RESPIRATORY TEST APPARATUS

Abstract: An apparatus for testing the respiratory ability of a subject, comprises a unit (10) through which the subject can inspire, the unit (10) including a pressure sensing device connected to a data processing unit (20). The data processing unit is arranged to compare the time-varying pressure, or a parameter thereof, with a prestored target.

Description: Respiratory Test Apparatus The present invention relates to an apparatus for testing the respiratory ability of subjects. There are a number of situations where it is necessary or desirable to test the respiratory ability of a subject, and indeed to improve that ability. For example, it is often necessary to test and improve the respiratory ability of a patient prior to a surgical operation and/or during the rehabilitation of such a patient. As another example, it is often desirable to improve the respiratory ability of athletes or other sportsmen. I have now devised an apparatus for testing and improving the respiratory ability of subjects. In accordance with the present invention, there is provided an apparatus which comprises a unit through which a subject can inspire, this unit including a pressure sensing device, and a data processing unit to which the pressure sensing device is connected, and arranged to compare the time- varying pressure, or a parameter thereof, with a prestored target. Preferably the apparatus is arranged to store a target for each individual subject. Preferably this target comprises a time-varying pressure profile taken from the subject during a pre-test trial inspiration, but then reduced by a predetermined fraction in pressure amplitude. Additionally or instead, the target may comprise an integral of the trial inspiration pressure profile, reduced by a predetermined fraction. Preferably the target is selected as the best result from a number, say three, trial inspirations. The apparatus is preferably arranged for the subject to carry our successive test inspirations, the measured results of each of these being compared against the target, with the time intervals between successive tests progressively reducing. Preferably, the apparatus prompts the subject to commence each successive inspiration (e.g. by means of a display and/or audible signal) . Preferably a set of successive tests (e.g. six tests) are carried out with the same interval (e.g. 60 seconds) between them, then a second set of tests are carried out with a smaller internal (e.g. 45 seconds) between them, and so on. At each test, the apparatus is arranged to determine if the subject has "passed" that test, in which case the apparatus prompts the subject to carry out the next test, and so on. At some stage, the subject will fail an individual test, and this completes the exercise: the point in the overall program at which the failure occurs is recorded. During each test, preferably the prestored target profile is continuously displayed on a visual display, and the measured profile is built up on the display as the subject breathes in: the subject is thus able to compare his performance with the target, and can adjust his effort in an attempt to exceed the target. This "feedback" to the subject is particularly valuable. Preferably the apparatus requires the measured time- varying profile to exceed the target profile by a predetermined margin, in terms of the integral of that curve (e.g. the area under the curve, which is therefore a measure of the work done) . Preferably also the apparatus requires the duration of the measured time-varying profile to exceed a predetermined fraction (e.g. 90%) of the duration of the target profile. Preferably the apparatus is arranged to display one or more of the following: the peak pressure of the target profile, the average peak pressure from the successive test, the integral of the target profile, the accumulating integral of each test profile, and the accumulated integral of the successive tests (corresponding to the total work done by the subject during the test program) . Preferably at each session of use, the subject creates a fresh target, in the manner described above, against which he compares his performance during the tests which he carried out in that session. The peak pressure, measured typically over the first second of each inspiration, gives an indication of measured respiratory muscle strength. The integral of each test profile is a measure of the work done. The accumulated integral, over all tests completed successfully in the session, is a measure of respiratory endurance. These results therefore provide an effective assessment of the subject's respiratory muscles. Through use of the above-described apparatus in successive sessions, I have found that the subject's respiratory ability improves significantly (particularly muscle strength and endurance) . An embodiment of the present invention will now be described by way of example only and with reference to the accompany drawings, in which: FIGURE 1 is a schematic diagram of an apparatus in accordance with the invention for testing the respiratory ability of a patient; FIGURE 2 is a typical time-varying measure of pressure sensed in a trial use of the apparatus of Figure 1; FIGURE 3 is a typical display of a target profile and a measured profile; and FIGURE 4 is a typical results grid following a test session. Referring to Figure 1 of the drawings, there is shown an apparatus for carrying out respiratory tests, the apparatus comprising a hand-held unit 10 having a mouthpiece 11, and through which the patient or subject inspires, and a personal computer 20 to which a manometer of the unit 10 is connected. The computer 20 includes a visual display unit (VDU) 22 and keyboard 24 is connected to a printer 26. The computer is loaded with a respiratory test program in accordance with the invention, arranged for the apparatus to function as follows. The computer creates and stores a record for each subject: thus for each subject, data is entered on the computer keyboard 24 to identify the subject, and various other items of data concerning the subject are also entered. In an initial phase, a target pressure profile for the subject is created and stored: thus, the VDU prompts the subject to break in through the hand-held unit 10; the negative pressure created within the air passage of the unit 10 is monitored by the manometer, and a corresponding time-varying profile P as shown in Figure 2 is displayed on the VDU and also stored. This procedure is carried out three times, with an interval of time (e.g. of two minutes) between each inspiration. The computer then selects the "best " pressure profile of the three (as a combination of the largest peak and longest duration) : the computer then calculates a target profile T which is predetermined fraction (e.g. 80%) in amplitude of the selected "best" pressure profile; this target profile is then displayed continuously on the VDU. After a rest, the subject is prompted by the computer to commence the testing phase. Thus, the subject breathes in again through the hand-held unit 10, and a trace of the measured pressure M is built up on the VDU, as shown in Figure 3: thus, as the subject breathes in, he can visually compare his performance against the target profile being displayed. Also the computer continuously calculates an integral of the trace which is being created (i.e. the area under the curve, therefore a measure of the work done) , and displays this accumulating figure on the VDU. The VDU also continuously displays the corresponding final integral of the target profile. If at the end of this test the computer finds that the integral of the subject's measured trace exceeds the integral of the target profile by a predetermined margin (e.g. by 10%), then the computer regards the subject as having "passed" the test. The computer then prompts the subject (via the VDU and/or by an audible signal) , to repeat the exercise, after an interval of 60 seconds. The test proceeds in this manner, until the subject has "passed " the test six times in succession (with 60 seconds between each test) . Then the test proceeds six more times, with a reduced interval (45 seconds) between successive tests, followed by six tests with 30 seconds intervals, six test with 15 second intervals, six tests with 10 seconds intervals, and finally six tests with 5 seconds intervals. However, at some stage during this test program, the subject will fail to exceed his target. Thus, Figure 4 shows the results for a subject who passed all six tests for each of the 60, 45, 30 and 15 seconds intervals tests (A to D) , then passed four of the tests at 10 seconds intervals but then failed the next test. It will be appreciated that the results for this subject can be categorised as "E4". The results table shown in Figure 3 is displayed on the VDU, together with the accumulated total of the intervals under the test curves (being a measure of the total work done) . This information can be printed out, and is also stored by the computer in the data record for that subject. At the next session of use by the same subject, the subject undergoes an initial phase as described above, and a new target profile is created in the same manner. The test then proceeds as deεcribed above. It will be appreciated that as a result of successive sessions of use of the apparatus, each subject improves his or her performance, firstly by progressing further through the full program of 36 tests, secondly by improving the accumulated "work done" figure, and also by improving the average peak pressure figure.

