Device for specific inhalation challenge, method of use and improved generator of particles

• US 5,320,108 A
• Filed: 11/08/1991
• Issued: 06/14/1994
• Est. Priority Date: 05/31/1989
• Status: Expired due to Term

• Current Assignee: Irsst Institut de Recherche EN Sante et EN Securite Du Travail Du Quebec
• Original Assignee: Irsst Institut de Recherche EN Sante et EN Securite Du Travail Du Quebec
• Inventors: Cloutier, Yves
• Primary Examiner(s): Green, Randall L.
• Assistant Examiner(s): REICHLE, KARIN M
• Application Number:
  US07/789,531
• Time in Patent Office: 949 Days
• Field of Search: 128/716, 128/719, 128/720, 128/725, 128/747, 128/200.18, 128/203.15, 128/203.25, 128/201.25, 128/203.16, 128/205.26
• US Class Current: 600/529
• CPC Class Codes: A61M 15/0086 Inhalation chambers

Abstract

The present invention relates to a device for specific inhalation challenges, especially bronchical provocation tests, including a compressed air supply, a particle generator an exposure room, an orofacial mask, a gas-aerosol photometer, a manometer, a valve and a suction pump. The invention also relates to a method of using the device and to an improved particle generator.

Claims

1. Apparatus for specific inhalation challenges, comprising:

aerosol generation means for continuously suspending in a flow of compressed air a predetermined amount of specific particles to thus generate a compressed aerosol of predetermined composition, said aerosol generation means comprising an inlet connected to a supply of compressed air by a tube, means connected to a supply of specific particles for continuously and uniformly mixing a part of said particles with the compressed air, and means defining a compressed aerosol outlet;

pressure adjustment means for adjusting the pressure of the compressed aerosol to a pressure close to atmospheric pressure, said pressure adjustment means comprising;

a suction pump including at least one suction pump inlet,

a manometer including at least one manometer inlet,

an exposure room comprising a duct having at least one lateral wall and opposite ends, each end being closed by a cover, said room further comprising;

an exposure room inlet positioned in one of said covers, said exposure room inlet including aerosol inlet means for permitting fluid communication between the exposure room and said compressed aerosol outlet,

a first exposure room outlet positioned in the other of said covers and including first fluid communication means for permitting fluid communication between the exposure room and said suction pump inlet, said first fluid communication means comprising suction pump adjustment means including a valve for permitting adjustment of a draft of said suction pump,

a second exposure room outlet positioned in said lateral wall and including second fluid communication means for permitting fluid communication between the exposure room and said manometer inlet,

a third exposure room outlet positioned in said lateral wall, and

a fourth exposure room outlet positioned in said lateral wall;

said apparatus further comprising mask means including an orofacial mask for covering natural apertures of the respiratory system of a subject, said mask means including means for permitting fluid communication between the mask and said third exposure room outlet;

a particle content measuring device including means for permitting fluid communication between an inlet of said device and said fourth exposure room outlet, said device also including means for continuously drawing a small part of the aerosol flowing in the room and measuring its particle content.

2. Apparatus as claimed in claim 1, wherein said aerosol generation means comprises a particle generator having

an inlet, defining the inlet of the aerosol generation means connected to the supply of compressed air,

an outlet, which is part of said means defining the compressed aerosol outlet of the aerosol generation means, and

said means connected to said supply of specific particles for continuously and uniformly mixing a part of said particles with the compressed air comprising:

a base including at least one post, a platform mounted on the post and positioned above the base,

a conveyor comprising a turntable pivotably mounted on said base and means including an electric motor for driving said turntable into a controlled axial rotation,

said supply of compressed air including an air ejector mounted on the platform,

a hopper mounted on the platform, and

a vibrator mounted on the platform;

wherein said air ejector comprises said inlet which is connected to the supply of compressed air, an air ejector outlet, an air ejector outlet tube comprising a first end and an opposite end, said first end being connected with the air ejector outlet, means including the opposite end of said air ejector outlet tube for defining said outlet which is part of said means defining the compressed aerosol outlet of the aerosol generation means, an opening positioned between the air ejector outlet and inlet, an air ejector pipe comprising a first end and an opposite end, said first end being connected with the opening, means including the opposite end of said pipe for defining a suction post such that compressed air flowing through said ejector creates a vacuum in the air ejector pipe;

wherein said hopper comprises a reservoir containing a predetermined amount of specific particles and having a reservoir top, a reservoir bottom, reservoir lateral walls that converge towards each other from the reservoir top towards the reservoir bottom, an opening in one of said reservoir lateral walls in the vicinity of the reservoir bottom, an endless screw passing through said opening and being at least partly in contact with said particles, and means for driving said screw in order to continuously and uniformly discharge particles through said opening in one of said reservoir lateral walls;

