WO2004028366A1

WO2004028366A1 - Breath sampling apparatus

Info

Publication number: WO2004028366A1
Application number: PCT/GB2003/004224
Authority: WO
Inventors: Hazel FERGUSON; Brian Mundell ROSS; Ivor MACKENZIE
Original assignee: Pan Diagnostics Limited
Priority date: 2002-09-28
Filing date: 2003-09-29
Publication date: 2004-04-08
Also published as: AU2003269224A1; GB0222577D0; GB2408687B; GB2408687A; GB0506107D0

Abstract

Apparatus for collecting a sample of breath from a mammalian (including human) subject for chemical analysis has a flexible bag with a first port formed in the wall of the bag and a second port formed in the wall of the bag. The first port provides an inlet for receiving the breath sample and a second port provides an outlet through which the breath sample may be discharged from the flexible bag. The breath sample may be analysed for hydrocarbon gas as an indication of oxidative stress.

Description

Breath Sampling Apparatus

The invention relates to apparatus for the collection of a breath sample, particularly the alveolar breath, and the measurement of hydrocarbon concentration in the sample as a means of measuring oxidative stress in a mammalian, including human, subject.

The taking of a sample of breath from a subject for analysis of the chemical composition of breath is a well-known method (UK Patent Application GB 2 363 196 A for example) which can be used as part of an evaluation of the subject's clinical condition. As another example, it may be desirable to analyse the subject's breath to evaluate the cleanliness of the subject's working surroundings.

Until now the devices for taking a breath sample have been relatively complex to use or have involved the use of plastic compounds which have reacted with the breath sample within the bag or the devices have been heavy and expensive to transport. We have devised a breath sampling device which is simple to use, light in weight and straightforward to manufacture. Additionally, the device can be used to store or retain a breath sample for analysis at a later date, whereby for example a sample can be taken at a particularly desirable or apposite time and stored for subsequent analysis according to the availability of analytical equipment or personnel.

According to one aspect of the present invention, there is provided breath sampling apparatus comprising a flexible bag with respective first and second sealable ports formed in the wall of the bag.

The first port provides an inlet for receiving the breath sample and a second port provides an outlet through which the breath sample may be discharged from the flexible bag. The second port also permits breath to pass through the bag to facilitate the collection of the alveolar volume of breath at the end of expiration by the subject, the ports being open while non-alveolar breath is passed through the bag, the second port being closed by the subject at the end of expiration and the first port being sealed or closed on removal from the mouth, the bag then containing air exhaled from the alveoli. The first port preferably contains a valve that permits the passage of the breath sample from the subject into the bag but impedes the passage of the breath sample from the bag. The first port and the second port may also include a stopper or bung or clamp device to maintain a gas-tight seal to preserve the integrity of the breath sample from contamination due to undesired gaseous ingress through the port and to prevent loss of the breath sample by egress of the breath sample through the port. The bag may be formed from a fluoroplastic material, for example a polyvinylfluoride or polytetrafluoroethylene plastics material.

The breath sample is transferred from the bag through the first port or the second port to the apparatus that analyses the composition of the breath sample, for example to analyse the stress oxidation level of the subject. The ports may have tubing attached thereto for transfer purposes.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows in perspective the breath sampling bag;

Figure 2 shows a method of fixing the inlet or outlet port to the flexible bag;

Figure 3 shows a one-way valve mechanism of the inlet port of the bag;

Figure 4 shows the internal (bag) side of the one-way valve mechanism of the inlet port in perspective;

Figure 5 shows a method for sealing the breath sample in the bag;

Figure 6 shows another method for sealing the breath sample in the bag;

Figure 7 shows yet another method for sealing the breath sample in the bag; and Figure 8 shows an embodiment which permits the extraction of the breath sample from the bag.

Referring initially to Figure 1, a flexible bag (1) is formed from a single sheet of flexible material which has been folded along one edge (2) and sealed, for example by heat welding or adhesive, along the remaining edges (3). Two ports (4) are incorporated in the bag, these ports preferably being located on opposite sides of the bag and offset in order to promote the mixing of the breath sample in the bag.

The flexible bag may also be formed from two or more sheets of flexible material sealed, for example, by heat or other welding or adhesive, along the edges.

With reference to Figure 2, the port (5) is made from an inert material (such as a fluorosilicone or a fluoroplastic material) having a lower flange (10) and is fitted through an opening in a wall (6) of the flexible bag. The port (5) may be screw-threaded and secured by means of a threaded nut (7), although other securing means may be employed including welding and gluing, or the use of an interference fitting. An O-ring (8) may be sealingly compressed by means of a washer (9) or by means of the inherent shape of the threaded nut or other securing fixing.

