DEVICE WITH FLOW RATE INDICATOR

Abstract

The present invention provides a device for alternatively indicating at least a first fluid flow rate and a second fluid flow rate. The device, which may be a spirometer (e.g. a peak flow meter) comprises an aperture, a mouthpiece and a body defining a fluid flow path extending between the aperture and the mouthpiece. The body comprises a fluid flow rate indicator operable to alternatively generate at least a first sound signal and a second sound signal indicative of the first or second fluid flow rate in a first direction. The fluid flow rate indicator comprises a corrugated portion having a plurality of corrugations extending into the fluid flow path.

Claims

1. A device for alternatively indicating at least a first fluid flow rate and a second fluid flow rate, the device comprising: an aperture; a mouthpiece; and a body defining a fluid flow path extending between the aperture and the mouthpiece, the body comprising a fluid flow rate indicator operable to alternatively generate at least a first sound signal and a second sound signal to indicate when the fluid flow rate in a first direction along the fluid flow path is at the first or second fluid flow rate, wherein the fluid flow rate indicator comprises a corrugated portion having a plurality of corrugations extending into the fluid flow path.

2. A device according to claim 1 wherein the body is at least partly formed of plastics material.

3. A device according to claim 1 wherein the corrugated portion is integrally formed with the body.

4. A device according to claim 1 wherein the body comprises a tubular portion having an axially oriented recess and the corrugated portion is provided within the axially oriented recess.

5. A device according to claim 1 wherein the corrugated portion surrounds the fluid flow path.

6. A device according to claim 1 wherein the corrugated portion has an axial length of between 50 and 300 mm.

7. A device according to claim 1 wherein the fluid flow path is a tubular fluid flow path having a diameter of equal to or greater than 5 mm.

8. (canceled)

9. A device according to claim 1 wherein the device is a patient inhalation/exhalation device comprising: at least one aperture for inlet or outlet of air into/from the device; a mouthpiece for communication with the mouth of the patient; a body defining an air flow path extending between the aperture and the mouthpiece along which air is drawn to the mouthpiece by inhalation by the patient or air is forced towards the aperture by exhalation by the patient, the body comprising an air flow rate indicator operable to alternatively generate at least a first and a second sound signal indicative of the air flow rate along the air flow path in a first direction, wherein the air flow rate indicator comprises a corrugated portion having a plurality of corrugations extending into the fluid flow path.

10. (canceled)

11. A device for indicating a fluid flow rate, the device comprising: an aperture; a mouthpiece; and a body defining a tubular fluid flow path extending between the aperture and the mouthpiece, the body comprising a fluid flow rate indicator operable to generate a sound signal indicative of the fluid flow rate along the fluid flow path, wherein the fluid flow rate indicator comprises a corrugated portion having at least one corrugation extending into the fluid flow path, and wherein the tubular fluid flow path has a diameter greater than 8 mm.

12. A device according to claim 11 wherein the body is at least partly formed of plastics material.

13. A device according to claim 11 wherein the corrugated portion is integrally formed with the body.

14. A device according to claim 11 wherein the body comprises a tubular portion having an axially oriented recess and the corrugated portion is provided within the axially oriented recess.

15. A device according to claim 11 wherein the corrugated portion surrounds the fluid flow path.

16. A device according to claim 11 wherein the corrugated portion has an axial length of between 50 and 300 mm.

17. A device according to claim 11 wherein the corrugated portion comprises a plurality of corrugations and the flow rate indicator is operable to alternatively generate at least a first and a second sound signal indicative of the air flow rate along the air flow path in a first direction.

18. A device according to claim 11 wherein the device is a patient inhalation/exhalation device comprising: at least one aperture for inlet or outlet of air into/from the device; a mouthpiece for communication with the mouth of the patient; a body defining a tubular air flow path extending between the aperture and the mouthpiece along which air is drawn to the mouthpiece by inhalation by the patient or air is forced towards the aperture by exhalation by the patient, the body comprising an air flow rate indicator operable to generate a sound signal indicative of the air flow rate along the air flow path, wherein the air flow rate indicator comprises a corrugated portion having at least one corrugation extending into the fluid flow path, and wherein the tubular fluid flow path has a diameter greater than 8 mm.

19. (canceled)

20. A system comprising: a device according to claim 1; and a sound receiver for detecting a sound signal.

21. A method of monitoring peak expiratory or inhalatory flow in a patient, the method comprising: providing a system according to claim 20, exhaling or inhaling through the mouthpiece of the device; detecting the sound signal generated.

22. A method according to claim 21 further comprising comparing the sound signal generated with a reference frequency and providing an alert if the generated sound signal has a lower frequency than the reference frequency.

23. Use of a device according to claim 1 for measuring lung volume or peak inhalatory/exhalatory flow in a patient.

24-27. (canceled)

Description

BRIEF DESCRIPTION OF FIGURES

[0128] FIG. 1 shows the flow rates at the resonant nodes in a 7 mm diameter tube; and

[0129] FIG. 2 shows the frequency response measurement with the top trace representing the sound frequencies and the bottom trace being background noise.

