Peak flow monitor

Abstract

The invention relates to a peak expiratory flow monitoring device. The peak expiratory flow monitoring device has a hollow body provided with a passage allowing medium flow. The hollow body contains a signal generator which is suitable for generating a signal when the flow rate of the medium passing through it reaches a predetermined value. The hollow body has first and second housing parts (12, 14) which can be connected to each other by rotation and which define a resonant cavity with an outlet opening. The housing parts (12, 14) have a locking mechanism by means of which they can be gradually fixed to each other, and thus the closing element (20) can be adjusted by changing the size of the outlet opening in predetermined steps. The first housing part (12) has an inlet opening formed by a nozzle (18). The medium conducting passage is formed at least between the nozzle (18) and the outlet opening.The device has a closing element (20) which is designed to narrow the outlet opening to a greater or lesser extent depending on the relative rotation positions of the casing parts (12, 14). The essence of the device according to the invention is that the closing element (20) consists of ribs (28) formed on one casing part (12) and a key arranged movably on the other casing part (14). The key is arranged axially movable in the grooves between the ribs (28) for the fastening of the casing parts (12, 14) to each other. à.

Description

The description is 10 pages long (including 3 pages of figures) HU 221 250 Bl can be adjusted by changing the pressure. The first housing part (12) has an inlet opening formed by a nozzle (18). The medium-conducting passage is formed at least between the nozzle (18) and the outlet opening. The device has a closing element (20) which is designed to narrow the outlet opening to a greater or lesser extent depending on the rotated positions of the housing parts (12, 14) relative to each other. The essence of the device according to the invention is that the closing element (20) consists of ribs (28) formed on one housing part (12) and a key arranged movably on the other housing part (14). The key is arranged to be axially movable in the grooves between the ribs (28) for fastening the housing parts (12, 14) to each other. The invention relates to a peak expiratory flow monitoring device that monitors the maximum flow rate of exhaled air. Peak expiratory flow rate (PEFR) is a measure of lung function that can be measured easily and accurately using a variety of devices. Peak expiratory flow rate monitoring is an accepted method for monitoring asthma status, as it can be reliably recorded by subjects using simple, portable devices without the assistance of a trained technician. Several such devices are described in patent specification PCT / GB96 / 01251 25. The aim of the invention is to implement a peak expiratory flow monitoring device that has a hollow body with a passage allowing medium flow. The hollow body contains a signal generator capable of generating a signal when the flow velocity of the medium passing through it reaches a predetermined value. The hollow body has first and second housing parts that can be connected to each other by rotation, which define a resonant cavity with an outlet opening. The housing parts have a locking mechanism by means of which they can be gradually fixed to each other, and thus the locking element can be adjusted by changing the size of the outlet opening in predetermined increments. The first housing part has an inlet opening formed by a nozzle 40. The medium-conducting passage is formed at least between the nozzle and the outlet opening. The device has a locking element that is designed to narrow the outlet opening to a greater or lesser extent depending on the rotated positions of the housing parts relative to each other. The essence of the device according to the invention is that the locking element consists of ribs formed on one housing part and a key arranged displaceably on the other housing part.The key is arranged to be axially movable in the grooves between the ribs for securing the casing parts to each other. In a possible embodiment of the device according to the invention, the resonating cavity with the outlet opening is largely delimited by the second housing part, the closing element 55 is arranged in the first housing part and is positioned so as to narrow the outlet opening to a greater or lesser extent, extending into the resonating cavity, depending on the relative rotation of the interconnected housing parts. 60 The cover part with the key is preferably provided with a rail, and the key is attached to a key holder slidably mounted on the rail. In a further possible embodiment of the invention, the key holder has a locking pin that is designed to be inserted into and retained in an opening formed in the cover part. The closure element is preferably cylindrical and is designed to extend into the second casing part when the casing parts are connected to each other. The inwardly extending edge of the closure element is spiral and is designed to narrow the outlet opening to a greater or lesser extent depending on the relative rotation of the casing parts. The housing parts are secured to each other by an internal, axial spindle in one housing part and a hub arranged on the other housing part. The spindle is rotatably mounted in the hub. The spindle is preferably connected