DETERMINATION OF AIR FLOW RATE THROUGH AN INHALER

Abstract

An accessory (40) for an inhaler (10) comprises a fastening structure (42) for fastening the accessory to the inhaler. The accessory has a pressure port (43). When the accessory is fastened to the inhaler, the pressure port is arranged upstream from a mixing zone (33) of the inhaler with respect to an air flow (F1) caused by inhalation by a patient through the inhaler. An electronic sensor (45) is in communication with the pressure port. The electronic sensor is sensitive to a pressure change at the pressure port caused by the air flow.

Claims

1.-15. (canceled)

16. An accessory for an inhaler, the inhaler comprising an inhaler housing having a housing wall, the inhaler having an air inlet for the entry of air into the inhaler and an air outlet for communication with the mouth of a patient, such that inhalation by a patient through the air outlet causes an air flow through the inhaler from the air inlet to the air outlet, the inhaler defining a mixing zone located between the air inlet and the air outlet for mixing the air flow with a drug, the accessory comprising: an accessory housing, the accessory housing defining an axial stop structure configured to abut to a proximal end face of the housing wall of the inhaler housing at the air inlet of the inhaler when the accessory is fastened to the inhaler, the accessory housing having a wall portion adjacent to the stop structure, configured to be essentially flush with the housing wall of the inhaler housing when the accessory is fastened to the inhaler, the wall portion and the housing wall of the inhaler housing delimiting a flow path of the air flow; a pressure port, the pressure port being formed by one or more openings in the wall portion of the accessory housing which is configured to be essentially flush with the housing wall of the inhaler housing, the pressure port being configured to be arranged upstream from the air inlet of the inhaler with respect to the air flow; and an electronic sensor for determining a flow rate of the air flow, the electronic sensor being received in the accessory housing, the electronic sensor being in communication with the pressure port, the electronic sensor being sensitive to a pressure change at the pressure port caused by the air flow.

17. The accessory of claim 16, wherein the pressure port is formed by a plurality of openings in the accessory housing, the openings being distributed circumferentially along a circumference of the air inlet of the inhaler when the accessory is fastened to the inhaler.

18. The accessory of claim 16, further comprising a fastening structure for fastening the accessory to the inhaler.

19. The accessory of claim 18, wherein the fastening structure comprises a ring configured to be arranged around the inhaler housing.

20. The accessory of claim 16, wherein the accessory is configured to modify the air flow adjacent to the pressure port in such a manner that a reverse air flow due to exhalation by the patient through the inhaler causes a pressure change at the pressure port with opposite sign as compared to the pressure change caused by the air flow due to inhalation.

21. An inhalation system comprising an inhaler and an accessory, the accessory being fastened to the inhaler, the inhaler comprising an inhaler housing having a housing wall, the inhaler having an air inlet for the entry of air into the inhaler and an air outlet for communication with the mouth of a patient, such that inhalation by a patient through the air outlet causes an air flow through the inhaler from the air inlet to the air outlet, the inhaler defining a mixing zone located between the air inlet and the air outlet for mixing the air flow with a drug, the accessory comprising: an accessory housing, the accessory housing having a wall portion adjacent to the air inlet of the inhaler, the wall portion being essentially flush with the housing wall of the inhaler housing, the wall portion and the housing wall of the inhaler housing delimiting a flow path of the air flow; a pressure port, the pressure port being formed by one or more openings in the wall portion of the accessory housing which is essentially flush with the housing wall of the inhaler housing, the pressure port being arranged upstream from the air inlet of the inhaler with respect to the air flow; and an electronic sensor for determining a flow rate of the air flow, the electronic sensor being received in the accessory housing, the electronic sensor being in communication with the pressure port, the electronic sensor being sensitive to a pressure change at the pressure port caused by the air flow.

22. The inhalation system of claim 21, wherein the accessory housing defines an axial stop structure, the axial stop structure abutting to a proximal end face of the housing wall of the inhaler housing at the air inlet of the inhaler, and wherein the wall portion of the accessory housing in which the pressure port is formed and which is essentially flush with the housing wall of the inhaler housing is arranged adjacent to the axial stop structure.

