VIASOL MARKETING (SE)
ARBORELIUS MAANS JR (SE)
| WO1993001891A1 | 1993-02-04 |
| EP0170715A1 | 1986-02-12 |
| 1. | Device by nebu sers of the kind , which during use create a horizontal aerosol flow(b) compπsing a superior part (1 ) an inferior part and liquid container (2) and a centre pιllar(6) having an air channel and a compressed air orifice (7) liquid channels (3) between the centre pillar and an exterior case (4) , and a plate or a bar (8), having a flat or slightly angled inferior surface, perpendicular to a primary gas jet (a) from said j o air orifice (7) , said jet being deviated by 90° after hitting said plate or bar thereby creating tne noπzontaliy expanding jet flow (b) containing a primary aerosol, characterised in that said horizontal jet flow (b) hits a circular baffle , the vortex separator(8,9, 10 ,1 1 ) , said device having the form of the frustum of a cone ,the wall 1 5 (9)of said frustum of a cone having an angle of 45r ± 30° in relation to the direction of the flow (b) , the larger diameter of said device opening towards the bottom of the container (2) while the smaller diameter opens into the superior part of the nebuliser housing ( 1 ) The vortex separator is permanently or detachably joined to the outer case (4) and the the plate or bar (8) for example with the vertical walls (l θ)and a cylinder 20 (" > ■ The device is further characterised in its function , the primary aerosol jet (b) is deflected towards the bottom of the container (2) after hitting the wall (9) of the vortex separator, by ejector effect creating the vortex flow (cd)contaιnιng gas and aerosol, around the wall (9) of the vortex separator 5 By condensation and impaction of large particles and inclusion of smali aerosol particles into the vortex flow the concentration and relative volume of small, respirable aerosol particles increases in the aerosol. |
| 2. | Device according to claim 1 o characterised in , that the vortex separator is connected to the superior part of the housing (1 ) and by joggles or similar devices fixed in an optimal position in relation to the flow of the primary aerosol (b) when part 1 and 2 of the nebuliser are joined. |
| 3. | An apparatus according to claim 1 . and/or 2 5 characterised in ,that the gas flow (e.) of equal size as the primary flow a, and which must leave the nebuliser body (1 2) , during the exhalation of the patient , by means of a tube (14) is stored in a reservoir bag (1 5) of plastic or other suitable material to form the first part of the following inhalation. |
| 4. | A nebuliser according to claims 1 , 2 and/or 3 characterised in that the mhalatory mouthpιece(12) is provided with a pendulous oneway valve (1 3) and a device in the form of valves or an aperture of a suitable size to provide the patient with air once the reservoir bag is empty and to allow exhalation. |
| 5. | Device according to the claims 1 and/or 2,3 and 4 characterised in , that within the superior part of the nebuliser housing (1 ) is arranged a wall (16) between the tubes ( 1 2) and ( 14) which forces the aerosol from the reservoir bag (1 5) towards the aerosolforming region during the first part of each inhalation in order to increase the concentration of respirable aerosol in that part of the breath. |
| 6. | Use of the vortex separator (8,9,10), as defined in the claim 1 in nebulisers where the primary aerosol is formed between an orifice plate with a central air orifice, and a second plate or a bar, and having liquid channels that end into two or more orifices or a circular slit close to the air orifice and in the same level as said air orifice and where transport of fluid to the aerosol forming area is caused by pressure drop within the rapidly expanding gas between said orifice plate and said plate or said bar. |
| 7. | Use of the vortex separator as defined in claim 1 in nebulisers in which the primary aerosol is formed when the liquid channel ends as a slit in the wall of the air channel (7) below but close to the level of the mouthpiece plate and transport of liquid is achieved by pressure drop in expanding gas in the air orifice . |
| 8. | Use of devices according to the claims 1 7 for producing a respirable aerosol for medical treatment by inhalation. |
| 9. | Use of devices according to the claims 1 7 for producing a submicronic aerosol for technical purposes. |
The present invention relates to an apparatus for production of submicronic homogeneous aerosol , also recognised as a nebuliser The invention may advantageously complement the technique described in Swedish patent EPO 01 9101 8 Using the present invention a smaller and more homogeneous aerosol is produced, even if the gas pressure, required to produce the aerosol is only 30-50% of that used with the original construction The new nebuliser further produces a smaller aerosol in a larger amount and with an equally low or lower gas flow than with the earlier invention The distribution of aerosol size is also more favourable than with the original version
However, the invention is not limited to use with EPO 01 9101 8 but may be applied in ail nebulisers where a primary aerosol is formed, which expands radially from a baffle in the form of a plate or a bar
Background Art
