WO2005056089A2

WO2005056089A2 - Apparatus

Info

Publication number: WO2005056089A2
Application number: PCT/IB2004/003956
Authority: WO
Inventors: Paolo Passarello; Marcello Raffaelli
Original assignee: Paolo Passarello; Marcello Raffaelli
Priority date: 2003-12-05
Filing date: 2004-12-02
Publication date: 2005-06-23
Also published as: WO2005056089A3; ITMO20030332A1; EP1696984A2

Abstract

Apparatus, comprising casing means (2, 30) suitable for containing a container (18) of a fluid (14) for medical infusion and provided with heating means for heating (7, 34) said fluid, support means (10, 20) of said casing means, characterised in that between said casing means and said support means removable coupling means (8, 9, 27, 29) is arranged, by means of which said casing means can be selectively coupled to or decoupled from, said support means; device, associable with a container of a fluid for medical infusion, comprising detecting means (39) arranged to detect, during use, a decrease in the volume of said fluid in said container and signal emitting means (35) arranged to emit a signal when said decrease is near a threshold value.

Description

Apparatus

The invention relates to a heating apparatus for containers of fluids, in particular fluids for medical use that are administratable by infusion, for example blood products, colloids, crystalloids and whole blood.

In hospital departments, the therapeutic need is known to infuse fluids placed at a temperature corresponding to the body temperature of the patient for whom they are intended. For example, in the case of serious hemorrhages in a patient urgent intervention is taken on the patient by infusing blood products to restore a physiological circulatory volume. In particular, for emergency medicine units it is important to have a stock of containers of fluids for infusion that are kept at body temperature inasmuch as medical workers cannot foresee the number of patients to be treated during any work shift.

Heating apparatuses are known, like those disclosed in German patent application No. DE10149377 and in United States patent NO.US5282264 , that are usable for heating containers, for example bags, of fluids for infusion. In order to be able to carry out infusion, the container must be removed from the heating apparatus and be connected to infusion tubing with drip adjuster. However, in this way the container, and therefore the fluid contained in it, remains exposed to ambient temperature for the entire duration of the infusion, with consequent progressive cooling of the fluid. Heating apparatuses have therefore been proposed that are able to bring the fluids to be infused up to body temperature and to keep them at this temperature during infusion. For example, heating apparatuses are known that act directly on the infusion tubing with drip adjusters: but they are apparatuses that have significant running costs as they are not adaptable to standard infusion tubing with drip adjusters and require specific sets of infusion tubing with drip adjusters.

Furthermore, they are bulky and must be located near the treated patient, thus creating a substantial hindrance to the medical workers present. These drawbacks significantly limit the use of the aforementioned apparatuses in medical-surgical practice.

Heating apparatuses are furthermore known, like the one disclosed in international patent application No. O8807384 , in which, during the infusion, the containers of the fluids to be administered are housed. They are substantially bulky apparatuses that have to be located near the patient and are therefore a hindrance to the medical workers present. Furthermore, these apparatuses have been conceived to heat, over a unit of time, only the quantity of fluid administered to the patient during the infusion, i.e. quantity of fluid contained in a single container.

By means of known apparatuses it is not therefore possible to lay up a stock of containers of fluids for infusion that are storable at body temperature whilst waiting to be used and are subsequently usable maintaining this constant temperature. Another drawback of the known apparatuses consists of the fact that when they comprise compartments in the interior of which the containers of the fluids to be infused are placed and heated, the latter are substantially non-visible to the assigned operators. In this way, it is inconvenient for the assigned operators to monitor the level of the fluid that remains in the container as the infusion progresses. More in general, even when the apparatus is shaped in such a way as to facilitate visual monitoring of the fluid in the container, the assigned operator has to carry out this monitoring periodically, thus interrupting other activities. This may be significantly inconvenient when a reduced number of operators has to take care of numerous patients, as frequently occurs in hospital departments.

An object of the invention is to improve the known apparatuses used to heat fluids for infusion. Another object is to supply a heating apparatus of fluids for infusion equipped with reduced overall dimensions. Another further object is to provide a heating apparatus for fluids for infusion that has moderate running costs. Another further object is to supply a heating apparatus that enables containers of fluid for infusion to be heated and kept at body temperature both during storage and during use. A yet further object is to supply a device, associable with a container of a fluid for infusion, which is able during use to detect and promptly alert an operator to the imminent finishing of the fluid in the container, if the container is not visually accessible to the operator.

