presenting a low resistance to gas flow.
  • the gas path is partially filled with a wicking material 26, which is pleated to provide a large surface area.
  • the wicking material 26 acts as a moisture store.
  • the moisture store holds moisture captured by the mechanism.
  • the moisture store may be considered a moisture capture means.
  • the moisture release mechanism the moisture store holds moisture which is released by the mechanism to humidify inhaled gas.
  • the moisture store may be considered a gas humidification means.
  • FIG 5 shows a device comprising a moisture capture mechanism 32 and a moisture release mechanism 33 and their associated moisture stores.
  • the moisture stores are formed from a single piece of a wicking material 26 which extends through the moisture capture mechanism along the device to and through the moisture release mechanism.
  • the wicking material also provides the moisture transport mechanism and the moisture stores are integral with the moisture transport mechanism.
  • an anti-microbial filter 28 is also incorporated into the device.
  • Figure 6 shows an alternative embodiment which works in the same way as that described in Figure 5.
  • the generally planar components of Figure 5 have been replaced with generally cylindrical components which fulfil the same function.
  • an anti-microbial filter 28 is also incorporated into the device and it will be appreciated that such a filter could be incorporated into all variations.
  • the cylindrical geometry of Figure 6 could be advantageous in creating a device that fits neatly into breathing circuits or endotracheal tubes so as to minimise dead space.
  • FIG 7 shows an alternative embodiment which works in the same way as that described in Figure 6.
  • both the moisture capture mechanism (C) and the moisture release mechanism (R) each comprise a large number of channels 40.
  • the moisture transfer mechanism comprises a plurality of strips of wicking material 41 which connect respective channels in the moisture capture mechanism and the moisture release mechanism.
  • the channels in the embodiment of Figure 7 are relatively short and there are a greater number of channels. By making the channels shorter, the pressure drop of air passing through each channel is reduced. Furthermore, the heat transfer is higher in the first part of the air channel due to entry effects before the flow is fully developed. It is an efficient use of space to make the channels only as long as that which makes use of this increased heat transfer.
  • the channels forming the moisture capture mechanism (C) are cooled by a heat- exchange structure which is cooled by cold fluid pumped through transfer conduit 44 around the heat-exchange structure and out conduit 48.
  • the channels forming the moisture release mechanism (R) are warmed by a heat-exchange structure (not shown) which is warmed by warm fluid pumped through an inlet transfer conduit 46 into the device, around the heat-exchange structure and out through an outlet transfer conduit (not shown).
  • the mechanisms are arranged in a disc-like geometry and are housed in a generally disc-shaped housing so as create a shape which is similar to an existing HME.
  • Various different arrangements of the channels are possible. For example, as shown there may be a generally circular central section 42 surrounded by partial concentric rings of channels
  • FIGS 8a and 8b show an alternative arrangement comprising a first coiled tube 50 which forms the moisture release mechanism (R) with warm fluid flowing through the coil and a second coiled tube 51 forming the moisture capture mechanism (C) with cold fluid flowing through the coiled tube.
  • the ends of each coiled tube are connected to a source of hot/cold fluid in a standard way.
  • the coiled tubes are both arranged in a double layered spiral with small gaps between each loop of the spiral through which the gas passes. Multiple layers to increase the heat transfer if required. Each layer is offset relative to the neighbouring layer to create a convoluted gas passage through these gaps. As shown, the offset is such that a neighbouring layer is arranged with its coils filling the gaps of the adjacent layer.
  • the size of the gaps can be chosen to optimise heat transfer from the circulating fluid to the gas while maintaining an acceptable flow resistance.
  • the geometry of the tubes can be chosen so as to promote turbulence in the gas and thus improve heat transfer. It is also possible to use thinner wall sections for the tubes than for the fins of the previous arrangement.
  • an optional secondary capture mechanism 52 is included in the gas flow path adjacent to the ventilator.
  • the secondary capture mechanism is similar to that used in a standard HME and may be made from foams or laminate coils.
  • the mechanism functions in a similar manner to that of a standard HME. Thus, it captures a fraction of the residual moisture in the exhaled air that has already passed through the moisture capture mechanism and releases this captured residual moisture to the inspired air stream.
  • Use of a secondary capture mechanism increases the efficiency at which the device recycles moisture and thus delivers a better supply to the patient. It may be incorporated in any of the embodiments shown not just Figures 8a and 8b. By locating the secondary capture mechanism in the breathing circuit, there is no increase in dead space.
  • An antimicrobial filter may also be included, e.g. as described above.
  • FIG 9 shows one example of a moisture transfer mechanism in which a cover of wicking material 60 is wrapped around the outer surfaces of the coiled tubes.
  • wicking material 60 is wrapped around the outer surfaces of the coiled tubes.
  • all four layers are axially aligned for ease of including the wicking cover.
  • wicking layers, sleeves or inserts may be used, e.g. in conjunction with the offset arrangement of Figures 8a and 8b.
  • FIG 10 shows an alternative device comprising a moisture capture mechanism (C) and a moisture release mechanism (R) each formed from a generally rectangular solid block of conducting material.
  • Each block comprises a central aperture 82, 84 which is adapted to receive a corresponding heat exchange structure 70, 72 which is a snug fit in the aperture.
  • Either side of the central aperture are a plurality of heat transfer elements in the form of fins 86 which define a plurality of slots along two edges of the blocks.
  • the slots define a plurality of gas flow channels through which gas can pass.