to the hub in a manner that prevents their axial disconnection and can only be separated by destroying the device. The invention will be described in detail below with reference to the drawing. In the drawing, Figure 1 is an exploded perspective view of the device according to the invention, viewed from the outlet opening of the device, Figure 2 is a perspective view of the device shown in Figure 1, viewed from the inlet of the device, Figure 3 is a cross-section of the device shown in Figure 1 taken along line 3-3, Figure 4 is a cross-section of the device shown in Figure 2 taken along line 4-4, Figure 5 is a partially sectioned side view of the device according to the invention from the outlet opening of the device (without sound generator), Figure 6 is a side view of the casing portion of the device shown in Figure 1 containing the outlet opening, Figure 7 is a partial side view of the closure mechanism of the device shown in Figure 1, Figure 8 is a top view of the part of the closure device shown in Figure 7, and Figure 9 is a partial bottom view of the portion of the closure device shown in Figure 7. The peak expiratory flow monitoring device of the invention is not a flowmeter in the sense that it does not measure the absolute flow through the device. The purpose of the device is to monitor a predetermined threshold value associated with the peak expiratory flow rate (PEFR) of the subject. Eb2 In the sense of the invention, the peak expiratory flow monitoring device is a threshold monitoring device, i.e. it monitors the PEFR value achieved by the subject and compares it with a diagnostic threshold value. A predetermined PEFR value is a diagnostic threshold value that depends on the treatment procedure prescribed for the subject after measuring the subject's expected or estimated PEFR value. The peak expiratory flow monitoring device 10 according to the invention, shown in Figure 1, has two mutually connectable housing parts 12 and 14 and a sound generator formed with a whistle structure 16. The housing part 12 forms an input sleeve and the housing part 14 forms an output sleeve, which are connected to each other in a manner described later. In use, the subject inhales as deeply as possible and then exhales air through a cylindrical tube forming a nozzle 18 at the inlet end of the inlet housing 12. The subject is generally asked not to cough or cause sudden bursts of exhaled air - such as croaking, coughing or interrupted flow caused by blocking the nozzle with the tongue. As will be apparent from the following, the peak expiratory flow monitoring device 10 of the invention is designed to minimize any inaccuracies resulting from such sudden bursts of exhaled air. As shown in Figure 3, the outlet housing 14 has an outer wall 24 defining a resonant cavity 46 having an outlet opening 26. The resonant cavity 46 extends along the axial length of the outlet housing 14. The horn-shaped central housing 22 of the whistle assembly 16 is axially disposed within the resonant cavity 46. The casing parts 12 and 14 can be connected to each other and the whistle assembly 16 can be inserted into the horn-shaped housing 22. The nozzle 18 extends into a cylindrical closure member 20, the upper edge 23 of which is cut off in a spiral manner. When the housing parts 12 and 14 are connected to each other, the closure member 20 extends into the outlet housing part 14 in such a way that, depending on the position of the upper edge of the closure member 20 relative to the walls of the opening 26, it closes the outlet opening 26 to a greater or lesser extent. The relative position of the upper edge of the closure member 20 and the walls of the opening 26, in turn, depends on the angular rotation of the housing parts 12 and 14 relative to each other. When the subject blows air through the nozzle 18 and the outlet housing 14, some of the exhaled air passes through the opening 26 and some through the whistle assembly 16. As the inlet housing 12 rotates relative to the outlet housing 14, the spiral closure 20 closes the opening 26 to a greater or lesser extent, thereby determining how much exhaled air passes through the whistle assembly 16. If a sufficient amount of air flows through the whistle assembly 16, it produces a sound. The whistle assembly 16 is a nonlinear device, and the length, shape, and mass of the whistle are selected to produce sound in the frequency range most sensitive to human hearing. (A whistle is considered linear if it produces sound of approximately twice the intensity at twice the airflow rate.) The whistle assembly 16 is capable of producing sound at a frequency of approximately 1000 Hz. Although the whistle assembly 16 is nonlinear, the peak expiratory flow monitoring device 10 can be made linear by appropriately designing the spiral closure member 20. More importantly, the whistle assembly 16 should produce a clear and rapid rise in tone when the exhaled air flow rate has exceeded its flow threshold. In this regard, the whistle assembly 16 can be considered an analog-to-digital converter device that is either on or off, but has no other state. The whistle assembly 16 is then manufactured to minimize dimensional variation between individual products by adhering to precise tolerances, so that each whistle assembly 16 sounds at the same flow threshold. This eliminates the need to calibrate all peak expiratory flow monitoring devices 10. In addition, the whistle assembly 