Another yet further object is to supply a device, associable with a container of a fluid for infusion, which is able during use to detect and promptly alert an operator to the imminent finishing of the fluid in the container, thereby preventing the operator from having to periodically check the level of fluid.

In a first aspect of the invention, an apparatus is provided, comprising casing means suitable for containing a container of a fluid for medical infusion and provided with heating means for heating said fluid, support means of said casing means, characterised in that between said casing means and said support means removable coupling means is arranged, by means of which said casing means can be selectively coupled to or decoupled from, said support means.

Owing to this aspect, it is possible to have an apparatus that can heat and maintain a fluid for infusion at a constant body temperature both during storage and during subsequent use, and can be placed at a distance from the patient, preventing problems of overall dimensions for the medical workers. In a second aspect of the invention, a device is provided, associable with a container of a fluid for medical infusion, comprising detecting means arranged to detect a decrease in the volume of said fluid in said container and signal emitting means arranged to emit a signal when said decrease is near a threshold value. Owing to this aspect of the invention, a device is made available that is able to alert an operator, when a fluid is infused inside a patient, to the imminent emptying of the container of the fluid, namely to the imminent completion of the infusion. This enables the progress of the infusion to be monitored when the container of the fluid is located inside an apparatus so that it is not directly visible to the operator. Furthermore, even when the container of the fluid is positioned during use in such a way as to be well visible to the operator, the aforementioned device nevertheless enables the operator to avoid periodically monitoring the level of the fluid in the container and to therefore be able to perform other tasks whilst waiting for the end of the infusion. This enables the operator to efficiently manage his tasks in the department, especially if he is forced to take care of a large number of patients. The invention will be better understood and implemented with reference to the enclosed drawings that show some exemplifying and non-limitative embodiments thereof, in which: Figure 1 is a partially sectioned fragmentary schematic view showing an apparatus for heating a container of a fluid for medical infusion in one operating phase;

Figure 2 is a partially sectioned fragmentary schematic view showing the apparatus in Figure 1 in a further operating phase; Figure 3 is a schematic cross-section of a part of the apparatus in Figure 1;

Figure 4 is a fragmentary and incomplete perspective view showing a component of a further embodiment of the apparatus in Figure 1;

Figure 5 is an incomplete and partially sectioned fragmentary perspective view showing the further embodiment of the apparatus in Figure 1 in one operating phase; Figure 6 is a fragmentary and incomplete perspective view of a constructional detail of the further embodiment of the apparatus in Figure 1;

Figure 7 is a fragmentary and incomplete perspective view showing the further embodiment of the apparatus in Figure 1 in a further operating phase. With reference to Figures 1 to 3, an apparatus 1 for heating a fluid 14 for infusion, for example a blood product contained in a container 18, for example a glass bottle, comprises a thermostatic casing 2 that is thermally insulating and, for example, cylindrical shell-shaped. The latter is divided approximately in half into a first portion 3 and a second portion 4 that are hinged on each other by means of a hinge 5. The first portion 3 and the second portion 4 have a cross- section that is approximately C-shaped and are oriented so as to have their respective concave faces facing each other. In this way, in the thermostatic casing 2 a chamber 6 is defined that can house the container 18 of the fluid 14. In the thickness of the first portion 3 and of the second portion 4 a plurality of electric resistances 7 is received that form a heating circuit supplied by an electric battery that is not shown that is also contained in the thickness of the first portion 3. The electric battery is connected to a plurality of electric contacts, for example reed contacts that are prior- art and are not shown, that are contained in a first hooking element 8, protruding from the first portion 3 of the thermostatic casing 2. The first hooking element 8 is shapingly coupled with a second hooking element 9, comprised in a supply unit 10, for example in the form of a four-sided plate made integral with a portion of wall P. In one embodiment that is not shown the supply unit 10 may be fitted to emergency vehicles, for example ambulances and/or helicopters.

