Device and method for providing a respiratory gas flow
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- DRAGERWERK AG
- Filing Date
- 2024-08-29
- Publication Date
- 2026-07-08
Smart Images
Figure DE2024100762_06032025_PF_FP_ABST
Abstract
Description
[0001] Device and method for providing a breathing gas flow
[0002] Description
[0003] The present invention relates to a device and a method for providing a respiratory gas flow for a ventilator, a ventilator with such a device and a use of such a device.
[0004] Ventilators are designed to support or take over a patient's respiratory effort. The goal is to supply the patient with sufficient oxygen and promote the removal of carbon dioxide from the lungs. A device for providing a breathing gas flow should be highly accurate with regard to the characteristics of the breathing gas flow, such as oxygen concentration, pressure, and volume, and be able to react to changes in these characteristics as quickly as possible.
[0005] Essentially, two device variants are commonly used in practice: compressed air-based devices and blower-based devices. Compressed air-based devices draw breathing gas from external sources, for example, a hospital's central gas supply. Blower-based devices, on the other hand, draw breathing gas primarily from the environment, with an internal blower drawing in ambient air. In addition, oxygen, for example from a gas cylinder, can be added to the ambient air if required for patient ventilation. A disadvantage of compressed air-based devices is that they are difficult or impossible to move, meaning their location cannot be changed, especially when the device is in use. This is particularly problematic if, for example, a patient is transferred to another ward in the hospital and still requires ventilation.Furthermore, compressed air-based devices typically have external compressors that supply breathing gas in the event of a central gas supply failure. Such compressors require a lot of energy and are heavy, making it impossible to relocate the compressed air-based device. A disadvantage of blower-based devices is their loud operating noise compared to pressure-based devices, which can have negative effects on the patient. They also have limitations in the type of ventilation, as some ventilation modes are only possible with a central gas supply and its higher breathing gas pressure.
[0006] Devices are known in the prior art, for example from US5823186A, in which compressed air-based and blower-based devices are combined, thus offering a high degree of flexibility with regard to the location of use in the case of blower operation, as well as with regard to ventilation modes. However, such devices known in the prior art are expensive and require a lot of space, with a large internal volume through which the breathing gas flows negatively impacting the dynamics of the device. Furthermore, some of these devices only offer the possibility of using up to two breathing gas sources simultaneously. Another problem is the fact that the various breathing gas sources have different pressures, which must be adjusted to a pressure suitable for the patient in order to provide a breathing gas flow.In this case, it is particularly important to have a control system designed to take different pressures into account and to be able to react quickly to changes, so that the device has a high level of dynamics.
[0007] Based on the solutions known from the prior art and the problems described above, the object of the invention is to create a compact and cost-effective device for providing a breathing gas flow, with which different gas flows from different sources can be combined as needed to form a breathing gas flow. It should be possible to flexibly use both pressurized, external sources and the ambient air as a source for providing the breathing gas flow. Furthermore, the device should be highly dynamic with regard to adjusting or changing the properties of the breathing gas flow, so that the adjustment or changing of the properties of the breathing gas flow to be provided can be implemented as quickly as possible. Key properties of the breathing gas flow are: breathing gas volume, breathing gas pressure and breathing gas concentration, which can be adjusted at least partially by a user.
[0008] The above object is achieved by a device for providing a respiratory gas flow for a ventilator with the features of claim 1, a method for providing a respiratory gas flow for a ventilator according to claim 11, a ventilator according to claim 16, and a use of a device according to claim 17. Further details of the invention emerge from the dependent claims, the description and the drawings. Features and details that are described in connection with the device according to the invention and the ventilator according to the invention also apply in connection with the method according to the invention, so that with regard to the disclosure of the individual aspects of the invention, reference is always made or can be made reciprocal.
[0009] The device according to the invention for providing a respiratory gas flow for a ventilator comprises a first inlet and a second inlet, each for connecting external gas sources, in particular for connecting to a central gas supply (CGS). The first inlet is fluidly connected to a mixing volume for mixing gas flows by means of a first gas line, and the second inlet is fluidly connected to a mixing volume for mixing gas flows by means of a second gas line. The first gas line has a first dosing unit with a first volume flow sensor arranged downstream of the first dosing unit. The second gas line has a second dosing unit with a second volume flow sensor arranged downstream of the second dosing unit. The device further comprises a third inlet, which is fluidly connected to the mixing volume by means of a third gas line.The third gas line has a blower and a check valve arranged downstream of the blower and upstream of the mixing volume. The blower is designed to draw in ambient air located outside the device via the third inlet and to convey the ambient air toward the check valve. Furthermore, the device comprises a fourth gas line that establishes fluid communication between the mixing volume and an outlet at which the respiratory gas flow is provided. The device is characterized in that the fourth gas line has a third volume flow sensor for measuring a total volume flow of the respiratory gas flow, and in that a control and regulating unit is provided that is configured to control the blower, the first dosing unit, and the second dosing unit.A measured value from the first volume flow sensor, the second volume flow sensor, and the third volume flow sensor, individually or in combination, as well as a concentration value of the respiratory gas flow and / or a pressure value for a pressure downstream of the mixing volume are taken into account. The concentration value indicates the concentration value of a respiratory gas component of the respiratory gas flow, in particular the concentration of oxygen in the respiratory gas flow.
[0010] External gas sources include, for example, a hospital's CGR, a gas cylinder, or an external compressor. These external gas sources typically operate at high pressure, particularly in the range of 2.7 to 6 bar, and supply the ventilator with air or a specific breathing gas, such as oxygen, or a specific therapy gas, such as nitric oxide, for ventilating a patient.
[0011] For the purposes of the invention, a patient is understood to mean both a human and an animal, whereby the patient is to be supplied with a mechanically provided respiratory gas flow and is in particular a person requiring medical monitoring, such as an infant, a child or an adult. Air, ambient air as well as a respiratory gas and a therapy gas are to be understood as respiratory gas components whose gas flows can contribute to the respiratory gas flow provided by the device according to the invention. The blower associated with the device according to the invention, also called a compressor or turbine, draws in ambient air through the third inlet and directs it further through the third gas line downstream towards the check valve and then into the mixing volume. The blower is electronically connected to the control and regulation unit.This changes an operating parameter of the fan, such as the speed of the fan, so that ambient air is sucked into the device as needed and a certain pressure and volume flow is created downstream of the fan.
[0012] The check valve upstream of the mixing volume and downstream of the blower allows a gas flow, in this case the ambient air, to pass only in one direction from the blower toward the mixing volume. This prevents a gas flow, such as air or oxygen, from escaping the device through the gas-permeable blower and the third inlet. This can be particularly the case when the blower is switched off and a gas flow is directed into the device through the first and / or second inlet.
[0013] The mixing volume, which is fluidly connected to the first, second, and third gas lines on the inlet side and to the fourth gas line on the outlet side, serves to mix the introduced gas streams. The shape, size, and structure of the mixing volume can be varied. In particular, the size of the mixing volume influences the dynamics of the ventilator into which the device according to the invention is integrated. In general, large volumes within a ventilator have a negative influence on the dynamics of the ventilator. A large volume, for example, can result in a sluggish response to settings or changes in the ventilation parameters, such as the oxygen concentration. For this reason, small mixing volumes are preferred. As will be explained in more detail below, the device according to the invention has a small mixing volume.This is possible in particular due to the inventive dosing of the respiratory gas components upstream of the mixing volume, since the mixing volume does not, for example, serve as a buffer volume for accommodating a respiratory gas flow under higher pressure, which also requires dosing downstream of the buffer volume. Such a buffer volume is significantly larger than the mixing volume of the device according to the invention.
