Flow measuring module, and ventilator, lung simulator or medical flow measuring device having such a flow measuring module

Abstract

The invention relates to a flow measuring module (116) which can be installed in a pneumatic path of a lung simulator, a ventilator or a flow measuring device, the flow measuring module (116) comprising a transverse main channel (11) having at least one flow sensor or differential pressure sensor (22) and being connectable to an electronics system. The aim of the invention is to allow a flow measurement to be carried out easily, variably and in a large measuring range. This is achieved in that the flow measuring module (116) comprises at least one breathing resistance insert (20) which can be exchangeably inserted into the main channel (11), the breathing resistance insert (20) being tubular with an open end face and an opposite end face which is closed by a resistance means (24), the resistance means (24) being formed by one or more through-openings in the closed end face.

Description

[0001] Flow measurement module and resuscitation device, lunar simulator or medical flow measurement device with such a technical area

[0002] The present invention describes a flow measurement module that can be installed in a pneumatic path of a lung simulator, a ventilator or, more generally, a medical flow meter, wherein the flow measurement module has a transverse main channel with at least one flow sensor or differential pressure sensor and can be connected to electronics.

[0003] State of the art

[0004] A ventilator is used for the respiratory therapy of patients, whether humans or mammals, with respiratory insufficiency. It is employed to support or replace breathing in humans and mammals when they are unable to breathe adequately or at all on their own. In such a ventilator, the flow of air must be measurable and tailored to the patient.

[0005] A lung simulator mimics the function of the human / animal lung and allows for practical training in ventilation using a ventilator without a patient. The major advantage of a lung simulator is that medical personnel can practice on a device without risk to real patients. Furthermore, the behavior of the lung simulator is repeatable, allowing scenarios to be performed multiple times to reinforce learning. Developers can also use lung simulator simulations to compare different ventilators. Lung simulators are used to simulate treatment approaches, such as the mechanical ventilation of a specific disease. In this application, the focus is on the physiological response of the simulated patient.Of particular relevance is the lung simulator's ability to respond to various treatment approaches, especially to the precise settings of the ventilator. Crucially, the same scenario can be repeated for multiple exercises. To achieve this, a more complex lung structure is integrated into a mannequin, allowing for the recording and playback of various data. Often, complex physiological models are required to simulate patient behavior. Even in lung simulators, the airflow must be precisely measurable and tailored to the simulated patient.

[0006] Since it was previously impossible to ventilate or simulate patient lungs of varying sizes, from babies to adults to large mammals such as horses or elephants, using a single setup, specially calibrated medical devices were employed. Simply adjusting the flow measurement and / or airway resistance to suit the individual patient was not feasible.

[0007] To date, differential pressure flow meters have become the standard for measuring flow rates in ventilators and lung simulators. In these meters, the airflow is forced through a resistance, causing a pressure drop. This pressure drop is then measured and used to calculate the airflow rate. Due to the simplicity of the measuring principle, differential pressure flow meters are used in various sectors of industry and medicine.

[0008] There are two approaches to such differential pressure flow meters: the single-channel approach and the bypass approach. In both cases, a pressure drop is generated via breathing resistance.

[0009] In the P2510502WO 1-channel approach, the generated pressure drop is measured directly with a pressure sensor. The entire flow measurement takes place in one channel.

[0010] In a differential pressure flow meter with a bypass connection, there is a small channel running parallel to the main channel. The flow through the main channel is forced through breathing resistance, creating a pressure drop. This pressure drop results in a small flow through the bypass. Finally, the flow in the bypass is measured, a process possible with various flow meters.

[0011] To increase the measurement range of flow measurements, the current approach generally involves creating multiple air channels with varying resistances. This requires more complex equipment or, during operation, connecting hoses to multiple inlets and outlets, which is more cumbersome. Multiple flow measurement devices in a single ventilator or lung simulator also naturally entail higher costs.