23. The inhalation system of claim 21, wherein the pressure port is formed by a plurality of openings in the accessory housing, the openings being distributed circumferentially along a circumference of the air inlet of the inhaler.

24. The inhalation system of claim 21, wherein the accessory comprises a fastening structure for fastening the accessory to the inhaler.

25. The inhalation system of claim 24, wherein the fastening structure comprises a ring that is arranged around the inhaler housing.

26. The inhalation system of claim 21, wherein the accessory is configured to modify the air flow adjacent to the pressure port in such a manner that a reverse air flow due to exhalation by the patient through the inhaler causes a pressure change at the pressure port with opposite sign as compared to the pressure change caused by the air flow due to inhalation.

27. The inhalation system of claim 21, wherein the inhaler comprises a drug reservoir received in the housing, the drug reservoir being configured to release an aerosolized drug into the mixing zone.

28. An accessory for an inhaler, the inhaler having an air inlet for the entry of air into the inhaler and an air outlet for communication with the mouth of a patient, such that inhalation by a patient through the air outlet causes an air flow through the inhaler from the air inlet to the air outlet, the inhaler defining a mixing zone between the air inlet and the air outlet for mixing the air flow with a drug, the accessory comprising: an accessory housing; a pressure port, the pressure port being arranged upstream from the air inlet of the inhaler with respect to the air flow when the accessory is fastened to the inhaler, the pressure port being formed by a plurality of openings in the accessory housing, the openings being distributed circumferentially along a circumference of the air inlet of the inhaler when the accessory is fastened to the inhaler; an electronic sensor for determining a flow rate of the air flow, the electronic sensor being received in the accessory housing, the electronic sensor being in communication with the pressure port, the electronic sensor being sensitive to a pressure change at the pressure port caused by the air flow.

29. The accessory of claim 28, further comprising a fastening structure for fastening the accessory to the inhaler.

30. The accessory of claim 29, wherein the fastening structure comprises a ring configured to be arranged around an inhaler housing of the inhaler.

31. The accessory of claim 28, wherein the accessory is configured to modify the air flow adjacent to the pressure port in such a manner that a reverse air flow due to exhalation by the patient through the inhaler causes a pressure change at the pressure port with opposite sign as compared to the pressure change caused by the air flow due to inhalation.

32. An inhalation system comprising an inhaler and an accessory, the accessory being fastened to the inhaler, the inhaler having an air inlet for the entry of air into the inhaler and an air outlet for communication with the mouth of a patient, such that inhalation by a patient through the air outlet causes an air flow through the inhaler from the air inlet to the air outlet, the inhaler defining a mixing zone between the air inlet and the air outlet for mixing the air flow with a drug, the accessory comprising: an accessory housing; a pressure port, the pressure port being arranged upstream from the air inlet of the inhaler with respect to the air flow, the pressure port being formed by a plurality of openings in the accessory housing, the openings being distributed circumferentially along a circumference of the air inlet of the inhaler; and an electronic sensor for determining a flow rate of the air flow, the electronic sensor being received in the accessory housing, the electronic sensor being in communication with the pressure port, the electronic sensor being sensitive to a pressure change at the pressure port caused by the air flow.

33. The inhalation system of claim 32, wherein the accessory comprises a fastening structure for fastening the accessory to the inhaler.

34. The inhalation system of claim 33, wherein the fastening structure comprises a ring configured to be arranged around the inhaler housing.

35. The inhalation system of claim 32, wherein the accessory is configured to modify the air flow adjacent to the pressure port in such a manner that a reverse air flow due to exhalation by the patient through the inhaler causes a pressure change at the pressure port with opposite sign as compared to the pressure change caused by the air flow due to inhalation.