16 is configured so that the dynamic and static flow thresholds of the whistle assembly 16 are close to each other, thereby minimizing the possibility of erroneous tone generation due to large fluctuations in airflow.Such fluctuations can occur, for example, when a shock-like airflow passes through the peak flow monitoring device 10 instead of a steady exhaled air flow. As shown in Figure 4, the whistle assembly 16 is inserted into the housing 22 and is located in the lower part of the outlet housing 14. The outer shape of the whistle assembly 16 and the inner shape of the housing 22 are formed as complementary frustocones. The inlet end of the whistle assembly 16 is open to the inlet end of the housing 22, and the outlet end of the whistle assembly 16 communicates with the air inside the horn-shaped mouthpiece of the housing 22. The horn-shaped mouthpiece, as well as the outlet housing 14, which forms a resonant cavity 46 around the housing 22, improve the audibility of the peak expiratory flow monitoring device 10. The inlet end of the housing 22 is provided with a transversely disposed baffle 44. The baffle 44 acts as a low-pass filter and prevents the subject from sounding the whistle assembly 16 with a shock-like flow. This prevents the test from accidentally giving an overly favorable result. The baffle 44 is located at the inlet end of the horn-shaped outlet housing 22. As shown in Figure 5, the outer diameter of the baffle 44 is slightly smaller than the inner diameter of the housing 22 at its inlet end, which facilitates the passage of exhaled air to the outlet of the housing 22. The inlet and outlet housing parts 12, 14 have complementary connection units by means of which the housing parts 12 and 14 can be connected to each other. HU 221 250 BI One such connection unit is formed as a single piece with the baffle 44. On the side facing the nozzle 18, the baffle 44 has a tubular spindle 72 sized to rotate in a hub 74 formed inside the nozzle 18. The hub 74 is supported by three radially arranged arms 76. The spindle 72 can be easily rotated in the hub 74 and is held in its adjusted position by an outwardly extending flange 78. When the spindle 72 is in the proper position in the hub 74, the flange 78 extends beyond the edge of the hub 74. The spindle 72 is notched in three places, which facilitates its insertion into the hub 74. To prevent removal of the spindle 72 from the hub 74, a locking pin 80 is pressed into the cylindrical interior of the spindle 72. The locking pin 80 is sized so as not to lock the spindle 72, but only to prevent removal of the spindle 72 from the hub 74 without damaging the peak expiratory flow monitoring device 10. In addition to the spindle 72 and the hub 74, the coupling units include an inwardly directed flange 54 located at the mating end of the outer wall 24 of the outlet opening on the housing portion 14, and an outer groove 56 extending around the outer side of the cylindrical closure member 20. The flange 54, the mating end of the inlet housing portion 14, and the groove 56 and closure member 20 are dimensioned to couple the inlet and outlet housing portions 12, 14 by engaging the flange 54 in the groove 56. The edges of the flange 54 and the groove 56 are rounded to facilitate easy rotation of the housing portions 12 and 14 relative to each other. The edges of the outlet opening 26 are defined by inwardly extending walls 49 which are connected to the outer wall 24 of the outlet housing 14. The walls 49 extend into the resonant cavity 46 and are sized to fit snugly against the outer surface of the closure member 20, thereby sealing the gap between the closure member 20 and the outer wall 24 of the resonant cavity 46 of the housing 14. The lower part of the cylindrical wall of the closure member 20 is provided with a plurality of ribs 28, which are located at equal distances from each other along the circumference of the closure member 20. The ribs 28 form part of the closure structure of the peak expiratory flow monitoring device 10 according to the invention. The locking mechanism has a key 32 which can be slid axially into the grooves between the ribs 28. The key 32 is integrated with a key holder 34 which is mounted on a rail 36 formed in the output housing portion 14. The purpose of this locking mechanism is to prevent the housing parts 12 and 14 from rotating relative to each other. The locking mechanism preferably provides a semi-releasable connection, i.e. after being locked in place, the locking mechanism can only be opened by destroying the peak expiratory flow monitoring device 10. It must be ensured that the locking mechanism is difficult to release. In the peak flow monitoring device 10 of the present invention, the locking mechanism is difficult to open due to the design of the rail 36 and the key holder 34. As shown in Figure 6, the rail 36 is bounded by an outer wall 38, and the rail 36 includes two parallel slots 40 located on either side of a central slot 42 formed in the wall 24 of the resonant cavity 46. The key holder 34 is shown in more detail in Figures 7, 8 and 9. In these figures, it can be clearly seen that the key holder 34 includes a sliding plate 48 from the bottom of which the key 32 and two sliding latches 50 extend downwardly. The sliding latches 50 are pressed into the slots 40 of the rail 36 and the key holder 34 is held inside the rail 36 while the key 32 is in the central slot 42 formed in