Method and device for determining volume flow, pressure and composition of a gas

Abstract

Method for determining the volume flow (V), pressure (p) and composition of a gas which is passed through a flow channel (12) during the breathing or ventilation of a patient (P), wherein the volume flow (V) of the gas conducted through the flow channel (12) is determined by means of a carrier membrane (16) which is arranged in the flow channel (12) substantially orthogonal to the flow direction (S) of the gas, wherein at least one first sensor (18) is attached to at least one surface (17) of the carrier membrane (16), wherein a pressure measuring device (20) is arranged in the flow channel (12), in particular in the region of its wall (W), wherein with this pressure measuring device (20) a static pressure (p) for the gas flowing within the flow channel (12) is measured in comparison to the external environment of the flow channel (12), and wherein the composition of the gas, in particular selected gases formed from the group of at least oxygen (O2) and carbon dioxide (CO2), is determined by at least one, in particular catalytic, second sensor (24) arranged within the flow channel (12), characterized by that the carrier membrane (16) is designed to be flexible and the first sensor (18) is designed on the surface (17) of the carrier membrane (16) in the form of a strain gauge, wherein the carrier membrane (16) does not have a piezo element, wherein the carrier membrane (16) is deformable within the flow channel (12) depending on the volume flow (V) of the gas, wherein upon movement of the carrier membrane (16) and / or deformation of the first sensor, at least one signal is generated depending on the volume flow (V) of the gas, that the carrier membrane (16) is connected to the inner peripheral surface (13) of the flow channel (12) in such a way that the carrier membrane (16) has a free end with which the carrier membrane (16) is movable back and forth within the flow channel (12), and that the flow of the gas within the flow channel (12) is laminarized adjacent to or near the support membrane (16).

Description

[0001] The invention relates to a method and a device for determining the volume flow, pressure and composition of a gas during breathing or ventilation of a patient.

[0002] In the field of medicine, when supplying patients with respiratory gas or breathing air, it is generally necessary to have precise information about this respiratory gas or breathing air. For this purpose, measurement parameters are recorded that are characteristic of a respiratory gas or breathing air that is supplied to the patient or is inhaled or exhaled by the patient. These measurement parameters include, in particular, the quantity of respiratory gas supplied, which is determined by the volume flow, the pressure of the supplied gas and its composition, particularly with regard to the proportions of oxygen and carbon dioxide it contains and their concentration.

[0003] According to the state of the art, volume flow sensors are constructed from a hot-wire anemometer. As is well known, hot-wire anemometry uses a very thin wire with a diameter of only a few micrometers, typically made of platinum, nickel, tungsten, or various alloys. The measuring principle is that this thin wire is electrically heated, with the heat transferred from this wire to the passing air serving to determine the flow velocity.

[0004] From DE 10 2010 030 324 A1, DE 20 2017 005 964 U1 and DE 11 2013 001 902 T5, ventilation devices are known in which volume flow or flow rate sensors based on a hot-wire anemometer are used.

[0005] Furthermore, DE 10 2017 124 256 A1 discloses a respiratory gas detection system in which the concentration of carbon dioxide in the respiratory gas is determined using a thermal conductivity sensor, which can be designed in the form of a hot-wire anemometer.

[0006] The provision of a hot-wire anemometer, especially for forming a volume flow sensor, is costly per se and is associated with the further disadvantage that, in conjunction with this, complex and fast control circuits are usually required in order to keep the hot wire at an averagely constant temperature.

[0007] Another measurement principle for determining volume flow, which is less complex than hot-wire anemometry, is based on the state of the art. A sensor, particularly in the form of a strain gauge, is mounted on a flexible carrier membrane. A gas flows through the carrier membrane, protruding into a flow channel through which the gas is directed to or away from a patient. The strain gauge converts the deformation of the flexible carrier membrane with the attached strain gauge when exposed to the gas flow into a signal. This signal generally has a clear functional relationship to the volume flow of the gas within the flow channel.A volume flow measurement using such strain gauges mounted on a flexible carrier membrane is known, for example, from GB 2121185 A, WO 2011 / 067734 A1, or WO 2015 / 169848 A1. However, it is not known from these publications that the devices shown therein, which, as explained, are equipped with strain gauges for measuring the volume flow of a gas, also enable the analysis of a gas flowing through a flow channel with respect to its individual components, such as oxygen or carbon dioxide.

[0008] EP 2 996 750 B1 discloses a device for providing respiration in emergencies. This device comprises a flow channel in the form of a flow tube and a flow sensor arranged therein. The flow sensor comprises a sensor holder at one end, which protrudes into the flow tube when the flow sensor is mounted. The flow sensor and the associated sensor holder are each designed as rigid bodies and are therefore not flexible or deformable.

[0009] EP 0 461 281 A1 discloses a device for detecting air flow through a passage in the form of a cavity. This device utilizes a piezoelectric film sensor 36 that extends through the entire cross-section of the cavity. The film sensor consists of a thin layer of piezoelectric polymer film coated with an electrode. An opening is formed in a central region of the film sensor, through which air or gas can flow. If air or gas passes through this opening, the piezoelectric film sensor 36 is set into vibration, and then, by means of the electrode applied thereto, electrical signals are generated, corresponding to the air or gas flow passing through the opening.

[0010] Accordingly, the object of the invention is to optimise, in connection with the breathing or ventilation of a patient with respect to a gas flowing to or from the patient, the determination of characteristic measurement parameters of this gas, which also include the analysis of the components of the gas, using particularly inexpensive and simple means.

[0011] The above object is achieved by a method having the features of claim 1 and by a device defined by the features of claim 13. Advantageous developments of the invention are the subject of the dependent claims.

[0012] The present invention provides a method for determining the volume flow, pressure, and composition of a gas that is passed through a flow channel during breathing or ventilation of a patient. The volume flow of the gas is measured by means of a flexible carrier membrane that is arranged in the flow channel essentially orthogonal to the flow direction of the gas, wherein at least one first sensor in the form of a strain gauge is attached to at least one surface of the carrier membrane, wherein the carrier membrane does not have a piezo element. The flexible carrier membrane can be deformed within the flow channel depending on the volume flow of the gas, wherein upon movement of the carrier membrane and / or deformation of the first sensor, at least one signal is generated that depends on the volume flow of the gas.Furthermore, a pressure measuring device is arranged in the flow channel, in particular in the region of its wall, wherein this pressure measuring device measures a static pressure for the gas flowing within the flow channel in comparison to the external environment of the flow channel. The composition of the gas, in particular selected gases formed from the group of at least oxygen (O2) and carbon dioxide (CO2), is determined by at least one, in particular catalytic, second sensor arranged within the flow channel. The support membrane is connected to the inner circumferential surface of the flow channel in such a way that the support membrane has a free end with which the support membrane is movable back and forth within the flow channel, wherein the flow of the gas within the flow channel is laminarized adjacent to or in the vicinity of the support membrane.