[0014] The first, second, and fourth gas lines each have a volume flow sensor, with the third volume flow sensor of the fourth gas line measuring the total volume flow downstream of the mixing volume and upstream of the device's outlet. The total volume flow refers to the respiratory gas flow provided by the device, i.e., the respiratory gas flow composed of the various gas flows flowing into the device through the inlets. The third volume flow sensor is preferably arranged near the mixing volume so that dynamic influences of the mixing volume do not need to be compensated for, and the volume flow of the respiratory gas flow can be precisely measured, and the respiratory gas flow to be provided can be precisely adjusted using the control and regulation unit.Furthermore, the inventive arrangement of the third volume flow sensor downstream of the mixing volume is advantageous because it eliminates the need for an additional volume flow sensor downstream of the blower and upstream of the mixing volume. The volume flow downstream of the blower and upstream of the mixing volume can be determined from the total volume flow and the volume flows of the first and / or second volume flow sensor.
[0015] In contrast, in the solutions known from the prior art, a volume flow sensor is usually arranged downstream and near the fan. Since the fan also generates small delivery quantities of ambient air that are to be measured, such volume flow sensors must be highly accurate. Due to these requirements, such volume flow sensors are associated with high costs. Advantageously, a particularly accurate and expensive volume flow sensor near the fan can therefore be dispensed with, whereby the device according to the invention has lower manufacturing costs and requires less installation space. The device according to the invention is designed in such a way that it can be used flexibly in that it can be adapted to the respective conditions of the operating site and the user's settings. The user's settings depend on the patient's needs and the type of ventilation.The device can be operated in various operating modes, with the respiratory gas flow to be provided being generated using various combinations of sources. The device can be operated in a first operating mode with the CGR, in a second operating mode with the CGR and the blower, in a third operating mode with partial CGR and the blower, and in a fourth operating mode with the blower. The respiratory gas flow provided by the device can thus be combined from up to three sources. These different combination options offer the greatest possible flexibility and are advantageously enabled by the design of the device according to the invention. Flexibility includes, in particular, the possibility of adaptation to patient needs, but also with regard to the device's reliability, whereby, for example, the blower is activated if the CGR fails, e.g. due to a defect.In this case, a change from the first operating mode to the fourth operating mode takes place.
[0016] It is conceivable to combine more than three sources, with the device correspondingly having more than three inlets. For example, a fourth inlet for an additional connection to an external gas source, such as the central gas supply (CGV), as well as a fifth gas line, which, like the first or second gas line, is configured with a dosing unit and a volume flow sensor. This allows, for example, an additional therapy gas to be combined or, with regard to reliability, an additional oxygen source to be fluidly connected to the device, which can be used as an alternative to oxygen from the central gas supply.
[0017] The respiratory gas components are dosed upstream of the mixing volume by the blower, the first dosing unit, and / or the second dosing unit, depending on the operating mode. The first and second dosing units, as well as the blower, are controlled by the control and regulation unit. Therefore, no dosing takes place downstream of the mixing volume. This is advantageous because it eliminates the need for a dosing valve located close to the patient, i.e., near the outlet. A low respiratory gas pressure is required at the device outlet, namely a pressure suitable for ventilating a patient, for example, 30 mbar. A dosing valve close to the patient, which is used in such low pressure ranges, is associated with high costs. These costs and the additional installation space required for such a valve are thus advantageously eliminated for the device according to the invention.Furthermore, the elimination of the near-patient dosing valve reduces the device's energy consumption. This is particularly advantageous in cases where the device and ventilator are transported and the power is supplied from the ventilator's energy storage unit. This reduces the load on the energy storage unit and allows for longer operating times for the ventilator.
[0018] The dosing of the breathing gas components takes place in the direction of flow through the first and second dosing units and / or the blower into the mixing volume. Known technical solutions sometimes involve dosing at least one breathing gas component from a dosing unit into a blower, particularly when oxygen is used as the breathing gas component. The disadvantage of this is that, for example, when oxygen is used, a breathing gas flow containing pure oxygen cannot be provided. On the one hand, the blower draws in air in addition to the dosed oxygen, thereby reducing the oxygen concentration, and on the other hand, the pressure is insufficient for this type of ventilation mode. Furthermore, dosing a breathing gas component into a blower typically requires additional volume, which negatively impacts the dynamics.The advantageous embodiment of the device according to the invention therefore has a high level of dynamics and the possibility of flexible use.
[0019] The control and regulation unit influences the properties of the provided breathing gas flow, such as pressure, volume flow, and / or oxygen concentration. It is electronically connected to at least the first and second dosing units, the blower, and the first, second, and third volume flow sensors.
[0020] Depending on the operating mode, the control and regulation unit controls the actuators, i.e. the first dosing unit, the second dosing unit and / or the blower. In the first operating mode, the actuators are controlled such that the first and second dosing units contribute to the breathing gas flow. In the second operating mode, the actuators are controlled such that the first dosing unit, the second dosing unit and the blower contribute to the breathing gas flow. In the third operating mode, the actuators are controlled such that the blower and the first or second dosing unit, depending on which gas is required from the CGF, contribute to the breathing gas flow. In the fourth operating mode, the actuators are controlled such that only the blower contributes to the breathing gas flow.
[0021] When controlling the actuators, the control and regulation unit takes into account at least one measured value of the first, second and third volume flow sensors individually or in combination as well as a concentration value of the respiratory gas flow and / or a pressure value for a pressure downstream of the mixing volume.
[0022] It is conceivable to determine the concentration value using an additional sensor downstream of the mixing volume. This could be an internal sensor within the device or an external sensor, for example, in the area of a breathing mask. Alternatively or additionally, the concentration value can be determined by the control and regulation unit using the measured volume flow values. The concentration value refers to the concentration of a specific breathing gas in the breathing gas stream, for example, oxygen or heliox, a mixture of helium and oxygen.
[0023] Furthermore, it is conceivable to determine the pressure value of the respiratory gas flow using an additional sensor, wherein the sensor is fluidly connected to, for example, a breathing mask, so that the pressure of the respiratory gas flow close to the patient can be measured by the sensor. Alternatively, an external sensor for measuring the pressure value is conceivable, for example in the area of a breathing mask, wherein the pressure value is transmitted electronically to the control and regulation unit. Furthermore, it is conceivable to calculate the pressure value, wherein, for example, an additional pressure sensor measures the inspiratory pressure of the fourth gas line. Using the inspiratory pressure value, the volume flow, and a stored resistance value for the fourth gas line, the pressure value, i.e. the pressure close to the patient, can be determined.
[0024] In a preferred embodiment of the device, the control and regulation unit comprises a multivariable controller with a single-loop blower control loop. The multivariable controller is characterized by having at least two reference variables. This makes it possible to take into account the interdependencies of several reference variables, such as pressure and volume flow of the respiratory gas flow, during control. A single-loop blower control loop is understood to be a control loop for the blower without subordinate control loops. Subordinate control loops are found, for example, in cascade controllers.
