US3661528A - Breath sampler - Google Patents

Abstract

A breath sampler device for use with an air analyzer. The sampler includes a chamber, an intake port leading into the chamber, an outlet port exiting from the chamber, and a breathing port through which a subject inhales from and exhales into the chamber. An intake check valve provides for unidirectional air flow through the intake port into the chamber, and an outlet check valve provides for unidirectional air flow out of the chamber through the outlet port. An air reservoir having a sampling region is associated with the outlet port. Upon exhalation, the outlet check valve opens and the air which has just been exhaled from the subject''s lungs is passed from the chamber into the air reservoir where it replaces the residual air contained in the reservoir sampling region from a previous exhalation. In order to discretely sample this expired air before it can be affected by conditions outside the subject''s body, a pressure sensing membrane is provided which responds to the decrease in pressure inside the chamber on subsequent inhalation to actuate a switch which closes a circuit to an electric pump which draws a sample of this expired air from the reservoir sampling region into the analyzer.

Description

United States Patent Falk [451 May 9, 1972 [54] BREATH SAMPLER [72] Inventor: Donald B. Falk, East Seaford, NY. [57] ABSTRACT A breath sampler device for use with an air analyzer. The sam- [73] Asslgnee' lnstrumezumon Associates New pler includes a chamber, an intake port leading into the chamber, an outlet port exiting from the chamber, and a [22] Filed: Apr. 2, 1970 breathing port through which a subject inhales from and exhales into the chamber. An intake check valve provides for [21] Appl' 25176 unidirectional air flow through the intake port into the chamber, and an outlet check valve provides for 52 US. Cl. ..23/2s4 R, 73/4215 uhidirwiohal air flow out of the Chamber through the outlet [51] Int Cl t "G01" 1/22, 601" 33/16 port. An air reservoir having a sampling region is associated 581 Field of Search ..23/254, 232, 254 E, 232 E; Whh the Outlet P P exhalation theOutlet check 73/4215 opens and the air which has just been exhaled from the subjects lungs is passed from the chamber into the air reservoir 5 References Cited where it replaces the residual air contained in the reservoir sampling region from a previous exhalation. In order to dis- UNITED STATES PATENTS cretely sample this expired air before it can be affected by conditions outside the subjects body, a pressure sensing mem- 2,172,038 9/1939 Scholander ..23/232 brane i provided which responds to the decrease in pressure 3'l96689 7/1965 For rester et inside the chamber on subsequent inhalation to actuate a 3,238,783 3/1966 Wright ..73/42l.5 switch which closes a circuit to an electric pump which draws Primary Examiner-Joseph Scovronek Assistant E.\'aminerR. M. Reese Attorney-Nist & Quartz a sample of this expired air from the reservoir sampling region into the analyzer.

4 Claims, 1 Drawing Figure 7672'p 74 Am 73 90v l 70 ANALYZER I r. \I 7 IO\ 98 5g u 2 35c 65 425G 39 38 t i 7TT\ as :1 s2

PATENTEDHAY 9 I972 ANNA Vmw INVE NTOR DONALD B. FALK ATTORNEY BREATH SAMPLER FIELD OF THE INVENTION This invention relates generally to analytic apparatus, and particularly concerns a breath sampler device for use with a medical lung function analyzer.

THE PRIOR ART Lung function analyzers are used to analyze samples of a patients breath in order to determine its compositions, and changes in its composition which occur over a period of time, under various conditions. From this information, diagnosticians draw important conclusions as to the condition of the patient's lungs, in cases where emphysema or other lung pathology is suspected.

A device of this type commonly employs a breath sampler comprising a chamber from which the patient inhales and into which he exhales. The chamber has an intake port through which the inhaled air is drawn, and an outlet port through which the exhaled air leaves. These ports are controlled by check valves arranged so that only fresh air is drawn into the chamber on the inhalation cycle, and expired air passes only through the outlet port on the exhalation cycle. As exhaled air leaves the chamber through the outlet check valve, a small sample of it is withdrawn by mechanically actuated means from a point just downstream from the outlet check valve and delivered over a sampling conduit to the analyzer.

In the past, the sampling conduit has lacked consistent control. The prior art arrangement yielded a relatively poor response, since the exhaled air passes continuously to the analyzer, and discrete volumes of air from successive exhalations are mixed randomly during passage through the sampling conduit.