The first hooking element 8 and the second hooking element 9 are prior-art and enable the thermostatic casing 2 to be easily and rapidly couplable with and decouplable from the supply unit 10. The second hooking element 9 comprises a plurality of electric reed contacts that are not shown that are arranged to interact with the reed contacts comprised in the first hooking element 8 when the thermostatic casing 2 is coupled with the supply unit 10. In this way, the supply unit 10, connected to the main electric power supply through an electric cable 11, is able to charge the electric battery of the thermostatic casing 2. On the first portion 3 a temperature display 12 is furthermore inserted, for example a prior-art liquid-crystal display, that enables the temperature existing inside the chamber 6 to be continuously monitored. As the first portion 3 and the second portion 4 are hinged on each other, the thermostatic casing 2 can be alternatively open or closed in "book" fashion. In order to keep the thermostatic casing 2 in the closed position, prior-art devices, for example Velcro closures 13, 13a, are provided. During use, the container 18 is inserted upturned in the open thermostatic casing 2. The latter is then reclosed and hooked to the supply unit 10, which charges the electric battery and operates the heating circuit formed by the plurality of electric resistances 7. In this way, the container 18 and therefore the fluid 14 contained therein are heated until they reach a desired temperature that is monitorable by an operator (not shown) by means of the display 12. Once the desired temperature has been reached, for example the body temperature of a patient who has to receive the fluid 14 for infusion, the thermostatic casing 2 can be unhooked from the supply unit 10 and after being brought up to the patient, not shown, is hooked to a support 15 by means of an eyelet element 16 with which the second portion 4 is equipped. At this point, prior- art infusion tubing with drip adjuster 17 can be connected to the container 18, closed in the thermostatic casing 2, and the fluid 14 can then be administered for infusion. From the moment in which the thermostatic casing 2 is decoupled from the supply unit 10 until the end of the infusion, the temperature of the fluid 14 is kept constant in the chamber 6 as the aforementioned heating circuit is supplied by the electric battery. For this purpose, the thermostatic casing 2 is provided with prior-art control means that is not shown, such as for example a microprocessor. The microprocessor interacts with the electric resistances 7 and is able to selectively direct towards the latter electric energy coming from the electric battery or from the supply unit 10, depending on whether the thermostatic casing 2 is unhooked from the supply unit 10 or is hooked onto it.

In one embodiment that is not shown, the thermostatic casing 2 is associated during use with infusion tubing with drip adjuster, the tubing of which is thermally insulated. This is obtained by making the infusion tubing with drip adjuster of a material provided with high thermal insulation, for example of a silicone material or of thermoplastic rubber. In another embodiment that is not shown, the thermostatic casing 2 is equipped with a main electric power supply device that is usable for keeping the temperature in the chamber 6 constant if for any reason the electric battery were unable to ensure correct operation of the heating circuit during the infusion. In a further embodiment that is not shown, the thermostatic casing 2 is at least partially made of a transparent material so as to enable the assigned operator to view the chamber 6 and the container 18 lodged therein. In another further embodiment that is not shown, a multiple supply unit is provided, that is couplable with a plurality of thermostatic casings 2 and is appropriately insulated from the external environment in such a way as to be able to receive a stock of fluid for infusion that is constantly kept at a temperature that is suitable for administration. This multiple supply unit can be placed in rooms that are different from those in which the patient to be treated is located, thereby avoiding any undesired hindrance to the medical workers assigned to the infusion. In a yet further embodiment that is not shown, the thermostatic casing 2 is made of a flexible material. With reference to Figures 4 and 5, an embodiment of the apparatus 1 is provided comprising a further supply unit 20, which can be located on a shelf M that is made integral with the portion of wall P by bracket means 21, and a further thermostatic casing 30, arranged to contain the container 18 (shown by a broken line) of the fluid 14. The further thermostatic casing 30 is alternatively couplable with or decouplable from the further supply unit 20, by means of a hooking portion 31.

The further supply unit 20 has a body 22 that is approximately semicylinder-shaped. The body 22 comprises a flat face, which is not shown, arranged to come into contact with a support surface S obtained in the shelf M, and a convex face 23, opposite the flat face. Between the flat face and the convex face 23, a first end face 24 and a second end face 25 are interposed that are parallel to each other and at right angles to the flat face. The first end face 24 comprises a socket 40 for connecting the further supply unit 20 to the main electric power supply through an electric cable, which is not shown, and an ON/OFF switch.

