US 3172406 A
Description (OCR text may contain errors)
March 9, 1965 F. M. BIRD ETAL 3,172,406
NEBULIZER Filed April 5. 1962 3 Sheets-Sheet 2 March 1965 F. M. BIRD QELYTAL 3,1 ,4
NEBULIZER l Filed April 5.; 1962 s sheet -sheet 3 Qf/ INVENTORS FORPEST M. BIRD HINRY 1.. PDHIVDORF United States Patent 3,172,496 NEBULHZER Forrest M. Bird, Airport Box 970, Palm Springs, Calif, and Henry L. Pohndorf, 1227 Brewster Drive, El Cerrito 7, Calif.
Filed Apr. 5, 1962, Ser. No. 185,247 3 Claims. (Cl. 128l94) This invention relates to improvements in nebulizers.
Nebulizers are pneumatic devices for breaking up a liquid into small particles and to entrain the small liquid particles in the stream of air or gas. They are used in pulmonary therapy and lung ventilation in order to supply the patient with air that is sufficiently moist so that the air passages will not be dried out by the ventilation.
In the past, considerable difficulties have been experienced with nebulizers, and often the respirator device was blamed for troubles that were caused by a faulty nebulizer. For example, attempts to keep a nebulizer bowl filled by continuously adding drops of the solution have frequently caused the bowl to become overfilled and to drown the jet-capillary junction, so that the efiiciency of the nebulizer dropped almost to zero. Yet users were likely to blame the respirator, pointing out that there was plenty of liquid in the nebulizer and disregarding the fact that the drowning made nebulization impossible.
Another trouble with nebulizers heretofore in use was their extreme sensitivity to the position or attitude in which they were disposed. The inlet stem of many nebulizers had to point exactly straight down and any pitching or rolling of the nebulizer that changed this critical position of the inlet stem markedly decreased the efiiciency of the nebulizer and altered its particle spectrum, i.e., the distribution of the sizes of particles of moisture placed into the air by the nebulizer. Moreover, when the level of the liquid in the bowl was low, the capillary tube that picked up the liquid had to be vertical in order to be immersed in the liquid; otherwise, no liquid would be picked up and none would be entrained in the air or oxygen supplied to the patient. Any movement of the patient tended to upset this true verticality of the capillary tube and prevented proper ncbulization.
Many of the workers who attend respirators in hospitals are not thoroughly schooled in the care and operation of nebulizers, and as a result frequently dangerous and annoying failures have occurred due to interference with these critical factors. Thus, even such necessary actions as ordinary nursing care, bathing the patient, making his bed, sitting him up to eat, or placing him on a bed pan have inadvertently caused unobserved nebulizer failure, sometimes with serious results. In addition, inexperienced or overworked personnel have frequently al lowed a nebulizer to overfill, or even worse, to dry out.
Another factor not appreciated about nebulizers has been that for different uses a different particle spectrum should be used, not the same particle spectrum for all patients in all cases. Moreover, there has been no way of changing the particle spectrum of a nebulizer.
These and other problems have been solved by the invention. For example, the present invention solves the problem of proper pickup by the capillary tube by providing an arcuate bottom body portion of the capillary unit which assures that liquid will be picked up over a wide range of directional roll of the nebulizer around its axis; the nebulizer of this invention can be rolled approximately 30 away from vertical on either side and it will still pick up the fluid properly.
Similarly, the nebulizer of this invention solves the related problem of failure to pick up the liquid that is caused by pitching forward and back so that the normally horizontal axis of the nebulizer is tilted up or down. The present invention solves the problem by using a frustoconical barrel and a frustoconical housing with a well where they meet to which fluid will flow to the bottom of the capillary unit over a wide angle of pitch. The invention also provides for the projection of cylindrical passageways into the housing and barrel, so that a liplike area prevents the liquid from flowing out and helping it to seek a point under the arcuate capillary intake.
The problem of drowning the capillary junction by immersion in liquid has also been solved by the present invention. When liquid is placed into either the barrel or the housing of this nebulizer, before joining those two parts together, the inward cylindrical projections measure the maximum fluid level. After assembly, the liquid seeks the major diameter of the unit, and a baffie adjacent the inlet tube prevents the liquid from flowing down the breathing hose. Also, overfilling is prevented by drain openings which bleed excess liquid from the nebulizer. The same expedient both prevents drowning of the ball and keeps liquid from flowing to the patients airway.