36. The inhalation system of claim 32, wherein the inhaler comprises a drug reservoir received in the housing, the drug reservoir being configured to release an aerosolized drug into the mixing zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

[0037] FIG. 1 shows, in a highly schematic longitudinal section, an inhalation system comprising an inhaler and an accessory according to a first embodiment, together with a remote control device;

[0038] FIG. 2 shows, in a highly schematic longitudinal section, a portion of an inhalation system comprising an inhaler together with an accessory according to a second embodiment;

[0039] FIG. 3 shows, in a highly schematic perspective view, an accessory according to a third embodiment;

[0040] FIG. 4 shows, in a highly schematic longitudinal section, a portion of the accessory in FIG. 3; and

[0041] FIG. 5 shows, in a highly schematic longitudinal section, an inhalation system comprising an inhaler and an accessory according to a fourth embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] FIG. 1 illustrates, in a highly schematic manner, an inhalation system according to a first embodiment. The inhalation system comprises an inhaler 10 and an accessory 40. The accessory 40 is attached to the inhaler 10 by means of a fastening structure 42 so as to be removable from the inhaler 10.

[0043] In the present example, the inhaler 10 is a typical pMDI inhaler. It comprises a generally cylindrical drug reservoir or drug container 11 having at its lower end a metering valve for controlled release of single doses of a drug through a hollow valve stem 12. The metering valve is actuated by pressing the valve stem 12 into drug container 11.

[0044] The drug container 11 is received in an inhaler housing 20. The inhaler housing 20 is generally L-shaped. The upright leg of the L forms an upwardly open receiving portion for the drug container 10. The receiving portion has the shape of a hollow cylinder extending upwardly to an upper end 22. The receiving portion is defined by a circumferential housing wall 21. At the open upper end 22 of the receiving portion, the housing wall 21 forms an annular end face. The drug container 11 is held in the receiving portion by a plurality of spacer ribs 23 extending radially inwardly from the housing wall 21. In consequence, the outer circumferential wall of the drug container 11 is spaced from the housing wall 21 of the housing 20, and axially extending air channels are thus formed between the housing wall 21 and the drug container 11.

[0045] At the lower end of the receiving portion, the inhaler housing 20 includes a hollow socket 30. The valve stem 12 of the drug container 11 is seated in the socket 30. The socket 30 defines a duct 31 leading from the exit of the valve stem 12 to a nozzle orifice 32. The nozzle orifice 32 opens out into the interior of the inhaler housing 20 in a lateral direction that is transverse to the cylinder axis of the receiving portion, but not necessarily perpendicular to the cylinder axis.

[0046] The transverse leg of the L-shaped housing 20 extends in the same lateral direction as the nozzle orifice 32. At its far end, it forms a hollow mouthpiece 24 for insertion into the mouth of a patient. The mouthpiece 24 is laterally open at its end 25. It usually has a flattened cross-sectional shape adapted to the anatomy of a human patient's mouth. This cross-sectional shape is generally different from the cross-sectional shape of the receiving portion.

[0047] The open upper end 22 of the receiving portion of the inhaler housing 20 together with the circumferential wall of the drug container 11 forms an air inlet, allowing air to enter the inhaler. The open end 25 of the mouthpiece 24 forms an air outlet. A flow path exists through the inhaler housing 20 between the air inlet and the air outlet. The nozzle orifice 32 is disposed in this air flow path. Downstream from the nozzle orifice 32, the inhaler housing 20 defines a mixing zone 33 for mixing the air flow with the drug released from the drug container 11.

[0048] In use, a patient holds the inhaler 10 and applies his mouth to the mouthpiece 24. The patient then inhales through the mouthpiece 24, thereby creating an air flow F1 through the inhaler housing 20 from the air inlet to the air outlet. After the patient has started inhaling through the mouthpiece 14, the drug container 11 is pressed downwardly to release a dose of drug. Due to the pressure in the drug container 11, the drug is propelled through the duct 31 and the nozzle orifice 32 into the mixing zone 33, where it mixes with the air flow to form an aerosol flow F1, and is inhaled by the patient.