[0012] Either the maximum measuring range is too small, the resolution for small flows is too low, the pressure drop in the flow measurement is too great, or the costs are too high, or the handling is too complicated. Since large humans / animals have a small pressure drop in their airways, it is important for lung simulators that the pressure drop due to resistance remains sufficiently low even for large flow ranges. For a low pressure drop in the airways to be simulated, the "internal pressure drop" of the lung simulator must be smaller than the minimum pressure drop in the airways. This is because a lung simulator cannot, in principle, simulate pressure drops smaller than its own "internal pressure drop."

[0013] P2510502WO For very small humans / animals, very small flow rates must be measured to achieve an accurate and realistic simulation. In contrast to large humans / animals, the minimum pressure drop can be greater, as the pressure drop in the respiratory tract of small humans / animals is higher. This facilitates the measurement of smaller flow rates.

[0014] When measuring large flows, the pressure drop during the flow measurement must be as small as possible. However, small pressure drops due to resistance do not allow for accurate flow measurement of small flows. This applies to the flow measurement of exhaled air in ventilators and lung simulators.

[0015] Description of the invention

[0016] The present invention aims to provide a variable and accurate flow measurement system for a main channel of a pneumatic path in a ventilator or lung simulator, covering a wider measuring range. This makes it easy and cost-effective to vary and measure the flow of exhaled air across a broader size range, suitable for use in infants, adults, and large mammals.

[0017] Optimized flow measurement can be achieved by using a flow measurement module with an interchangeable breathing resistance insert, each with a suitable resistance, in ventilators, lung simulators, or flow meters.

[0018] Variations in feature combinations or minor adjustments to the invention can be found in the detailed description, illustrated in the figures, and included in the dependent patent claims.

[0019] P2510502W0 Brief description of the drawings

[0020] A preferred embodiment of the invention is described in detail below in connection with the accompanying drawings.

[0021] Further features, details, and advantages of the invention will also become apparent from the following description of slightly modified embodiments of the invention, some of which will be clear to a person skilled in the art simply from the drawings. These are illustrated in

[0022] Figure 1 shows a schematic perspective view of a lung simulator connected to a ventilator.

[0023] Figure 2 shows a schematic setup of a lung simulator with a flow measurement module according to the invention, including an interchangeable breathing resistance insert, while

[0024] Figure 3 shows the flow measurement module, usable in a ventilator or lung simulator, in its installed state and in detail.

[0025] Figure 4 shows an exploded view of the flow measurement module.

[0026] P2510502WO Description

[0027] A known configuration of a lung simulator 1 with a display 2 and a union nut 3, to which a ventilator 4 is connected via a breathing tube 10, is shown in Figure 1 for a general understanding of the use of the lung simulator 1 and the ventilator 4. The newly introduced flow measurement using a flow measurement module 116 is explained below with an example of its integration into the lung simulator 1.

[0028] The lung simulator 1 has a switching and control unit I, with an upper dashed box and a pneumatic path II, with the lower dashed box shown in Figure 2.

[0029] The switching and control unit I comprises an electronics unit 119, with a computing unit 120, a memory 121, a user interface 122, a data interface 123, mechanical operating elements 125 and the display 2. Via the electronics unit 119, to which at least one pressure sensor 115 is connected, several actuators along the pneumatic path II, which includes at least one pressure sensor 115 and the memory 121, can be read and controlled by the computing unit 120.

[0030] The lung simulator 1, a corresponding ventilator 4, or the electronics 119 can be operated via the mechanical controls 125 and the user interface 122. The lung simulation program and the parameters for the simulated patient or the ventilation of a patient can be set using the user interface 122. Lung simulation data or ventilation data can be output via the data interface 123 using various interface standards such as USB, serial, CAN, WiFi, Bluetooth, NFC, or other currently known standards. In addition to wireless methods such as Bluetooth,

[0031] P2510502W still robust cable connections such as USB or CAN are interesting for many applications.