THE INVENTION The present invention utilizes an electrically controlled pump in cooperation with the sampling conduit and an associated reservoir for the air which has just been exhaled from the patient's lungs, which is the air to be sampled, so that the passage of exhaled air to the lung function analyzer is positively controlled. This exhaled air displaces the residual air from a previous exhalation which is contained in the portion of the reservoir which is in cooperation with the sampling conduit so as to provide a discrete breath to be sampled. The operation of the pump is controlled by a diaphragm'switch which is responsive to a pressure sensitive membrane. The pressure sensitive membrane senses the pressure changes which occur in the breath chamber during inhalation to close the switch and actuate the pump to draw air from the reservoir, which air is preferably the last part of the expired breath which reflects the capillary gas concentration in the alveolus of the lung. As a result the pump is operated in sharply responsive fashion to draw exhaled air through the sampling conduit when the patient inhales immediately subsequent to an exhalation, and to be inoperable during exhalation so as to prevent the drawing of air through the sampling conduit during exhalation.

This results in a fast and sensitive pump operation so that the air which has just been exhaled from the patients lungs may be sampled selectively, and in addition provides the capability for segregating and accumulating the end portions of discrete breaths for analysis, which is necessary to avoid random mixing. Mixing tends to average out the breath concentration over a period of time, whereas under certain circumstances it may be desired to analyze the breath content as of a sharply defined point in the respiratory cycle.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing includes a vertical section taken through a conventional T-shaped breath collection conduit and appropriate hose connections thereto; along with a partly schematic representation of a pump controlled breath sampling connection leading from the T-conduit to the analyzer, and automatic control apparatus therefor, in accordance with this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The patients breath is collected in a T-shaped enclosure, generally designated 10. This includes a cylindrical member 11 defining a centrally located breath collecting chamber 12 which has threeport openings 26, 32 and 20; and threecylindrical conduits 14, 16 and 18 connected thereto by means of threaded connections to appropriate openings in the member 11. Threegaskets 19 are provided for sealing purposes.Conduit 18 is a breathing conduit through which the patient inhales and exhales. It is threadedly connected to abreathing port 20 for communication with the breath chamber 12 so that the patients respiration draws air from the chamber 12 into theconduit 18 during the inhalation cycle, as represented by arrow 22, and forces expired air throughconduit 18 into the chamber 12 during the exhalation cycle, as indicated byarrow 24.

Conduit 14 is an intake conduit. It is threadedly connected to anintake port 26 for communication with the chamber 12 so that, on the inhalation cycle, fresh air, represented byarrow 28, is drawn in through the intake port and passes through the breath chamber 12 in the manner indicated by arrow 30. Subsequently the inhaled air passes through the breathingconduit 18 to reach the patient, as indicated by arrow 22.

Conduit 16 is an outlet conduit. It is threadedly connected to anoutlet port 32 for communication with the breath chamber 12 so that, on the exhalation cycle, the expired air forced through the breathingconduit 18, as indicated byarrow 24, passes through the breath chamber 12 and outlet conduit 16 as indicated byarrows 34 and 35 respectively. Preferably, elastomeric intake and outlet hoses36 and 38 are coupled to the inlet and outlet conduits l4 and 16 respectively.Outlet hose 38 and outlet conduit 16 act as areservoir 39 for the most recently exhaled air, thereservoir 39, functioning in a manner to be described in greater detail hereinafter. Thereservoir 39 should be of sufficient overall dimension to preferably retain at least a portion of the air just exhaled from the patients lungs in the outlet conduit 16, where it may be sampled in a manner to be described in greater detail hereinafter, for a sampling interval, which is determined by the inhalation of the patient. Theoutlet hose 36 may be eliminated if the outlet conduit 16 is of sufficient overall dimension to function as areservoir 39 by itself.

In order to insure the undirectional flow of fresh air into the breath chamber 12 through theintake port 26, and of exhaled air out of the breath chamber through theoutlet port 32, there are provided intake and outlet check valves assemblies 40 and 42 respectively. The check valve assemblies each include aseating cylinder 44 provided with a radially outwardly extendingannular flange 46. Theflange 46 of the intake check valve assembly is received within anannular recess 47 formed in the internal surface of theintake conduit 14, and is held in place by being clamped against the annular end surface of the cylindrical chamber member 11 surrounding theintake port 26. Similarly theradial flange 46 of the outlet check valve assembly is received in anannular recess 49 formed in the interior wall of the chamber member 1 l surrounding theoutlet port 32, and is clamped in place by the outlet conduit 16. As shown and as presently preferred, the movable valving element of eachassembly 40 and 42 is an integrally formed plastic member, generally designated 48, which comprises acircular diaphragm 50, anannular ring 52, and a plurality of spaced helically shapedresilient filaments 54 connecting thecircular diaphragm 50 andannular ring 52.