[0013] Similarly, the invention provides a device with which the volume flow, pressure, and composition of a gas can be determined during breathing or ventilation of a patient. Such a device comprises a flow channel that can be connected to a ventilator and through which the gas can flow, at least one flexible support membrane arranged in the flow channel substantially orthogonal to the flow direction of the gas, wherein at least one first sensor in the form of a strain gauge is attached to at least one surface of the support membrane, wherein the support membrane does not have a piezo element, wherein the support membrane is deformable within the flow channel depending on the volume flow of the gas, and upon movement of the support membrane and / or deformation of the first sensor, at least one signal can be generated depending on the volume flow of the gas, a pressure measuring device,which is arranged in the flow channel, in particular in the region of its wall, wherein this pressure measuring device can be used to measure a static pressure for the gas flowing within the flow channel in comparison to the external environment of the flow channel, and at least one, in particular catalytic, second sensor arranged within the flow channel, with which a composition of the gas, in particular selected gases formed from the group of at least oxygen (O2) and carbon dioxide (CO2), can be determined. The support membrane is connected to the inner circumferential surface of the flow channel in such a way that the support membrane has a free end with which the support membrane can be moved back and forth within the flow channel. At least one laminarization device is provided within the flow channel, with which the flow of the gas directed towards the support membrane is laminarized,wherein the laminarization device is arranged adjacent to or near the support membrane.,

[0014] According to the present invention, the first sensor, which is attached to at least one surface of the flexible support membrane, is designed in the form of a strain gauge (short: "SG"). Typically, a movement or deflection of the flexible support membrane upon contact with the gas flowing through the flow channel leads to a deformation of the SG, which then generates an electrical signal that is dependent on, for example, proportional to, the volume flow passing through the flow channel.

[0015] To optimize bidirectional measurement of the volume flow with the flexible support membrane, an advantageous development of the invention provides for first sensors to be mounted on both sides of the support membrane, i.e., on opposite surfaces thereof. Nevertheless, it should be noted at this point that bidirectional measurement of the volume flow is already possible if a first sensor in the form of a strain gauge is provided only on or on one surface of the flexible support membrane, i.e., only on one side thereof.

[0016] A first sensor in the form of a strain gauge can be attached externally to a surface of the flexible support membrane, for example, by adhesive bonding. In addition or alternatively, it is also possible to structurally incorporate a strain gauge into the material of the flexible support membrane.

[0017] The measurement of the volume flow for a gas conducted through the flow channel by at least one first sensor is considerably simpler and more cost-effective compared to the measurement technology based on hot-wire anemometry in that this first sensor is mounted in the form of a strain gauge on the surface of a flexible carrier membrane and, when the first sensor is deformed, which occurs when the gas flows against the carrier membrane and the carrier membrane is deflected as a result, an electrical signal is generated which is dependent or proportional to the volume flow of the gas.

[0018] As already explained, according to an advantageous development of the invention, it may be recommended that first sensors in the form of a strain gauge be mounted on the opposite surfaces of the flexible support membrane. This allows for the measurement of the volume flow of a gas flowing through the flow channel in both directions.

[0019] The invention is based on the essential finding that it is possible to simultaneously measure or determine, in a robust and reliable manner, several measurement parameters for a gas that is either directed to the patient or has been exhaled by the patient and is flowing away from them. These parameters include the volume flow (= "flow"), which, as explained, is determined using a first sensor attached to a flexible carrier membrane and, according to the invention, a strain gauge, and the pressure of the gas, and in particular also the components of the gas, for example the proportions of oxygen and / or carbon dioxide, which are contained in the gas directed through the flow channel and can be determined using the second sensor.

[0020] The device according to the invention provides a compact and inexpensive combination device, preferably in the form of a disposable article, with which the above-mentioned measurement parameters for a gas flowing from or to the patient can be determined in a simple and robust manner.

[0021] In an advantageous development of the invention, the determination of said measurement parameters of the gas conducted through the flow channel (i.e., volume flow, pressure, and composition of a gas) is carried out for the portion of the gas that flows through the flow channel toward the patient and is accordingly inhaled by the patient or actively flows into the patient's lungs. In this context, the gas that is directed toward the patient can be referred to as "fresh gas."

[0022] In an advantageous development of the invention, the volume flow, pressure, and composition of a gas are determined for the portion of the gas flowing through the flow channel away from the patient and thus exhaled by the patient. In this context, the gas exhaled by the patient and flowing away from him or her can be referred to as "patient gas."

[0023] In an advantageous development of the invention, an evaluation unit is provided for the method or device. This makes it possible for the measured values ​​of a first sensor mounted on the flexible support membrane, the pressure measuring device, and the second sensor to be transmitted to this evaluation unit. Such transmission of the measured values ​​to the evaluation unit can be done via cable, thus eliminating the possibility of these measured values ​​being corrupted by other (interference) signals.

[0024] For further processing or further use of the measured values ​​received by the evaluation unit from the first sensor, the pressure measuring device, and the second sensor, it is advantageous if these measured values ​​are digitized. For this purpose, the evaluation unit can be equipped with suitable means that are programmed in such a way that the measured values ​​from the first sensor, the second sensor, and the pressure measuring device can be digitized and preferably also stored in the evaluation unit.

[0025] In an advantageous development of the invention, a transmitting unit is provided that is in signal communication with the evaluation unit, preferably also via a cable. Thus, the measured values ​​of the first sensor, the second sensor, and the pressure measuring device received by the evaluation unit can be transmitted to the transmitting unit for subsequent transmission of these measured values ​​by the transmitting unit to another external device.

[0026] It is advantageous if the evaluation unit and the transmitter unit are integrated into a single device. This saves space and enables short cable and data connections between the individual electronic components of these units.

[0027] The data transmission of the measured values ​​from the first sensor, the second sensor, and the pressure measuring device from the transmitting unit to an external device can be carried out wirelessly via a radio link or similar. For example, the Bluetooth communication protocol or the ZigBee communication protocol is suitable for this wireless data transmission.