[0025] The multi-variable controller with a single-loop blower control circuit is particularly advantageous for the aforementioned second and third operating modes of the device according to the invention, wherein the breathing gas flow is composed of the ambient air of the blower and a gas flow from the first and / or second gas line, for example oxygen from the CGV.
[0026] A blower, such as the one used in the device according to the invention, physically represents a pressure source. However, in relation to a control system, it can also be used as a volume flow source, whereby the control is implemented as dynamic volume flow control. In known technical solutions, a cascade control is used for this purpose, whose outer pressure control loop is stabilized with lower-level control loops, for example a lower-level volume flow control loop and a lower-level speed control loop. One reason for using a cascade control is the simple design of the sub-control loops. In cascade controls with nested control loops, the lower-level control loops, also called inner control loops, must be faster than the higher-level control loop in order to achieve stable reference variable behavior.However, since the pressure and speed of the fan are dynamically equivalent, but the subordinate speed control loop must be faster than the outer pressure control loop, the overall dynamics of the cascade controller are slowed down.
[0027] The multivariable controller with a single-loop blower control circuit does not exhibit such a slowdown, so that better dynamics, i.e. faster control, can be achieved. This takes advantage of the fact that the volume flow control with the first and / or second dosing unit reacts slightly more dynamically than the pressure control with the blower. The first and / or second dosing unit delivers its gas portion to increase the pressure shortly before the blower delivers its gas portion, in this case ambient air, by increasing the speed. This slight time offset leads to a decoupling of the actuators, i.e. the first and second dosing units and the blower, of the multivariable controller. Due to its pressure source properties, the blower supplements the missing gas portion according to the reference variables of the multivariable controller.The blower is selected so that the aforementioned dynamic difference relative to the first and / or second dosing unit is as small as possible. Factors such as the mass inertia, the motor, and the fan impeller of the blower are taken into account. This advantageously eliminates the need to adjust the dynamic differences, with the faster first and / or second dosing unit being adapted to the slower blower, resulting in improved dynamics of the device.
[0028] According to a preferred embodiment of the device, the total volume flow, the concentration value, and the pressure value can be fed to the multivariable controller as actual values. Furthermore, taking into account the actual values and at least one value of a target concentration, a target pressure, and / or a target volume stored as a target value, the multivariable controller generates a blower control signal for controlling the blower and / or a first control variable for a first target volume flow and / or a second control variable for a second target volume flow. The target concentration, the target pressure, and the target volume are the reference variables of the multivariable controller. These can be adjusted by a user, for example, using an input unit of the ventilator. It is also conceivable for the reference variables to be stored in the ventilator or transmitted to the ventilator. Depending on the ventilation mode, different combinations of the reference variables are necessary.For pressure-controlled ventilation, the target pressure and the target concentration are particularly necessary, while for volume-controlled ventilation, the target volume and the target concentration are particularly necessary. Furthermore, a combination of the target concentration, target pressure, and target volume is also necessary, for example, for volume-controlled ventilation with a limitation of the ventilation pressure. In addition to the target volume, a target volume flow for the respiratory gas flow to be provided can also be a reference variable.
[0029] Depending on the operating mode of the device, the multi-variable controller can generate the corresponding control variables using the respective actual values and reference variables. In the case of the first operating mode, the first control variable for the first target volume flow and the second control variable for the second target volume flow are generated. The first control variable is used to control the first dosing unit and the second control variable is used to control the second dosing unit. It is conceivable that only one of the control variables is generated if only a single external gas source at the first or second inlet contributes to the breathing gas flow. Furthermore, the respective control variable is suitable for directly controlling the respective dosing unit or as an input variable for further control of a volume flow, in particular as an input variable for a volume flow controller.In the second operating mode, the first control variable, the second control variable, and the blower control signal are generated to control the blower. In the third operating mode, the blower control signal and the first control variable or the second control variable are generated, depending on which external gas source contributes to the breathing gas flow. In the fourth operating mode, the blower control signal is generated. The blower control signal is suitable for controlling the blower. This could be, for example, a speed setting or a voltage.
[0030] The multivariable controller is therefore advantageously able to take into account the physical coupling of the various actuators, particularly when multiple actuators are in use, where they contribute to the breathing gas flow, pressure buildup, and volume flow. Furthermore, the multiple actuators also influence the oxygen concentration of the breathing gas flow. The actuators are the first dosing unit, the second dosing unit, and the blower.
[0031] In the first operating mode and volume-controlled ventilation, the multivariable controller generates the first and second control variables for the first and second dosing units using the target volume and the target concentration. The dosing units generate a first and a second partial respiratory gas flow, which are combined upstream of the mixing volume or in the mixing volume and result in the respiratory gas flow downstream of the mixing volume. The first and second control variables determine the distribution of the target volume and the target concentration between the first and second dosing units. The dosing units preferably have a high degree of positioning accuracy, ensuring precise dosing of the partial respiratory gas flows. In this case, the first and second dosing units are controlled directly using the first and second control variables.Alternatively or additionally, it is conceivable that the first and second control variables are fed to a further control unit, which takes these control variables into account and, in turn, generates a further control variable that controls the first and / or second dosing unit. Such a further control unit in the form of a volume flow controller will be explained in more detail later in the description.
[0032] In the second and third operating modes, i.e., in cases where the blower and at least one dosing unit contribute to generating the respiratory gas flow, the multivariable controller generates the blower controller signal in addition to the first and / or second control variable, as described above. Due to the dynamic decoupling of the actuators mentioned above, the controller component for the blower can be designed separately. This controller component is preferably designed as a PID controller, with the I component being calculated, for example, once per ventilation stroke. The control deviation of this PID controller is the difference between the target pressure and the pressure value, with the pressure being measured, for example, close to the patient.
[0033] In a preferred embodiment of the device, the control and regulation unit comprises a volume flow controller. The first control variable for the first target volume flow and the measured value of the first volume flow sensor, as well as the second control variable for the second target volume flow and the measured value of the second volume flow sensor, can be supplied to the volume flow controller as input values. Furthermore, the volume flow controller generates a first dosing control signal for controlling the first dosing unit and / or a second dosing control signal for controlling the second dosing unit, taking the input values into account.This can be a single volume flow controller or, preferably, two volume flow controllers, with the first control variable and the measured value of the first volume flow sensor being supplied as input values to a first volume flow controller, and the second control variable and the measured value of the second volume flow sensor being supplied as input values to a second volume flow controller. In this case, the first volume flow controller generates the first dosing control signal and / or the second volume flow controller generates the second dosing control signal.
[0034] The respective control variable for the target volume flow from the multivariable controller is the reference variable of the respective volume flow controller. The volume flow controller compares the respective control variable with the measured value of the respective volume flow sensor and generates the respective dosing controller signal. Inaccuracies in the first and second dosing units can advantageously be at least partially compensated for by means of the first and second volume flow controllers, so that the partial volume flows can be precisely dosed and a proper breathing gas flow is achieved. According to a preferred embodiment of the device, the third gas line has a shut-off valve downstream of the blower and upstream of the mixing volume.
[0035] The shut-off valve is capable of closing the third gas line, thus interrupting the fluid communication between the blower and the mixing volume. In this case, no fluid communication takes place upstream of the mixing volume through the third gas line.