In a longitudinal and approximately middle portion of the convex face 23, a groove 24 is obtained comprising a concave seat 26, with which the further thermostatic casing 30 is associable in a shapingly coupled manner. From an end edge 28 of the seat 26, pointing towards the first end face 24, four electric contacts emerge, made in the form of plugs 27. Each plug 27 is arranged to be received in a respective socket, which is not shown, obtained in the hooking portion 31 of the further thermostatic casing 30. From an approximately middle portion of the end edge 28 a guide stem 29 furthermore emerges that is arranged to be received in a shapingly coupled manner in a corresponding recess, which is not shown, which is obtained in the hooking portion 31. In one portion of the convex face 23 comprised between the flat face and the groove 24, and opposite, during use, the wall portion P, a control panel 42 is obtained that is equipped with a liquid-crystal display, "soft-touch" keys and prior-art light emission diodes (LEDs) .

In one embodiment that is not shown, the further supply unit 20 is fixed directly to the portion P by prior-art fixing means . In another embodiment that is not shown, the further supply unit 20 may be fitted to emergency vehicles, for example ambulances and/or helicopters.

In a further embodiment that is not shown, a multiple supply unit is provided, couplable with a plurality of further thermostatic casings 30 and suitably insulated from the external environment so as to be able to receive a stock of the fluid for infusion kept constantly at a temperature that is suitable for administration. This multiple supply unit can be placed in rooms that are different from those in which the patient to be treated is located, thereby avoiding any undesired hindrance to the medical workers assigned to the infusion.

The further thermostatic casing 30 comprises a cylindrical portion 32 that can be made of a transparent material and is arranged to receive the container 18 and is interposed between the hooking portion 31 and a closing portion 33. The hooking portion 31 is substantially cylinder-shaped and has on one of its side walls a further control panel 35 provided with LEDs. The hooking portion 31 furthermore comprises some coloured LEDs (four example four red LEDs), which are not shown and are arranged near the cylindrical portion 32. From one face of the hooking portion 31 opposite the cylindrical portion 32 a hook 36 extends that is arranged to hook during use the further thermostatic casing 30 to the support 15. Inside the cylindrical portion 32 a further chamber 37 is defined in which the container 18 is inserted (shown as a broken line) and which is closed at opposite ends by the hooking portion 31 and by the closing portion 33. The further chamber 37 comprises a heating element 34, substantially shaped as an elongated four-sided plate, having one end integral with the hooking portion 31 and an opposite free end terminating near the closing portion 33. As the heating element 34 has a curved cross-section so as to define a concavity turned to a longitudinal axis, which is not shown, of the cylindrical portion 32, the container 18 is partially surrounded by the heating element 34 when it is inserted into the further chamber 37.

Whilst the hooking portion is made integral with the cylindrical portion 32, the closing portion 33 is removable from the latter, owing to the presence of rapid engagement means, for example of the bayonet or screw type. The closing portion 33 is substantially shaped as a hollow truncated cone, the apex of which, turned in a direction opposite the cylindrical portion 32, is traversed by a transit hole, which is not shown, through which an end portion of the container 18, when inserted into the further chamber 37, can protrude externally.

With reference to Figure 6, inside the hooking portion 31 an electronic unit 38 is contained that manages operation of the further thermostatic casing 30 and is connected to the further control panel 35 and to the heating element 34. The electronic unit 38 is connected to a prior-art device for detecting weight variations, for example a load cell 39, with which the hook 36 is associated.