[0028] In an advantageous development of the invention, the external device to which the measurement data is sent from the transmitting unit can be a control device for patient ventilation. In other words, such a control device can be part of a ventilator with which the method according to the invention is carried out and / or with which the device according to the invention is used. Based on this, the measured values ​​from the first sensor, the second sensor, and the pressure measuring device can then be suitably processed by the control device of the ventilator and taken into account for controlling or regulating a patient's ventilation.

[0029] In an advantageous development of the invention, the volume flow, pressure, and composition of the gas fed into a flow channel leading to the patient can be controlled, preferably regulated, by means of the aforementioned control device of a ventilator depending on the measured values ​​of the first sensor mounted on the flexible carrier membrane, the pressure measuring device, and the second sensor, which is particularly catalytic. This ensures that the patient's breathing is actually supported or controlled / regulated by the ventilator only with the necessary parameters that correspond to predetermined values.

[0030] In an advantageous development of the invention, a display unit can be provided that is in signal communication with the control device. This display unit can be used to appropriately visualize both the measured values ​​of the first sensor, the second sensor, and the pressure measuring device transmitted by the transmitting unit, as well as the control variables of the control device used to support or control a patient's ventilation.

[0031] When applying or implementing the present invention, the volume flow for a gas conducted through the flow channel is determined, as explained, by a first sensor which is located on at least one surface of a flexible support membrane arranged substantially orthogonally to the flow direction. The aim here is for the gas to flow against the flexible support membrane evenly and free of turbulence. For this purpose, the invention provides for the gas flow within the flow channel to be laminarized or evened out adjacent to or in the vicinity of the support membrane. A laminarization device used for this purpose can be arranged upstream and / or downstream of the support membrane, viewed in the direction of the patient.This means that such a laminarization device is either arranged only on one side of the support membrane, for example, upstream of the support membrane (for the "fresh gas" discussed above) as viewed in the direction of the patient, or that such laminarization devices are arranged on both sides of the support membrane. The latter ensures that the patient gas flowing from the patient's direction toward the support membrane is also specifically laminarized before reaching the support membrane.

[0032] To protect the patient from contaminants and / or germs or bacteria in the "fresh gas" supplied to them, an advantageous development of the invention can provide a particle and / or bacteria filter for the fresh gas introduced into or flowing into the flow channel. This filter ensures that the "fresh gas" flowing toward the patient is effectively filtered for particles and / or bacteria or germs.

[0033] Similarly, according to an advantageous development of the invention, a particle and / or bacteria filter for the patient gas can be arranged in the flow channel. This ensures that the patient gas exhaled by the patient and flowing away from him is effectively filtered for contaminants and / or germs or bacteria, preventing them from being transported further in the flow channel and possibly reaching a ventilator connected to the flow channel.

[0034] With regard to the aforementioned particle and / or bacterial filters, it should be noted that they effectively filter out any disruptive particles from the gas, including virus particles (also known as "virions"). This means that with the help of a particle and / or bacterial filter, viruses or "virions" can also be filtered out of the gas, both in the "fresh gas" flowing toward the patient and in the patient gas exhaled by the patient. This ensures that viruses are neither absorbed by the patient nor released into the environment or to the ventilator.

[0035] In an advantageous development of the invention, it is possible to convert the volume flow that has been determined and directed through the flow channel into a total gas volume. This is possible both for the "fresh gas" directed toward the patient and for the "patient gas" exhaled by the patient.

[0036] Based on the determination of the total volume of gas conducted through the flow channel, as explained above, it is also possible to determine the remaining service life of a particle and / or bacterial filter used in conjunction with the invention. Once this service life has been reached, either this filter or the entire device according to the invention, including this filter, can be replaced in a timely manner to avoid contamination of the patient and / or the ventilator.

[0037] In an advantageous development of the invention, a laminarization device and a particle and / or bacteria filter can be combined into an integrated unit. This leads to the advantage of a small space requirement within the flow channel at the point where both laminarization of the gas flow and filtration are desired. The arrangement of such an integrated unit consisting of a laminarization device and a particle and / or bacteria filter can be specifically arranged either on one side of the support membrane or on both sides of the support membrane.

[0038] In an advantageous development of the method according to the invention, it can be provided that the volume flow (flow) conducted through the flow channel is converted into at least one volume value based on a derived variable. This volume value can be a tidal volume (V T) and / or a minute volume (V M ) act.

[0039] According to an advantageous development, the device according to the invention comprises a battery or accumulator unit that is electrically connected to the electrical or electronic components of the device for supplying energy. The capacity of this battery or accumulator unit is expediently selected to be large enough to ensure a power supply for the electrical or electronic components of the device connected to the battery or accumulator unit for a period of at least 24 hours, preferably at least 36 hours, more preferably at least 48 hours.

[0040] If the device according to the invention is designed as a disposable item, it can be provided that the battery or accumulator unit is removable from a housing of the device. This approach allows the battery or accumulator unit to be disposed of separately from the device for environmental reasons, or—in the case of a pure accumulator unit—to be reused for a new device after a suitable charging process.

[0041] Preferred embodiments of the invention are described in detail below with reference to a simplified schematic drawing. They show: Fig. 1 a device according to the invention in a basic sectional view according to a first embodiment, Fig. 2 a device according to the invention in a basic sectional view according to a second embodiment, Fig. 3 a longitudinal sectional view through a flow channel of the device of Fig. 1, Fig. 4 a longitudinal sectional view through a flow channel of the device of Fig. 2, Fig. 5 a front view of a flexible carrier membrane according to the embodiment of Fig. 1, Fig. 6 a front view of a flexible carrier membrane according to the embodiment of Fig. 2, Fig. 7 a device according to the invention in a basic sectional view according to a third embodiment, Fig. 8 shows a device according to the invention in a basic sectional view according to a fourth embodiment, Fig. 9 a fundamentally simplified side view of a flexible carrier membrane of the device according to the invention, and Fig. 10 a fundamentally simplified side view of a flexible carrier membrane of the device according to the invention according to a further embodiment.

[0042] With reference to the Fig. 1-10, preferred embodiments of a device 10 according to the invention and a corresponding method are illustrated and explained below, with which a patient is breathed or ventilated through a flow channel. Identical features in the drawings are provided with identical reference numerals. It is specifically noted that the drawing is merely simplified and, in particular, not to scale.

[0043] In a first embodiment according to Fig. 1, the device 10 according to the invention comprises a flow channel 12 which leads from a ventilator 14 to a patient P.

[0044] Within the flow channel 12, a flexible support membrane 16 is attached to its inner circumferential surface 13. The two arrows in Fig. 1 at the lower end of the support membrane 16, it is symbolized that at this point the support membrane 16 is not connected to the inner circumferential surface 13 of the flow channel 12 and is thus movable back and forth within the flow channel 12 with its free end formed thereby.

