CA1245929A - Method and apparatus for the diagnosis of respiratory diseases and allergies - Google Patents

Abstract

OF
CARL PETER KREMER, JR.
FOR
METHOD AND APPARATUS FOR THE DIAGNOSIS OF
RESPIRATORY DISEASES AND ALLERGIES

Abstract of the Disclosure Method and apparatus for coating the airways of the lung of a patient substantially uniformly with a mist formed by aspirating a liquid which includes re-stricting the maximum size of the particles of the mist to about 1.2 microns with the major portion of the particles being in the range of .056 microns to 1 micron causing the mist to behave as a gas, conduits for feeding the mist together with a gas containing oxygen to a patient to be inhaled during the normal breathing process, and valves connected with the con-duits for diverting the exhaled mist and gas through a discharge path, By radioactively tagging the liquid prior to production of the mist, the uniform deposi-tion of the mist throughout the entire lung without encountering heavy accumulations in the large airways and at branch points, enables the production of high definition image scans of the lung.

Description

~2~59~9 A 598-4 This invqntion relates to the diagnos.is of respiratory di-sease and more specifically to a novel and improved method and apparatus utilizing an aerosolized radioactive isotope for ven tillation of the lungs to enable the production of multiple im-ages of relatively high re901ution and contrast to facilitate location of emboli, tumors and the like as well as other diseases affecting the respiratory tract without the danger o hyperdepo-sition and loss of image clarity Heretofore, diagnosis of respiratory diseases was princi-pally effected by perfusion lung scans and ventillation utilizing radioactive gases. The use of radioactive aerosols was also con-sidered but it was found thaE with known systems excessive depo-sition or rainout occurred.not only in the upper respiratory tract, the oral pharynx or the trachea but also a~ ai~rway inter-sections Moreover, uneven deposition of the m~st was observed betwe~n the central and peripheral areas o the lung, According-ly, when ventillation SC~8 ~re deemed desirable? rad~oactive gases such as xenon and k~ypton are generally relied upon not withstanding the relatively high cost entailed in producing the gas, patient inconvenience, extremely limited time in which to obtain even one image of the lung and the need Eor containment and disposition o the exhaled gas This inventlon overcomes the problems heretofore entailed in the diagnosis o lung diseases and provides a method and appa-ratus utilizing a radioactive mi9t which avolds the difficulties entailed with gases as well as the problems heretofore encoun-tered with aerosols. More specifical.ly, it ha~ been found that . .

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~L24~9;~9 with the utilization of aerosols wherein the particle size is maintained below approximately 1.2 microns with by far the major portion of the particles being well below 1 micron, the mist be-haves much the same as a gas and does not produce material rain-out or hyperdeposition in the upper respiratory tra~t, pharynx or trachea. Moreover, there is substantially uniform deposition throughout the entire lung without accumulation at airway branch-ing points and the patient can be in any position and is not re-quired ~o hold his breath during the scanning operation and ample time is available for mul~iple scans Furthermore ? the isotope being in aerosol form can, upon bsing exhaled, ~e filtered out and safçly stored until the radioactivity reache~ a safe level for ~onvenient disposition, Radioactive gases hQwever cannot be fil~ered and great care is required for containment and stor-age, the latter requirin~ extended periods of timç as compared to aero~ols.
Anpther object of ~h invention resides in the provision of a novel and improved method and apparatus for the diagnosis of lung diseases characterized by its simplicity, reliahility, ease oE operation and relatively low cost.
Still another object of the invention resides in the provi-sion oE novel and improved diagnostic apparatus which enables multlple photographic view9 oE the Lung to be reco~ded with lit-tle if any patient inconvenience.
A still further object oE the invention resid~s in the pro-vision of a novel and improved method and apparatuq for m~aking image ventillation studies of the lung which affqrds greatly im-, l , . .

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proved resolut-ion and contrast.
The invention utilizes a nebulizer wherein the maximum particle size is essentially limited to 1.2 microns with a neg-ligible quantity of particles larger than 1.2 microns. A uni-directional air inlet is coupled to the output of the nebulizer and the output is also coupled through a unidirectional flow valve and a T- or Y- connector to a mouthpiece or face mask through which the patient inhales the mist produced by the nebu-lizer. The third or discharge opening on the connector includes a unidirectional flow valve for the discharge of mist and air exhaled by the patient and a filter for the removal of the radio-active mist. The.output from the filter is preferably fed to a suitable container for storage until the radioactivity decays to a safe level for disposal, Since the nebulizer is usually oper-ated continuously by a compressed air supply, means are also pro-vided at the output of the nebulizer to prevent the development of exçess pressure during ~he exhaling periods, - ~he above and other obJects and advantages of the invention will become more apparent from the following description and accompanying drawings forming part of this application, IN T~ DRAWINGS-Figure 1 is a side elevational view in partially diagram-matic form of one embodiment of apparatus in accordance with the invention; and Figure 2 is a side elevational view in partially diagram-matic form of a modification of the invention shown in Figure 1.