wherein said turntable includes a disk having a top surface and a concentric axis of rotation, said conveyor also including a groove provided in the top surface and concentric with its axis of rotation, said groove having a smooth bottom and smooth lateral walls that diverge from each other from the bottom of said groove to the top surface of the disk, said turntable being rotationally mounted on said base in such a way that distinct segments of the groove are respectively positioned under the opening in one of the reservoir lateral walls and the means for defining a suction post; and

wherein said vibrator comprises an electromechanical device which includes means for communicating vibrations to the reservoir of the hopper in order to continuously bring the particles contained in the reservoir towards the reservoir bottom and thus allow full contact between at least a part of said screw and the particles.

3. Apparatus as claimed in claim 2, wherein said means for driving said screw comprises an electric stepping motor.

4. Apparatus as claimed in claim 2, wherein said means for communicating vibrations to the reservoir includes means for providing said vibrations at a frequency of approximately 50 Hertz.

5. Apparatus as claimed in claim 1, wherein the exposure room comprises a tube and said lateral wall includes a cylindrical surface, said covers being of such a diameter that they fit against respective ends of said tube, said exposure room further comprising an O-ring seal having a diameter such that the O-ring seal can be positioned between an end of the tube and one of said covers, and fastening means for holding one of said covers against an end of the tube, thereby collapsing the O-ring seal.,

said exposure room inlet being defined by a first connecting sleeve passing through and integral with said one of said covers, said sleeve being connected to said aerosol generation means by an aerosol-to-exposure room connection tube having opposite ends and which is part of said aerosol inlet means, one end of said connection tube being connected to the first connecting sleeve while the opposite end of said tube is connected to the outlet of the aerosol generation means,

said first outlet being defined by a second connecting sleeve passing through and integral with the other of said covers, said second connecting sleeve being connected to said suction pump inlet by said adjustment means, a tube included in said first fluid communication means, said tube having opposite ends, and said tube being provided with said valve and having one end thereof connected to the second connecting sleeve while the opposite end of said tube is connected to the suction pump inlet,

said second outlet being defined by a third connecting sleeve passing through and integral with said cylindrical surface, said third connecting sleeve being connected with of said manometer inlet by a tube included in said second fluid communication means, said tube having opposite ends, one end thereof being connected to the third connecting sleeve while the opposite end of said tube is connected to said manometer inlet, and

said third and fourth outlets being defined by respective fourth and fifth connecting sleeves passing through and integral with said cylindrical surface, said fourth connecting sleeve being connected with means including a sixth connecting sleeve for defining an orofacial mask inlet and being part of said means for permitting fluid communication between the mask and the third exposure room outlet, and said fifth connecting sleeve being connected by a tube included in said means for permitting fluid communication between an inlet of said device and said fourth outlet, said tube having opposite ends, one end thereof being connected to the fifth connecting sleeve while the opposite end of said tube is connected with means including a seventh connecting sleeve for defining said inlet of the measuring device.

6. Apparatus as claimed in claim 5, wherein said sixth connecting sleeve includes a unidirectional valve, and wherein said mask means is further provided with a second mask outlet defined by an eighth connecting sleeve, one end of said eighth connecting sleeve being integral with said mask means while another end of said eighth connecting sleeve is connected with one end of a tube located at a position distant form the subject.

7. Apparatus as claimed in claim 5, wherein said connection tube positioned between the exposure room inlet and the aerosol generation means comprises:

a first fitting having three openings, two of said openings of said first fitting being connected respectively to the first connecting sleeve and to one end of the aerosol-to-exposure room connection tube, while the third opening of said first fitting is connected to another compressed air supply by another tube having opposite ends and a valve, one end of said another tube being connected to said another compressed air supply while the opposite end of said another tube is connected to the third opening of said first fitting, and said opening of said first fitting which is connected to the first connecting sleeve having a diameter larger than a diameter of any of the other openings of said first fitting;

a second fitting and a third fitting, each provided with three respective openings, two of said respective openings being connected through a first segment of said aerosol-to-exposure room connection tube that is positioned between the compressed aerosol outlet and the first fitting and respective third openings being connected with inlets of another manometer, said another manometer having two distinct inlets; and

a fourth fitting having three openings, two of said fourth fitting openings being connected through a segment of said first segment of said aerosol-to-exposure room connection tube positioned between said second and third fittings, the third opening of said fourth fitting being connected to a suction pump inlet of a second suction pump by a second suction pump inlet tube having opposite ends and a valve, one end of said second suction pump inlet tube being connected via a second suction pump inlet pipe to the third opening of the fourth fitting while the opposite end of said second suction pump inlet tube is connected to said suction pump inlet of the second suction pump.