[0045] First sensors 18 in the form of strain gauges (short: “DMS”) are attached to the two opposing surfaces 17 of the carrier membrane 16. In the Fig. 1 these DMS are simply symbolized by dashed lines.

[0046] Fig. Figure 5 shows a front view of a flexible carrier membrane 16 according to the embodiment of Fig. 1, namely from the direction of a flow direction S.

[0047] From this it can be seen that several strain gauges are arranged on a surface 17 of the carrier membrane 16, which are symbolized here in a simplified representation by dotted lines.

[0048] Furthermore, the presentation of Fig. 5 that a lower free end of the support membrane 12 has no contact with the adjacent inner circumferential surface 13 of the flow channel 12. This ensures the aforementioned reciprocating mobility of the lower free end of the flexible support membrane 16 if the support membrane 12 is subjected to the flow of gas conducted through the flow channel 12.

[0049] The carrier membrane 16 is additionally in the Fig. 9 is shown in a fundamentally simplified side view. This shows that a cross-section of the support membrane 16 is essentially constant, with first sensors or strain gauges 18 being attached to the two opposite surfaces of the support membrane 16, symbolized here in a highly simplified manner by dashed lines.

[0050] To ventilate the patient P, a gas is passed through the flow channel 12. The arrows “S” in the illustration of Fig. 1 symbolizes the two possible flow directions - from this it can be seen that a gas can flow through the flow channel 12 both in the direction of the patient P (in Fig. 1 from left to right) and, after the patient has exhaled, away from the patient P (in Fig. 1 from right to left).

[0051] The attachment of the support membrane 16 to the inner circumferential surface 13 of the flow channel 12 is such that the support membrane 16 is arranged in the flow channel 12 essentially orthogonal to the flow direction S of the gas. This has the advantage that the support membrane 16 can be used for a bidirectional measurement of the volume flow V, which will be explained separately below.

[0052] The flexible support membrane 16 with the attached strain gauges 18 serves to determine the volume flow V of the gas within the flow channel 12. Accordingly, in the illustration of Fig. 1, to the right of the carrier membrane 16, is symbolized by the symbol V in a circle. Details are explained separately below.

[0053] The flow channel 12 of the device 10 can be connected to a Y-connector (not shown) leading to the patient P. Taking this Y-connector into account, the first sensor 18 (or the two strain gauges 18) mounted on the flexible carrier membrane 16 can be used to determine both the inspiratory flow of a "fresh gas," which is conducted through the flow channel 12 toward the patient and then inhaled by the patient, and the expiratory flow of a patient gas that has been exhaled by the patient. Accordingly, with the carrier membrane 16 and the strain gauges 18 applied thereto, a bidirectional measurement of the volume flow V is possible, namely both for the "fresh gas" FG, which flows toward the patient P, and for the patient gas PG, which has been exhaled by the patient and flows away from him.

[0054] The device 10 comprises a pressure measuring device 20 with which a static pressure p is determined or measured for the gas flowing within the flow channel 12.

[0055] The pressure measuring device 20 can be arranged in or on a wall W of the flow channel 12.

[0056] The static pressure p within the flow channel 12 can be measured by equipping the pressure measuring device 20 with a strain gauge (“SG”) 21. In this case, the static pressure p within the flow channel 12 is determined in comparison to the ambient pressure prevailing outside the flow channel 12 based on the deformation of the SG 21.

[0057] In addition, the pressure measuring device 20 can also be equipped with a piezo element 22. In this case, the static pressure p prevailing within the flow channel 12 is measured in a known manner, taking into account a mechanical force acting on the piezo element 22, in particular from the direction of the flow channel 12.

[0058] The symbolically simplified representation of Fig. 1 illustrates that when the pressure measuring device 20 is mounted on the flow channel 12, the strain gauge 21 or the piezo element 22 can run in a part of the wall W of the flow channel 12 or in alignment therewith.

[0059] The device 10 further comprises a second sensor 24, which can be used to determine the composition of the gas flowing through the flow channel. Such an analysis of the gas can be used to determine, in particular, the proportions of oxygen O2 and / or carbon dioxide CO2, or possibly other gases that may be present in the gas.

[0060] The second sensor 24 can be designed in the form of a catalytic foil, which as such is part of the state of the art and therefore requires no further explanation at this point.

[0061] Additionally or alternatively, the second sensor 24 can be based on the ultrasonic measurement principle. Accordingly, the composition and concentration of individual gas components within the gas stream are determined using an ultrasonic sensor.

[0062] Irrespective of its measuring principle, the second sensor 24, when used with the device 10 according to the invention, fulfils the function of a gas analyzer with which, as explained, various gas components and their concentrations contained in the gas passed through the flow channel can be measured.

[0063] The Fig. The arrangement or positioning of the second sensor 24 within the flow channel 12 shown in Figure 1 is to be understood merely as an example. Alternatively, it can also be provided that the second sensor 24 is arranged in a secondary channel (not shown) running parallel to the flow channel 12, which branches off from the flow channel or opens into it. A measurement of the gas components and their concentration with a second sensor 24 arranged in this alternative secondary channel is possible with the same reliability as with the Fig. 1 with respect to the second sensor 24.

[0064] With regard to the second sensor 24, it is further noted that the device 10 may also comprise a plurality of such sensors 24, which may be provided, for example, at different locations along the flow channel 12. This plurality of second sensors 24 may either be based on the same measuring principle or operate according to different measuring principles, for example, according to a catalytic film or the ultrasonic measuring principle as explained above.

[0065] The device comprises an evaluation unit 26, which is designed to receive the measured values ​​from the first sensor 18, the pressure measuring device 20, and the second sensor 24. For this purpose, the evaluation unit 26 can be connected by cable to the first sensor 18, the pressure measuring device 20, and the second sensor 24. In other words, a signal cable each leads from the first sensor 18, the pressure measuring device 20, and the second sensor 24 to the evaluation unit 26, thereby transmitting the individual measured values ​​to the evaluation unit 26.

[0066] The evaluation unit 26 may have a memory (not shown). Accordingly, the measured values ​​of the first sensor 18, the pressure measuring device 20, and the second sensor 24 can be stored or filed in the memory of the evaluation unit 26.