An apparatus for production of an aerosol by means of compressed gas, which expands in the apparatus and thereby provides the energy required for production of the aerosol is known from several earlier constructions as for example , SE 449 400 (EPO 01 9 101 8) comprising a liquid container connected to a liquid channel, said liquid channel opens into one or several liquid orifices being located in the vicinity of and being directed substantially perpendicularly towards a first plate, that said liquid orifices are located in a second plate oriented substantially parallel to and being smaller than said first plate, that an air channel opens in an air orifice, preferentially centrally in said second plate surrounded hy said liquid oπfic p s that compressed gas expanding between said first and second plate provides energy to create a reduced pressure between said plates which transports liquid from said liquid orifices, said liquid will adhere to said first plate and form a radially expanding film , which film by means of the expanding gas will flow radially over said first plate while thinning out to break into small homogeneous droplets at the edge of said first plate
Already in 1 982 a nebuliser for production of submicronic aerosol was described, in which an inferior primary aerosol was improved by means of that said inferior, radially expanding aerosol impacts on a conical or doom-shaped upwards closed secondary baffle ( Ref 1 ) However, the aerosol density : the weight liquid or drug /volume of gas was very low Earlier known art is also a nebuliser (Ref 2) in which a primary horizontally expanding aerosol is deflected downwards after impaction on a conical secondary baffle, which in it s uppermost end is connected to a pipe which opens into surrounding air By ejector effect a gas flow of > 20 L/min is created , provided that the
outlet (the inhalation tube) of the nebuliser is unobstructed. By virtue of the high air flow aerosol particles evaporate and shrink in size, and fluid loss due to evaporation becomes great in the apparatus. The aerosol density becomes very low When a patient inhales from the apparatus, the gas flow through the apparatus is governed by the patients inhalation . The flow created by the ejector effect ceases and the character of the aerosol then depends on the patient ' s breathing A couple of nebulisers with a similar construction have later been marketed
Disclosure of the invention
The present invention relates to an apparatus , as defined in the attached patent claims, for production of medical or technical aerosols having an homogeneous particle size, which ran be varied very much depending on the design of the apparatus and on the gas pressure used to operate it With a suitable dimension of these variables it is possible to produce an aerosol having a high concentration of fluid , ma ly transported in submicronic particles, havmg the quality of being retained in small airways or alveoli to more than 90 per cent while conventional jet aerosols produce a high percentage of large particles, which mainly settle in the mouth, throat or large airways, where the effect «s poor or absent. Hence, the apparatus is suitable in the medical discipline for delivering drugs, which are destroyed in the intestines, like insulin and similar peptide hormones and drugs where a rapid effect after resorption or a high effect with a small dose is desired, for example for rapid pain relief with morphine The apparatus is also suitable for producing technical aerosols of homogeneous size and high density, with high efficiency
The present invention is characterised in that a primary aerosol, preferentially generated in a nebuliser of the kind described in EPO 01 9101 8 and which expands radially , while releasing energy, at a suitable distance impacts on a circular, secondary baffle in the form of the frustum of a cone , which deflects the gas jet and small particles having low inertia towards the bottom of the liquid container, while large particles impact on the baffle wall and drip down into the liquid container
By ejector effect a negative pressure is created in the upper part of the circular baffle, openly communicating with the upper part of the nebuliser housing, and a positive pressure below said baffle and in the liquid container The upper end of the circular baffle opens into the superior part of the nebuliser housing , but is not connected to a tube opening into the surrounding atmosphere. Driving gas and aerosol will consequently stream around the lower bqrder of circular conical baffle and with accelerating speed be
sucked down into the uppermost smaller aperture of said baffle. By experience the ejector flow may be 4-6 times the primary flow and hence > 1 5 L/min Hence a vortex of rapidly running gas and aerosol particles is formed brushing up the exterior surface and down the interior one of the circular baffle where it crosses the mainly horizontally expanding surface of primary aerosol and driving gas (b) and will influence and modify the aerosol production and quality to such an extent that an adequate designation of the device would be the "vortex separator". The vortex separator influences and modifies the primary aerosol by following mechanisms: 1 ; To a certain degree depending on the surface tension of the liquid , but for saline-based drug solutions at a particle diameter of about 2μm, smaller particles have a surface tension which overcomes the capillary force, while 2; the opposite holds true for larger particles Aerosol particles larger than 2 μm in the vortex flow, will when passing the horizontal primary aerosol jet. wet and join, condense with, similar particles in the jet stream, hit the circular baffle, and return to the liquid container, while smaller fractions do not wet each other or large particles and hence follow the vortex flow .