Nebulizer efficiency has been found to depend upon the absolute intersection of the center lines of the air jet and the capillary tube. The present invention insures an accurate permanent adjustment of this critical factor by holding the capillary unit in the housing by a snap clamp at an upper point and an anchoring peg at the base of the capillary. Not only does this insure the proper alignment but it also prevents inadvertent loosening of the capillary during operation.
An important feature of the nebulizer of this invention is its versatility, for its barrel and housing are so designed that it may be used in either a mainstream applicationone in which all the air supplied to the patient is fed through the nebulizeror a sidestream application-one in which only a small proportion of the ventilating gas fed to the patient is relied upon to pick up and nebulize a suitable preparation, this sidestream being added to the mainstream. Moreover, both continuous and intermittent nebulization become feasible with this invention.
The invention also includes a novel way of enabling continuous filling of the nebulizer during use, by means of an intravenous hypodermic needle. During such continuous filling by drops, overfilling is prevented by the drain openings alrealy referred to.
The size of the capillary ball determines the amount of moisture by weight that is delivered to the nebulizer outlet and also regulates the particle size; hence a series of removable capillaries may be provided with calibrated ball sizes, properly numbered and charted so that the proper particle spectrum can be obtained in all cases.
Other objects and advantages of the invention will appear from the following description of a preferred form of nebulizer embodying the principles of the invention.
In the drawings:
FIG. 1 is a view in side elevation of a nebulizer embodying the principles of the present invention.
FIG. 2 is a considerably enlarged View in section taken along the line 2-2 in FIG. 1.
FIG. 3 is a view, reduced with respect to FIG. 2 but enlarged with respect to FIG. 1, taken in section along the line 3-3 in FIG. 2.
FIG. 4 is a very greatly enlarged fragmentary view of a portion of the device showing the relationship between the air-jet nozzle, the capillary orifice, and the ball.
FIG. 5 is a fragmentary view in section showing how the liquid has access to the bottom of the capillary tube even when the nebulizer is pitched sharply forward.
FIG. 6 is a viewsimilar to FIG. 5 showing how the liquid still has access to the bottom of the capillary tube when the nebulizer is pitched sharply backward.
FIGS. 7 and 8 are fragmentary views in cross-section showing how the capillary tube can pick up liquid even when the nebulizer is rolled to either side.
The nebulizer shown in the drawings comprises four main parts, each of which is made from molded plastic, although not necessarily the identical kind of plastic, and each of which is a single integral piece: a barrel 11, a housing 12, a capillary unit 13, and a stopper 14, the latter being used in sidestream applications but not in mainstream applications. Transparency is important in order for the physician to be able to observe the jet and capillary functions, the liquid level, and other factors; so the barrel 11 and housing are both preferably made from transparent plastic. Transparency is less important for the other elements.
The barrel 11 has a generally cylindrical tubular. portion 15 and a generally frustoconical shell 16. The tubular portion 15 provides an interior passageway 17. having an inlet end 18 inside the nebulizer and an outlet end 19 outside the nebulizer. The passageway17 is approximately cylindrical but has an inner portion 20 converging at about 2 from the inlet 18 to the midpoint 21 between the inlet 18 and the outlet 19 and then an outer portion 22v diverging from there to the outlet 19 at about 2. This provides somewhat of a desirable venturi effect.
The outer wall of the tubular portion 15 preferably has a central larger-diameter portion '23 between an outside smaller-diameter portion 24 and an inside smaller-diam eter portion 25. Either of the two outer portions 23 or 24 may be attached to a proper outlet fitting, such as a tube leading to the patient, a T, or other suitable device from which the neublized gas is conductedto the patient.
The frustoconical shell 16 is joined to the tubular portion 15 by a short radial end wall 26 meeting the inner end 27 of the central large-diameter portion 23. Hence, the inner portion of the tubular portion 15 projects well within the nebulizer. This structure enables the nebulizer to be pitched forward without leaking fluid.