[0067] For further processing of the measured values ​​from the first sensor 18, the pressure measuring device 20, and the second sensor 24, it is advantageous if these measured values ​​are available in digitized form. Accordingly, the evaluation unit 26 can be programmed in such a way that the measured values ​​received from the first sensor 18, the pressure measuring device 20, and the second sensor 24 are appropriately digitized following this reception. In this regard, it is understood that these digitized measured values ​​can then also be stored in the memory of the evaluation unit 26.

[0068] The device 10 also includes a transmitting unit 28, which can be mounted anywhere on the device in the same way as the evaluation unit 26. This transmitting unit 28 is in signal communication with the evaluation unit 26, preferably via a cable. Alternatively, it is also possible for the transmitting unit 28 to be in signal communication directly with the first sensor 18, the pressure measuring device 20, and the second sensor 24, also preferably via a cable. In any case, the transmitting unit 28 is provided and designed to transmit the measured values ​​of the first sensor 18, the pressure measuring device 20, and the second sensor 24, or the corresponding data received by the evaluation unit 26, to an external device, preferably wirelessly via a radio link F or the like. The external device can be a control or regulating device of a ventilator, which will be explained separately below.

[0069] The transmitting unit 28 and the evaluation unit 26 can expediently be integrated into a common device. Thus, these two units then form a common component for the device according to the invention, which enables both the reception of the measured values ​​from the first sensor 18, the pressure measuring device 20, and the second sensor 24, optionally digitizing these measured values, and subsequently sending or transmitting these measured values ​​to another external device.

[0070] The device 10 is equipped with a battery or accumulator unit 29, to which the individual electrical or electronic components of the device 10 are connected. Accordingly, these components, namely the first sensor (or strain gauge) 18, the pressure measuring device 20, the second sensor 24, the evaluation unit 26, and the transmitter unit 28, are appropriately supplied with energy by the battery or accumulator unit 34.

[0071] The flow channel 12 of the device 10 can be connected to or attached to a ventilator 14.

[0072] The ventilator 14 has a control device 15. With the aid of this control device 15, a breathing gas supplied to the patient through the flow channel 12 of the device 10 can be adjusted to predetermined values ​​with respect to the parameters volume flow V, pressure, and / or composition of the gas, preferably in the manner of a control or regulation.

[0073] The ventilator 14 includes a battery or accumulator unit 34. With the help of this battery or accumulator unit 34, the ventilator 14 can be operated without mains power if necessary, for example, in the event of a mains power failure. Thanks to the battery or accumulator unit 34, "emergency operation" of the ventilator 14 is ensured for at least a few hours or even days.

[0074] The external device to which the measured values ​​of the first sensor 18, the pressure measuring device 20 and the second sensor 24 are transmitted from the transmitting unit 28 of the device 10, preferably via a radio link, can be the control device 15 of the ventilator 14. In the illustration of Fig. In Figure 1, this radio link is labeled "F" and symbolized by individual radio waves. As explained elsewhere above, this radio link F can be based on the Bluetooth communication protocol or the ZigBee communication protocol.

[0075] The ventilator 14 is equipped with a display unit D. On the display of this display unit D, the individual measured values ​​of the device 10, which have been received via the radio link F from the control or regulation device 15, and / or the respective parameters selected for the gas introduced into the flow channel 12, can be visualized.

[0076] The invention and the associated method now work as follows: An inspiratory gas, hereinafter also referred to as “fresh gas” FG, is introduced into the flow channel 12 by the ventilator 14 with a predetermined volume flow V, a predetermined pressure p and a predetermined gas composition and directed towards the patient P.

[0077] When the fresh gas FG flows onto the flexible support membrane 16, the support membrane 12 is deflected, which in the longitudinal section of Fig. 3 is directed to the right and is symbolized by the double-dash-dotted line 16'. As a result of this deflection, the strain gauges 18 attached to the surfaces 17 of the support membrane 16 are deformed. The electrical resistance of the strain gauges 18 changes accordingly, with the corresponding electrical signals being sent to the evaluation unit 26. The magnitude of these electrical signals or the degree of change in the electrical resistance of the strain gauges 18 depends on the deflection of the flexible support membrane 16, for example, proportional thereto, and thus represents a parameter for the volume flow V with which the fresh gas FG is conducted through the flow channel 12 and, as explained, flows against the flexible support membrane 16.

[0078] By means of the flexible carrier membrane 16, the volume flow V of the patient gas PG can also be measured, which has been exhaled by the patient P. When the flexible carrier membrane 16 is flowed against by the patient gas PG, the carrier membrane 16 is now deflected in the opposite direction, which in the longitudinal section of Fig. 3 is directed to the left and is symbolized by the double-dash-dotted line 16". In the same way as before during the deflection by the fresh gas FG, the electrical resistance of the two strain gauges 18, which are attached to the surfaces 17 of the carrier membrane 16, is now changed during the deflection 16" to the left of the carrier membrane 16 caused by the patient gas PG. As a result, electrical signals are generated by the strain gauges 18 and sent to the evaluation unit 26. These electrical signals represent a parameter for the volume flow V, with which the patient gas PG now flows through the flow channel 12.

[0079] The optional measurement of the volume flow V either for the fresh gas FG or for the patient gas is shown in the diagram of Fig. 1 is also symbolized by a double arrow running horizontally in the central area of ​​the carrier membrane 16.

[0080] For the functioning of the device 10 according to the invention and the corresponding method, it is important that, at the same time as the measurement of the volume flow V, which, as explained above, is carried out either for the fresh gas FG or for the patient gas PG, the static pressure p present within the flow channel 12 for the gas conducted through the flow channel 12 (i.e., the fresh gas FG or the patient gas PG) is determined with the aid of the pressure measuring device 20. Likewise, at the same time, the individual components of the respective gas and their concentration(s) are determined with the aid of the second sensor 24.

[0081] In the same way as for the strain gauge 18, the measured values ​​of both the pressure measuring device 20 and the second sensor 24 are then sent to the evaluation unit 26.

[0082] After receipt of the above-mentioned measured values ​​by the evaluation unit 26, and if necessary following an optional digitization, which is possible by means of the evaluation unit 26 as explained, these measured values ​​are sent to the transmitting unit 28 and then transmitted from the transmitting unit 28 via the radio link F to the control device 15 of the ventilator 14.

[0083] During operation of the ventilator 14, the received measured values ​​of the device 10, i.e., the determined current information regarding the volume flow V, pressure p, and composition of the gas (either the fresh gas FG or the patient gas PG) conveyed through the flow channel 12, can be taken into account or processed by the control device 15 of the ventilator 14, for example, in a control system. Based on this, it is then possible to appropriately adjust the fresh gas FG, which is conveyed through the flow channel 12 toward the patient P.