An increasing number of newly formed small particles join the vortex flow and consequently concentrate in said flow.
A flow of the same magnitude as the primary gas flow driving the nebuliser continuously escapes the vortex flow towards the superior part of the housing. Suitably , with earlier known art (Ref 1 ) , this aerosol volume is stored in a bag of a suitable material during the patient ' s exhalation , with the effect, that all produced aerosol will be inhaled by the patient An optimum primary flow (driving flow) should therefore be 4,0 to 5,5 1/mιn Preferentially, the larger part of the produced aerosol should be delivered to the part of the breath which reaches small airways and alveoli, which corresponds to about 70 per cent of the normal respiratory minute volume of about 8 1/mιn.
Between the tube going to the reservoir bag and the mhalatory mouthpiece a deflector is suitably arranged, forcing gas from the bag towards the region of the vortex flow increasing the amount of respirable particles during the first part of the following inhalation. The character of the aerosol can be varied very much by variation in the design of;
1 The devices creating the primary aerosol.
2: The diameter of the vortex separator where hit by the primary aerosol. 3: The angle of the conical wall of the vortex separator m relation to the primary aerosol. 4. The area of the superior opening of the vortex separator.
The invention will be descπbed below with reference to the appended drawings which illustrate an example of a selected and practically tested embodiment as defined in the patent claims. Fig 1 . shows a vertical longitudinal section of one type of nebuliser according to this invention
Fig 2 shows a magnified section of the aerosol producing parts Fig 3. shows the function of a nebuliser according to the invention The nebuliser may be constructed in plastic or other suitable material and the quality chosen depending on whether the apparatus is intended for single or multiple use In figs 1 -3 , ( 1 ) denotes the upper part of the nebuliser housing and (2 ) the inferior part of the same, which also is the liquid container, while ( 3) denotes liquid channels , conducting the liquid for formation of aerosol to the top of the exterior case ( 4 ) where the upper end forms an orifice plate (5) The centre pillar ( 6 ) can be moulded in one part with the liquid container ( 2) or fitted with an O-ring or arranged in another suitable way . In the centre of the centre pillar (6) the air conduit ( 7 ) ends into the air orifice in the centre of the orifice plate ( 5) An optimum diameter of the Coanda plate (8) is 4 to 8 mm and of the orifice plate ( 5 ) 30 to 75 per cent thereof The vortex separator (9 ) , having the form of a frustum of a cone is connected to the superior surface of the Coanda plate and with the outer case 4 with two or more vertical walls ( 1 0 ) and with a cylinder ( 1 1 ) which fits on the exterior case 4, and with it s position is optimised by, for example, a joggle, on 4 A similar but somewhat inferior function is obtained if the Coanda plate 8 is substituted by a horizontal bar, preferentially with a flat and with the oπface plate parallel inferior surface, having a width of 1-3 mm The inhalation mouthpiece is designed ( 1 ) and an one way valve with low resistance ( 1 3 ), while ( 1 4 ) designs the tube leading to the reservoir bag ( 1 5 ) for aerosol and
(1 6) a wall which deflects aerosol and gas from the reservoir bag towards the aerosol forming zone at the beginning of the inhalation