The shell 16 diverges from the wall 26 at an angle of about 22 relative to the axis, i.e., an included angle of about 44. It is provided with an outer cylindrical peripheral portion 30 providing a suitable socket 31 which may be of the bayonet type or, as shown, an interiorly threaded member. Also, the shell 16 is provided with a pair of drain openings 32, one on each side, on the same vertical level as the bottom of the, inlet 18 and axially in line with the inlet 18. These openings 32 prevent overfilling.
The housing 12 has a generally cylindrical tubular portion 35 and a generally frustoconical shell 36. The tubular portion 35 provides a passageway 37 with an outer inlet 38 to which the mainstream hose may be attached or, when that is not used, the stopper 14 may be used to plug the inlet 38. The outer periphery of the portion 35 is provided with a stud 40, and the stopper 14 has an integrally molded strap 41 extending from an outer flange 42. Thus, when the stopper 14 is in place, the strap 41 is flexible enough to flex as shown in FIG. 3, and at other times the strap 41 holds the stopper 14 to the housing 12 so that it will not get lost.
The tubular portion 35 has an inner portion 43, diverging inwardly, axially in line with the tubular portion 15 of the barrel but spaced away from it. A bafile 44 extends up to about the level of the horizontal axis 45 of the nebulizer, being generally semicircular. The baffle 44 prevents liquid from flowing down into the mainstream hose (when the hose is being used) when the nebulizer is pitched back at even a quite considerable angle. So long as normal care is taken, therefore, there is no reason why the liquid should flow into either of the tubular portions 15 or 35. There can be approximately 57 of pitch total without spilling in this manner.
The inner portion 43 is stepped down from the outer portion 46 at a step or shoulder 47, an extension of which provides a small radial portion 48 to which the frustoconical shell 36 isintegrally joined, with results similar to those already remarked upon in connection with the barrel 11. The frustoconical shell'36 diverges at an angle of about 35 from the axis, or an included angle of about and it terminates in an outer peripheral cylindrical portion 56 and is provided with suitable means for joining it to the barrel 11, such as an exteriorly threaded portion 51 fitting into the interior threads 31. A suitable O-ring gasket 52 may be used at this point to prevent leakage. The cylindrical portion 50 provides the low point 53 of the nebulizer, when it is held in its normal position, and therefore the liquid tends to seek the bottom of that portion over quite a tilt, both forward and backwards.
An air jet tube 55 is provided as an integral portion of the housing 12. It extenclsup at an angle of about 23 to the axis from an outwardly projecting portion 56 to whichasuitable' hose may be attached, and it has an interior passageway 57 which is tapered so that it gradually becomes narrower as the gas moves into it, being smallest at its outlet 58. This outlet 53 is located just below the low point of the inner passageway 43 and is in line with the center of the ball 60, which is formed as part of the capillary unit 13. Integral with the walls of the jet tube 55 is a bifurcated clamp 61 having two arms 62 joined together by a cross portion 63 which also acts as a stop. Vertically below that, the shell 36 is provided with a conformation forming a peg-receiving socket or opening 64 with an outer end wall 65.
The capillary unit 13 comprises a body portion 70, a peg 71, an upwardly extending capillary tube 72 and a stem 73 supporting the ball 60. Thebody portion 70 extends from one side of the housing to the other and is provided with an arcuate lower surface 74 which is'itself recessed to define a tube-like opening 75 between itself and the cylindrical wall 59. The body 70 is provided at its ends with'projecting portions 76 which serve to keep even the arcuate edge 74 from actual contact with the wall 50 of the housing 12 and therefore insure that the passageway 75 is always accessible to the liquid. The passageway 75 serves to collect the liquid 77 and the conical shape of the housing 12 and barrel 11, together with their arcuate body portions 50 and 3t meanthat the liquid 77 can enter the capillary tube 72 even when the nebulizer is rolled over an angle of about 30 on each side of its truly vertical position, which, of course isintended to be maintained normally. This means that: accidental displacements, such as occur when attending to the patient, will not cut off the supply of liquid 77 to the capillary tube 72.
