Aerosol Heating Nebulizer and Method of Aerosol Heating in Nebulizer

Spraying Chamber

This invention relates to medical equipment and can be used in aerosol therapy.

The most widely used type of medical inhalators intended foraerosol therapy are compressor inhalators consisting of a compressor and a nebulizer (the spraying chamber).

The compressor is used for gas compression, and the nebulizer is filled with the medicine solution which should be further converted to aerosol. Aerosol is produced by supplying compressed gas from the compressor to the spraying chamber the latter consisting of a closed cup, a nipple with a nozzle, a cap, a reflector and a mouthpiece. Compressed gas (typically air) supplied at a high pressure to the nipple comes out through the nipple nozzle. As a result, the air flowrate at the nozzle output increases and therefore the local air pressure decreases. The resultant air rarefaction causes the medicine solution to move through the supply channels forming between the outer nipple surface and the cap covering the nipple towards the nozzle output where it mixes with the air flow and decomposes into discrete particles. The reflector provided at the nozzle output or, alternatively, can be provided as part of the cap, is intended to split large particles into finer ones which are then entrapped by the air flow and delivered to the patient through the mouthpiece.

The main disadvantage of compressor inhalators is that when aerosol is produced its temperature decreases compared to the ambient temperature due to the Joule-Thomson throttle effect. Said aerosol temperature decrease may be as large as 7-10 °C relative to the ambient temperature of the procedure room, and this may cause undesired consequences for the patient because inhalation procedure with cool aerosol is uncomfortable and causes coughing. As a result the accuraterequired dosage of the medicine to be delivered to the patient cannot be maintained. Aerosol heating increases the comfort of the inhalation procedure and is absolutely necessary for patients having expressed bronchoidal anaphylaxis (high sensitivity to cold).

Known are a method and a device for the heating of medicinal aerosols in compressor inhalators (L.V. Osipov, Individual Ultrasonic and Compressor Inhalators, Moscow, IsoMed, 2003, p. 32-33; L.V. Osipov et al., Application of Ultrasonic and Compressor Inhalators (Nebulizers) for the Treatment of Respiratory Diseases and Lungs. User Practical Guide. Moscow, IsoMed, 2014, p. 38-43). The method used in Pari Term compressor inhalators (Pari GmbH, SpezialistenfureffectiveInhalation041 D01 10 2/99) implies aerosol heating with a heater having a corrugated surface that is installed at the output of the spraying chamber and connected to the device power unit via a cable passing above the spraying chamber near the mouthpiece.

Said aerosol heating method has the following disadvantages:

^• 1. The presence of the heater power cable in the vicinity of the mouthpiece that is put into the patient's mouth requires special electrical safety measuresthat represent discomfort during the inhalation procedure.

^! 2. Absence of the possibility of sterilization or complete disinfection of the heater installed at the output of the spraying chamber and may act as the settling site for the patient's infected exhalation products.

3. Noticeable time required for establishing the preset temperature mode because the heat is delivered through a gas media having low heat conductivity.

4. Lower medicine dosing accuracy for medicine delivered to the patient in an aerosol form due to uncontrolled medicine solution drop sedimentation on the heater inner surface during aerosol flow passage near the heater.

^• Known is (RU Patent 2642778, published 27.02.2015) is ^' a nebulizer comprising a liquid spraying head, an air channel through which the sprayed liquid is pushed out of the nebulizer, wherein said air channel allows changing the direction of the flow formed by the air inhaled and exhaled by the patient, further wherein the spraying device comprises a medicine storage chamber, a vibration source allowing vibration transmittal to the liquid and a mesh, wherein said air channel allows directing the flow along the mesh, said head further comprises a sensing means providing for flow detection, and all the nebulizer components that are in contact with the liquidand the air inhaled and exhaled by the patient are located in the nebulizer head, the nebulizer further comprising a control means wherein said control means comprises excitation circuits for vibration source control. Said sensor means may further comprise a flow heat gage providing for flow detection based on temperature measurement. Said flow temperaturesensor may comprise an electrically controlled thermocouple on the front side of said flow temperature sensor wherein the front side of said flow temperature sensor faces the inner area of the air channel. Said flow temperature sensor may further comprisean electrically controlled thermocouple on the front side of said flow temperature sensor and at least one contact pad on the rearside of said flow temperature sensor wherein one contact pad is electrically connected to said thermocouple. Said thermocouple may comprise a heater and at least one two temperature sensors.