[0084] Further embodiments of the invention are explained below. Insofar as these embodiments have the same functional principle as the embodiment of Fig. 1, to avoid repetition, reference may be made to the explanations to Fig. 1.

[0085] Fig. 2 shows a second embodiment of the device 10 according to the invention. In contrast to the embodiment of Fig. 1, the support membrane 16 is designed in the manner of a "sail". The support membrane 16 extends essentially orthogonally to the flow direction S of the gas completely through a diameter of the flow channel 12, regardless of its cross-sectional geometry. This means that the support membrane 16 is fastened with its opposite regions B, i.e., with both an upper edge region and a lower edge region, to the inner circumferential surface 13 of the flow channel 12. This type of fastening of the support membrane 16 is also shown in the longitudinal sectional view of Fig. 4 as well as in the frontal view of the carrier membrane 16 according to the illustration of Fig. 6 shown.

[0086] The front view of Fig. 6 further illustrates a possible course of individual strain gauges 18 which are attached or provided on a surface 17 of the carrier membrane 16.

[0087] With regard to the second embodiment of the device 10, a deflection of the carrier membrane 16, which occurs in the case of an inflow through the gas guided in the flow channel 12, is in the Fig. 4 is shown in a simplified manner.

[0088] When the inspiratory fresh gas FG flows against the carrier membrane 16, particularly in its central area, it is deflected to the right, as shown in Fig. 4 is symbolized by the double-dash-dotted line 16'. This results in a deformation of the strain gauge 18. As a result, in the same way as in the embodiment of Fig. 1, due to a change in the electrical resistance of the strain gauges 18, electrical signals are then sent from the strain gauges 18 to the evaluation unit 26, wherein these electrical signals represent a characteristic value for the volume flow V with which the fresh gas FG is passed through the flow channel 12.

[0089] When flowing through the expiratory patient gas PG, the carrier membrane 16 in the second embodiment - with reference to the longitudinal section view of Fig. 4 - to a flow from right to left. Accordingly, there is a deflection to the left, particularly in the central area of ​​the flexible carrier membrane 16, as shown in the Fig. 4 is symbolized by the double-dash-dotted line 16". The deformation of the strain gauge 18 that occurs here leads, as already explained, to a change in its electrical resistance, as a result of which corresponding electrical signals are then sent to the evaluation unit 26.

[0090] The second embodiment of the device 10 according to Fig. 2 has, with respect to the attachment of the carrier membrane 16 with its opposite regions B to the inner circumferential surface 13 of the flow channel 12, compared to the embodiment of Fig. 1 has the advantage that any spatial positioning of the device 10 has little to no influence on the response behavior of the flexible carrier membrane 16 and its deflection when this carrier membrane 16 is laterally flowed against by a gas.

[0091] Otherwise, the operation of the second embodiment of the device 10 corresponds to Fig. 2 those of Fig. 1.

[0092] Fig. Figure 7 shows a third embodiment of the device 10 according to the invention. In addition to the second embodiment, laminarization devices 30 are arranged within the flow channel 12, namely on both sides of the support membrane 16 and adjacent thereto. These laminarization devices 30 are shown in Fig. 7 each symbolized in a highly simplified manner by vertical dash-dotted lines.

[0093] If fresh gas FG or patient gas PG is passed through the flow channel 12 toward the support membrane 16, this gas flows through the laminarization devices 30. As a result, the gas is homogenized and freed from possible turbulence before reaching the support membrane 16.

[0094] Given that the gas flow against the support membrane 16 has been evened out or laminarized by the laminarization devices 30, a better, i.e., more uniform, flow is achieved for the support membrane 16, which in turn leads to an optimized deflection of the support membrane 16 due to the gas flow. As a result, a more precise measurement of the volume flow V can be achieved using the support membrane 16 and the strain gauge 18 mounted thereon, because, for example, "fluttering" of the support membrane 16 due to turbulence is prevented.

[0095] Otherwise, the operation of the third embodiment of the device 10 corresponds to Fig. 7 of those of Fig. 1.

[0096] Fig. 8 shows a fourth embodiment of the device 10 according to the invention. In addition to the third embodiment, particle and / or bacterial filters 32 are arranged within the flow channel 12 adjacent to the laminarization devices 30, which are shown in a symbolically simplified manner by hatched areas.

[0097] These particle and / or bacterial filters 32 effectively retain any disruptive particles, contaminants, bacteria, germs, or the like that may be contained in the fresh gas FG and / or the patient gas PG. As a result, these particles, contaminants, bacteria, germs, or the like cannot reach the patient P, the ventilator 14, or the environment. In this context, it is again pointed out that the particle and / or bacterial filters 32 are also suitable for filtering out viruses or associated virus particles ("virions") from the fresh gas FG and / or the patient gas PG.

[0098] With regard to the particle and / or bacterial filters 32, it is expedient if they are designed as an integrated unit with the laminarization devices 30. In this case, the fresh gas FG or the patient gas PG, when flowing through such an integrated unit, is both laminarized in terms of its flow and appropriately filtered.

[0099] With regard to the particle and / or bacterial filters 32, it is specifically emphasized at this point that, in contrast to the illustration in Fig. 8, for the device 10 according to the invention, if necessary, can also be provided without the laminarization devices 30. Furthermore, it is possible to arrange a particle and / or bacteria filter 32, if necessary, only on one side of the carrier membrane 16.

[0100] The representation of Fig. Figure 8 further shows a housing 36, which is provided for the device 10 and is symbolized here only in a simplified manner by a dot-dash rectangle. With regard to this housing 36, it is understood that all essential components of the device 10 are housed or integrated in this housing 36. In this respect, the housing 36 also fulfills a protective function for the components of the device 10 accommodated therein. It is understood that the Fig. 8 shown housing 36 in the same way also for the embodiments according to the Fig. 1, Fig. 2 and Fig. 7 may be provided.

[0101] Otherwise, the operation of the fourth embodiment of the device 10 corresponds to Fig. 8 of those of Fig. 1.

[0102] In addition, with regard to the third and fourth embodiments of the device 10, it should be noted that, in contrast to the illustrations in Fig. 7 or Fig. 8, an attachment of the carrier membrane 16 to the inner circumferential surface 13 of the flow channel 12 is also possible in the manner as in the first embodiment of Fig. 1 has been shown and explained.