8. A device as claimed in claim 7, further comprising a filter which includes a foam disc positioned inside the second suction pump inlet pipe.

9. Apparatus as claimed in claim 5, wherein a disc of foam is positioned inside said exposure room between the first exposure room outlet and the other exposure room outlets.

10. Apparatus as claimed in claim 1, wherein said measuring device is a photometer.

11. Apparatus as claimed in claim 10, wherein said photometer is connected to at least one of the following devices:

a digital reader, a graphic recorder, or an integrator.

12. Apparatus as claimed in claim 1, further comprising size measuring means for measuring the size of particles of the aerosol and a fifth outlet in the lateral wall of the exposure room, said fifth outlet being defined by a connecting sleeve passing through and integral with said lateral wall, said fifth outlet being positioned close to the third and fourth outlets, and said sleeve of the fifth outlet being connected with an inlet of said size measuring means.

13. Apparatus as claimed in claim 12, wherein said size measuring means includes a cascade impactor.

14. Apparatus as claimed in claim 12, wherein said third, fourth, and fifth outlets of said exposure room are positioned in a single plane at angles of 120°

from each other, said plane being perpendicular to a longitudinal axis of the exposure room, said exposure room forming a tube.

15. Apparatus as claimed in claim 12, wherein a disc of foam is positioned inside said exposure room between the first exposure room outlet and the other exposure room outlets.

16. A method for carrying out specific inhalation challenges, comparing the steps of:

continuously suspending in a flow of compressed air a predetermined amount of specific particles to thus generate a compressed aerosol of predetermined composition;

supplying said aerosol to an exposure room;

adjusting the pressure of the compressed aerosol to a pressure close to atmospheric pressure;

covering the natural apertures of the respiratory system of a subject with an orofacial masks, and placing the orofacial mask in fluid communication with the exposure room;

placing a particle content measuring device in fluid communication with said exposure room and continuously drawing a small part of the aerosol flowing into the room in order to measure its particle content.

17. A method for carrying out specific inhalation challenges, comprising the steps of:

opening a valve positioned between a first suction pump and a first outlet of an exposure room;

starting the first suction pump, a second and a third suction pump, and a device intended to continuously draw part of an aerosol flowing in an exposure room in order to measure a particle content of the aerosol flowing in the exposure room;

establishing a flow of compressed air through a particle generator which includes a turntable, a vibrator, and a screw;

starting the vibrator to cause particles to contact the screw, starting the screw to convey them to the turntable, and driving the turntable into a constant speed of rotation to bring the particles to an air ejector which mixes the particles in the flow of compressed air;

partly closing the valve positioned between the first suction pump and the first outlet of the exposure room until the pressure read on a first manometer is set close to atmospheric pressure;

reading the concentration of particles in the aerosol on a photometer which is part of the said device, and, if the particle content of the aerosol is excessive, performing one of the following two steps;

(1) partly opening a valve positioned between a second supply of compressed air and an opening of the exposure room to dilute the aerosol and subsequently checking on a second manometer whether or not the aerosol is flowing in the appropriate direction, and (2) partly opening a valve positioned between the third suction pump and another opening of the exposure room in order to divide the aerosol and subsequently adjusting the valve position between the first suction pump and the first outlet of the room to the pressure read on the first manometer;

repeating the reading step until the concentration read on the photometer corresponds to the one at which a subject has to be challenged; and

covering natural apertures of the respiratory system of a subject with an orofacial mask and having the subject breathe at least one time a part of the aerosol that is flowing in the exposure room while the photometer is continuously and simultaneously measuring the particle content of the aerosol and a cascade impactor is determining the particle size of the aerosol.

18. A method as claimed in claim 17, wherein the pressure inside the exposure room is always set slightly lower than atmospheric pressure.

19. A method as claimed in claim 18, wherein each of the suction pumps having at least one outlet that is connected to the outside of the room, and wherein an outlet of a tube connected to the orofacial mask is also connected with the outside of the room, said method further comprising the steps of causing exhaust air to be evacuated outside of the room.

20. A method as claimed in claim 17, further comprising the step of timing the challenge by a chronometer.

21. Apparatus for specific inhalation challenges, comprising:

aerosol generation means for continuously suspending in a flow of compressed air a predetermined amount of specific particles to thus generate a compressed aerosol of predetermined composition;

pressure adjustment means including an exposure room for adjusting a pressure of the compressed aerosol to a pressure close to atmospheric pressure;

mask means including an orofacial mask for covering natural aperture of the respiratory system of a subject;

means for permitting fluid communication between said mask and said exposure room;

means for permitting fluid communication between said aerosol generation means and said exposure room;

measuring means for drawing a part of the aerosol flowing in the room and measuring its particle content.