[0036] When ventilating patients, particularly in intensive care, maneuvers are used to improve treatment. One such maneuver is the P.01 maneuver, which is used to measure a patient's airway pressure. This maneuver measures the airway pressure generated by the patient's inspiratory effort for 100 ms. During this time, no respiratory gas components are supplied by the ventilator, creating a negative pressure that corresponds to the patient's respiratory gas pressure. Furthermore, with high-frequency ventilation, the ventilation mode of a ventilator, a negative pressure occurs within the ventilator's gas lines.
[0037] With regard to the device and the P0.1 maneuver, the first and second dosing units must be closed. Due to the negative pressure that develops during the P0.1 maneuver or during high-frequency ventilation, the supply of breathing gas through the third gas line must be interrupted, as the permeable blower and the check valve allow ambient air into the device if a negative pressure exists downstream of the check valve. Advantageously, closing the shut-off valve prevents ambient air from entering the mixing volume if a negative pressure occurs downstream of the shut-off valve. Following the maneuver or high-frequency ventilation, the shut-off valve is reopened, and the supply of breathing gas through the device continues.
[0038] Preferably, the shut-off valve is controllable by a processing unit, such as the control and regulation unit. Alternatively or additionally, the shut-off valve can be operated manually and / or controlled electronically. This allows the user to manually close and reopen the shut-off valve, for example, in the case of high-frequency ventilation, where the shut-off valve must be permanently closed. This allows the operation of the shut-off valve to be adapted to different user needs.
[0039] The shut-off valve is preferably designed as a large-bore shut-off valve. A large-bore shut-off valve with a large internal cross-section exhibits low flow resistance, resulting in only a minimal pressure drop when a breathing gas component flows through. A large-bore shut-off valve is particularly advantageous in the case of a blower that generates only a low maximum pressure.
[0040] In a preferred embodiment of the device, the control and regulation unit is configured to control the shut-off valve depending on an input and / or depending on an operating mode of the ventilator.
[0041] Preferably, the input is manual, electronic, for example, via a digital input unit of the ventilator. This allows a user to change the state of the shut-off valve. Alternatively or additionally, the state of the shut-off valve is automatically adjusted based on a specific operating mode, for example, in the P.01 maneuver described above. Advantageously, the shut-off valve can be controlled manually and / or automatically, allowing the device to be used flexibly.
[0042] According to a preferred embodiment of the device, the mixing volume has a volume in the range of 50 ml to 300 ml. Preferably, the mixing volume has a volume of 150 ml, particularly preferably, the mixing volume has a volume of 200 ml.
[0043] In practice, mixing volumes for ventilators in the range of around 700 ml are common. Such a mixing volume ensures good mixing of different respiratory gas components by slowing the introduced gas flows and their gas exchange. The size of a mixing volume influences the dynamics of the ventilator. In general, the larger the volume, the lower the dynamics. In particular, the time required for a change in concentration, for example, that of oxygen, to occur in the respiratory gas flow is increased. Due to the small size of the proposed mixing volume, very good dynamics can be achieved, and changes to the ventilator settings can be implemented quickly. The range of 50 ml to 300 ml for the mixing volume is selected to ensure good dynamics and good mixing of the introduced gas flows over a ventilation range of 1 l / min (1.667 x 10'). 5 m 3 / s) to 180 l / min (0.003 m 3 / s). It is conceivable that the mixing volume is a simple hollow space or, preferably, additionally has a geometry that, for example, creates turbulence in the mixing volume, which promotes mixing. For a mixing volume of 150 ml and especially 200 ml, particularly good dynamics with good mixing across the entire ventilation range were observed.
[0044] In a preferred embodiment of the device, the fourth gas line has a concentration sensor for determining the concentration value. This is preferably an electrochemical sensor for measuring oxygen concentration. Alternatively or additionally, the control and regulation unit is configured to determine the concentration value using the measured values of the volume flow sensors.
[0045] As previously mentioned, the concentration value can be determined using a corresponding sensor and / or through calculations. The combination of both variants offers the possibility of checking the sensor value or the calculated value, so that, for example, a defective sensor can be detected. Furthermore, the sole calculation of the concentration value results in a cost-effective and compact device, as an additional sensor is not required. Overall, the device therefore offers particular flexibility in practical use and is adaptable to the user's needs. According to a preferred embodiment, the device has a pressure sensor for determining the pressure value. The sensor preferably measures the pressure of the provided respiratory gas flow close to the patient. The pressure sensor has, for example, a fluid-communicating connection to a breathing mask.Furthermore, it is conceivable to calculate the pressure value using an inspiratory pressure value, an expiratory pressure value, as well as the measured volume flows and a resistance value of a hose system of the device. The inspiratory pressure value is determined by a pressure sensor that is fluidly connected to the fourth gas line, and the expiratory pressure value is determined by another pressure sensor that is fluidly connected to an expiratory line of a ventilator. The resistance value of the hose system of the device is predetermined and is available to a computing unit, for example, the control and regulation unit, for calculating the pressure value.
[0046] In a preferred embodiment of the device, a fourth inlet for an external medium-pressure gas source is fluidly connected to the first dosing unit or the second dosing unit.
[0047] A medium-pressure gas source is a source that supplies a breathing gas component at a medium pressure, where a medium pressure is, for example, in a range of 300 mbar to 700 mbar. The external medium-pressure gas source preferably supplies oxygen at a pressure of 500 mbar and can, for example, be a so-called oxygen concentrator. This draws in ambient air, compresses it, and filters the nitrogen it contains using a filter membrane or a molecular sieve. The oxygen concentrator therefore supplies almost pure oxygen, which can be used to enrich the breathing gas stream with oxygen. The external medium-pressure gas source is fluidly connected to the first or second dosing unit via the fourth inlet. It is conceivable that the fourth inlet is fluidly connected to the first gas line upstream of the first dosing unit, thus establishing fluid communication with the first dosing unit.Furthermore, it is conceivable that the fourth inlet is fluidly connected to the second gas line upstream of the second dosing unit, thus creating fluid communication with the second dosing unit.
[0048] As previously described, the first and second inlets, and thus also the first and second dosing units, are suitable for high pressures, for example from the central gas supply (CGV) at a pressure of 2.7 bar to 6 bar. This preferred embodiment of the device advantageously offers the possibility of dosing a gas flow at medium pressure as an alternative to the high-pressure gas flow. Furthermore, it is possible to use the first dosing unit to dose a gas flow at high pressure from the central gas supply (CGV) and the second dosing unit to dose a gas flow at lower pressure from the external medium-pressure gas source, or vice versa. Advantageously, no additional dosing unit or volume flow sensor is required for this fourth inlet, thus saving costs and installation space.