[0103] Fig. 10 shows a further variant for a possible design of the carrier membrane 16, which is similar to the first embodiment of Fig. 1 is attached only with its upper end to the inner circumferential surface 13 of the flow channel 12 and thus has a lower free end. In the same way as in the Fig. 1 is in the Fig. 10 by the two arrows adjacent to the lower end of the support membrane 16, it is clear that a deflection of the support membrane 16 to the right or to the left is possible when it is flowed by the fresh gas FG (from the left) or by the patient gas PG (from the right). The side view of Fig. Figure 10 illustrates that this variant of the carrier membrane 16 is trapezoidal in cross-section along its longitudinal extent, with the cross-section decreasing towards the lower free end. First sensors 18, preferably in the form of strain gauges, are attached to the two opposite surfaces of the carrier membrane 16, for example according to an arrangement of Fig. 5.

[0104] The variant of a carrier membrane 16 according to the embodiment of Fig. 10 has compared to the embodiment of Fig. 1 a greater bending stiffness in the direction of flow S, and is thus suitable for relatively large volume flows V of a gas which is passed through the flow channel 12. In this regard, it should be noted that the above-shown embodiments of the device 10 according to Fig. 1, Fig. 7 and Fig. 8 alternatively with a carrier membrane according to the embodiment of Fig. 10 can be equipped.

[0105] In all of the aforementioned embodiments of the device 10, it is possible for additional coatings having hygroscopic, hydrophilic, hydrophobic, and / or protein-repellent properties to be applied to the surfaces of the support membrane 16 and the first sensors 18 mounted thereon. Such coatings can be applied to the entire surface or locally to the surface(s) of the support membrane 16. If such a coating has hygroscopic properties, this leads, among other advantages, to the ability of viruses and / or bacteria to bind to the water droplets that adhere to or on this coating.

[0106] Finally, for all of the embodiments of the device 10 according to the invention shown and explained above, it should be noted that the carrier membrane 16 does not extend in its width across the entire cross-section of the flow channel 12, but is arranged only in a partial area of ​​the cross-section of the flow channel 12, for example in the form of a rectangular strip. As a result, it is always possible for a gas guided within the flow channel 12 to flow laterally past the carrier membrane 16, as is shown, for example, in the front views according to Fig. 5 and Fig.6. This means that a flexible support membrane 16, viewed across the width of the flow channel 12, is only as large as is necessary for sufficient flow and the desired deflection of the support membrane 16, in order to thereby obtain measurement signals by means of the first sensors 18, which represent a characteristic value for the volume flow V of the gas. List of reference symbols 10 Device 12 flow channel 13 Inner peripheral surface (of the flow channel 12) 14 Ventilator 15 Control or regulation device 16 flexible carrier membranes 17 Surface (of the carrier membrane 16) 18 first sensor (in the form of a strain gauge and possibly also a piezo element) 20 pressure measuring device 21 strain gauges 22 Piezo element 24 second sensor (particularly in the form of a catalytic film) 26 Evaluation unit 28 Transmitter unit 29 Battery or accumulator unit (of device 10) 30 Laminarization device 32 particle and / or bacterial filters 34 Battery or accumulator unit (of the ventilator 14) 36 housings (for the individual components of the device 10) B opposite areas of the carrier membrane 16 D Display unit F radio link p pressure (of a gas within the flow channel 12) P Patient FG fresh gas PG patient gas S Flow direction V volume value V volume flow W wall (of the flow channel 12)