During use, an operator (not shown) can remove the closing portion 33 from the cylindrical portion 32, and thus insert the container 18 into the further chamber 37. After reclosing the latter, by again connecting the closing portion 33 to the cylindrical portion 32, the operator can couple the further thermostatic casing 30 with the further supply unit 20. This is obtained by sliding the cylindrical portion 32 parallel to the seat 26 in a direction indicated by the arrow FI (Figure 5) , until the hooking portion 31 is brought up to the end edge 28 of the seat 26. In this way, the plugs 27 and the respective sockets of the hooking portion 31 are brought up to one another and owing to the presence of the guide stem 29 they are easily coupled. By acting on the switch 41, the operator switches on the further supply unit 20, which, at the same time, charges an electric battery (not shown) with which the electronic unit 38 is equipped and starts up the heating element 34, bringing the latter to the required temperature, for example the body temperature of a patient. During this heating and battery-charging phase, the further thermostatic casing 30 is located parallel to the seat 26 of the further supply unit 20, and therefore horizontally. As a result, the position occupied by the fluid inside the container 18 is such as to enable the heating element 34 to heat the fluid in an optimal manner. After checking, through the display of the control panel 42, the charge status of the battery and the reaching of the required temperature, the operator can decouple the further thermostatic casing 30 from the further supply unit 20, by sliding the cylindrical portion 32 in a direction indicated by the arrow F2 (Figure 5), parallel to and opposite direction FI . From this moment, the further thermostatic casing 30 continues to maintain at the required temperature the container 18 and therefore the fluid for infusion contained in the latter, owing to the activity of the electric battery charged by the further supply unit 20. Owing to the LEDs in the further control panel 35, which are made in different colours and can be actuated by different temperature values, the operator can monitor the temperature maintained inside the further chamber 37 and intervene in the event of undesired variations. The electronic unit 38 comprises prior-art monitoring means (for example a microprocessor) , which is not shown, that interacts with the heating element 34 and is able to selectively direct electric energy coming from the electric battery or from the further supply unit 20 to the heating element 34, depending on whether the further thermostatic casing 30 is unhooked from the further supply unit 20 or is hooked onto the latter. With reference to Figure 7, after hooking the further thermostatic casing 30 to the support 15 by means of the hook 36, the operator connects the infusion tubing with drip adjuster 17 to the end portion of the container 18, which protrudes outside the closing portion 33, and proceeds to infuse the fluid, the temperature of which is kept constant for the entire duration of the treatment.

In one embodiment that is not shown, the further thermostatic casing 30 can be associated, during use, with infusion tubing with drip adjuster the tubing of which is thermally insulated. This is obtained by making the infusion tubing with drip adjuster of a material with high thermal insulation, for example a silicone or thermoplastic rubber material. When the further thermostatic casing 30 is hooked onto the support 15 by means of the hook 36, which is in turn connected to the load cell 39, the latter is deformed by the effect of the weight of the container 18, i.e. by the effect of the volume of the fluid contained in the latter, and generates a corresponding electric signal, which is in turn sent to the electronic unit 38 and is there amplified and translated into a weight measurement. As the infusion proceeds, the volume of fluid in the container 18 is progressively reduced and the weight of the latter is equally reduced. As a result, the deformation initially produced in the load cell 39 by the weight of the container 18 full of fluid is also progressively reduced.

When the electronic unit 38, through the load cell 39, records a preset threshold weight value of the container 18, corresponding to a minimum volume of fluid in the latter, the LEDs comprised in the hooking portion 31 are actuated and flash warning the operator of the imminent emptying of the container 18.

In one embodiment that is not shown, the further control panel 35 comprises a series of further LEDs, made in three different colours: green, yellow and red. When the container 18 is full, namely at the start of the infusion, a green LED lights up; when the volume of fluid in the container 18 is near the above threshold value, a yellow LED is actuated. Finally, when the threshold value is reached, a red LED lights up that is larger than the previous LEDs. In another embodiment, which is not shown, the further control panel 35 comprises prior-art acoustic alarms that are actuated together with the different previously disclosed LEDs through the effect of temperature variations in the further chamber 37 and/or of the volume of fluid in the container 18. The disclosed invention thus provides a heating apparatus for fluids administratable by infusion that is easy and rapid to use that enables the presence of bulky elements near the patient to be avoided and the fluid to be kept at a temperature that is suitable for use in a substantially continuous manner. Furthermore, owing to the use of a device for detecting weight variations, such as the load cell disclosed above, the progressive emptying of the container of the fluid during infusion can be kept under control in a manner that is significantly convenient for an assigned operator.

Claims

1. Apparatus, comprising casing means (2; 30) suitable for containing a container (18) of a fluid (14) for medical infusion and provided with heating means (7; 34) for heating said fluid (14), support means (10; 20) of said casing means (2; 30), characterised in that between said casing means (2; 30) and said support means (10; 20) removable coupling means (8, 9; 27, 29) is arranged, through which said casing means (2; 30) can be selectively coupled to or decoupled from said support means (10; 20) .

2. Apparatus according to claim 1, wherein said support means (10; 20) is fixed to a portion of wall (P) through fixing means and is electrically connected to a main electric power supply device.

3. Apparatus according to claim 1, or 2, wherein said removable coupling means (8, 9; 27, 29) comprises mechanical coupling means (29) .