EXPERIMENTAL DETAILS

[0130] A corrugated tube having an internal diameter of 7 mm and a corrugated portion comprising 25 corrugations and an axial length of 99 mm was formed of polypropylene. Various flow rates through the corrugated tube were applied and the frequency of the sound signals generated were detected using a frequency monitor.

[0131] The results are shown in Table 1 below and in FIGS. 1 and 2:

TABLE-US-00001 TABLE 1 Resonant node Frequency/Hz Flow rate L/min 1 1.5 12 2 3.0 25 3 4.4 39 4 6.1 50 5 7.6 60 6 9.1 74 7 10.4 96 8 11.8 111 9 13.3 127

[0132] It can be seen that the device provides a plurality of resonant nodes with increasing flow rate through the device generating an increasing frequency sound signal.

[0133] Adult human respiratory flow typically ranges from 50 to 700 L/min and therefore, whilst the 7 mm diameter device may suitable for measurement of child respiratory flow, larger diameter devices are envisaged for measurement of adult respiratory flow.

[0134] Using the data generated using the 7 mm device, the predicted flow rates at various nodes in larger diameter devices were calculated for devices having dimensions shown in Table 2 below:

TABLE-US-00002 TABLE 2 Internal Axial length of corrugated Surface area of corrugated diameter/mm portion/mm portion/m.sup.2 8 100 5.0272 10.sup.5 9 100 6.3626 10.sup.5 12.5 100 1.23 10.sup.4 13.085 100 1.35 10.sup.4

[0135] The calculations are shown below in Tables 3 (8 mm diameter), 4 (9 mm diameter), 5 (12.5 mm diameter) and 6 (13.085 mm).

TABLE-US-00003 TABLE 3 8 mm diameter tube Airspeed across corrugate to create sound based on 7 mm Predicted Resonant diameter test flow rate Resonant node results m/sec Volume m.sup.3/s L/min frequency Hz 1 6.2 3.117 10.sup.4 19 1.5 2 12.4 6.234 10.sup.4 37 2.8 3 18.6 9.351 10.sup.4 56 4.2 4 24.8 1.247 10.sup.3 75 5.6 5 31.0 1.558 10.sup.3 94 7.0 6 37.2 1.870 10.sup.3 112 8.3 7 43.4 2.182 10.sup.3 131 9.7 8 49.6 2.493 10.sup.3 150 11.1 9 55.8 2.805 10.sup.3 168 12.5 10 62.0 3.117 10.sup.3 187 13.9 11 68.2 3.429 10.sup.3 206 15.3 12 74.4 3.740 10.sup.3 224 16.7 13 80.6 4.052 10.sup.3 243 18.0

TABLE-US-00004 TABLE 4 9 mm diameter tube Airspeed across corrugate to create sound based on 7 mm Resonant diameter test Predicted flow node results m/sec Volume m.sup.3/s rate L/min 1 6.2 3.945 10.sup.4 24 2 12.4 7.890 10.sup.4 47 3 18.6 1.183 10.sup.3 71 4 24.8 1.578 10.sup.3 95 5 31.0 1.972 10.sup.3 118 6 37.2 2.367 10.sup.3 142 7 43.4 2.761 10.sup.3 166 8 49.6 3.156 10.sup.3 189 9 55.8 3.550 10.sup.3 213 10 62.0 3.945 10.sup.3 237 11 68.2 4.339 10.sup.3 260 12 74.4 4.734 10.sup.3 284 13 80.6 5.128 10.sup.3 308

TABLE-US-00005 TABLE 5 12.5 mm diameter tube Airspeed across corrugate to create sound based on 7 mm Resonant diameter test Predicted flow node results m/sec Volume m.sup.3/s rate L/min 1 6.2 7.610 10.sup.4 46 2 12.4 1.552 10.sup.3 91 3 18.6 2.283 10.sup.3 137 4 24.8 3.044 10.sup.3 183 5 31.0 3.805 10.sup.3 228 6 37.2 4.566 10.sup.3 274 7 43.4 5.327 10.sup.3 320 8 49.6 6.088 10.sup.3 365 9 55.8 6.849 10.sup.3 411 10 62.0 7.610 10.sup.3 457 11 68.2 8.370 10.sup.3 502 12 74.4 9.131 10.sup.3 548 13 80.6 9.892 10.sup.3 594

TABLE-US-00006 TABLE 6 13.085 mm diameter tube Airspeed across corrugate to create sound based on 7 mm Resonant diameter test Predicted flow node results m/sec Volume m.sup.3/s rate L/min 1 6.2 8.338 10.sup.4 50 2 12.4 1.668 10.sup.3 100 3 18.6 2.502 10.sup.3 150 4 24.8 3.335 10.sup.3 200 5 31.0 4.169 10.sup.3 250 6 37.2 5.003 10.sup.3 300 7 43.4 5.837 10.sup.3 350 8 49.6 6.671 10.sup.3 400 9 55.8 7.505 10.sup.3 450 10 62.0 8.338 10.sup.3 500 11 68.2 9.172 10.sup.3 550 12 74.4 1.001 10.sup.2 600 13 80.6 1.084 10.sup.2 650

[0136] It can be seen that as the diameter increases, a device sounding at a wide range of flow rates covering the normal adult respiratory range can be obtained.

[0137] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the invention as defined in the claims.