Thering 52 surrounds thecylinder 44, and is friction fit, thereon. Thediaphragm 50 seats against the end wall of thecylinder 44 for sealing purposes when the check valve assembly is in its closed condition. It is held in that position by the resilience of thehelical filaments 54 which tend to draw thediaphragm 50 axially toward theannular ring 52, and therefore toward thecylindrical member 44. When thefilaments 54 resiliently yield to allow thediaphragm 50 to move axially away from thecylindrical member 44, thediaphragm 50 comes out of sealing engagement with thecylindrical member 44. When this happens, air within the interior of thecylindrical member 44 escapes between the end wall of the cylindrical member and the confronting surface of thecircular diaphragm 50, and then passes through the spaces between thefilaments 54. This constitutes the open condition of thecheck valve assembly 40 or 42. 1

Check valve assembly 40 opens on the inhalation cycle, in response to the reduced pressure in the chamber 12, to permit the air intake illustrated byarrows 28, 30 and 22. It closes on the exhalation cycle, in response to the increased pressure in chamber 12, to prevent exhaled air from escaping back through theintake port 26. Similarly, the outlet check valve assembly 42 opens on the exhalation cycle, in response to the increased pressure in breath chamber 12, to permit the outflow of expired air, which is preferably the air which has just been exhaled from the patients lungs, in the manner illustrated by thearrows 24, 34 and 35; and closes during the inhalation cycle in response to the decreased pressure in the breath chamber 12 in order to prevent re-inhalation of expired air through theoutlet port 32.

The internal wall of the outlet conduit 16 is formed with an annular groove 56 which is located a spaced distance downstream from the outlet check valve assembly 42. This groove 56 serves to retain and position a motion-limitingassembly 58 which extends transversely across the outlet conduit 16 and which serves to limit the opening motion (motion to the right in the FIGURE) of thediaphragm 50 in the outlet check valve assembly 42. The motion-limiting assembly 58 comprises a pair of circularly arcuate sections 60 (only one is visible in the Figure) which are compressively received along their circular arcuate edges by the groove 56 and it comprises a transverse arm 62 (seen in section view in the Figure) which extends between and is attached to each of thearcuate sections 60.

in accordance with the present invention, a sampling conduit, generally designated 64, is provided in cooperation with thereservoir 39 to conduct a small sample of the exhaled air, which has preferably just been exhaled from the patients lungs, from apoint 65 in thereservoir 39 along the outlet conduit 16 located just downstream from the outlet check valve assembly 42, to ananalyzer 66 which is a conventional type of air analyzer; although the invention may be utilized with any type of air analyzer. The sampling conduit includes a short length oftubing 68 having aninlet 69 tapped into thereservoir 39 at thedownstream point 65 in the outlet conduit 16, and a pair of connectingpipes 72 and 74. The location of thesampling conduit inlet 69 permits the exhaled air from the last part of the patients expiration to be sampled and accumulated for analysis. Connectingpipes 72 and 74 haveinlets 73 and 75, andoutlets 77 and 79, respectively. Theinlet 73 ofpipe 72 is in communication withtube 68 through achamber 70, and thus in communication with thereservoir 39. Theoutlet 79 ofpipe 74 is in communication with theinput 81 to theanalyzer 66. The flow of expired air from connectingpipe 72 to connectingpipe 74 is controlled by an electrically actuatedpump 76, which can-be any appropriate type of pump structure but is preferably adiaphragm pump 76.

Thediaphragm pump 76 prevents the passage of air therethrough when thepump 76 is off or inoperable. The intake end ofpump 76 is in communication'with theoutlet 77 of connectingpipe 72 and the outlet end is in communication with theinlet 75 of connecting pipe -74. As shown and preferred, a reciprocatingrod 80, of short stroke, is connected to the pump to operate it. Therod 80 is operatively connected to avibrator 78 which controls the movement of therod 80 and, hence, the movement. of the flexible diaphragm within the pump so as to pump air from the inlet to the'outlet. Air is thus passed between connectingpipes 72 and 74 and on to theanalyzer 66.

Thevibrator 78 is electrically actuated by a switch which controls the flow of electrical power from a suitable source, here shown illustratively as aD.C. battery 91 to thevibrator 78. The switch which is preferably adiaphragm switch 90, includes a pressure sensing, or pressure responsive flexible membrane ordiaphragm 92, shown schematically in the figure by a dotted line, and a pair of contacts which close in response to small displacements of the diaphragm. Theflexible member 92 is flexed to close the controls when the internal air pressure within thehousing 94 decreases, and is returned to its rest state to reopen the contacts from the flexed state when the internal air pressure within thehousing 94 is increased. Apressure communication hose 96 leads from the interior of thehousing 94 and is coupled to atube 98 which taps through the chamber-forming member 11 to communicate with the breath chamber 12 to sense pressure changes.