Claims: Claims 1) An apparatus for testing the respiratory ability of one or more subjects, the apparatus comprising a unit through which a subject can inspire, said unit including a pressure sensing device, and a data processing unit to which the pressure sensing device is connected, said data processing unit being arranged to compare the time-varying pressure, or a parameter thereof, with a prestored target. 2) An apparatus as claimed in claim 1, arranged to store a said target for each individual subject. 3) An apparatus as claimed in claim 2, in which each said target comprises a time-varying pressure profile taken from the subject during a pre-test trial inspiration reduced by a predetermined fraction in pressure amplitude. 4) An apparatus as claimed in claim 2, in which each said target comprises an integral of a trial inspiration pressure profile, reduced by a predetermined fraction. 5) An apparatus as claimed m any preceding claim, arranged for the subject to carry out successive test inspiration, the measured results of each of these being compared against the target, with the time intervals between successive tests being progressively reduced. 6) An apparatus as claimed m claim 5, arranged to prompt the subject to commence each successive inspiration. 7) An apparatus as claimed in claim 5 or 6, arranged to record the point in an overall program of tests at which the subject fails a test. 8) An apparatus as claimed in any preceding claim, arranged to display the prestored target and to build up a display of the measured profile as the subject breathes in. 9) An apparatus as claimed in any preceding claim, arranged to require the measured time-varying profile to exceed the target profile by a predetermined margin, in terms of the integral of the corresponding curve. 10) An apparatus as claimed in any preceding claim, arranged to require the duration of the measured time-varying profile to exceed a predetermined fraction of the duration of the target profile. 11) An apparatus as claimed in any preceding claim, arranged to display one or more of: the peak pressure of the target profile, the average peak pressure from the successive tests, the integral of the target profile, and the accumulated integral of the successive tests. 12) An apparatus for testing the respiratory ability of one or more subjects, the apparatus being substantially as herein described with reference to the accompanying drawings.

Inventors: CHATHAM KENNETH, CHATHAM, KENNETH
Applicants: CHATHAM KENNETH, MEDRUS TECH LTD, CHATHAM, KENNETH, MEDRUS TECHNOLOGY LIMITED
Application year: 1996
Main classification: A61B5
IPC codes: A61B5, A63B23