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~Z~i929 While the desirability of utilizing radioactive aeroscls or mists for the diagnosis of lung diseases had been suggested because of convenience and relatively low cost, the procedure has not heretofore been utilized because of excessive deposition of the aerosols in large airways, posterior pharynx, trachea, stomach and the like. It was also generally considered that a satisactory radioactive mist must merely no~ include particles larger than 2 microns in mean mass aerodynamic diameter. With the invention now to be described, it has been found that parti-cle sizes not only should not exceed 1.2 microns but that the particles of the aerosol should be in the range of about .056 microns to about 1.2 microns with approximately 90% of the parti-cles being under 1 micron. Under these conditions, the aerosol behaves as a gas and the desired objectives can be achieved In preparation of the aerosol for the production of radio-active scans, either 99m technetium-sulphur colloid or 99m tech-netium-diethylene triamine penta-acetate unctio~ed satisfac-tsrily and have half lives of about 6 hours which provides ade-quate ~ime for multiple image scans and yet a shart enough half li~e to provide for convenient disposal. Gases not only require the patient to hold his breath during an image scan which affords time for only a single scan but known satisfactQry gases such as krypton has a half life oE less than 30 seconds making it diffi-cult to provide time for even the single scan and forms oE tagged Xenon have half lives of Erom ~ to 30 days making disposal diffi-cult. The radioactive technetium compounds referred to above are generally available in Nuclear Medicine Departments for rou-5~29 tine clinical.cliagnostic procedures and accordingly constitute arelatively inexpensive and available aerosol ~or the conduct of ventillation scans, Referring now to Figure 1 showing a partially dia~rammatic elevational view of one form of apparatu9 in accordance with the invention, the nebulizer is generally denoted by the numeral 10 and includes a compressed gas inlet 11 and an outlet 12. The nebulizer may take any desired form though in the illustrated embodiment, the housing would include a suitable reservoir, an aspirator for producing the mist and the gas such as oxygen or air should be supplied at the rate of the order of 6 to 10 liters per minute, In the instant embodiment of the invention, a four-way connector generally denoted by the numeral 13 is coupled to the outlet 12 of the nebulizer 10 by the t~lbular leg 14. A uni-directional air inlet valve 15 is connected to a second tubular le~ 16 of the four-way connector 13, a second unidirectional out-let valve 17 and particle filter 18 are connected to a third leg lC3 of the four-way connector 13 and a fourth le~ 2a of the.con-nec~or 13 is connected to flexible tubing 21 hav~ing ~ bellows configuration for delivery oE the aerosol to the patient, It is preferable to e.nclose the nebulizer 10 together with the four-way connector l.3 within a container 22 ormed of lead or other radiation shi.elding material since the nebulizer will contain a radioactive liquid.
The outlet end o~ the tubing 21 is connected to a third uni-directional valve 23 which may be contained within a second con-tainer 24 also formed of lead or other radiation shielding mate . . .

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rial. The outlet of the one way valve 23 is coupled ~o one leg 25 of a Y-connector 26 disposed within the container 24 and the second leg 27 of the ~-connector is coupled to a ~lexible tube 28 similar to that of the tube 21. A mouthpiece 29 for the pa-tient is secured to the end of the tube 28 so that the patient can conveniently inhale the mist generated by the nebulizer 10 together with air entering the one-way valve 15. While a simple mouthpiece 29 has been illustrated, a suitable facemask may re-place the mouthpiece i~ so desired. The unidirection~l flow valve 23 may take any desired form and may preEerably be adjust-ed to prevent flow during the presence oE atmospheric pressure on the downstream side of the valve and provide for free flow whe~ the downstream pressure is reduced during the time the pa-tient is in the process of inhaling When utilizing aerosols for ventillation scans, the patient may inhale and exhale several times in order to be certain that the radioactive mist has been uniformly deposited througho~lt the entire ~ung. During the exhaling periods, the p~tient will ex-hale t~rough the mouthpiece or facemask, as the ~ase may be, and through the tube 28. Since the one-way va-lve 23 wi~l prevent reverse flow of mist, the exhaled aerosol will pass outwardly through the leg 30 oE the Y-connector 26, a one-way valve 31 and a Lilter 32 and the exhaled air and/or gas will be discharged throu~h the tube 33 The filter 32 retains the aerosol exhaled by the patient and contains the filtered aerosol until the level of radioactivity has decreased to a safe level for convenient disposal. During the exhaling period, the valve 23 will remain closed and it is therefore desirable to prevent development of _l .. " .... ~.. ~