Said nebulizer is not a compressor type one, and its design has a fundamental difference from the design of the compressornebulizers, said difference being that a vibrator and a mesh are used, the mesh size being several micrometers in diameter. A disadvantage of said nebulizer is its complex design and the quite complicated and specific aerosol heating method used in said nebulizer due to the design principle of said nebulizer, said aerosol heating method not being suitable for use in compressor nebulizers.

Known is (RU Patent 164003, published 20.08.2016) a compressor inhalator comprising a spraying chambercasc, a heated metallic nipple with a narrow nozzle in the top part of saidnipple and a heater installed on the nipple body, a reflector near the nozzle output, a mouthpiece and a flexible hose connected to the compressor and the nipple input, wherein said heater is in the form of copper plates that are attached through a ceramic/polymer heat conducting dielectric material on a heat conducting coil attached onto said nipple and connected to the power source.

Said device has the following substantial disadvantages:

- due to the high specific heat capacity of the metallic nipple and the metallic heater coil the time required for heating the medicine solution in the spraying chamber of the nebulizer is at least 3-5 minutes which extends the medical procedure preparation time.

- the temperaturesensor measures the heater temperature which may differ noticeably from the temperature of the medicine solution, and therefore the required temperature of the medicine solution cannot be maintained with a sufficient accuracy. This may cause medicine solution overheating with its temperature raising to above 42-43 °C which is inadmissible when medicine solutions of biological origin are used.

The following information source is shown as the closest counterpart of this invention.

The technical objective of the means provided herein is to expand the application field and increase the efficiency of nebulizer aerosol therapy.

The technical result achieved with this invention is to significantly reduce the heating time of the medicine solution before the start of the medical procedure and reduce the time required for establishing the required aerosol temperature, increase the accuracy of maintaining the requiredmedicine solutionand aerosol temperatures, reduce the risk of overheating the medicine solution and raise the accuracy of a medicine dosage.

It is suggested to achieve said technical result by using the aerosol heating nebulizer the design of which is provided herein. Said nebulizer comprises a spraying chamber case the top part of which has a nipple with a narrow output opening in the form of a nozzle above which a cap with a wide bottom part is installed, said spraying chamber has a detachable cover with a reflector allowing its attachment near the output nozzle of a replaceable separator, a flexible compressed gas supply pipe connected to said nipple, an electric heater in the form of a thin plate with a low heat capacity made from a material having a good heat conductivity, said plate being located on the bottom of the top part of said spraying chamber, to the rear surface of said thin plate a heater is attached the area and size of which are almost similar to the area and shape of said thin plate, a temperaturesensor located on the rear surface of said thin plate, a mouthpiece inserted into the cover, a base plate on which the spraying chamber case in mounted, a LED and a heating control circuit board installed under the heater.

Preferably the bottom part of said cap has a diameter that is slightly smaller than the spraying chamber bottom diameter and a shape replicating the shape of said thin plate, and further has radial extensions providing for the required gap size for preheating and medicine solution delivery to the channels between the nipple and the cap.

' The attachment points of the thin plate to the bottom of the top part of said spraying chamber, as well as the flexible pipe inputs in the bottom part of the case, the heater power cable input and the heating control circuit board input and the spraying chamber bottom part attachment to the base plate are hermetically sealed.

The spraying chamber space between the rear surface of the heater and the underlying heating control circuit board is filled with a highly heat insulating

It is further suggested to achieve said technical result by using the herein provided material method of aerosol heating in the nebulizer spraying chamber providing for comfortable inhalation procedure and accurate dosage of the medicine delivered to the patient in an aerosol form, said method comprising supplying compressed gas via the flexible pipe to the nipple of the spraying chamber and developing air rarefaction at the output of the nipple nozzle for using said air rarefaction to supply the medicine solution filled into the spraying chamber to the nipple nozzle via the narrow channels between the nipple surface and the cap put onto the nipple and having an opening coaxial with the nozzle, mixing the medicine solution with the outgoing air flow for the conversion of said medicine solution to an aerosol that is directed onto the reflector and then delivered to the patient through the mouthpiece or a mask attached to the output of the spraying chamber, wherein a thin layer of the medicine solution is heated during the passage of the medicine solution between the surface of the wide bottom part of the cap and the high heat conductivity plate on the bottom of the spraying chamber, said heating being provided using an electric heater located on the rear surface of the thin plate, further wherein the spraying chamber space between the rear surface of the heater and the underlying heating control circuit board is filled with a highly heat insulating material.

To avoid the risk of medicine solutionoverheating during heater temperature growth to above a specific level, the method provides heating interruptionor diminish electrical power of heating until the temperature decreases- to the admissible level as a result of heater cooling.