the rail 36. By securing the housing portion 12 at a predetermined angular position relative to the housing portion 14, the spiral closure member 20 is positioned relative to the outlet opening 26, thereby determining the actual size of the opening 26. As previously mentioned, the size of the opening 26 is determined by the treatment method. The ribs 28 allow for precise adjustment of the peak expiratory flow monitoring device 10 in small increments. As shown in Figure 3, the closure element 20 also has a stop element 66 which abuts a stop 68 when the housing parts 12 and 14 are in their maximum rotated position relative to each other. The closure member 20 abuts the stop 68 in the maximum closed or maximum open position of the peak expiratory flow monitoring device 10. In the maximum closed position, the upper edge 23 of the closure element 20 is as close to the upper end of the opening 26 as the relative rotation of the housing parts 12 and 14 allows. In the other extreme position - the maximum open position - the upper edge 23 of the closure element 20 is as close to the lower end of the outlet opening 26 as the relative rotation of the housing parts 12 and 14 allows. In use, the clinician determines the diagnostic threshold of the subject, and based on this, the clinician either assembles the peak flow monitoring device 10 or has it assembled by the subject. During assembly, the inlet and outlet housings 12 and 14 are connected together with the closure members 20 positioned in a position determined by the subject's treatment procedure. To facilitate assembly, appropriate markings 70 are provided on the nozzle 18. The markings 70 are configured in accordance with the treatment procedure. The markings 70 represent flow rate values. The person being tested only needs to use the home monitoring device 10. The instructions for this, i.e. when to measure and how to use the peak flow monitoring device 10, are provided to the person being tested before use. The slide latches 50 include latch elements 50.1 that hold the key holder 34 in the rail 36. However, the slide latches 50, the key 32, and the slots 40 and the central slot 42 are dimensioned such that HU 221 250 Bl to allow relatively easy sliding of the key holder 34 in the rail 36. The sliding plate 48 of the key holder 34 is formed on its lower side with a V-shaped narrowing 58 to form a locking projection 48.1. The narrowing 58 allows the locking projection 48.1 to be easily bent out of the plane of the sliding plate 48. In this position, the bent locking projection 48.1 allows for easy assembly of the locking mechanism, as it allows the key holder 34 to be inserted into the rail 36 with the key 32 located away from the ribs 28 formed on the cover part 12. The locking projection 48.1 of the sliding plate 48 has a downwardly directed locking pin 59. The purpose of the locking pin 59 is to secure the key holder 34 in the rail 36 after the casing parts 12 and 14 have been adjusted to the correspondingly rotated position. This can be done by sliding the key holder 34 in the direction of the nozzle 18. An arrow 60 is pressed onto the upper side of the sliding plate 48 in order to clearly indicate the required sliding movement. Before sliding the key holder 34 into the location described above, the treating physician adjusts the appropriate relative rotation of the housing parts 12 and 14 in accordance with the treatment prescribed for the subject. After selecting the correct angular position, the key holder 34 is slid into place in such a way that the key 32 fits into the corresponding groove between the ribs 28 formed on the closing element 20 of the housing part 12. The opposite ends of the ribs 28 are rounded, and the front end of the key 32 is tapered. The purpose of this design is to facilitate the introduction of the key 32 into the groove between the ribs 28. Once the key 32 has been placed in the correct position between the ribs 28, the locking projection 48.1 of the sliding plate 48 can be bent back into the plane of the sliding plate 48. To do this, the locking pin 59 is pushed into the opening 64 formed in the rail 36. The locking pin 59 has an enlarged head 59.1 which can be forced into the opening 64 with a certain amount of pressure. When the locking pin 59 is in place in the opening 64, the locking projection 48.1 of the sliding plate 48 is retained in the wall 38 of the rail 36. The gap between the sliding plate 48 and the walls 38 is made as small as possible. This ensures that it is difficult to lift the sliding plate 48 if any attempt is made to open the locking mechanism, for example if the locking projection 48.1 is attempted to be lifted in the opposite direction to the locking pin 59 in the opening 64. If necessary, the peak flow monitoring device 10 can be pre-configured specifically for children or adults. The size of the opening 26 can be determined so as to allow a maximum flow rate of up to 450 1 / min in the former case, and a maximum flow rate of up to 800 1 / min in the latter case. The peak expiratory flow monitoring device 10 can be easily calibrated for adults. Optionally, one or more additional outlets - not shown in the figure - can be formed in the resonant cavity 46 of the horn-shaped housing 22, preferably in its wall. The above description relates to an exemplary embodiment of the invention, but the invention can be implemented in many other embodiments within the claimed scope.

