WO1997013456A1

WO1997013456A1 - Fitness testing apparatus

Info

Publication number: WO1997013456A1
Application number: PCT/GB1996/002469
Authority: WO
Inventors: William Nevil Heaton Johnson; David Kerridge; Ian Williamson
Original assignee: Durand (Assignees) Limited
Priority date: 1995-10-10
Filing date: 1996-10-09
Publication date: 1997-04-17
Also published as: GB9520696D0; AU7222496A

Abstract

Apparatus for testing the physical condition of an individual includes a mouthpiece, face mask or the like into which the individual can breathe. The apparatus preferably includes means for determining the volume of the individual's lungs. The apparatus may also include means for analyzing chemically the individual's breath, with a view to detecting specific medical conditions.

Description

Title: "Fitness Testing Apparatus"

THIS INVENTION relates to apparatus for testing the physical condition of an individual by reference to his breathing and/or breath.

According to one aspect of the invention there is provided apparatus for testing the physical condition of an individual including a mouthpiece, face mask or the like into which the individual can breathe and means for analyzing physical characteristics of the individual's respiration system and/or chemical characteristics of the individual's breath.

GB2237117 discloses a method of and apparatus for measuring the volume of a body cavity and in which the body cavity is placed in communication with a closed space of known volume, the known volume is changed by a predetermined amount and the resulting pressure changes are measured to arrive at a measurement of the volume of the body cavity. Whilst GB2237117 is primarily concerned with the measurement of the volume of the nasal airway, the specification also proposes utilisation of the same technique to measure residual or other lung volumes.

In one embodiment of the present invention, apparatus based on that disclosed in GB2237117 is used in a self-contained apparatus, incorporating appropriate processing means and arranged to provide on a display, print-out or analogous device a readily interpreted indication of findings. The preferred apparatus has an associated mouthpiece into which the user breathes or blows according to instructions displayed and the apparatus may be arranged to measure, for example, lung capacity, residual lung capacity or the difference in lung volume with lungs fully inflated and with lungs fully deflated as a measure of the breathing efficiency. The apparatus preferably also incorporates means for performing a chemical analysis on the user's exhaled breath, with a view to providing a warning as to whether, for example, the user has an excessive blood alcohol content or may be suffering from any of several medical conditions.

It is envisaged that such a machine may be provided in public-access areas and may, for example, be coin- operated, rather in the same manner as the familiar public weighing machines. Such a machine might, for example, be installed in a gymnasium or in premises adjoining a sports ground for use by athletes. Such a machine may also include means for measuring certain external characteristics of an individual, for example, a form of "tape measure" for measuring chest circumference with the lungs inflated and deflated.

In a preferred embodiment, the machine may incorporate a magnetic stripe card reader, the arrangement being such that individuals would be provided with respective magnetic stripe cards for insertion in the machine and that, each time an individual uses the machine, the machine not only displays the relevant data established from that use of the machine but also records that data on the individual's card. Preferably, in this case, the machine would be arranged to maintain, on an individual's card, a record of the respective readings, with associated dates, over a succession of previous uses of the machine and the machine is able on selection of the appropriate operator's mode to display that record, or a summary thereof, for the benefit of the user so that the user can determine whether a regime of exercise or training has produced a desirable (or undesirable) effect. For example, the machine could provide an indication as to whether lung capacity or breathing efficiency had improved over a period. The machine might thus serve as a means for indicating to an athlete whether he was currently fully fit or whether a regime of training was effective.

Such machines might be installed in hotels, "keep- fit" establishments, or the like establishments or leisure or entertainment premises, where its use would have some informative or entertainment value. The machine, in such instances, might usefully be arranged to determine the alcohol content of the user's breath and might, for example, provide an indication as to whether or not the level of alcohol in the user's blood was in excess of that with which he might legally drive a motor vehicle.

The apparatus may incorporate a breath-activated trigger, operable when flow rate approaches (or significantly departs from) zero.

The apparatus may have a branch connection extending to a container of predetermined volume, which container can be disconnected and replaced by a container of different predetermined volume, whereby the volume of the closed space of known volume in the apparatus can be changed.