  • the slots are open and not enclosed by a solid face. Accordingly it is relatively easy to incorporate the moisture transfer mechanism.
  • a sheet of wicking material 83 is folded into a concertina shape and a fold is placed in each of the plurality of slots to form the moisture transfer mechanism connecting the moisture capture mechanism and moisture release mechanism.
  • a plurality of strips could be placed one in each slot.
  • the moisture transfer mechanism may also be easily inserted using this arrangement. Open fin designs can be applied to any of the embodiments and bring the advantage of ease of insertion of the moisture transport material during manufacture, e.g. a similar arrangement is achieved in Figure 4 or could be implemented without difficulty in Figure 7.
  • the heat exchange structure which fits in the moisture capture mechanism is connected to an external temperature-controlled fluid bath (not shown).
  • the external bath is filled with a heat-transfer fluid and stabilised at a low temperature.
  • the cold fluid is then pumped along the inlet transfer conduit 74 and flows into a cavity inside the heat exchange structure 72 cooling it down.
  • the cooled fluid flows out outlet transfer conduit 78 whereby a closed fluid circuit is formed.
  • the moisture release mechanism is connected to an external temperature-controlled fluid bath (not shown which is filled with a heat-transfer fluid and stabilised at a high temperature.
  • the warm fluid is then pumped along the inlet transfer conduit 76, into a cavity inside the heat exchange structure 70 and out outlet transfer conduit 80.
  • the mating aperture 84 there is a thermal transfer to the block which warms the block together with the plurality of fins.
  • Each aperture may be termed a mating section for the corresponding heat exchange structure 70, 72.
  • An important requirement is that there is good heat transfer between the heat exchange structures and the blocks, both of which are solids. The heat transfer improves if there is a higher force between the two components.
  • a mechanical advantage may be used to achieve this, e.g. if a user applied 50N force to a mechanism with 5 times the mechanical advantage, a contact of 250N can be achieved.
  • each heat exchange structure 70, 72 has a generally wedge (or finger-like) shape which allows the heat exchange structure 70, 72 to mate with a high force.
  • An alternative may be to use a clamp arrangement. Selection of softer materials can help to improve thermal transfer. For example, a softer grade of aluminium could be used or an intermediate layer incorporated.
  • the two contacting surfaces may be smooth or have matching corrugations (or similar patters) to increase the surface area of the contacting surfaces.
  • a temperature sensor (not shown) may be attached to the heat exchange structure. This is preferably located as close to the external wall as possible in order that the regulated temperature does not suffer from temperature difference between the fluid in the cavity and the temperature probe.
  • An advantage of this system of Figure 10 is that no fluid connection needs to be made to the part of the device adjacent the user's mouth which we may term the "mouthpiece".
  • the wedge shaped heat exchange structures and their fluid connections to the temperature controlled baths are another separate element of the device which may be termed an "umbilical".
  • the "mouthpiece” may be a single use device and the "umbilical” may be reused with another compatible mouthpiece.
  • costs are reduced in the single-use mouthpiece component. Accordingly, additional budget may be spent on improving the closed fluid circuit of the umbilical by using higher quality lagging and connections.
  • there is little requirement for maintenance of the fluid in the temperature controlled baths because the closed fluid circuit never has to be broken to fit the mouthpiece component.
  • the fins may include a surface texture, which may be added on moulding.
  • the surface may be treated with plasma or corona surface treatment to make the surface hydrophilic.
  • the surface texture could provide the moisture transport mechanism and thus alleviate the need for a separate moisture transfer element.
  • the size of the channels defining the gas flow path should preferably be kept small so as to promote turbulence and therefore promote heat transfer.
  • the geometry of the fins or wedge may be chosen so as to obtain the required heat transfer for the minimum volume or for the minimum weight.
  • the heat exchanger can be split into elements, each comprising a fin, a gap between fins, a wall enclosing a coolant channel and a half-width of the coolant channel.
  • the heat transferred through each element can be calculated by standard equations (e.g. taken from Incropera, Frank P. & DeWitt, David P. (1996) 'Fundamentals of Heat and Mass Transfer' Fourth Edition, John Wiley & Sons Inc.), and will increase with increasing fin length.
  • the number of elements in a given mass or volume can be found by geometric calculations and will decrease with increasing fin length.
  • the total heat transferred is then the heat transferred through each element multiplied by the number of elements. This function can be optimised using numerical or graphical methods to determine an optimum fin length.
  • the coolant/warmed fluid is water.
  • the range is 100-200 W/m 2 K for a die cast part, 300-700 W/m 2 K for an injection moulded part
  • Metals are a natural choice of the construction of the moisture capture and release elements due to their good thermal conductivity.
  • Another possibility is the use of thermally conductive polymers, such as carbon-loaded polymers.
  • One advantage is that there is greater flexibility on design because the polymer can be injection moulded at low cost. For example, it is possible to mould thinner fins and tubes in polymer than in metal. This may make the overall device lighter.
  • a similar result may be achieved by using light metals, e.g. aluminium.
  • By optimising the thermal transfer geometry it is possible that the lower thermal conductivity of conductive polymers compared to metals need not be a limit to performance.
  • the devices described above enable high levels of humidity to be supplied to a patient close to body temperature while minimising the amount of condensation, the risk of infection and avoiding the need for an external water supply.
  • the devices combine the advantages of a standard HME or HMEF with a known heated humidifier.