In the operation of the breath sampling device, as the patient exhales, the air just exhaled from the lungs follows the path indicated byarrow 24 through thebreathing conduit 18 and breathingport 20, and the path indicated byarrow 34 through the breath chamber 12, theoutlet port 32, and the outlet check valve assembly 42 to the outlet conduit 16 and theoutlet hose 38 comprising thereservoir 39. Thereservoir 39 retains at least a portion of this exhaled air in the area ofpoint 65 for a sampling interval and the exhaled air displaces any residual air remaining in this area from a previous exhalation. At this time the outlet check valve assembly 42 is opened in the manner described as exhalation raises the pressure in the breath chamber 12 above ambient. Theflexible membrane 92 which is flexed from its rest position due to a decrease in pressure, remains at rest and the switch is therefore open and no power is supplied tovibrator 78 frompower source 91. Thepump 76 is, therefore, in the inoperative state and no air is drawn through thesampling conduit 64 to theanalyzer 66.

After the exhalation cycle terminates, the pressure in the breath chamber 12 drops back to ambient and later goes below ambient as subsequent inhalation begins. The pressure reduction causes the internal pressure within thehousing 94 to decrease thereby flexing themembrane 92 from the rest position and closing theswitch 90. This connectspower source 91 to the electrical circuit of thevibrator 78 turning the pump on. The exhaled air contained in the area of theinlet 69 of thesampling conduit 64, which is atpoint 65 in the outlet circuit 16 of thereservoir 39 is pumped through theconduit 64 to theanalyzer 66. During the normal cycle of operation of exhalation and subsequent inhalation, the inhalation immediately follows the exhalation and the last part of the air which has just been exhaled from the lungs of the patient is accumulated and drawn into theanalyzer 66 without being mixed with the remainder of the patients exhaled breath.

When the inhalation cycle terminates, the pressure in the breath chamber 12 rises toward ambient, and later, goes above ambient as exhalation begins. This pressure increase causes an increase in the internal pressure within thehousing 94 thereby returning themembrane 92 to the rest position and opening theswitch 90, once again turning off thepump 76. As the exhalation cycle begins again, the exhaled air from the previous breath is displaced from thesampling region 65 and replaced by the exhaled air from the current exhalation cycle. Themembrane 92 is returned to rest at the completion of the inhalation cycle promptly opening theswitch 90 prior to the commencement of the exhalation cycle so that the last part of the exhaled air from discrete breaths is segregated and accumulated. As a result, the sampling cycle terminates under control of theswitch 90 at the start of the patients inhalation subsequent to exhalation, just as rapidly and with the same sensitive pressure response as it begain.

It will therefore be appreciated that the present system provides improved breath sampling apparatus for use in a medical lung function analyzer or any other gas sampling application in which speed and sharpness of response and high sensitivity to small pressure changes are required, along-with the ability to accumulate the last part of successive breaths, to enable selective analysis of this part of the exhaled breath.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In breath sampler apparatus of the type including an enclosure having a breathing port, an intake port, an outlet port, an intake check valve arranged for unidirectional air flow through said intake port into said enclosure in response to inhalation at said breathing port, and an outlet check valve arranged for unidirectional air flow from said enclosure through said outlet port in response to exhalation at said breathing port; the improvement comprising:

a sampling conduit communicating with said enclosure downstream from said outlet check valve;

means for withdrawing air from said sampling conduit;

electrically controlled means for actuating said air withdrawing means; i

an electrical circuit connected to energize said actuating means;

a switch connected to control said electrical circuit whereby to turn said actuating means on and off, said switch including means for sensing the air pressure in said enclosure;

said switch being responsive to said pressure sensing means to connect said electrical circuit in a manner to cause said actuating means to turn on said means for withdrawing air whereby to draw a breath sample through said sampling conduit when the air pressure in said enclosure decreases during inhalation through said breathing port, and to atfect said electrical circuit and actuating means in a manner to turn off said means for withdrawing air when the pressure in said enclosure increases during exhalation into said breathing port.

2. Apparatus as in claim 1, wherein said means for withdrawing air includes a pump, and said electrically conlO trolled means is connected to said pump for actuating and deactuating said pump.

Claims (3)

1. 2. Apparatus as in clAim 1, wherein said means for withdrawing air includes a pump, and said electrically controlled means is connected to said pump for actuating and deactuating said pump.
2. 3. Apparatus as in claim 2 wherein: said switch includes a hollow housing, and said pressure sensing means is a flexible membrane and is disposed within said housing, a decrease in pressure in said enclosure causing a decrease in pressure in said housing and an increase in pressure in said enclosure causing an increase in pressure in said housing.
3. 4. Apparatus as in claim 2 wherein: said electrically controlled means is a vibrator and said vibrator is operatively connected to said pump for causing the reciprocation thereof when said vibrator is energized.

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