From the center and bottom portion of the passageway 75, a capillary passage 78 extends up inside the tube 72 and at an angle inclined back about 8 from the vertical toward the nebulizer inlet 38 and toward the air jet outlet 58. Like the air jet passageway 57, the capillary passage 78 becomes narrower as it approaches its upper end. At its upper end the tube 72 is provided with an orifice 80 which is concave and has sharp outer edges, so that the meniscus which is formed by the surfacee tension of the liquid 77 tends to draw liquid up into the path of air issuing from the jet orifice 58.
As air (or oxygen) from the small jet orifice 58 blasts across the top of the concave, slightly inclined capillary orifice 80, the velocity of its air stream lowers the pressure above the capillary orifice 80 into the subambient range. The subambient pressure above the capillary orifice 80 and the ambient or positive pressure on top of the liquid 77 covering the bottom of the capillary tube 72 forces the liquid up the capillary passage 78. As the liquid rises up the capillary passage 78, its meniscus is concave, because the walls of the capillary passage 78 are wet by the liquid solution 77. As the liquid level in the capillary passage 78 rises ever so slightly above the sharp edges of the concave top 80, the jet stream of air leaving the orifice 58 draws a small droplet off the top of the capillary orirfice 80. As the small droplet leaves the orifice 80, it accelerates very rapidly for a distance of slightly over thirty thousandths of an inch and then it is slammed against the ball 69, where it is fractured into many smaller portions. Most of the particles larger than 5 microns in diameter formed by the collision of the droplet with the ball 60 cling to the ball 60, coalesce with other particles, run down the base of the ball 60 and the stem 73, and return to the liquid 77 in the reservoir. Those particles greater than 5 microns which do leave the ball 60 are deflected against the walls 36 of the bowl by the flaring jet stream. There they coalesce and return to the liquid reservoir. Most of the particles smaller than 4 microns float out of the nebulizer, buoyed up by the density of the entraining air or oxygen. For the range of specific gravities of solution commonly nebulized in medical practice, the optimum particle spectrum has about 20% of the particles smaller than 2 microns and 80% lying between 2 microns and 4 microns in diameter. The particles smaller than 2 microns become very small and are evaporated by the drying action inside the body due to the increase in temperature encountered there and other factors, while the larger particles decrease in size but are still large enough to moisten the peripheral airways.
The capillary unit 13 fits into the clamp 61 between the two arms 62 and the peg 71 fits into the peg socket 6 5 with a shoulder 31 serving as a stop. Thus, the stop member 63 at the clamp 61 and the shoulders 81 and 65 positively locate both the orifice 80 of the capillary tube 72, the arcuate capillary body 70, and the ball 60 in their proper position. It will be noted from the lines drawn in FIG. 4 that the axis 59 of the air jet is in line with the center 82 of the ball and that the orifice 80 of the capillary tube 72 is positioned with its side wall almost blocking the jet but with its concave portion 80 about on a line with the lower edge of the jet orifice 58.
It is often desired to have a liquid solution continuously supplied to the nebulizer. For this purpose, the shell 36 is provided with a needle-type liquid inlet device 85. A projecting cylindrical wall 86 lies approximately perpendicular to the frustoconical wall of the shell 36, above the tubular portion 35 and well above the center axis 45. The wall 86 has an external lip 87 around its upper end and an interior lip 88 near the top of a conical interior wall 90. The inner and lower end 91 of this interior wall 0 is a very thin wall portion of the shell 36. A common inch No. 27 intravenous needle may be inserted into this cavity 90 and locked in it by the lip 88. The needle perforates the thin membrane 91 as it enters. The needle may be connected to an intravenous drip arrangement, readily available in hospitals, to provide leakage of liquid at a measured rate into the housing 12. The drip openings 32 serve to bleed out any excess liquid that may enter and prevent liquid from entering the inlet 18 of the barrel tube 15, keeping liquids away from the patients airway. The openings 32 also insure that the ball 60 and orifices 58 and 80 will not be drowned. When the intravenous needle is withdrawn from the socket 90, the nebulizer functions as before, because the gas flows developed for ventilating the lung are so large that they are not affected to any 6 significant amount by the slight leakage of air through the remaining perforations.