A portable version of the machine might be provided for individuals, such as athletes or persons suffering from relevant medical conditions or for use in large-scale screening programmes, for example for screening pupils in whole schools or the inhabitants of a whole village or applications of that sort.

As indicated above, apparatus embodying the invention may be used as a diagnostic aid, particularly for screening purposes. For example, apparatus in accordance with the invention can provide a non-invasive and socially acceptable way of providing a quick and convenient health check, based on physical and chemical parameters of breathing. This apparatus may thus:

(a) Measure residual lung volumes and monitor these over time, to assess fitness, response to stopping smoking, losing weight, etc.

(b) Use this volume to measure disease of the lungs, e.g. asthma.

The apparatus may also be arranged to make other respiratory measurements, such as peak flow FEV, spiro etry FVC. Thus, for example, the apparatus may incorporate a peak flow meter to measure the maximum volume of air per unit time inhaled or exhaled.

The apparatus may, at the same time analyze the user's breath to detect, for example, carbon monoxide (smokers) , or C₂H₃OH or the presence of Helicobacter pylerii (risk of ulcers or ulcer disease) .

The chemical analysis carried out by the machine may include detection and measurement of free radicals or their products. To provide an assessment of risks of cancer or hardening of the arteries and the machine might, on making a detection of such a risk, provide the user with an indication of appropriate counter-measures to take such as taking anti-oxidants e.g. vitamin C.

The chemical analysis undertaken (which may use non-chemical techniques such as gas chromatography or i.v. spectroscopy) may also be adapted to detect by products of certain micro-organisms or infections embodying such.

The apparatus in accordance with the invention may be of particular benefit as a means for diagnosing, or assisting in the diagnosis of lung diseases and other diseases such as tumours or other diseases of the nasal cavity, in third world countries where expensive equipment such as radiography equipment, which would normally be used in such diagnosis in developed countries might not be available or readily available. The apparatus in accordance with the invention may, by the same token, allow the dosage of X-rays to which patients or persons being screened are subjected in the first instance.

The apparatus may be solar-powered or even be operated or powered by clockwork, in embodiments specifically intended for third world countries.

As noted above, the apparatus can be readily configured as a portable apparatus requiring no great skill on the part of the operator. The apparatus may provide a recorded read-out, for example a print-out on paper or on a magnetic record medium, which can be sent to a central location for interpretation and diagnosis by a trained physician or technician or may be arranged to render the data collected by it in electronic form for transmission to a remotely located physician or technician for interpretation and diagnosis. The apparatus may utilise computer-aided measurement techniques, for example using appropriate computer software to minimise measurement variation due to oscillations in base line pressure.

In the preferred method and apparatus of the present invention, an air-displacing device such as a resiliently compressible hollow vessel, a bellows, a piston and cylinder unit or the like is so arranged, when triggered, to change its volume rapidly, and to a predetermined extent or increment in a predetermined and accurately repeatable manner. In use of the apparatus, the interior of such air-displacing device is placed in communication with the subject's lungs and airways via an appropriate mouthpiece which the subject sealingly engages with his or her mouth, after inhaling fully, and the air- displacing device is caused to undergo its predetermined volume change, whereby the volume of the system comprising the interior of the pumping device, any tube or the like extending from the pumping device to said mouthpiece, and the subject's lungs and airways is changed by the amount of said predetermined volume change or increment. The pressure prevailing in this system, for example in the vicinity of the mouthpiece, is monitored during such volume change and the total volume of the system is assessed from a correlation between the volume change or increment and the corresponding pressure change or increment. Since the volume, prior to the predetermined pressure change, of the part of said system provided by the apparatus is predetermined, the apparatus can be calibrated in terms of lung volume against measured pressure change. It will be understood that the triggered volume change may be positive or negative, that is to say the apparatus, when triggered, may reduce its volume, producing a positive pressure pulse, or may increase its volume, producing a negative pressure pulse. The applicants have realised that when the apparatus described utilises a relatively small and rapid volume change, the apparatus effectively only measures the volume of the "upper airways", and even here the distance into the lungs over which the volume measured is strongly dependant on the actual size of the airways. This is because the pressure pulse generated by the bellows movement or the equivalent can penetrate further down a wide passage within the time of the measurement (i.e. the time taken to generate the maximum pressure change) than down a narrow passage. A variant apparatus may be arranged to measure the equilibrium pressure before and after the volume change to arrive at an assessment of the total lung volume.