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  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Pulmonology (AREA)
  • Engineering & Computer Science (AREA)
  • Anesthesiology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Air Humidification (AREA)

Abstract

La présente invention a pour objet un dispositif permettant d'humidifier un gaz dans le système respiratoire d'un patient, le dispositif comprenant un passage dans lequel le gaz passe de l'alimentation à un patient ; un orifice de gaz du patient dans lequel le patient inhale ou exhale ; un mécanisme de capture d'humidité active relié à l'orifice de gaz du patient qui capture l'humidité dans le gaz exhalé ; un mécanisme de libération d'humidité active relié à l'orifice de gaz du patient qui libère ladite humidité capturée dans le gaz inhalé ; et un mécanisme de transport d'humidité permettant de transporter l'humidité capturée depuis ledit mécanisme de capture d'humidité jusqu'audit mécanisme de libération d'humidité.
PCT/GB2010/051893 2009-11-13 2010-11-12 Dispositif d'humidification de gaz d'un respirateur WO2011058371A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0919903A GB0919903D0 (en) 2009-11-13 2009-11-13 Ventilator gas humidification device
GB0919903.5 2009-11-13

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WO2011058371A1 true WO2011058371A1 (fr) 2011-05-19

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012072997A1 (fr) * 2010-12-03 2012-06-07 Intersurgical Ag Perfectionnements se rapportant aux systèmes respiratoires
WO2013148734A1 (fr) 2012-03-30 2013-10-03 Carefusion 207, Inc. Transport de liquide dans un composant respiratoire
CN104010688A (zh) * 2011-11-01 2014-08-27 英特外科股份公司 呼吸系统的改进
WO2014209907A3 (fr) * 2013-06-25 2015-11-19 Breathe Technologies, Inc. Ventilateur ayant un système de refroidissement intégré
EP3027256A1 (fr) * 2013-07-29 2016-06-08 ResMed Limited Échangeur de chaleur et d'humidité pour une interface patient
US9642979B2 (en) 2011-09-30 2017-05-09 Carefusion 207, Inc. Fluted heater wire
US9867959B2 (en) 2011-09-30 2018-01-16 Carefusion 207, Inc. Humidifying respiratory gases
US10168046B2 (en) 2011-09-30 2019-01-01 Carefusion 207, Inc. Non-metallic humidification component
WO2021206628A1 (fr) * 2020-04-06 2021-10-14 ResMed Asia Pte. Ltd. Concentrateur d'oxygène avec gestion d'humidité
US11648369B2 (en) 2016-12-14 2023-05-16 Koninklijke Philips N.V. Humidification of a pressurized flow of breathable gas