In operation, the nebulizer is assembled by locating the capillary unit 13 in the housing 12 by means of the peg 71 and the clamp 61 to assure a perfect positioning of the ball 60, the jet nozzle 58, and the capillary orifice 80. Liquid may be placed in the bottom of the housing 12 or barrel 11, which is held at an angle while the parts are threaded together. The O-ring 52 prevents leakage at the socket 31 and the liquid is then within the bowl and in the lower half of it, accessible to the capillary tube 72. For mainstream operation, the stopper 14 is withdrawn from the opening 46, and the main airtube is attached to the inlet 38. A supply of air or oxygen is also attached to the air jet fitting 56, and a suitable outlet member is attached to the tube portions 23 or 24 and lead to the patients airway, directly or indirectly.
During mainstream operation, the air jet from the orifice 58 blows across the capillary orifice 80, lowering the pressure there, drawing liquid up the capillary, picking it up, and blasting it against the ball 60, breaking up the particles. In the meantime the mainstream entrains the particles smaller than about 4 microns and carries them out the outlet 19 into the patients airway.
Even if the nebulizer is pitched forward or backward to a considerable angle, this does not affect the capillary action or affect the efficiency of the nebulizer, because the liquid still seeks the lowest point, which is at the arcuate passage 75. Likewise, movement from side to side not affect operation, due to the provision of the arcuate passage 75.
For sidestream operation, the stopper 14 is inserted to close the opening 46, and the main air stream is fed downstream of the outlet 19 from the nebulizer. Otherwise, the operation remains the same.
For continuous feeding and loading of the nebulizer with liquid, a hypodermic needle is inserted in the socket and through the thin skin 91 piercing it, and fluid then drips from a suitable supply, via the needle, into the housing 12. It usually drips on top of the cylindrical portion 43 and washes down the side of it into the fluid reservoir therebelow.
To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.
1. In a nebulizer for supplying small liquid particles in a main stream of gases supplied to a patient; a hollow body adapted to contain a liquid, the body being formed with axially aligned inlet and outlet passages having relatively large cross-sectional areas for carrying the main stream of gases for the patient through the body, a jet tube extending into the body for supplying additional gases into the body, the jet tube being arranged in the body at an angle with respect to the axially aligned inlet and outlet passages so that the additional gas jetting therefrom mixes with the main stream gases and assists the flow of main stream gases through the body, a capillary tube having inlet and outlet openings mounted in the body and having its inlet opening adapted to be disposed in the liquid in the body, the outlet opening of the capillary tube being adjacent the outlet end of the jet tube so that the gases discharged from the jet tube carry liquid from the outlet opening of the capillary tube into the main stream of gases passing through the body, said body including a cylindrical portion and frusto-conical portions on opposite sides and adjacent the cylindrical portion, said inlet and outlet pipe extending through said frusto-conical portions at the apex ends thereof, a member secured to the lower end of the capillary tube and disposed in the cylindrical portion of the body, the member having an arcuate lower edge concentric with the cylindrical portion and spaced from the cylindrical portion to define a narrow arcuate capillary-like passage between the cylindrical portion and said member, the inlet end of the capillary tube being adjacent said passage, said member serving to permit said nebulizer to be operative even though it is rolled from side to side through a substantial angle and pitched forward or rearwardly through a substantial angle in which the liquid in the hollow body would normally be out of engagement with the inlet end of the capillary tube Without the use of said member.
2. A nebulizer as in claim 1 wherein said member is formed with an arcuate recess concentric with said cylindrical portion and wherein the inlet end of the capillary tube opens into the arcuate recess.
3. A nebulizer as in claim 1 together with spacer means provided on said arcuate member for maintaining a predetermined spacing between the arcuatesurface of said member and said cylindrical portion.
References Cited by the Examiner UNITED STATES PATENTS Silten 128-173 2,040,630 5/36 5 2,605,764 8/53 Adams ct al. 12s 194 2,696,210 12/54 Hickman 128173 2,726,896 12/55 McKinnon 239338 2},906 ,463 9/59 Curry 128173 3,018,971 1/62 Cheney 239 338 10 3,069,097 12/62 Cheney 239338 FOREIGN PATENTS 487,211 6/38 Great Britain. 15 686,006 1/53 Great Britain. 709,848 6/54 Great Britain. 988,479 5/51 France.
LOUIS R. PRINCE, Primary Examiner.
20 RICHARD J. HOFFMAN, JORDAN FRANKLIN,