The spraying chamber has a detachable top part, and the attachment points of the thin plate to the bottom of the top part of said spraying chamber, as well as the flexible pipe inputs in the bottom part of the case, the heater power cable input and the heating control circuit board input and the spraying chamber bottom part attachment to the base plateare hermetically sealed in order to provide for spraying chamber disinfection with a disinfecting solution.

Preferably, the spraying chamber components that are in contact with the medicine solution and the aerosol are made from materials selected from the group of materials approved for use in contact with medicines.

Preferably, the material of the spraying chamber top part is selected to be transparent for providing the possibility of controlling the level and volume of the medicine being filled in.

Preferably, the range of aerosol particle sizes is controlled by using replaceable separator attachments which are installed above the nipple.

Preferably, for informing the user that the required medicine solution temperature is reached and the inhalation procedure can be initiated by starting compressed gas supply, the spraying chamber case has at a side in the bottom part, a LED connected to the heating control circuit.

The volume and hence the surface area of the spraying chamber top part are preferably provided as small as possible in order to reduce the heat loss, the time, required for establishing the requisite heating mode and the residual quantity of the medicine solution settling on the spraying chamber walls in the course of the procedure.

Wherever possible, the heaters are preferably posistor heaters.

The subject matter of the invention disclosed herein is that the nebulizer spraying chamber of a compressor inhalator supplies compressed gas through the air pipe to the nipple of the spraying chamber case, develops air rarefaction at the output of the narrow opening (nozzle) of the nipple for using said air rarefaction to supply the medicine solution filled into the spraying chamber to the nipple nozzle via the narrow channels between the nipple surface and the cap put onto the nipple and having an opening that is similar to the opening of the nozzle, mixes the medicine solution with the outgoing air How for the conversion of said medicine solution to an aerosol jet that is directed onto the reflector for producing fine aerosol which is then delivered to the patient through the mouthpiece or a mask attached to the output of the spraying chamber, wherein, according to this invention, the medicine solution is heatedusing an electric heater that is located on the bottom of the top part of the spraying chamber intended for filling in the medicine solution and is in the form of a thin plate with a low heat capacity made from a material having a good heat conductivity, to the rear surface of said thin plate a heater is attached the area and size of which are almost similar to the area and shape of said thin plate, said plate being selected planar, conical or spherical, wherein the bottom part of the nipple is wide, its diameter being slightly smaller than the spraying chamber bottom diameter and its shape replicating the shape of the thin plate, and having radial extensions providing for the required gap size for medicine solution delivery to the channels between the nipple and the cap.

In accordance with this invention, to the rear surface of the thin plate, temperature sensors connected to the heating control circuit are attached which stop heating or diminish electrical power of heatingwhen the heater temperature exceeds the preset level in order to avoid the overheating of the medicine solution and start heating when the heater temperature decreases to the requisite level as a result of heater cooling.

Posistor heaters can be used as the heaters because the resistivity of posistor heaters increases with rising its temperature hence stabilizing the heating temperature and protecting the medicine solution from overheating.

The heating control circuit board is installed at a certain distance below the heater, and heat losses during heating are avoided by filling the spraying chamber space between the rear surface of the heater and the underlying heating control circuit board with a highly heat insulating material.

Further, in accordance with this invention, the attachment points of the thin plate to the bottom of the top part of said spraying chamber, as well as the flexible pipe inputs in the bottom part of the case, the heater power cable input and the heating control circuit board input and the spraying chamber bottom part attachment to the base plate are hermetically sealed in order to provide for spraying chamber, cap, cover and mouthpiece disinfection with a disinfecting solution.

The volume and hence the surface area of the spraying chamber top part are preferably provided as small as possible in order to reduce the heat loss, the time required for establishing the preset heating mode and the residual quantity of the medicine solution settling on the spraying chamber walls in the course of the procedure.

The spraying chamber components that are in contact with the medicine solution and the aerosol are made from materials selected from the group of materials approved for use in contact with medicines.

The material of the spraying chamber top part is selected to be transparent for providing the possibility of controlling the level and volume of the medicine being filled in.

The range of aerosol particle sizes is controlled by using replaceable separator attachments which are installed above the nipple.

For informing the user that the required medicine solution temperature is reached and the inhalation procedure can be initiated by starting compressed gas supply, the spraying chamber case has at a side in the bottom part, a LED connected to the heating control circuit.