[0049] Furthermore, the invention relates to a method for providing a respiratory gas flow for a ventilator with a device designed according to one of the previously described embodiments. The method comprises the following steps:
[0050] - Receiving at least one setpoint value of a setpoint concentration, a setpoint pressure and / or a setpoint volume
[0051] - Opening the first and / or second dosing unit and / or activating the fan taking into account the at least one setpoint
[0052] - Determine the total volume flow
[0053] - Determine the concentration value of the breathing gas flow and / or the pressure value of the fourth gas line
[0054] - Controlling the first dosing unit, the second dosing unit and / or the blower by the control and regulating unit taking into account the at least one setpoint value as a function of the total volume flow, the concentration value and / or the pressure value. The method is suitable for being carried out by the device described above. In the first method step, the setpoint values are received, whereby the type of ventilation mode, for example compressed air-based or volume-based, determines which setpoint values are at least necessary. As described above, at least the setpoint pressure and the setpoint concentration are required for a compressed air-based ventilation mode and at least the setpoint volume and the setpoint concentration are required for volume-based ventilation. Furthermore, it is conceivable that all three setpoint values are required, in particular in the case of a volume-based ventilation mode with a pressure limitation.
[0055] The setpoints can be adjusted, for example, via an input unit on the ventilator or stored in the ventilator's data memory so that they can be transmitted to the control unit. It is conceivable that the setpoints could be transmitted digitally to the ventilator and forwarded to the control unit.
[0056] In the second process step, the actuators are opened or activated according to the operating mode. For example, an initial dosing is carried out by the respective actuators depending on the setpoints. In the first operating mode, the first and second dosing units are at least partially opened; in the second operating mode, the first and second dosing units are at least partially opened and the blower is activated. The activated blower draws in ambient air and passes it on. In the third operating mode, the blower is activated and the first or second dosing unit is at least partially opened, depending on which external gas source is to contribute to the breathing gas flow. In the fourth operating mode, the blower is activated.
[0057] In the subsequent third process step, in which an initial breathing gas flow is available, its volume flow, the total volume flow, is determined. In the first operating mode, in which only the external sources, such as the CGF, contribute to the breathing gas flow, the first volume flow value from the first volume flow sensor and the second volume flow value from the second volume flow sensor are added together. In this case, the total volume flow is calculated. Otherwise, the total volume flow is measured using the third volume flow sensor.
[0058] In the fourth step, the concentration value and / or the pressure value are determined. Depending on the ventilation mode, these values are required for controlling the control unit. The concentration value and the pressure value can be determined using suitable sensors. Alternatively, or additionally, the concentration value can be calculated, as described above.
[0059] In the fifth process step, the respiratory gas flow is controlled using the setpoints, the total volume flow, and the pressure and / or concentration values. This is carried out by a control and regulation unit, as previously described. Depending on the operating and ventilation mode, the total volume flow, the concentration value, and the pressure value are compared with the setpoints, any deviation is determined, and based on this, a control signal is generated for the first dosing unit, the second dosing unit, and / or the blower. The process is advantageously suitable for implementing the various operating modes and utilizing various combinations of actuators.
[0060] According to a preferred development of the method, the control and regulating unit controls the first dosing unit, the second dosing unit and / or the blower in such a way that the respiratory gas flow downstream of the mixing volume has a low pressure level which is in the range from 0 to 120 hPa.
[0061] A low-pressure level is defined as a pressure range suitable for ventilating a patient. The proposed range of 0 to 120 hPa includes pressure values for a respiratory gas flow suitable for continuous ventilation, as well as pressure values suitable for special ventilation modes, such as the treatment of obstructive airway diseases. Furthermore, it is conceivable that negative pressures may develop downstream of the mixing volume, particularly in the range of -30 to 0 hPa, caused primarily by external influences. This could be caused, for example, by the patient breathing independently while connected to the ventilator.
[0062] As previously described, the respective actuator is controlled depending on the respective operating mode. Dosing takes place only upstream of the mixing volume, eliminating the need for further dosing downstream of the mixing volume by an additional dosing unit, as is known in the prior art.
[0063] This advantageously covers a wide pressure range, making the provided breathing gas flow suitable for various ventilation modes. Furthermore, no additional dosing unit downstream of the mixing volume is required to regulate the breathing gas flow, thus saving costs and space.
[0064] According to a preferred development of the method, the control and regulation unit puts the blower into a passive state so that it makes no contribution to the breathing gas flow, wherein the blower is switched on and the ambient air sucked in is blocked by the check valve.
[0065] The passive state of the blower is a condition in which the blower is operating and drawing in ambient air, but this air does not contribute to the provided breathing gas flow because the pressure generated is lower than the pressure required for the check valve to allow the ambient air to pass through. Thus, in this case, the drawn-in ambient air is not passed on to the mixing volume because the check valve is blocked, i.e., impermeable to the ambient air. The pressure limit at which the check valve becomes permeable downstream depends on the check valve itself and the ambient conditions. The control and regulation unit, the blower, and the check valve are configured and / or suitable to bring about such a passive state of the blower.It is conceivable that the pressure limit for the respective check valve is stored in the control and regulation unit, so that the control and regulation unit generates a control signal for the blower to achieve this passive state. Furthermore, it is conceivable that the control and regulation unit generates this control signal taking the measured volume flows into account. In this case, a control signal is generated so that the blower makes no contribution to the total volume flow, but rather only the first and / or second dosing unit contributes to the total volume flow. This has the advantage that the passive state of the blower is reliably achieved regardless of changing ambient conditions.
[0066] The method is therefore capable of placing the blower into a passive state, where it is already operating but does not contribute to the respiratory gas flow. The blower is therefore not completely shut down and does not need to be restarted if it is to contribute to the respiratory gas flow, for example, in the second operating mode. Due to its function, starting up the blower requires a certain amount of time, as the blower must first start up or accelerate. This time is advantageously shortened by the passive state. Furthermore, starting up the blower from the passive state affects the dynamics of the ventilator, which are thereby further improved.
[0067] According to a preferred development of the method, the blower is activated when the blower is inactive and a pressure and / or volume flow insufficient condition is detected. The inactive blower condition refers to a switched-off blower that, for example, does not contribute to the respiratory gas flow, as in the first operating mode.
[0068] If an undersupply of pressure and / or volume flow is detected, the fan is activated, i.e. switched on, so that it contributes to the breathing gas flow. The undersupply is preferably detected in the control and regulation unit. For example, the current pressure value and / or the current total volume flow value is compared with a corresponding limit value. It is conceivable that the limit value(s) are stored in the control and regulation unit or that the control and regulation unit has access to them. It is also conceivable that the current pressure value and / or the current total volume flow value are compared with the corresponding target values.If the current pressure value and / or the current total volume flow value is smaller than the respective limit value or the respective setpoint by several times, for example more than five times in a row or over a period of 30 seconds, an undersupply is detected and the fan is activated.
[0069] Supply failures can occur, particularly when supplied by external sources, such as a central gas supply (CGV) in the first operating mode. In the worst case, this can mean that no breathing gas flow can be provided. To prevent this, the control and regulation unit compares the pressure value with a pressure limit and / or the total volume flow with a volume flow limit. Depending on the ventilation mode, as described above, the limit values are relevant individually or together. If an undersupply of pressure and / or volume flow is detected, it can be assumed that a defect, as described above as an example, exists and the external sources are at least partially not contributing to the breathing gas flow. In this case, the control and regulation unit regulates the blower so that it contributes to the breathing gas flow. For example, an automatic changeover from the first to the third or fourth operating mode takes place.In an advantageous manner, a breathing gas flow continues to be provided, even in the case where at least one of the external sources unexpectedly fails to contribute to the breathing gas flow, for example due to a defect.