[0032] As shown in the diagram of Figure 2, the pneumatic path II runs after the union nut 3 along a main channel 11, indicated by dashed lines, through a flow measurement module 116 and then via a first actuator 110, a second actuator 111, and a third actuator 112 to an inhalation / exhalation air connection 6, where at least one pressure sensor 115 can measure the air pressure in the main channel 11. The air flow is indicated by the double arrows in the main channel 11.

[0033] Here, using the example of a lung simulator 1, the first actuator 110 is designed as a blower that can generate positive pressure on the left side of the main channel 11, while the third actuator 112 is designed as a blower that can generate negative pressure on the left side of the main channel 11. The second actuator 111 is designed as a valve with a cross-section adjustable by a stepper motor. The pneumatic path II can be designed less complexly in a ventilator 4, whereby the flow measurement module 116 and its capabilities are crucial in this patent application.

[0034] The crucial flow measurement module 116 can optionally be installed in the main channel 11 of the pneumatic path II of the lung simulator 1 or the ventilator 4 and provide flow measurement over the enlarged and adjustable measuring range.

[0035] The flow measurement module 116 is permanently integrated or attached to the main channel 11 in pneumatic path II, allowing breathing air to flow through the main channel 11. The flow measurement module 116 of interest here, marked with a dotted box in the diagram of Figure 2, will now be described in detail with reference to Figures 3 and 4.

[0036] P2510502WO explained. The pressure sensor 115 can, but does not have to, be part of the flow measurement module 116.

[0037] A main channel wall encloses the main channel 11 in the area of ​​the flow measurement module 116. A breathing resistance insert 20 is inserted into the recessed main channel 11 and can be detachably stored airtight within the main channel 11. The breathing resistance insert 20 is tubular with a round, oval, or polygonal cross-section, an open end face S1, and an opposing closed end face S2 with at least one opening, preferably with a plurality of openings.

[0038] At the outer end of the main channel wall, partially crossing the main channel 11, an insert recess 1101 is cut out and at the outermost end a main channel thread 1100. By means of the union nut 3, which has a thread 30, the breathing resistance insert 20 can be interchangeably fixed in the main channel 11.

[0039] The breathing resistance insert 20 is designed as an interchangeable module in the flow measurement module 116 and can be made of plastic or metal. The breathing resistance insert 20 is designed as a tube with one open end / open end face and one end / closed end face with a resistance 24. The resistance 24 comprises the at least one opening. The outer cross-section of the breathing resistance insert 20 is preferably circular. It is important that the outer cross-section of the breathing resistance insert 20 is matched to the inner cross-section of the main channel 11 so that the breathing resistance insert 20 can be inserted into the main channel 11 or the insert recess 1101 and fits airtight accordingly.

[0040] The inner cross-section of the main channel 11 is typically between 50 mm 2 and 1000mm 2 preferably at 500mm 2 + / - 10%, usually

[0041] P2510502WO preferred at 490mm2 The outer cross-section of the breathing resistance insert 20 must be designed according to the inner cross-section of the main channel 11.

[0042] The resistance 24 forms a fixed or molded front surface of the breathing resistance insert 20 and has at least one opening as a through-hole through which air can flow.

[0043] The maximum differential pressures to be achieved across the resistor 24 are typically between + / - 2mbar and + / - 20mbar, and are ideally fixed at approximately + / - 5 mbar for babies, adults and large mammals.

[0044] Since changing the resistance 24 alone is more difficult, different breathing resistance inserts 20 with different resistances 24 are used. Here, three different breathing resistance inserts 20 are chosen as a basis: one for an adult patient, a second breathing resistance insert 20 for simulating a newborn patient, and a third breathing resistance insert 20 for large mammals.

[0045] The flow area, the number of holes and the cumulative cross-sectional area of ​​all holes through the resistance 24 depends on the patient.

[0046] For babies, the flow rate range is between + / - 30 L / min and + / - 100 L / min, ideally + / - 80 L / min.

[0047] The number of holes should be roughly between 1 and 400, preferably between 25 and 75, especially between 50.