[0049] The accessory 40 comprises an accessory housing 41, which is held on the inhaler housing 20 by means of the fastening structure 42. In the present example, the fastening structure 42 forms a ring that is sled onto the open upper end of the receiving portion of the inhaler housing 20. At its upper end, the ring has an inwardly extending flange that rests on the upper end face of the housing wall 21 at the open upper end 22 of the receiving portion, thereby forming an axial stop structure together with the upper end 22 of the receiving portion. This ensures that the accessory housing 41 is fastened to the inhaler housing 20 in a defined axial position.

[0050] Inside the accessory housing 41, a carrier 49 in the form of a printed circuit board is disposed. The carrier 49 carries an electronic pressure sensor 45, electronic circuitry 47, and a battery 48. An opening in accessory housing 41 defines a pressure port 43. The electronic pressure sensor 45 communicates with the pressure port 43 pneumatically via a duct 44.

[0051] The pressure port 43 is arranged in an inwardly facing wall portion of the accessory housing 41 that is immediately adjacent to the open upper end 22 of the inhaler housing 20. The pressure port 43 is arranged such that the air flow F1, immediately before it enters the inhaler housing 20 at the air inlet, overflows the pressure port 43. The surface of the wall portion of the accessory housing 41 in which the pressure port 43 is arranged is flush with the inside surface of the housing wall 21 of the inhaler housing 20. These surfaces together delimit the air flow F1 at the air inlet. The accessory 40 of the first embodiment does not have any structure that projects into the air flow F1. Thereby it is ensured that the air flow F1 is disturbed as little as possible by the presence of the accessory 40.

[0052] In use, the air flow F1 caused by inhalation by the patient causes a negative pressure at the pressure port 43 due to the Bernoulli/Venturi effect caused by the acceleration of the air flow when it enters the inhaler. The magnitude of the negative pressure is directly related to the magnitude of the flow rate of the air flow F1. The negative pressure is registered by the electronic pressure sensor 45. The electronic circuitry 47 reads out the electronic pressure sensor 45 and determines a flow rate parameter from the sensor signals read out from the electronic pressure sensor 45. To this end, the electronic circuitry 47 may employ calibration data that relate measured pressure values to known flow rate values of air flow F1.

[0053] Based on the flow rate parameter, the electronic circuitry 47 generates an output signal. The output signal can be, e.g., a digital signal that directly represents the flow rate parameter. In other examples, the output signal can be a digital signal that indicates whether the flow rate parameter is within a predetermined range.

[0054] The electronic circuitry 47 can comprise structure for generating user feedback for the patient, based on the output signal. For instance, the electronic circuitry can include a tone generator to generate an audible signal that indicates to the patient whether the flow rate is within a desired range. As another example, the electronic circuitry can include a vibrator to generate a tactile signal in the form of a vibration pattern that indicates to the patient whether the flow rate is within a desired range. As yet another example, the electronic circuitry can include a display, e.g., an LCD display or one or more LEDs, to generate a visual signal that indicates to the patient whether the flow rate is within a desired range.

[0055] The electronic circuitry can comprise a wireless communication module for transmitting the output signal via a wireless link to a remote device 60. The remote device 60 can be, e.g., a smartphone, a tablet computer, or a notebook computer. In other embodiments, the remote device can be a dedicated device specifically configured for interaction with the accessory 40. In yet other embodiments, the remote device can be a remote server. The wireless communication module can be, e.g., a Bluetooth module for establishing a point-to-point link between the accessory 40 and the remote device 60, or it can be a WiFi module for connecting the accessory 40 to a wireless LAN that includes the remote device 60.

[0056] In the present example, the remote device 60 executes a computer program (an app) that causes the remote device 60 to receive the output signal from the accessory 40 via the wireless link and to generate user feedback using an output device of the remote device. For instance, the app can cause the remote device to display user feedback and/or instructions for correct handling of the inhaler on a display screen of the remote device. In another example, the app can cause the remote device to output an audible signal, e.g., a voice message, via a loudspeaker of the remote device, instructing the user to handle the inhaler in a specific manner. In yet another example, the app can cause the remote device to provide tactile feedback, e.g., by vibrating, depending on the manner in which the patient handles the inhaler. This can all be done in real time.