[0070] According to a preferred development of the method, the third gas line between the check valve and the mixing volume is shut off depending on an input and / or depending on an operating mode of the device. As previously described, a so-called maneuver may be necessary during ventilation, particularly during intensive care ventilation, of a patient. For example, the patient's inspiratory effort is tested, resulting in a negative pressure that is measured.
[0071] However, such a negative pressure can only arise if the device is sealed, i.e. no gas flow enters the device during the maneuver. Due to the fact that the blower is permeable to gas, even when it is not in operation, the third gas line is closed during such a maneuver. Thus, when the negative pressure occurs, no gas flow flows through the third inlet and the blower. This is achieved, for example, with the previously described shut-off valve, which is closed in this case. The first and second dosing units are also closed during the maneuver. Furthermore, a negative pressure can arise within the device during high-frequency ventilation, as described above, which is why the third gas line is also shut off during high-frequency ventilation.
[0072] Closing is achieved by an input, which can be manual or automatic, i.e., via an electronic control system. The shut-off valve is operated manually or, for example, closed and opened by a signal from an input unit of the ventilator. Automatic shut-off and unlocking of the third gas line is also conceivable, with the control and regulation unit automatically controlling the shut-off valve depending on the operating mode—in this case, the execution of a maneuver.
[0073] Furthermore, the invention relates to a ventilator with a device which is designed according to one of the previously described embodiments and / or which can carry out a method according to at least one of the previously described embodiments.
[0074] The proposed ventilator comprises the device and preferably an input unit and a signaling unit, wherein the input unit and the signaling unit are connected to the control and regulation unit of the device for data exchange. The device is designed according to one of the previously described embodiments. The input unit can be a touch display or a display with control elements. The signaling unit can have an acoustic and / or optical signal generator and / or be capable of generating and transmitting a digital signal.
[0075] The ventilator is advantageously flexible and suitable for different operating modes. Furthermore, due to the aforementioned advantages of the device, it is compact and easy to transport. This makes it easy to transfer a patient to another ward while continuing ventilation. Due to its compact size and the small number of components, for example, the elimination of a dosing unit located downstream of the mixing volume, the ventilator is also low-cost.
[0076] Furthermore, the invention relates to a use of a device according to one of the previous embodiments, wherein the control and regulation unit of the device comprises a multi-variable controller with a single-loop fan control circuit
[0077] As previously described, the multivariable controller is characterized by having at least two reference variables. This makes it possible to take into account the interdependencies of several reference variables, such as pressure and volume flow of the breathing gas flow, during control. As previously described, a single-loop blower control loop is a control loop for the blower without any subordinate control loops. Subordinate control loops are found, for example, in cascade controllers.
[0078] As previously described, the multivariable controller with a single-loop fan control circuit exhibits advantageous dynamic behavior, allowing particularly fast control. Further features, objects, and effects of the invention will become apparent from the following description of specific embodiments and the accompanying figures. Embodiments of the invention are described without limiting the general inventive concept.
[0079] In the figures shows:
[0080] Fig. 1 : a schematic block diagram of an embodiment of the device according to the invention,
[0081] Fig. 2: a flow diagram of an embodiment of the method according to the invention,
[0082] Fig. 3: a schematic block diagram of the ventilator with an embodiment of the device according to the invention, and
[0083] Fig. 4: a schematic control scheme of an embodiment of the device according to the invention.
[0084] Embodiments of the invention are described in detail below with reference to the accompanying figures. Similar components in several figures are provided with the same reference numerals.
[0085] Fig. 1 shows a preferred embodiment based on a schematic block diagram of the device 10 according to the invention with a first inlet 1, a second inlet 2 and a third inlet 3. The first inlet 1 is fluidly connected to a mixing volume 11 via a first gas line 4. The first gas line 4 comprises a first dosing unit V1 and a first volume flow sensor S1 arranged downstream of the first dosing unit V1 and upstream of the mixing volume 11. The second inlet 2 is fluidly connected to the mixing volume 11 via a second gas line 5. The second gas line 5 comprises a second dosing unit V2 and a second volume flow sensor S2 arranged downstream of the second dosing unit V2 and upstream of the mixing volume 11. The third inlet 3 is fluidly connected to the mixing volume 11 via a third gas line 6.The third gas line 6 comprises a blower 8 and a check valve 9 arranged downstream of the blower 8 and upstream of the mixing volume 11, wherein the passage direction of the check valve 9 lies in the flow direction from the blower 8 to the mixing volume 11. The mixing volume 11 is fluidly connected to an outlet 18 via a fourth gas line 7, wherein the fourth gas line 7 comprises a third volume flow sensor S3.
[0086] The first and second inlets 1, 2 are fluidly connected to a central gas supply (CGS), not shown, wherein in this exemplary embodiment the first inlet 1 is connected to an oxygen supply and the second inlet 2 is connected to an air supply. The third inlet 3 is fluidly connected to the ambient air of the device. The outlet 18 provides the respiratory gas flow AS for ventilating a patient 19. The first dosing unit V1, the first volume flow sensor S1, the second dosing unit V2, the second volume flow sensor S2, the blower 8 and the third volume flow sensor S3 are electronically connected to a control and regulating unit 15 for data acquisition and / or control, as indicated by the dashed lines in Fig. 1. The control and regulating unit 15 comprises at least one computing unit, which can be a microprocessor, for data acquisition, control and regulation.The first and / or second dosing unit V1, V2 and / or the blower 8 are controlled such that a designated respiratory gas flow AS is available at the outlet 18 of the device 10. The designated respiratory gas flow AS is understood to be a respiratory gas flow AS whose properties are specified by a user. The control and regulation unit 15 is controlled taking into account a measured value SV1, SV2, SV3 of the first, second and third volume flow sensors S1, S2, S3, a concentration value M1 of the respiratory gas flow AS and a pressure value M2 for a pressure downstream of the mixing volume 11. The control of the aforementioned respective actuators V1, V2, 8 and the consideration of the aforementioned respective values depend on the operating mode of the device 10.
[0087] The device 10 can be operated in four different operating modes, each of which differs in the composition of the breathing gas flow AS. In the first operating mode, the breathing gas flow AS is formed from the two external gas sources, i.e. air and oxygen from the CGA. In the second operating mode, the breathing gas flow AS is formed from the two external sources and the blower 8. This operating mode is particularly useful when the CGA supplies oxygen and another breathing gas component, for example heliox, so that these two breathing gas components from the CGA and ambient air, which is sucked in by the blower 8, contribute to the breathing gas flow AS. In the third operating mode, the breathing gas flow AS is formed from an external gas source and the blower 8, i.e. oxygen and ambient air. In the fourth operating mode, the breathing gas flow AS is formed from the blower 8, i.e. the ambient air.
[0088] Depending on the operating mode and depending on the setpoints F1, F2, F3, the control and regulation unit 15 controls the actuators V1, V2, 8, i.e. the first dosing unit V1, the second dosing unit V2 and / or the blower 8. The total volume flow SV3 of the third volume flow sensor S3 and the volume flow SV1 of the first volume flow sensor S1 and / or the volume flow SV2 of the second volume flow sensor S2 as well as the pressure value M2 and / or the concentration value, in this case the oxygen concentration value M1, are taken into account.
[0089] The target values, i.e., the target oxygen concentration F1, the target pressure F3, and the target volume F2, are fed to the control and regulation unit 15 from an input unit (not shown). The pressure value M2 and the oxygen concentration value M1 refer to the respiratory gas flow AS.