4. Apparatus according to claim 3, wherein said mechanical coupling means (29) comprises rod means (29) arranged to be slidingly inserted into respective recess means made in an end portion (31) of said casing means (30).

5. Apparatus according to any preceding claim, wherein said removable coupling means (8, 9; 27, 29) comprises electric coupling means (27).

6. Apparatus according to claim 5, as appended to claim 4, wherein said electric coupling means (27) comprises plug means (27), arranged to be inserted into respective electric socket means obtained in said end portion (31).

7. Apparatus according to any preceding claim, wherein said casing means (2; 30) is thermally insulated.

8. Apparatus according to any preceding claim, wherein said casing means (2; 30) is openable and closable in such a way as to internally receive said container (18).

9. Apparatus according to any preceding claim, wherein said casing means (2; 30) is made in the form of a shell.

10. Apparatus according to claim 9, as appended to claim 4, wherein said shell comprises a cylindrical portion (32) that is integral with said end portion (31).

11. Apparatus according to claim 10, wherein said shell furthermore comprises a further end portion (33) , opposite said end portion (31) and shaped in such a way as to be able to be alternatively associated with or removed from said cylindrical portion (32) by rapid engagement means .

12. Apparatus according to any preceding claim, furthermore comprising electric battery means arranged to supply said casing means (2; 30) when separated from said support means (10; 20).

13. Apparatus according to any preceding claim, wherein said casing means (2; 30) comprises casing means (2) made of a flexible material.

14. Apparatus according to any preceding claim, wherein said casing means (2; 30) is made at least in part of a transparent material .

15. Apparatus according to any preceding claim and furthermore comprising monitoring means interacting with said heating means (7; 34) and such as to selectively direct electric power to said heating means (7; 34) from said electric battery means or from said main electric power supply, as the case may be.

16. Apparatus according to any preceding claim, wherein said heating means (7; 34) comprises electric resistance means (7) .

17. Apparatus according to any preceding claim, wherein said heating means (7; 34) comprises heating plate means (34), configured in such a way as to be able to at least partially surround said container (18) during use.

18. Apparatus according to any one of claims from 15 to 17, as appended to claim 4, wherein said monitoring means comprises electronic unit means (38) located inside said end portion (31).

19. Apparatus according to any preceding claim, furthermore comprising detecting means (39) arranged to detect a decrease in the volume of said fluid (14) in said container (18) and signal emitting means (35) arranged to emit a signal when said decrease is near a threshold value.

20. Apparatus according to claim 19, wherein said detecting means (39) comprises load cell means (39) that is actuated when it is subjected to a deformation, said deformation depending on the volume of said fluid (14) contained in said container (18).

21. Apparatus according to claim 20, wherein said load cell means (39) is associated with hook means (36) arranged to hook, during use, said casing means (2; 30) onto support means (15).

22. Apparatus according to any one of claims from 19 to 21, wherein said signal emitting means (35) produces a light signal.

23. Apparatus according to any one of claims from 19 to 22, wherein said signal emitting means (35) produces an acoustic signal.

24. Apparatus according to any preceding claim, wherein infusion tubing with drip adjuster means comprising thermally insulated conduit means is associable with said casing means (2; 30) .

25. Apparatus according to claim 24, wherein said conduit means is made of a material provided with high thermal insulation.

26. Apparatus according to claim 25, wherein said material comprises a silicone material.

27. Apparatus according to claim 25, or 26, wherein said material comprises thermoplastic rubber.

28. Device, associable with a container (18) of a fluid (14) for medical infusion, comprising detecting means (39) arranged to detect a decrease in the volume of said fluid (14) in said container (18) and signal emitting means arranged to emit a signal when said decrease is near a threshold value.

29. Device according to claim 28, wherein said detecting means (39) comprises load cell means (39) that is actuated when it is subjected to a deformation, said deformation depending on the volume of said fluid (14) contained in said container (18).

30. Device according to claim 29, wherein said load cell means (39) is associated with hook means (36) arranged, during use, to hook casing means (2; 30) containing said container (18) onto support means (15).

31. Device according to any one of claims 28 to 30, wherein said signal emitting means (35) produces a light signal.

32. Device according to any one of claims 28 to 31, wherein said signal emitting means (35) produces an acoustic signal.