[0057] In addition, the app can cause the remote device to store the received output signals for later readout, and/or to transmit the received output signals or quantities derived from the received output signals, such as statistical data, to a remote server for analysis. This enables the monitoring of the usage of the inhaler by medical personnel. In other embodiments, the output signals are directly transmitted from the attachment to a remote server for analysis.

[0058] The electronic pressure sensor 45 can, in particular, be a differential pressure sensor that is based on a flow measurement principle. A differential pressure sensor of this type has two sensor ports: a sensor inlet and a sensor outlet. A pressure difference between the sensor inlet and the sensor outlet causes a sensor gas flow through a sensor flow channel defined inside the differential pressure sensor. A flow-sensitive structure is arranged adjacent to the sensor flow channel for measuring a flow rate of the sensor gas flow through the sensor flow channel. Thus, a differential pressure sensor of this type essentially acts as a flow sensor that is configured to determine the pressure difference based on the determination of a flow rate through a flow channel between the sensor ports.

[0059] A suitable flow sensor that can be used to determine differential pressure is disclosed, e.g., in US 2016/0161314 A1. The inlet and outlet tubes of the flow sensor disclosed in this document can act as the sensor ports referred to in the present disclosure.

[0060] If a differential pressure sensor or flow sensor is used, one of the sensor ports of the sensor is pneumatically connected to the pressure port 43 in a fluid-tight manner. The other sensor port advantageously is pneumatically connected to the environment of the accessory 40 in a region that is not influenced by the air flow F1. To this end, the accessory housing 41 can comprise a reference port 46 in the form of an opening, the opening being arranged in a region of the accessory housing 41 that faces away from the inhaler. The opening causes the pressure inside the accessory housing 41 to be equal to the pressure of the environment of the accessory 40 in a region that is unaffected by the air flow F1. The sensor port that is not connected to the pressure port 43 can therefore be simply open towards the inside of accessory housing 41, without a fluid-tight connection being required between this sensor port and the reference port 46.

[0061] It should be noted that the accessory 40 of the first embodiment cannot distinguish between a flow F1 caused by inhalation through the inhaler and a reverse flow in the opposite direction, as it would be caused by exhalation through the inhaler.

[0062] FIG. 2 schematically illustrates a second embodiment that avoids this disadvantage. The second embodiment is largely identical to the first embodiment, and only a portion around the upper open end of the inhaler housing 20 is illustrated. Elements that have the same functionality as in the first embodiment are designated with the same reference signs as in FIG. 1.

[0063] A key difference of the second embodiment as compared to the first embodiment lies in the design of the accessory housing 41 in the immediate vicinity of the pressure port 43. Whereas in the first embodiment the pressure port 43 is arranged in a smooth wall portion of the accessory housing 41 that modifies the air flow F1 only minimally, in the second embodiment the accessory housing 41 comprises a flow-modifying structure 51 that deliberately projects into the flow path of the air flow F1 to modify the air flow. In the present example, the flow-modifying structure 51 acts as a local barrier immediately downstream from the pressure port 43 for a reverse air flow F2, thereby creating a positive dynamic pressure (velocity pressure) at the pressure port 43 for the reverse air flow F2. In this manner, the air flow F1 due to inhalation and the reverse air flow F2 due to exhalation can be readily distinguished by the sign of the pressure change at the pressure port 43.

[0064] Also illustrated in FIG. 2 is the fluid-tight connection between the electronic sensor 45 and the duct 44 that leads to the pressure port 43, symbolized by a gasket 52.

[0065] FIGS. 3 and 4 illustrate a third embodiment of an accessory 40. Again, elements that have the same functionality as in the first embodiment are designated with the same reference signs as in FIG. 1.