In a variant of the apparatus it is possible to determine the flexibility of the upper airways of a person, by measuring the apparent volume by the aforementioned technique utilising small and rapid volume changes, for each of a series of different volume changes, (e.g. for different bellows sizes) in each case with the subject breathing in fully. An assessment of a number of subjects using this technique was carried out, an "apparent volume" in each case being calculated, from well established physical laws, the basis that the part of the system provided by the patient was of fixed volume and that the peak pressure change, resulting from triggering of the bellows or the like was the equilibrium change. The magnitude of the volume change in the bellows or the like was plotted, in a graph, against the calculated apparent volume, for each subject. It was found that the graph for each subject had two well defined parts, namely a first straight line region of steadily increasing "apparent volume", followed by a region in which the apparent volume stayed at a steady "plateau" value. The first, increasing straight line regions were extrapolated back to zero bellows volume change and the result was taken as the true volume. It was assumed that all the difference between "apparent" and true volume was due to tissue movement, the tissues moving inwards in response to the lowered pressure and thus partially neutralising the full pressure drop, (in cases where the bellows or the like increased in volume on triggering) (or of course, the opposite incremental decrease in bellows volume) . The calculated tissue movement volume was plotted against the increasing pressure changes imposed by the bellows for all the "apparent" volumes (both "increasing" and "plateau" values) , and there was found in every case a similar line, steadily increasing with pressure. This line, which approximates to a straight line, has different gradients with different subjects and is a measure of the flexibility of the "upper airway" of the subject. It has been found that in general women have more flexible airways than men, just as women have significantly smaller "true" volumes than men. It is postulated that the "flexibility" is related to the "lung compliance" (which at present is normally measured by a difficult and unpleasant method) , and that it is related to the health, and perhaps the age, of the subject. In particular it is believed that asthma and similar diseases result in lower flexibility, while sleep apnoea and similar conditions may lead to higher flexibility.

As well as volumes, these measurements give an estimation of the tissue movement, called here Pressure

Compensating Volume Change or PCVC. The calculation is as follows:

PιVχ = P₂V₂ assuming equilibrium pressure to be reached throughout the volume and no change of temperature. Actually in the short times involved, 1-2 sec. the change of volume is largely adiabatic rather than isothermal, but since the calibration curves on glass vessels containing different volumes are obtained under similar conditions, the small error involved may be ignored and is smaller than the variation of measurements.

P_x in the above equation is the initial pressure, before triggering the bellows, and V-_. is the "true" volume of the cavity. P₂, the pressure at the peak of the pressure pulse following bellows triggering corresponds to P₂ = P, - Δ P (where Δ P is read from the instrument), (i.e. the bellows increase the external volume by Δ V) . V₂, derived from the above equation) is the volume of the stressed (lung) cavity, V₃, plus the external volume change (the unchanged external volume, "deadspace" was made as small as possible in the design of the instrument) .

Thus V₃ = V₂ - Δ V and PCVC = V₃ - V-_

PCVC is obviously related to "compliance" but is measured very differently. (Note. For increases rather than decreases in pressure the signs in the above equations must be switched) .

The applicants believe that the quantity PCVC calculated as set out above may prove a useful indicator in the diagnosis of such conditions as asthma and sleep apnoea.

It will be appreciated that the apparatus is not confined in its usefulness to the monitoring or assessment of the lungs but may, appropriately adapted, be used for monitoring and assessment of other cavities.

Claims

1. Apparatus for testing the physical condition of an individual including a mouthpiece, face mask or the like into which the individual can breathe and means for analyzing physical characteristics of the individual's respiration system and/or chemical characteristics of the individual's breath.

2. Apparatus for use in testing physical fitness including means for determining the volume of a body cavity and for providing an output significant of such measurement or of a trend in such measurement over a period of time.

3. Apparatus for testing the physical condition of an individual, substantially as hereinbefore described.

4. Any novel feature or combination of features described herein.