~2~S~g excessive pressure within the tube 21 caused by compressed air entering the inlet 11 of the nebulizer 10. For this purpose, the tubing 21,-being in the form oE a bellows, will tend to expand and thus limit the pressure. L~ desired, the one-way valve 17 may be utilized and adjusted to act as a relief valve to limit the maximum pressure ln the tube 21 When the relief valve 17 is utilized, an aerosol filter 18 is provided to filter out and contain the aerosol and the remaining gas is discharged through the pipe 34 If desired, pipes 33 and 34 may be coupled together and fed to a holding container which will retain the gaseous ma-terial until the radioactivity has decreased to a level permlt ting normal disposal.
The nebulizer 10 may take any desired form provided however that the aerosol particles generated thereby are within the ranges set forth above One such nebulizer which will generate a mist meeting the requirements outlined above ifi illustrated and described in United States Patent No. 4,116,387~
Figure 2 illustrates a modified embodiment o~ the invention wherein a large particle t~ap is included in the event the speci fic nebulizer 10 utilized may have an excess number oE large par-ticles.
In the Eigures, like numerals have been used to denote cor-responding elements in each figure.
In Figure 2, it will be observed that the leg 20 extending from the four-way connector 13 is curved upwardLy and receives the vertical leg of an elbow 35 having a plurality of inclined bafEles 36. The horizontal output leg of the elbow 35 is then ,- _., .. _,~.. . ....... .. " . . . . . ...

` ~2~5i9~3 coupled to the bellows-shaped tubing 21 for delivery oE the mist to a patient.
The baffle arrangement contalned within the elbow 35 pro-vides a circuitous path for the mist with the result that the larger particles which because of their greater mass will tend to collide with one of the baffles and be removed from the re-mainder of the aerosol. These larger particles upon reconversion to a liquid will automatically drain back into the nebulizer and enter the liquid reservoir therein. If desired, a separate drain may be employed for returning this liquid directly to the reser-voir or to an individual receiver The method and apparatus for the production of lung scans utilizing an aerosol has been found to be exceedingly effective not only from the standpoint of reduced costs an~ convenience far the patient but vastly improved image scans have been obtain-able wkich greatly facilitate diagnosis o precise difficulties involving the entire lung.
While the invention is particularly useful for the produc-tion of image scans of tlle lung" it is of course useful for medi-cation of the lung in the treatment of disease. For instance, the method and apparatus would be useful for treatment of the lung with antimicrobials, antifungals, tagged anticancer drugs and the like. The method and apparatus is also useful for pro-vocative allergy testing to determine the body ~eaction, for in-stance, to histamines and antigens such as ragweed and the like While only certain embodiments of the invention have been illustrated and described, it is apparent that alterations, ~5~29 changes and mDdifications may be made without departing from the true scope and spirit thereof.

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Claims (7)

THE EMODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for producing a mist to be inhaled by a pa-tient and having gaseous properties to facilitate pervasion of the entire lung with substantially uniform deposition throughout all the airways therein comprising means including an outlet for continuously aspirating a liquid utilizing gas pressure to produce a mist to be inhaled by a patient con-tinuously during each inspiratory phase, said mist having particles within the range of .056 microns to 1.2 microns with the major portion of the particles being less than one micron, a conduit including pressure limiting means connected at one end to said outlet, a unidirectional flow valve commu-nicating with said conduit for the admission of ambient air, a second unidirectional flow valve connected to the other end of said conduit, a second conduit connected to said second flow valve and terminating in an outlet to facilitate in-haling of the mist by the patient, and a third unidirectional flow valve connected to said second conduit and arranged to permit flow in a direction opposite to said first and second valves whereby said patient, upon inhaling, will draw mist from said aspirating means and upon exhaling, the exhaled mist and gas will be discharged through said third flow valve.

2. Apparatus according to claim 1 including large parti-cle intercepting means interposed between the output of said aspirating means and said first conduit.

3. Apparatus according to claim 1 wherein said gas pres-sure is in the range of 6 to 10 Liters per minute and said pressure limiting means comprises an undulating bellow-like wall on said first conduit.

4. Apparatus according to claim 1 wherein said pressure limiting means comprises a pressure relief valve commu-nicating with the outlet of said aspirating means.

5. Apparatus according to claim 1 wherein said mist is radioactive and said third flow valve includes a filter for removal of the radioactive mist while permitting discharge of the gas such as air or oxygen combined with the mist.

6. Apparatus according to claim 5 wherein said pressure limiting means comprises a pressure relief valve and a filter for the removal of the radioactive mist while permitting dis-charge of the gas such as air or oxygen combined with the mist.

7. Apparatus for producing a mist to be inhaled by a pa-tient and having gaseous properties to facilitate pervasion of the entire lung with substantially uniform deposition throughout all the airways therein comprising means including an outlet for continuously aspirating a liquid utilizing gas pressure to produce a mist having to be inhaled continuously during each inspiratory phase, said mist particles within the range of .056 microns to 1.2 microns with the major portion of the particles being less than 1 micron, a conduit connected at one end to said outlet, a unidirectional flow valve communicating with said conduit for the admission of ambient air, means coupled to the other end of said conduit to facilitate inhaling of the mist by the patient, and a second unidirectional flow valve connected to said conduit and arranged to permit flow in a direction opposite to said first flow valve whereby said patient upon inhaling will draw mist from said aspirating means and upon exhaling, the exhaled mist and gas will be discharged through said second flow valve.