[0066] As in the first and second embodiments, the fastening structure 42 is designed as a ring for attachment to the inlet end of the inhaler, more specifically, to the upper end 22 of the receiving portion of the inhaler housing. As in the first and second embodiments, the accessory housing 41 forms an axial stop with the upper end face of the inhaler housing to define the correct axial position of the accessory 40 on the inhaler housing. By the design of the fastening structure, the accessory 40 can only be attached to the inlet end of the inhaler, whereas it is impossible to accidentally fasten the accessory 40 to the outlet end, i.e., to the mouthpiece of the inhaler, due to its different shape.

[0067] The housing 41 of the accessory 40 according to the third embodiment has a plurality of openings, in particular, four openings, arranged along the circumference of the open end 22 of the receiving portion of the inhaler housing. As apparent from FIG. 4, all openings communicate pneumatically with a common duct 44, which in turn communicates pneumatically with the electronic sensor 45. In this manner, all openings together form the pressure port 43 of the third embodiment. Each opening has a sufficiently small individual cross-sectional area that dust or drops of liquid cannot easily enter the duct 44. At the same time, the openings together have a total cross-sectional area that gas exchange is possible between the inside and the outside of the duct 44 at a sufficiently high rate for ensuring proper operation of the electronic sensor 45.

[0068] As apparent from the schematic representation in FIG. 4, the electronic sensor 45 can be a differential pressure sensor or flow sensor, having two sensor ports 53, 54, the first sensor port being connected in a fluid-tight manner to the duct 44, while the second sensor port is in pneumatic communication with the environment via the reference port 46.

[0069] An accessory according to the third embodiment has been tested in conjunction with a commercially available pMDI. Measurements showed that an inhalation air flow of 601/min caused a pressure difference of about 20 Pa between the two sensor ports. A differential pressure of this magnitude can be readily detected by commercially available differential pressure sensors.

[0070] FIG. 5 illustrates a fourth embodiment of an accessory 40, together with a correspondingly configured inhaler 10. Again, elements that have the same functionality as in the first embodiment are designated with the same reference signs as in FIG. 1.

[0071] As in the first to third embodiments, the accessory 40 is attached to the outside of the inhaler housing 20 and can be easily removed from the inhaler. In the fourth embodiment, the circumferential wall 21 of the inhaler housing 20 is provided with a through-hole upstream from nozzle orifice 32, and the pressure port 43 is formed by the open end of a short pipe that extends into this through-hole to measure the flow rate of the air flow F1 without significantly disturbing the air flow. By arranging the pressure port 43 upstream of the nozzle orifice 32 with respect to the inhalation air flow F1, it is ensured that the electronic sensor 45 cannot be contaminated with the drug that is released through the nozzle orifice as long as the inhaler is used properly.

[0072] In a modification of the fourth embodiment (not illustrated in the drawings), the accessory 40 or the inhaler housing 20 is provided with a flow-modifying structure adjacent to the pressure port 43 inside the inhaler housing 20 in order to be able to distinguish between inhalation and exhalation, as discussed above in conjunction with the second embodiment.

[0073] While the accessory of the first to third embodiment can be fitted to any existing inhaler, the inhaler of the fourth embodiment may require adaptation to the intended use by providing the inhaler housing 20 with the through-hole for the pressure port 43.

[0074] While exemplary embodiments of the invention have been illustrated with reference to the drawings, the invention is by no means limited to these embodiments, and many modifications are possible without departing from the scope of the present invention. For instance, the electronic sensor can be of a different type than described above. In particular, the electronic sensor can be any other type of pressure sensor, for instance an absolute pressure sensor or a relative pressure sensor that is based on a different measurement principle than a flow measurement. In particular, the pressure sensor can be a barometric pressure sensor. The accessory can be fastened to the inhaler in a different manner than described. For instance, the accessory can be clamped to the inhaler body by two prong-like arms. The accessory of the present invention can also be used with other types of inhalers than the pMDI shown.