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2267661A (en) * 1992-06-11 1993-12-15 Pall Corp Heat and moisture exchanging filters
WO1996035911A1 (fr) * 1995-05-11 1996-11-14 Elastek, Inc. Lit d'elastomere pour chauffer et humidifier des gaz de respiration
US6397842B1 (en) * 1998-06-09 2002-06-04 Smiths Group Public Limited Company Fluid-treatment devices
US20040045549A1 (en) * 2000-06-21 2004-03-11 Smith Daniel John Conduit with heated wick
US20040211421A1 (en) * 2003-02-20 2004-10-28 Bird Products Corporation, A California Corporation Air-to-air heat exchange for medical ventilator
US20060021615A1 (en) * 2004-07-30 2006-02-02 Kertzman Systems, Inc. Water transport method and assembly including a thin film membrane for the addition or removal of water from gases or liquids
EP2039387A1 (fr) * 2007-09-24 2009-03-25 Covidien AG Système et procédé pour le conditionnement de gaz respiratoires

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2267661A (en) * 1992-06-11 1993-12-15 Pall Corp Heat and moisture exchanging filters
WO1996035911A1 (fr) * 1995-05-11 1996-11-14 Elastek, Inc. Lit d'elastomere pour chauffer et humidifier des gaz de respiration
US6397842B1 (en) * 1998-06-09 2002-06-04 Smiths Group Public Limited Company Fluid-treatment devices
US20040045549A1 (en) * 2000-06-21 2004-03-11 Smith Daniel John Conduit with heated wick
US20040211421A1 (en) * 2003-02-20 2004-10-28 Bird Products Corporation, A California Corporation Air-to-air heat exchange for medical ventilator
US20060021615A1 (en) * 2004-07-30 2006-02-02 Kertzman Systems, Inc. Water transport method and assembly including a thin film membrane for the addition or removal of water from gases or liquids
EP2039387A1 (fr) * 2007-09-24 2009-03-25 Covidien AG Système et procédé pour le conditionnement de gaz respiratoires

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
FRANK P.; DEWITT, DAVID P.: "Fundamentals of Heat and Mass Transfer", 1996, JOHN WILEY & SONS INC.

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3173118A1 (fr) * 2010-12-03 2017-05-31 Intersurgical AG Améliorations relatives à des systèmes de respiration
US10029059B2 (en) 2010-12-03 2018-07-24 Intersurgical Ag Breathing systems
WO2012072997A1 (fr) * 2010-12-03 2012-06-07 Intersurgical Ag Perfectionnements se rapportant aux systèmes respiratoires
US10888683B2 (en) 2010-12-03 2021-01-12 Intersurgical Ag Relating to breathing systems
US9867959B2 (en) 2011-09-30 2018-01-16 Carefusion 207, Inc. Humidifying respiratory gases
US9724490B2 (en) 2011-09-30 2017-08-08 Carefusion 207, Inc. Capillary heater wire
US10168046B2 (en) 2011-09-30 2019-01-01 Carefusion 207, Inc. Non-metallic humidification component
US9642979B2 (en) 2011-09-30 2017-05-09 Carefusion 207, Inc. Fluted heater wire
US9669181B2 (en) 2011-11-01 2017-06-06 Intersurgical Ag Breathing systems
CN104010688A (zh) * 2011-11-01 2014-08-27 英特外科股份公司 呼吸系统的改进
EP2830695A4 (fr) * 2012-03-30 2016-01-27 Carefusion 207 Inc Transport de liquide dans un composant respiratoire
WO2013148734A1 (fr) 2012-03-30 2013-10-03 Carefusion 207, Inc. Transport de liquide dans un composant respiratoire
WO2014209907A3 (fr) * 2013-06-25 2015-11-19 Breathe Technologies, Inc. Ventilateur ayant un système de refroidissement intégré
US9795758B2 (en) 2013-06-25 2017-10-24 Breathe Technologies, Inc. Ventilator with integrated cooling system
EP3027256A1 (fr) * 2013-07-29 2016-06-08 ResMed Limited Échangeur de chaleur et d'humidité pour une interface patient
US10695521B2 (en) 2013-07-29 2020-06-30 ResMed Pty Ltd Heat and moisture exchanger for a patient interface
EP3027256A4 (fr) * 2013-07-29 2017-04-05 ResMed Limited Échangeur de chaleur et d'humidité pour une interface patient
US11554239B2 (en) 2013-07-29 2023-01-17 ResMed Pty Ltd Heat and moisture exchanger for a patient interface
US11596760B2 (en) 2013-07-29 2023-03-07 ResMed Pty Ltd Heat and moisture exchanger for a patient interface
US11648369B2 (en) 2016-12-14 2023-05-16 Koninklijke Philips N.V. Humidification of a pressurized flow of breathable gas
WO2021206628A1 (fr) * 2020-04-06 2021-10-14 ResMed Asia Pte. Ltd. Concentrateur d'oxygène avec gestion d'humidité

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