The liquid ducts 3, constitute 2-3 grooves, cut in the surface of the centre pillar each having a surface area of 0,05 to 1 mm 2 The liquid channels are formed when the exterior case 4 is forced over the centre pillar and open into a number of orifices or a circular slit, around and close to the air orifice in the plane of the orifice plate 5 or as a circular slit in the wall of the air channel 0,2-1 ,5 mm below the surface of the orifice plate In fig 3, the Coanda plate 8 forces the primary high energy air jet ( a) todeflect horizontally by 90° and by wall effect adhere to it s surface while it spreads radially during pressure drop, over the surface of the plate as the secondary flow (b) The negative pressure created, sucks liquid from the liquid orifices and forms a primary aerosol, partly at the impaction on the Coanda plate , partly when the film of air and liquid on the inferior surface of the Coanda plate is liberated at it s border and spreads
radially as the secondary flow ( b ), which contains aerosol particles of different sizes f om submicronic to about 100 μm. The aerosol jet b is partially deflected as the tertiary flow (c) , towards the bottom of the container Particles bigger than 10μ mainly adhere to the wall 9 of the vortex separator, while smaller fractions mainly j oin the flow c The ejector effect of the expanding flow b and the initially downward flow c, create a negative pressure in the upper part of the vortex separator and a pronounced positive pressure in the space below the vortex separator, which is equalised when the flow (c) initiates a vortex flow (c-d) around the periphery of the vortex separator. By virtue of the rapid flow large particles will impact and disappear when the flow (c), turns upwards between the lower border of the wall 9 and the container wall 2 , and at the abrupt and narrow change of direction when entering the superior opening of the vortex separator. The vortex flow (c-d) thereafter passes almost perpendicularly through the secondary flow (b), which contains the primarily formed aerosol Particles in this aerosol, being smaller than 2μm, are towed into the flo (c-d) which increases the fraction of small particles in the flow (d) below (b), which joins the initiating vortex flow (c) Particles larger than 2μm condense, join other large particles and impact onto the wall of the vortex separator The flow through the vortex separator must, however, be modified by the primary flow, by the angle of the wall of the vortex separator in relation to the flow (b) and by the area of the superior opening of the vortex separator 9, because a to potent vortex flow (c-d), may cause that also large particles in flow (b) do not impact onto the wall 9 but join the vortex flow A fraction of particles larger than 10 μm may then disturb the quality of the delivered aerosol. Using optimised flows and diameters of the vortex separator a very concentrated and small aerosol is obtained already with moderate primary flows and pressures, like 2-5 L/min and 1 -2 Bar (1 00-200 kPa)
Continually a flow (e) , of the same sizze as the primary flow (a), will stream into the reservoir bag 1 5 through the tube 14. At inhalation the rapid inhalation flow at the beginning creates the flow (f) which is directed towards the aerosol formation zone by the deflector wall 16 and continues to the patient ' s airways as the flow (g), which once the reservoir bag 1 5 is empty will be equal to flow (a). Means for providing surrounding air in the form of a vaive or a suitably dimensioned hole thus should be arranged in the mouthpiece in order to admit inhalation when the bag 15 is empty and to allow exhalation. The invention is of course not limited to to this realisation , but the vortex separator may improve all primary aerosols.The use of the vortex separator with other designs for production of a primary aerosol, or aerosols modified on a baffle giving the secondary aerosol a radially expanding flow , capable of initiating a vortex flow, thus also falls under the invention
References
1 : Arborelius M Jr: Generation of a microaerosol suitable for deposition in peripheral airways. Eur, J. Respir. Dis 1982:63, Suppl. 1 1 9:1 9-27 2: Sales promotion for "Sidestream" nebuliser.