The following results are achieved:

- increasing inhalator usage comfort and providing the necessary level of electrical safety due to the arrangement of the electric heater and the power cable below the spraying chamber and the hermetization of the part of the nebulizer case in which energized components are located;

- reducing the time of achieving the heating mode providing for higher aerosol temperature due to faster heating of the thin layer of the medicine solution in the narrow channels between the heated plate surface at the bottom of the top part of the spraying chamber and the bottom surface of the cap;

- providing sterilization or disinfection of the spraying chamber after stopping of the aerosol therapeutic procedure due to the detachable top part of the spraying chamber;

- increasing the dosage accuracy of the medicine solution delivered to the patient in a medicine solution form to the patient, both due to aerosol heating and the small inner surface area of the top part of the spraying chamber on which uncontrolled quantities of aerosol particles may settle;

- avoiding the risk of medicine solution overheating with its temperature raising to above a certain level which is inadmissible when medicine solutions of biological origin are used;

- controlling the range of aerosol particle sizes depending on the respiratory ways sections where medicine solution particles arc to be delivered.

The subject matter of this invention will be illustrated below with an embodiment of the aerosol heating method to be patented and the attached drawings which show:

Figure 1 : drawing of an embodiment of the aerosol heating nebulizer spraying chamber which implements the method provided herein;

Figure 2: photo of an experimental device schematically illustrated in Fig. 1.

Figures 3 and 4: graphs of aerosol temperature as a function of time for the experimental embodimentillustrated in Figs. 1 and 2 (data obtained during technical tests).

The heating method is implemented using the nebulizer spraying chamber (Fig. 1 ) comprising the spraying chamber case 1 , the nipple 7 with the narrow output opening in the form of nozzle above which the cap 8 is installed with a wide bottom in the lower part, the detachable cover 10 with a rellector on which the detachable separator 9 is attached near the nozzle output, the power cable 2, the air pipe 3 for compressed gas supply, the heating control circuit board 4, the heater 5 with heat insulation on the rear surface, the thin plate 6 having good heat conductivity, the temperature sensor 12, the mouthpiece 1 1 , the LED 13 and the base plate 14.

The aerosol heating method provided herein using the device provided herein is implemented as follows.

The top part of the spraying chamber 1 of the nebulizer the cover 10 of which is open is filled with the required quantity of medicine solution following which the cover with the mouthpiece 1 1 inserted is closed, the air pipe 3 is connected to the compressor and voltage is supplied to the circuit power cable 2; after the LED is on signalizing the achievement of the required temperature of the medicine solution, the compressor is switched on. The compressor can be selected as a compressor unit of any commercial compressor inhalator, e.g. the compressor unit of an Elisir device manufactured by Flaem Nuova, Italy.

During spraying chamber operation, the thin layer of the medicine solution between the plate 6 and the bottom surface of the cap 7 is rapidly heated. After the compressor is on the heated medicine solution is supplied due to air rarefaction from the bottom to the top part of the nipple 7 and the inner surface of the cap 8 which is put onto the nipple. As aerosol forms, it settles cooled from the temperature of the medicine solution being supplied, but as the medicine solution was preliminarily heaterd the aerosol temperature at the output of the mouthpiece 1 1 connected with the cover 10 is higher compared to the ambient temperature. For example, for a medicine solution layer heating temperature of 40-41°C the aerosol temperature at the output of the mouthpiece 1 1 is 30-35°C which is comfortable for inhalation by the patient.

In accordance with this invention, as the medicine solution temperature exceeds a certain preset level the heater power is switched off or adjusted at more low levelas follows. As the medicine solution temperature exceeds the signal generated by the temperature sensor 12 activates the power supply cut-off circuit; as a result heating stops and the heater temperature decreases as a result of natural cooling. The necessity of switching power supply off also arises if there is no medicine solution left in the spraying chamber or if the uses turns the compressor inhalator on without filling medicine solution into the spraying chamber 1.

Experimental devices implementing the aerosol heating method provided herein and schematically illustrated in Fig. 1 have been fabricated.

Figure 2 shows photo of an experimental device schematically illustrated in

Fig. 1.

Figures 3 and 4 show graphs of the spraying chamber heater temperature as a function of timeafter heating start and after compressor switch-on, as well as the mouthpiece output aerosol temperature after compressor switch-on. The data were obtained during technical tests of the deviceillustrated in Fig. 2. It can be seen that the heater provides a high heating rate and short heating mode stabilization time (approx. 1 min.) and automatic heating switch-off after the medicine solution in the spraying chamber is out and there is unit overheating hazard. Figure 3 shows a early stage of the tests. The dashed line shows the heater temperature and the solid line shows the aerosol temperature. Figure 4 shows the finalstage of the tests. The dashed line shows the heater temperature and the solid line shows the aerosol temperature. The compressed air pressure at the nebulizer input was 0.94 bar during the tests.