[0048] This corresponds to a cumulative cross-sectional area of ​​all N holes between 50 mm 2 and 140mm2 , preferably >80 mm 2 and less than 100mm 2 .

[0049] P2510502WO For adults, the flow range is between + / - 150 b / min and + / - 400 L / min, ideally + / - 300 L / min.

[0050] The number of holes should be roughly between 1 and 700, preferably between 80 and 105, especially 95.

[0051] This corresponds to a cumulative cross-sectional area of ​​all N holes between 95 mm 2 and 270mm 2 , preferably >160 mm 2 and less than 170mm 2 .

[0052] For large mammals, such as horses, donkeys, cattle, zebras, rhinoceroses, tapirs, elephants, giraffes, the flow rate range is between + / - 300 L / min and + / - 1000 L / min, ideally + / - 500 l / min.

[0053] The number of holes can range from 1 to 1200, but preferably the number is 1.

[0054] This corresponds to a cumulative cross-sectional area of ​​all N holes between 160 mm 2 and 445 mm 2 , preferably >270 mm 2 and less than 290mm 2 .

[0055] The breathing resistance insert 20 does not have to be round, but if it has a round cross-section, it should have a radial coding to prevent twisting during insertion.

[0056] To ensure that the breathing resistance insert 20 can be inserted precisely and airtight into the main channel 11, a positioning aid 201, shown here as a circumferential bead 201, is molded into it. A sealing ring 21 is additionally positioned between the outer wall of the breathing resistance insert 20 and the inner surface of the main channel wall. The radial sealing ring 21 prevents any fluid from flowing between the breathing resistance insert 20 and the main channel 11.

[0057] The air can flow through the main channel 11 and thereby through the breathing resistance insert 20 including resistance 24, as indicated by the dashed arrow in Figure 3. Depending on the size of the

[0058] P2510502WOWiderstandes 24, different pressures pl, p2 occur in the longitudinal direction in front of and behind the resistor 24 in the main channel 11.

[0059] Along the length of the breathing resistance insert 20, in the direction of its expansion upstream of the resistance 24, at least one bypass opening 202 is recessed in the circumferential wall of the breathing resistance insert 20. When installed, this bypass opening is functionally connected to a bypass channel 23 that leads through the main channel wall from the main channel 11 and back in. The bypass channel 23 leads out of the main channel 11 to the left of the resistance 24 and back into the main channel 11 to the right of the resistance 24, thus forming a bypass around the resistance 24. The direction of flow through the main channel 11 is irrelevant. A flow sensor or differential pressure sensor 22 is arranged along the bypass channel 23.

[0060] As shown in the exploded view in Figure 4, the replacement of the breathing resistance inserts 20 is easily accomplished by loosening the union nut 3 from the main channel thread 1100 and pulling the breathing resistance insert 20 out of the main channel 11. Of course, the breathing tube 10 must be disconnected beforehand to allow access to the breathing resistance insert 20. A different breathing resistance insert 20 with a different resistance 24 can be selected and reinstalled in the main channel 11. The bypass channel 23, the flow sensor or differential pressure sensor 22, as well as the other components from pneumatic path II and the switching and control unit I remain unchanged.

[0061] In another embodiment, the sealing ring 21 is pushed onto the breathing resistance insert and is not attached in the main channel 11, so that the sealing ring 21 can be pulled out together with the breathing resistance insert 20.

[0062] P2510502WO By installing the breathing resistance insert 20 with a defined resistance 24 in the main channel 11, a pressure drop across the resistance 24 is generated as soon as a gas (air or air / oxygen / CO2 mixture) flows through the main channel 11 and the breathing resistance insert 20. This pressure drop leads to a small flow in the bypass channel 23, which is then measured by the flow sensor or differential pressure sensor 22 and transmitted to the electronics 119. In the processing unit 120, a lookup table or an analytical function is used to infer the flow in the main channel 11 from the measured flow in the bypass channel 23.