Claims

[1] Method for determining the volume flow (V), pressure (p) and composition of a gas which is passed through a flow channel (12) during the breathing or ventilation of a patient (P), wherein the volume flow (V) of the gas conducted through the flow channel (12) is determined by means of a carrier membrane (16) which is arranged in the flow channel (12) substantially orthogonal to the flow direction (S) of the gas, wherein at least one first sensor (18) is attached to at least one surface (17) of the carrier membrane (16), wherein a pressure measuring device (20) is arranged in the flow channel (12), in particular in the region of its wall (W), wherein with this pressure measuring device (20) a static pressure (p) for the gas flowing within the flow channel (12) is measured in comparison to the external environment of the flow channel (12), and wherein the composition of the gas, in particular selected gases formed from the group of at least oxygen (O2) and carbon dioxide (CO2), is determined by at least one, in particular catalytic, second sensor (24) arranged within the flow channel (12), characterized by , that the carrier membrane (16) is designed to be flexible and the first sensor (18) is designed on the surface (17) of the carrier membrane (16) in the form of a strain gauge, wherein the carrier membrane (16) does not have a piezo element, wherein the carrier membrane (16) is deformable within the flow channel (12) depending on the volume flow (V) of the gas, wherein upon movement of the carrier membrane (16) and / or deformation of the first sensor, at least one signal is generated depending on the volume flow (V) of the gas, that the carrier membrane (16) is connected to the inner peripheral surface (13) of the flow channel (12) in such a way that the carrier membrane (16) has a free end with which the carrier membrane (16) is movable back and forth within the flow channel (12), and that the flow of the gas within the flow channel (12) is laminarized adjacent to or near the support membrane (16). [2] Method according to claim 1, characterized by that the determination of volume flow (V), pressure (p) and composition of a gas is carried out for a fresh gas (FG) which flows through the flow channel (12) in the direction of the patient (P) and is accordingly inhaled by the patient (P) or actively flows into the lungs of the patient (P). [3] Method according to claim 1 or 2, characterized bythat the determination of volume flow (V), pressure (p) and composition of a gas is carried out for a patient gas (PG) which flows through the flow channel (12) away from the patient (P) and has been exhaled accordingly by the patient (P). [4] Method according to one of claims 1 to 3, characterized by that the measured values ​​of a first sensor (18) mounted on the flexible carrier membrane (16), the pressure measuring device (20) and the in particular catalytic second sensor (24) are transmitted preferably by cable to an evaluation unit (26). [5] Method according to claim 4, characterized by that the measured values ​​received by the evaluation unit (26) are digitized. [6] Method according to claim 4 or 5, characterized bythat the measured values ​​are transmitted from the evaluation unit (26) to a transmission unit (28), preferably that the transmission unit (28) and the evaluation unit (26) are integrated in a common device. [7] Method according to claim 6, characterized by that the measured values ​​are transmitted from the transmitting unit (28) to a regulating or control device (15) for patient ventilation, preferably that the regulating or control device (15) comprises a display unit (D), further preferably that the regulating or control device (15) is part of a ventilator (14). [8] Method according to claim 7, characterized by that the transmission of the measured values ​​from the transmitting unit (28) to the regulating or control device (15) for patient ventilation is carried out wirelessly and in particular via the Bluetooth communication protocol or via the ZigBee communication protocol. [9] Method according to one of the preceding claims, characterized bythat a particle and / or bacteria filter (32) is provided for fresh gas (FG) flowing into the flow channel (12), with which the gas flowing towards the patient (P) is filtered with regard to particles and / or bacteria or germs. [10] Method according to one of the preceding claims, characterized by that a particle and / or bacteria filter (32) is provided for patient gas (PG) flowing into the flow channel (12), with which the gas flowing in the direction of a ventilator (14) is filtered with regard to particles and / or bacteria or germs. [11] Method according to claim 9 or 10, characterized by that the volume flow (V) which has been passed through the flow channel (12) and determined is converted into a total volume (V) in order to determine the remaining service life of the particle and / or bacteria filter (32) on the basis thereof. [12] Method according to one of the preceding claims, characterized bythat the volume flow (V̇) guided through the flow channel (12) is converted to at least one volume value (V) on the basis of a derived variable, preferably that the volume value (V) is in particular a tidal volume (V T ) and / or a minute volume (V M ) is. [13] Device (10) for determining volume flow (V), pressure (p) and composition of a gas during breathing or ventilation of a patient (P), comprising a flow channel (12) which can be connected to a ventilator (14) and through which the gas can flow, at least one carrier membrane (16) which is arranged in the flow channel (12) substantially orthogonal to the flow direction (S) of the gas, wherein at least one first sensor (18) is attached to at least one surface (17) of the carrier membrane (16), a pressure measuring device (20) which is arranged in the flow channel (12), in particular in the region of its wall (W), wherein with this pressure measuring device (20) a static pressure (p) for the gas flowing within the flow channel (12) can be measured in comparison to the external environment of the flow channel (12), and at least one in particular catalytic second sensor (24) arranged within the flow channel (12), with which a composition of the gas, in particular selected gases formed from the group of at least oxygen (O2) and carbon dioxide (CO2), can be determined, characterized by , that the carrier membrane (16) is flexible and the first sensor (18) is in the form of a strain gauge, wherein the carrier membrane (16) does not have a piezo element, wherein the carrier membrane (16) is deformable within the flow channel (12) depending on the volume flow (V) of the gas, wherein upon movement of the carrier membrane (16) and / or deformation of the first sensor (18), at least one signal can be generated depending on the volume flow (V̇) of the gas, that the carrier membrane (16) is connected to the inner peripheral surface (13) of the flow channel (12) in such a way that the carrier membrane (16) has a free end with which the carrier membrane (16) is movable back and forth within the flow channel (12), and that at least one laminarization device (30) is provided within the flow channel (12), with which the flow of the gas guided in the direction of the support membrane (16) is laminarized, wherein the laminarization device (30) is arranged adjacent to or in the vicinity of the support membrane (16). [14] Device (10) according to claim 13, characterized by an evaluation unit (26) which is in signal connection, preferably by cable, with the first sensor (18) mounted on the flexible carrier membrane (16), the pressure measuring device (20) and the in particular catalytic second sensor (24). [15] Device (10) according to claim 14, characterized bythat the evaluation unit (26) is programmed in such a way that the measured values ​​received by at least one first sensor (18) mounted on the flexible carrier membrane (16), the pressure measuring device (20) and the in particular catalytic second sensor (24) can be digitized after reception and stored in the evaluation unit (26). [16] Device (10) according to one of claims 13 to 15, characterized bya transmitting unit (28) which is in signal communication, preferably by cable, with the evaluation unit (26) and / or with a first sensor (18) mounted on the flexible carrier membrane (16), the pressure measuring device (20) and the in particular catalytic second sensor (24), wherein the transmitting unit (28) is designed to transmit the measured values ​​of the first sensor (18), the pressure measuring device (20) and the in particular catalytic second sensor (24) or the data received from the evaluation unit (26) to an external device, preferably wirelessly via a radio link (F) or the like, preferably in that the transmitting unit (28) and the evaluation unit (26) are integrated in a common device. [17] Device (10) according to claim 16, characterized bythat the external device is designed in the form of a regulating or control device (15), preferably that the regulating or control device (15) is in signal connection with a display unit (D). [18] Device (10) according to claim 17, characterized by that the regulating or control device (15) is part of a ventilator (14) for patient ventilation and is programmed in such a way that the volume flow (V), the pressure (p) and the composition of the gas which is guided into a section of the flow channel (12) leading to the patient (P) can be controlled, preferably regulated, as a function of the measured values ​​of a first sensor (18) attached to the flexible carrier membrane (16), the pressure measuring device (20) and the second sensor (24), which is in particular catalytic. [19] Device (10) according to one of claims 13 to 18, characterized bythat the flexible support membrane (16) extends substantially orthogonally to the flow direction (S) of the gas completely along a diameter of the flow channel (12) and is fastened at least with its opposite regions (B) to an inner peripheral surface (13) of the flow channel (12). [20] Device (10) according to one of claims 13 to 19, characterized by that the laminarization device (30) is arranged upstream and / or downstream of the carrier membrane (16) as seen in the direction of the patient (P). [21] Device (10) according to one of claims 13 to 20, characterized byat least one particle and / or bacteria filter (32) arranged within the flow channel (12), preferably that a particle and / or bacteria filter (32) is arranged upstream and / or downstream of the carrier membrane (16) as seen in the direction of the patient (P), further preferably that the particle and / or bacteria filter (32) and the laminarization device (30) are designed as an integrated unit. [22] Device (10) according to one of claims 13 to 20, characterized by that an additional full-surface or local coating is applied to at least one surface (17) of the carrier membrane (16) and a first sensor (18) attached thereto. [23] Device (10) according to claim 22, characterized by that the additional coating has hygroscope properties. [24] Device (10) according to one of claims 13 to 23, characterized bythat the pressure measuring device (20) is equipped with a strain gauge (21) or with a piezo element (22), with the deformation of which the static pressure (p) of the gas within the flow channel (12) can be measured. [25] Device (10) according to one of claims 13 to 24, characterized by a battery or accumulator unit (29) which is electrically connected to the electrical or electronic components of the device (10) for supplying energy, preferably the capacity of the battery or accumulator unit (34) is selected to be large enough to ensure an energy supply for the electrical or electronic components of the device (10) connected to the battery or accumulator unit (34) for a period of at least 24 hours, preferably at least 36 hours, more preferably at least 48 hours. [26] Device (10) according to one of claims 13 to 25, characterized bythat the individual components of the device (10) are integrated into a common housing (36), preferably that the flow channel (12) fulfils the function of a common housing (36) for the remaining components, further preferably that the device (10) is designed as a disposable article.

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