With reference to Figures 3 and 4, a membrane of fluoroplastic film (11) is held in place across the flange of the inlet port by one of more supports (12) made from a material (such as a metal) which is chemically sufficiently inert that the composition of the breath sample will not be affected by being in contact with the material. As the subject blows into the bag through the inlet port, the membrane (11) lifts away from the flange of the port (10) to allow the breath to enter the bag; when the subject stops breathing the inherent flexibility of the bag exerts a pressure on the contents of the bag, the pressure within the bag is raised above atmospheric pressure and the pressure difference thus created causes the membrane to press against the flange of the inlet port to form a seal, thus preventing the breath sample from escaping through the inlet port. With reference to Figure 5 and in order to seal the breath sample in the bag for example, for retention during shipment from one place to another, a flexible tube (13) of an inert material (such as fluorosilicone or fluoroplastic) is fitted to the inlet or outlet port. The tube is occluded by means of a clamp (14).

Figure 6 shows an alternative sealing method, in which a conical stopper or bung (15), made from a flexible but chemically inert material (such as fluorosilicone or fluoroplastic), is pressed into the inlet or outlet port to form a gas-tight seal.

In the alternative method shown in Figure 7, a screw cap (16) mates with a thread on the outside of the inlet or outlet port (17). A septum (18), manufactured from a chemically inert material (such as fluorosilicone or fluoroplastic film with a compressible backing), is carried within the cap and makes a gas-tight seal such that the material of the cap cannot come into direct contact with the breath sample. As shown in Figure 8, the cap may be provided with an aperture (19) to allow a hypodermic syringe needle to penetrate the septum to allow extraction of the breath sample from within the bag into the cylinder of the syringe.

A further embodiment of this invention is the use of fluorosilicone materials on the inner surfaces of the bag, ports and valve such that the breath sample cannot come into intimate contact with plastic materials of a reactive nature which could alter the chemical composition of the breath sample.

In yet a further embodiment, an outer covering or enveloping bag may be used to enclose the breath sampling bag with only the inlet and outlet ports visible, in order to prevent light from reaching the breath sample, to facilitate the printing or writing of information on the outer surface of the covering bag or to allow the application of a styling finish to the outer bag.

In another aspect, the invention provides a method for collecting a breath sample from a mammalian, including human, subject, the method comprising causing the subject to breathe through a first port of a bag (as hereinbefore described) to inflate the bag to a super-atmospheric pressure and sealing the port to retain the breath sample therein for subsequent analysis. It has been found that breath samples may be retained for up to two months without deterioration or degradation becoming apparent and, even after this period, degradation is a slow process.

The analysis may be for assessing the oxidative stress of the subject and may determine the presence and/or amount of hydrocarbon gas in the expired breath sample collected in the bag. The hydrocarbon gas may be separated from the remainder of the breath constituents by chromatography and the presence or amount determined by mass spectrometry. The hydrocarbon gas may comprise ethane or butane. Other methods of determining the presence or amount of hydrocarbon include flame ionisation detection, infra-red chromatography, fourier transformed infra-red spectroscopy, laser spectroscopy, nuclear magnetic spectroscopy, different thermal analysis and differential scanning calorimetry. Alternatively, the presence or amount of hydrocarbon gas in the breath sample is determined by an electronic device. Preferably, the breath sample is passed from the breath sampling bag through a device to remove water vapour, before analysis for hydrocarbon.

Claims

1. Breath sampling apparatus comprising a flexible bag having respective first and second sealable ports formed in the wall of the bag.

2. Breath sampling apparatus according to claim 1, in which the inlet port and outlet port are disposed on opposite sides of the bag.

3. Breath sampling apparatus according to claim 2, in which the inlet port and outlet port are mutually offset.

4. Breath sampling apparatus according to any preceding claim, in which the bag is formed from a fluoroplastic material.

5. Breath sampling apparatus according to any preceding claim, in which at least one port includes a one way valve.

6. A breath sampling bag according to claim 5, in which the valve comprises a fluoroplastic film diaphragm.

7. Breath sampling apparatus according to any preceding claim, in which at least one port includes clamp means for sealing the port and retaining a breath sample within the bag.

8. Breath sampling apparatus according to claim 7, in which the sealing means comprises a cap with a screw thread and includes a septum.

9. Breath sampling apparatus according to claim 8, in which the cap contains an aperture to permit the extraction of the breath sample by hypodermic syringe piercing the septum.

10. Breath sampling apparatus according to any preceding claim, in which the bag is enclosed in an outerbag such that only the orifices of the inlet and outlet ports are exposed.

11. A method for collection a breath sample from a mammalian, including human, subject, the method comprising causing the subject to breathe through a first port of a bag as claimed in any of claims 1 to 10 to inflate the bag to a super-atmospheric pressure and sealing the port to retain the breath sample therein for subsequent analysis.