[0063] The flow measurement module 116 with interchangeable breathing resistance insert 20 allows the resistance 24 to be easily varied, whereby the resistances 24 are adjusted to the lung simulation or to the patients being ventilated. Thus, a new resistance 24 can be installed in the same device 1, 4 and the measuring range can be changed.

[0064] Instead of the bypass approach, the pressure drop through the breathing resistance insert 20 or the differential pressure across the resistance 24 can be measured directly. This requires two measuring channels instead of one bypass channel. These are arranged identically to the bypass channel but do not have a continuous connection, thus preventing any flow through the measuring channel. Here, even multiple differential pressure sensors for different measuring ranges could be used within the main channel 11. With the single-channel principle, the arrangement is exactly the same, except that no flow can pass through the sensor because the differential pressure is measured via a piezoelectric membrane.

[0065] In both approaches, with and without bypass channel 23, the flow measurement can be supplemented with additional pressure measurements, humidity measurements and an oxygen measurement.

[0066] P2510502WO, which are also embedded in the main channel 11. Corresponding sensors would then also be operatively connected to the electronics 119.

[0067] Optionally, a sieve can be attached within the breathing resistance insert 20 to calm the airflow and to keep out coarse dirt particles. Such a sieve is indicated by dashed lines in Figure 4. Preferably, the sieve has a thickness that is less than or equal to half the thickness of the resistance 24.

[0068] The proposed solution allows a single lung simulator to cover multiple flow ranges and thus simulation ranges for different humans / animals. Flow measurement can be specifically tailored to the patient type without requiring a completely new lung simulator. This results in lower costs for the end user.

[0069] In conventional flow measurements, especially in flow measurements using lung simulators, it has so far been necessary to either offer different devices for different patients or, if one device is offered for all patient groups, to make compromises in the flow measurement in order to cover the entire range.

[0070] Another advantage is the adjustment and calibration of the flow measurement. In our solution, the flow measurement of the Lung Simulator 1 is individually adjusted and calibrated with each breathing resistance insert. This means that the flow measurement can be changed by the user without having to recalibrate the Lung Simulator 1. Therefore, only the calibration of one device needs to be maintained, instead of multiple devices, as would be the case if a neonatal device and a separate adult device had to be maintained.

[0071] P2510502WOOne final advantage is that it is possible to subsequently adjust the flow measurement by developing a new respiratory resistance insert 20 for a new patient group.

[0072] The flow measurement module 116 presented here can also be part of a medical flow meter in general for various applications. For example, in a calibration device for ventilators.

[0073] P2510502WO Reference List

[0074] 1 Lung simulator

[0075] 1 Switching and control unit

[0076] II pneumatic path

[0077] 2 ads

[0078] 3 Union nuts (connection for the ventilator hose)

[0079] 30 threads

[0080] 4 ventilators

[0081] 6 Connection for inhalation / exhalation air

[0082] 10 breathing tubes

[0083] 11 Main channel (pneumatic path)

[0084] 1100 main channel thread

[0085] 1101 Insert recess

[0086] 110 First actuator (blower which can generate overpressure on the left) 111 Second actuator (valve with stepper motor which has an adjustable cross-section)

[0087] 112 Third actuator (blower which can create a suppression on the left)

[0088] 115 Pressure sensor (digital or analog with A / D converter)

[0089] 116 Flow measurement module

[0090] 119 Electronics

[0091] 120 computing units for calculating the flow in the main canal

[0092] 121 storage

[0093] 122 User interface

[0094] 123 data interfaces

[0095] 125 mechanical controls (e.g., on / off switches)

[0096] 20 breathing resistance deployment

[0097] 201 Positioning aid (circumferential bead)

[0098] 202 Bypass opening

[0099] 21 sealing ring

[0100] 22 Flow sensor or differential pressure sensor (with thermal measuring principle) 23 Bypass channel

