EP3840812A1

EP3840812A1 - Method for operating an actuator in a medical apparatus, and device therefor

Info

Publication number: EP3840812A1
Application number: EP19780358.8A
Authority: EP
Inventors: Matthias Van Der Staay
Original assignee: Imtmedical AG
Current assignee: Imtmedical AG
Priority date: 2018-08-24
Filing date: 2019-08-20
Publication date: 2021-06-30
Also published as: JP7406558B2; CN112584886A; WO2020039341A1; JP2021534945A; US20210308401A1

Abstract

The invention relates to a method for operating an actuator (22) in a medical apparatus (20), the actuator (22) being connected to a tube system. The medical apparatus (20) comprises: a control apparatus (28) having a pressure controller (35) for controlling a gas pressure; and a computing system (30). The method comprises the following steps: providing a nasal cannula at the tube system; defining a nasal gas end pressure at the pressure controller (35); controlling a nasal gas pressure at the actuator (22) by means of the pressure controller (35), in particular toward the nasal gas end pressure; discharging a conditioned gas from the actuator (22) to the tube system. The invention further relates to a device for operating the actuator (22).

Description

Method for operating an actuator in a medical device and a device therefor

The invention relates to a method for operating an actuator in a medical device according to claim 1 and a device therefor according to the preamble of claim 9.

Nasal flow therapy or high-flow oxygen therapy (FIFOT) is respiratory therapy, especially for use in hospitals, in which oxygen is supplied to a patient together with compressed air and humidification. The flow rates are higher than in conventional oxygen therapy.

High-flow oxygen therapy is usually used for patients who suffer from acute respiratory insufficiency in the clinical setting (e.g. hypoxemic, respiratory insufficiency). These patients are usually in the intensive care or monitoring unit and require respiratory assistance to stabilize them and to monitor the blood gases.

WO 201 5/155342 A1 shows a high-flow oxygen therapy system which has a gas supply, a humidifier, a nebuliser, an external nasal interface and an aerosol supply line and a gas supply line. The aerosol supply line and the gas supply line are controlled by a valve, with a flow control device being present which regulates the aerosol flow and the gas flow in the system.

There are currently medical devices on the market, such as the HFT500 from the firm a MEK-I CS CO. , LTD. (www.m ek-ics.com), which enable the use of high-flow oxygen therapy. Such a medical device comprises an actuator and a hose system connection for connecting a hose system to the actuator. The tubing system usually includes a nasal cannula.

A disadvantage of the known solutions is that such medical devices are set and regulated with regard to the gas flow. The constant gas flow increases the work of breathing, which in turn leads to exhaustion or stress for the patient. US 2012/009061 0 A1 discloses a CPAP device and a method for determining air flow properties of a mask system for treating sleep disorders (SDB), which can be used to characterize different mask systems. An air supply hose and a patient connection device or patient interface with a diffuser are shown as mask system s. The CPAP device has a flow generator which is connected to the mask system and which has a controllable air blower, a flow sensor and a pressure sensor and a processor. The processor is configured to determine airflow properties at the diffuser outlet. Generic devices are disclosed in WO 201 1/054038 A1, US 2016/287824 A1, WO 2017/109634 A1 and US 2018/036499 A1.

A disadvantage of the aforementioned solutions is that the devices mentioned there have no pressure control which is suitable for controlling the nasal gas pressure of different mask systems, as a result of which a disproportionately high gas consumption occurs on the device.

It is the object of the present invention, at least in part, to remedy one or more disadvantages of the prior art. In particular, a method for operating an actuator in a medical device and a device therefor are to be created which reduce the gas consumption in the medical device.

The object is achieved by the method and the device as defined in the independent claims. Advantageous further developments are set out in the figures and in the dependent claims.

The invention relates to a method for operating an actuator in a medical device, the actuator being connected to a hose system, and the medical device having a control device with a pressure regulator for regulating a gas pressure and having a computing system, the method having the following Steps include:

Providing a nasal cannula on the tube system (step a));

Setting a nasal gas pressure at the pressure control (step b)); Regulating a nasal gas pressure at the actuator with the aid of the pressure control, in particular towards the nasal gas pressure (step c));

Dispensing a conditioned gas from the actuator to the hose system (step d)).