Claims

PATENT CLAIMS 1. A peak expiratory flow monitoring device having a hollow body provided with a passage for allowing medium flow, said hollow body comprising a whistle structure (16) functioning as a signal generator, said hollow body being adapted to generate a signal when a predetermined value of the flow rate of the medium passing therethrough is reached; said hollow body having first and second housing parts (12, 14) which are rotatably connectable to each other, said housing parts (12, 14) defining a resonant cavity (46) having an outlet opening (26), said housing parts (12, 14) having a locking mechanism by means of which they can be progressively secured to each other, thereby allowing said closing element (20) to be adjusted by varying the size of said outlet opening (26) in predetermined increments; the first housing part (12) has an inlet opening formed by a nozzle (18), and the medium conducting passage is formed at least between the nozzle (18) and the outlet opening (26);further, the device has a closing element (20) which is designed to narrow the outlet opening (26) to a greater or lesser extent depending on the relative positions of the casing parts (12, 14), characterized in that the closing element (20) consists of ribs (28) formed on one casing part (12) and a key (32) displaceably arranged on the other casing part (14), this key (32) being arranged axially displaceably in the grooves between the ribs (28) for fastening the casing parts (12, 14) to each other.; 2. Device according to claim 1, characterized in that the resonating cavity (46) with the outlet opening (26) is largely delimited by the second housing part (14), and the closing element (20) is arranged in the first housing part (12) and is positioned so as to narrow the outlet opening (26) to a greater or lesser extent, extending into the resonating cavity (46) depending on the relative rotation of the interconnected housing parts (12, 14).

3. Device according to claim 1 or 2, characterized in that the housing part (14) with the key (32) is provided with a rail (36), and the key (32) is attached to a key holder (34) slidably mounted on the rail (36).

4. Device according to claim 3, characterized in that the key holder (34) has a locking pin (59) which is designed to be inserted into and retained in an opening (64) formed in the cover part (14).

5. The device according to any one of claims 1-4, characterized in that the closing element (20) is cylindrical and is designed to extend into the second covering part (14) in the connected position of the covering parts (12, 14), and furthermore the inwardly extending edge of the closing element (20) is spiral and is designed to narrow the outlet opening (26) to a greater or lesser extent depending on the relative rotation of the covering parts (12, 14).

6. Device according to any one of claims 1-5, characterized in that the housing parts (12, 14) are fixed to each other by means of an internal, axial spindle (72) in one housing part (14) and a hub (74) arranged on the other housing part (12), and the spindle (72) is rotatably mounted in the hub (74).

7. The device according to claim 6, characterized in that the spindle (72) is connected to the hub (74) in a manner that prevents their axial disconnection and can only be separated by destroying the device (10).