[0101] 24 resistor

[0102] S1 open end face, S2 closed end face with resistance

[0103] P2510502WO

Claims

Patent claims 1. Flow measurement module (116) installable in a pneumatic path (II) of a lung simulator (1), a ventilator (4) or generally a medical flow meter, wherein the flow measurement module (116) has a transverse main channel (11) with at least one flow sensor or differential pressure sensor (22) and is connectable to an electronics (119), characterized in that the flow measurement module (116) comprises at least one breathing resistance insert (20) that can be inserted into the main channel (11) interchangeably, wherein the breathing resistance insert (20) is tubular in shape with an open end face and an opposing end face closed with a resistance (24), wherein the resistance (24) is formed by one or more through-openings in the closed end face and the breathing resistance insert (20) can be attached interchangeably in the main channel (11).

2. Flow measuring module (116) according to claim 1, wherein a union nut (3) can be attached to one end of the flow measuring module (116) by means of a main channel thread (1100) of the main channel (11) and the flow measuring module (116) can be connected to a breathing tube (10), wherein the breathing resistance insert (20) is detachably and airtightly replaced in the main channel (11) by means of the union nut (3) and its thread (30) and the main channel thread (1100).

3. Flow measuring module (116) according to one of the preceding claims, wherein the cumulative cross-sectional area of ​​the through holes in the closed end face of the resistor (24) is determined according to the application: P2510502WOa) between 50 mm 2 and 140mm 2 for 1 to 400 through holes, b) between 95 mm 2 and 270mm 2 with 1 to 700 through holes, and c) between 160 mm 2 and 445 mm 2 for 1 to 1200 through holes, lies.

4. Flow measurement module (116) according to one of the preceding claims, wherein the outer cross-section of the breathing resistance insert (20) and the inner cross-section of the main channel (11) are circular in design, wherein the cross-sections are adapted to the airtight insertion and the fastening of the breathing resistance insert (20) into the main channel (11).

5. Flow measurement module (116) according to one of the preceding claims, wherein a positioning aid (201) is formed on the outer surface of the breathing resistance insert (20) as a circumferential bead (201).

6. Flow measurement module (116) according to one of the preceding claims, wherein a sealing ring (21) is arranged between the outer surface of the breathing resistance insert (20) and an inner surface of the main channel wall of the main channel (11).

7. Flow measurement module (116) according to one of the preceding claims, wherein a recess (1101) for partial accommodation of the breathing resistance insert (20) is provided in the main channel (11) of the flow measurement module (116). P2510502WO8. Flow measurement module (116) according to one of the preceding claims, wherein at least one bypass opening (202) is recessed in the circumferential wall of the breathing resistance insert (20), which, in the state installed in the main channel (11), directs air into a bypass channel (23), wherein the flow sensor or differential pressure sensor (22) is arranged within the bypass channel (23) and the bypass channel (23) is led back into the main channel (11) after the resistance (24).

9. Flow measuring module (116) according to one of the preceding claims, wherein the inner cross-section of the main channel (11) is between 50 mm 2 and 1000mm 2 preferably at 500mm 2 The range is + / - 10%.

10. Flow measurement module (116) according to one of the preceding claims, wherein additional pressure measurements, humidity measurements and an oxygen measurement are carried out in the main channel (11) of the flow measurement module (116) by integrating suitable sensors connected with the electronics (119) into the main channel (11).

11. Set comprising a flow measurement module (116) according to one of the preceding claims and two or more different breathing resistance inserts (20) with different resistances (24), comprising a different number of through holes in the closed front face of the respective breathing resistance insert (20), adapted for flow measurement in children, adults and large mammals in ventilators (4) or lung simulators (1). P2510502WO12. Lung simulator (1) or ventilator (4), characterized in that a flow measurement module (116) according to one of claims 1 to 10 is fixed in the course of a main channel (11) of a pneumatic path (I), wherein the breathing resistance insert (20) with different resistances (24) can be detachably attached within the main channel (11) of the lung simulator (1) or ventilator (4). P2510502WO

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