[0090] In the first operating mode, the actuators V1, V2, 8 are controlled such that the first and second dosing units V1, V2 contribute to the respiratory gas flow AS. In the second operating mode, the dosing devices V1, V2, 8 are controlled such that the first and second dosing units V1, V2 and the blower 8 contribute to the respiratory gas flow AS. In the third operating mode, the actuators V1, V2, 8 are controlled such that the blower 8 and the first dosing unit V1 contribute to the respiratory gas flow AS. In the fourth operating mode, the actuators V1, V2, 8 are controlled such that only the blower 8 contributes to the respiratory gas flow AS.
[0091] Fig. 2 shows a flow diagram of an embodiment of the method according to the invention. In a first method step 20, the setpoints F1, F2, F3 are received by the control and regulation unit 15. Which setpoints F1, F2, F3 are relevant depends on the type of ventilation mode. In a compressed air-based ventilation mode, at least the setpoint pressure F3 and the setpoint oxygen concentration F1 are received. In a volume-based ventilation mode, at least the setpoint volume F2 and the setpoint oxygen concentration F1 are received. The corresponding setpoints F1, F2, F3 are transmitted digitally to the control and regulation unit 15, for example, from an input unit 33 of the ventilator 30.
[0092] In a second method step 21, the actuators V1, V2, 8 are opened or activated according to the operating mode. For example, a first dosing is carried out by the respective actuators V1, V2, 8 depending on the setpoints F1, F2, F3. In the first operating mode, the first and second dosing units V1, V2 are at least partially opened; in the second operating mode, the first and second dosing units V1, V2 are at least partially opened and the blower 8 is activated. The activated blower 8 sucks in ambient air and passes it on into the mixing volume 11. In the third operating mode, the blower 8 is activated and the first dosing unit V1 is at least partially opened. In the fourth operating mode, the blower 8 is activated.
[0093] In a subsequent third method step 22, in which a first respiratory gas flow AS is provided, its volume flow SV3 is measured using the third volume flow sensor S3. This is the total volume flow SV3.
[0094] In a fourth method step 23, the concentration value M1 is measured with an oxygen concentration sensor 31 and the pressure value M2 with a pressure sensor 32. In a fifth method step 24, the respiratory gas flow AS is controlled. This is carried out by the control and regulation unit 15, as previously described. Depending on the operating and ventilation mode, the total volume flow SV3, the concentration value M1 and the pressure value M2 are compared with the target values F1, F2, F3. If a deviation is detected, at least one control signal RV1, RV2, R3 is generated in order to control the first or second dosing unit V1, V2 and / or the blower 8 and at least to reduce the detected deviation.
[0095] Fig. 3 shows a schematic block diagram of the ventilator 30 with an embodiment of the device according to the invention. The device in Fig. 3 comprises, in addition to the device in Fig. 1, a shut-off valve V3, a fourth inlet 16, an oxygen concentration sensor 31 for measuring the oxygen concentration M1, and a pressure sensor 32 for measuring the near-patient pressure M2. The shut-off valve V3 is fluidly connected to the third gas line 6 and is arranged downstream of the check valve 9 and upstream of the mixing volume 11. The fourth inlet 16 is fluidly connected to the first dosing unit. The oxygen concentration sensor 31 is fluidly connected to the fourth gas line 7 and is arranged downstream of the mixing volume 11 and upstream of the third volume flow sensor S3.The pressure sensor 32 is fluidly connected to a patient's breathing gas mask (not shown) and enables the measurement of a near-patient pressure M2. The ventilator 30 further comprises an input unit 33 and a signaling unit 34. The input unit 33 is designed as a touch display. The signaling unit 34 comprises optical and acoustic signaling elements. The input unit 33 and the signaling unit 34 are electronically connected to the control and regulation unit 15 for data exchange.
[0096] The additional shut-off valve V3 compared to Fig. 1 is electronically connected to the control and regulation unit 15 and enables the third gas line 6 between the check valve 9 and the mixing volume 11 to be closed. This enables the ventilator 30 to carry out a so-called maneuver, as described above. The maneuver is started using the input unit 33, after which a digital signal is sent from the input unit 33 to the control and regulation unit 15. The control and regulation unit 15 then closes the shut-off valve V3 as well as the first and second dosing units V1, V2 so that the maneuver, for example the P.01 maneuver, can take place. Following the maneuver, the shut-off valve V3 is opened again and the previously interrupted operating mode is returned to and the regulation and control of the respective actuators V1, V2, 8 is continued.
[0097] Fig. 4 shows a schematic control scheme of an embodiment of the device 10 according to the invention. The setpoint values F1, F2, F3 input into the input unit 33: the setpoint oxygen concentration F1, the setpoint pressure F3, and the setpoint volume F2, can be fed to the multivariable controller 41 of the control and signal unit 15 as reference variables. Furthermore, the measured oxygen concentration M1 of the oxygen sensor 31, the measured pressure M2 of the pressure sensor 32, and the measured volume flow, the total volume flow SV3, of the third volume flow sensor S3 can be fed to the multivariable controller 41. Depending on the operating and ventilation mode and depending on the setpoints F1, F2, F3 and taking into account the measured oxygen concentration M1, the measured pressure M2 and the measured total volume flow SV3, the multi-variable controller 41 generates a first setpoint volume flow R1, a second setpoint volume flow R2 and a blower control signal R3.The blower 8 can be controlled directly using the blower control signal R3. The first target volume flow R1 can be fed to a first volume flow controller 42, and the second target volume flow can be fed to the second volume flow controller 43. The first volume flow controller 42 generates the first dosing control signal RV1 for the first dosing unit V1 as a function of the first target volume flow R1 and taking into account the measured first volume flow SV1 by the first volume flow sensor S1. The second volume flow controller 43 generates the second dosing control signal RV2 for the second dosing unit V2 as a function of the second target volume flow R2 and taking into account the measured second volume flow SV2 by the second volume flow sensor S2. Depending on the operating mode, the blower 8 generates a third volume flow VS3, the first dosing unit V1 generates a first volume flow VS1 and the second dosing unit V2 generates a second volume flow VS2.The volume flows VS1, VS2, VS3 can be fed to the mixing volume 11 for mixing. The respiratory gas flow AS generated from at least one of the volume flows VS1, VS2, VS3 is provided to the patient 19. Furthermore, the oxygen concentration sensor 31 measures the oxygen concentration M1, the third volume flow sensor S3 measures the total volume flow SV3, and the pressure sensor 32 measures the pressure M2 of the respiratory gas flow AS.