The method is carried out, in particular, before a nasal flow therapy application or a high-flow oxygen therapy is carried out on a patient, the patient having to do less of his own breathing work due to the pressure regulation during the subsequent nasal flow therapy application. The pressure regulation regulates to a constant gas pressure, which is specified. In the application, the required peak flows of the gas or respiratory gas can be covered and a lower gas consumption can be achieved in the medical device, the applied oxygen concentration remaining unchanged. The nasal gas pressure is the gas pressure after the tube system. A conditioned gas has a gas pressure and gas flow predetermined by the actuator. The tube system usually includes a tube and a nasal cannula.

The medical device is advantageously a respirator, with the aid of the pressure control on the actuator the lung pressure of the patient being better controllable or adjustable. With the method according to the invention, the patient experiences increased comfort due to an adaptive gas flow.

The pressure control is preferably carried out on the basis of at least one nasal measured pressure value or on the basis of at least one pressure approximation value. In the case of pressure control with at least one nasal pressure measurement, the method described here can be carried out without an adjustment step. The medical device adapts automatically to changes in the hose system. With pressure control based on at least one pressure approximation value, nasal pressure measurement can be omitted, which means that the hose system can be manufactured more cost-effectively and the medical device can be operated with different hose systems or hose system accessories and therefore more universally.

A change in the nasal gas flow in the tube system is particularly preferred. Dam it is at least a pressure approximation Determine different nasal gas flow, the nasal cannula is typically not connected to a patient. For example, the change in the nasal gas flow is linear, so that at least one pressure approximation is easily determinable. The nasal gas flow is the gas flow in the hose system.

The change in the nasal gas flow is preferably between 0 liters per minute and 100 liters per minute. The nasal gas flow can change from high gas flow values to low gas flow values or vice versa, from low gas flow values to high gas flow values. This enables a multitude of pressure approximation values to be determined, which can serve as the basis for particularly precise pressure control on the actuator.

In particular, the change in the nasal gas flow takes place in a predetermined time interval, for example within 10 seconds. This means that at least one pressure approximate value can be determined reproducibly.

The nasal gas flow in the tube system is preferably changed before the nasal gas pressure is established at the pressure control (step b)). This allows the medical device to be adjusted to the device / hose system configuration before use on the patient, thereby avoiding excessive gas pressures and ensuring increased patient safety afterwards.

Preferably, the at least one pressure approximation value is calculated on the basis of at least one internal pressure measurement value and on the basis of at least one differential pressure approximation value in the hose system. An internal pressure measurement can be determined with a pressure measurement sensor in the medical device, which is located in the area of the hose system connection. An external pressure measurement sensor on the hose system is therefore not necessary.

A differential pressure approximation value in the hose system is preferably calculated on the basis of the internal gas flow. The internal gas flow is measured with the aid of a flow measurement sensor arranged in the medical device or indirectly via a suitable differential pressure-based one Flow measurement method determined mt. This means that, at the very least, an approximate pressure value can be determined with the aid of a simple measurement setup with exactly one pressure measurement sensor and with exactly one flow measurement sensor, which precisely determines the gas consumption in the medical device and subsequently prevents excessive gas consumption becomes.

In particular, the at least one differential pressure approximation value is calculated using a mathematical function, whereby the at least one pressure approximation value can be reliably determined in one adjustment step. For example, the mathematical function is a polynomial function or a quadratic function, which is solved using a least-square method, for example. Dam it is the at least one pressure approximate value particularly easily determined.

The at least one differential pressure approximation value is preferably called from a table in the computing system. The at least one differential pressure approximation value can be provided or preconfigured by the manufacturer of the medical device or can be stored in the table of the computing system during the adjustment steps. The differential pressure approximation values are assigned to the respective internal gas flow values, so that a conclusion can be drawn from a measured gas flow value about a differential pressure approximation value.

In particular, the at least one differential pressure approximation value is determined with the aid of at least one nasal pressure measurement value. This means that at least a differential pressure approximation can also be determined while the medical device is in use, which increases patient safety. At the same time, an internal pressure measurement value is supplemented with a nasal pressure measurement value, and from this the pressure approximation value is determined. Dam it, nasal pressure measurement is used to automatically detect a change in the tube system - for example after changing the nasal cannula on the tube system.

A minimum gas flow through the hose system is preferably determined. By applying a minimal gas flow, carbon dioxide leaching in the breathing gas can be ensured. The minimum gas flow can be easily based on body size or the ideal body weight and / or the sex of a patient, entered into the medical device by the user or using established theories, for example based on OTIS et. al, determine.