[0098] List of reference symbols
[0099] 1 first entry
[0100] 2 second entrance
[0101] 3 third entrance
[0102] 4 first gas pipeline
[0103] 5 second gas line
[0104] 6 third gas pipeline
[0105] 7 fourth gas pipeline
[0106] V1 first dosing unit
[0107] V2 second dosing unit
[0108] 8 fans
[0109] 9 Check valve
[0110] 51 first volume flow sensor
[0111] 52 second volume flow sensor
[0112] 53 third volume flow sensor
[0113] 10 Device for providing a breathing gas flow
[0114] 11 Mixing volume
[0115] 15 Control and regulation unit
[0116] 16 fourth entrance
[0117] 18 Outlet
[0118] 19 patients
[0119] 20 first procedural step
[0120] 21 second procedural step
[0121] 22 third procedural step
[0122] 23 fourth procedural step
[0123] 24 fifth procedural step
[0124] 30 ventilators
[0125] 31 Oxygen concentration sensor
[0126] 32 pressure sensor
[0127] 33 Input unit
[0128] 34 Signaling unit
[0129] V3 shut-off valve
[0130] 41 Multivariable controller 42 First volume flow controller
[0131] 43 second volume flow controller
[0132] F1 Target oxygen concentration
[0133] F2 Target volume
[0134] F3 Target pressure
[0135] M1 measured oxygen concentration
[0136] M2 measured pressure
[0137] SV1 measured first volume flow
[0138] SV2 measured second volume flow
[0139] SV3 measured total volume flow
[0140] R1 Control variable for a first target volume flow
[0141] R2 Control variable for a second target volume flow
[0142] R3 Fan control signal
[0143] RV1 first dosing controller signal
[0144] RV2 second dosing controller signal
[0145] VS1 first volume flow
[0146] VS2 second volume flow
[0147] VS3 third volume flow
[0148] AS Atemgasstrom
Claims
1. Device (10) for providing a respiratory gas flow (AS) for a ventilator (30) with a first inlet (1) and a second inlet (2) for connecting external gas sources, wherein the first inlet (1) is connected to a mixing volume (11) by means of a first gas line (4) and the second inlet (2) is connected to a mixing volume (11) by means of a second gas line (5) in a fluid-communicating manner, and the first gas line (4) has a first dosing unit (V1) with a first volume flow sensor (S1) arranged downstream of the first dosing unit (V1), and the second gas line (5) has a second dosing unit (V2) with a second volume flow sensor (S2) arranged downstream of the second dosing unit (V2), with a third inlet (3),which is fluidly connected to the mixing volume (11) by means of a third gas line (6), and the third gas line (6) has a blower (8) and a check valve (9) arranged downstream of the blower (8) and upstream of the mixing volume (11), wherein the blower (8) is designed to suck in ambient air via the third inlet (3) and to convey the ambient air in the direction of the check valve (9), and with a fourth gas line (7) which establishes fluid communication between the mixing volume (11) and an outlet (18) at which the breathing gas flow (AS) is provided, characterized in that the fourth gas line (7) has a third volume flow sensor (S3) for measuring a total volume flow (SV3), and in that a control and regulating unit (15) is provided which is configured to control the blower (8), the first dosing unit (V1) and the second Dosing unit (V2) taking into account a measured value (SV1, SV2,SV3) of the first volume flow sensor (S1), the second volume flow sensor (S2) and the third volume flow sensor (S3) individually or in combination, a concentration value (M1) of the respiratory gas flow (AS) and / or a pressure value (M2) for a pressure downstream of the mixing volume (11).
2. Device (10) according to claim 1, characterized in that the control and regulating unit (15) has a multi-variable controller (41) with a single-loop fan control circuit.
3. Device (10) according to claim 2, characterized in that the Multivariable controller (41 ) as actual values (SV3, M1 , M2) of the Total volume flow (SV3), the concentration value (M1) and the pressure value (M2) can be supplied and the multi-variable controller (41), taking into account the actual values (SV3, M1, M2) and at least one value stored as a setpoint of a setpoint concentration (F1), a setpoint pressure (F3) and / or a setpoint volume (F2), generates a blower controller signal (R3) for controlling the blower (8) and / or generates a first control variable for a first setpoint volume flow (R1) and / or a second control variable for a second setpoint volume flow (R2).
4. Device (10) according to claim 3, characterized in that it has a volume flow controller (42, 43) to which the first control variable for the first desired volume flow (R1) and the measured value (SV1) of the first volume flow sensor (S1) and the second control variable for the second desired volume flow (R2) and the measured value (SV2) of the second volume flow sensor (S2) can be fed as input values (R1, SV1, R2, SV2) and which, taking into account the input values (R1, SV1, R2, SV2), generates a first dosing controller signal (RV1) for controlling the first dosing unit (V1) and / or a second dosing controller signal (RV2) for controlling the second dosing unit (V2).
5. Device (10) according to one of the preceding claims, characterized in that the third gas line (6) has a shut-off valve (V3) downstream of the blower (8) and upstream of the mixing volume (11).
6. Device (10) according to claim 5, characterized in that the control and regulating unit (15) is configured to open the shut-off valve (V3) in dependence an input and / or depending on an operating mode of the ventilator (30).
7. Device (10) according to one of the preceding claims, characterized in that the mixing volume (11) has a volume in the range of 50 ml to 300 ml.
8. Device (10) according to one of the preceding claims, characterized in that the fourth gas line (7) has a concentration sensor (31) for determining the concentration value (M1) and / or the control and regulation unit (15) is configured to determine the concentration value by means of the measured values (SV1, SV2, SV3) of the volume flow sensors (S1, S2, S3).
9. Device (10) according to one of the preceding claims, characterized in that the device (10) has a pressure sensor (32) for determining the pressure value (M2).
10. Device (10) according to one of the preceding claims, characterized in that a fourth inlet (16) for an external medium-pressure gas source is fluidly connected to the first dosing unit (V1) or the second dosing unit (V2).
11. A method for providing a respiratory gas flow (AS) for a ventilator () with a device (10) according to one of the preceding claims, characterized by the following steps: - Receiving at least one setpoint value (F1, F2, F3) of a setpoint concentration (F1), a setpoint pressure (F3) and / or a setpoint volume (F2) - Opening the first dosing unit (V1) and / or the second dosing unit (V2) and / or activating the fan (8) taking into account the at least one setpoint value (F1, F2, F3) - Determine the total volume flow (SV3) - Determining the concentration value (M1) of the breathing gas flow (AS) and / or the pressure value (M2) of the fourth gas line (7) - Controlling the first dosing unit (V1), the second dosing unit (V2) and / or the blower (8) by the control and regulating unit (15) taking into account the at least one setpoint value (F1, F2, F3) as a function of the total volume flow (SV3), the concentration value (M1) and / or the pressure value (M2) 12. The method according to claim 11, characterized in that the control and regulating unit (15) controls the first dosing unit (V1), the second dosing unit (V2) and / or the blower (8) in such a way that the respiratory gas flow (AS) downstream of the mixing volume (11) has a low pressure level which is in the range from 0 to 120 hPa.
13. Method according to claim 11 or 12, characterized in that the control and regulation unit (15) puts the blower (8) into a passive state so that it makes no contribution to the respiratory gas flow (AS), the blower (8) being switched on and the ambient air sucked in being blocked by the check valve (9).
14. Method according to one of claims 11 to 13, characterized in that when the blower (8) is inactive and when an undersupply of pressure and / or undersupply of volume flow is detected, the blower (8) is activated.
15. Method according to one of claims 11 to 14, characterized in that the third gas line () between the check valve (9) and the mixing volume (11) is shut off as a function of an input and / or as a function of an operating mode of the device.
16. Ventilator (30) with a device (10) according to one of the claims 1 to 10.
17. Use of a device (10) according to claim 1 or according to one of claims 3 to 10, wherein the control and regulating unit (15) of the device (10) has a multi-variable controller (41) with a single-loop fan control circuit.