The minimum gas flow in the computing system is preferred calculated, where V _{d is} the dead space, k is a factor between 0.05 and 2 and T _{e is} an expiration time. The minimum gas flow can thus be set without the help of a user of the medical device, thereby relieving the burden on him.

In particular, the dead space V _{d is} calculated using an ideal body weight of the patient and a Radford constant, the Radford constant typically being 2.2 ml / kg. This makes it easy to determine the dead space V _d for a large number of applications.

The factor k = 0.33 is preferably used to calculate the minimum gas flow, as a result of which the minimum gas flow can be calculated easily and a particularly high level of patient safety is ensured.

In particular, T _{e is} an expiration time calculated with the computing system. This allows the minimum gas flow to be matched to the patient's current breathing activity.

Alternatively, the minimum gas flow is determined using a flow approximation, which is determined on the basis of an internal gas flow and on the basis of a leakage flow in the hose system. The leakage flow can typically be calculated using the nasal gas pressure.

The dead space V _{d is} estimated based on estimated values derived from the flow approximation, for example on the basis of a minute volume M _v , a breathing frequency f, an expiratory time constant RC-, so that the dead space V _{d is determined} automatically in the computing system of the medical device. For example, the dead space V _d with certainly. The minimum gas flow can then be calculated with this dead space V _d , as described above. The user does not have to make any settings on the medical device. The algorithm ensures that the carbon dioxide leaching is always in the optimal range.

The minimum gas flow is preferably set to a value between 0 and 100 liters per minute. The minimum gas flow can thus be limited to a value suitable for a patient.

The previously calculated minimum gas flow is preferably limited, an effective, internal, maximum gas flow being used as the starting point. The effective, internal, maximum gas flow of the gas in the hose system can be found in the medical device e.g. B. determine by measuring the gas flow with an internal flow measurement sensor in the medical device for a specified period of time. This time period is typically in a range between 10 seconds and 60 seconds, in particular in a range between 25 seconds and 45 seconds, in particular 36 seconds. By further limiting the internal gas flow, a situation-appropriate carbon dioxide leaching in the gas is guaranteed.

In particular, the calculated minimum gas flow is limited with an upper limit of 0.8 times the effective, internal, maximum gas flow and limited with a lower limit of 0.2 times the effective, internal, maximum gas flow. This further improves patient safety.

A maximum, average gas flow through the hose system is preferably provided. It is permissible for the gas flow to exceed a maximum in two cases, but to remain below the maximum average gas flow on average, the maximum being to be understood as a limitation. The limitation guarantees sufficient humidification of the gas that is provided in the hose system.

The average, maximum gas flow is preferably set to a value between 10 liters per minute and 200 liters per minute. This ensures that the patient can be supplied with sufficiently humidified gas. The average, maximum gas flow is particularly preferably set to a value of 60 liters per minute. Dam it provides a sufficiently humidified gas for the majority of applications, so that the user does not have to explicitly take care of this parameter setting on the medical device.

In particular, the average, maximum gas flow is regulated on the basis of a gas moisture value. The average, maximum gas flow is regulated with the flow control in the medical device based on the determined gas moisture value. Dam it can provide an optimally humidified gas in the hose system. For example, the medical device is connected to a humidifier or comprises a humidifier itself.

Alternatively, the average, maximum gas flow is determined on the basis of an oxygen concentration in the gas. The oxygen concentration is typically measured or determined. This prevents a high average oxygen flow.

The nasal gas flow is preferably regulated in such a way that it is always within the range between the minimum gas flow and the medium maximum gas flow and thus ensures the carbon dioxide leaching out of the patient, the humidification of the gas and an excessively high oxygen consumption ,

The nasal gas flow is preferably regulated as an inner cascade of the nasal gas pressure, with which a cascaded control structure is used which ensures a nasal gas flow between the required minimum gas flow and the required average, maximum gas flow.

The nasal gas end pressure (step b)) is preferably determined automatically, so that the user of the medical device does not have to set this parameter setting by hand and there is therefore increased patient safety. The control algorithm in the computing system of the medical device adopts the determination of the nasal gas pressure.

Preferably, in the control algorithm, there is a complete comparison of a minimal internal gas flow measured in the medical device and the minimal gas flow and regulates the nasal gas pressure towards the nasal gas pressure. In other words In other words, the control algorithm increases the nasal gas pressure if the measured, minimum internal gas flow is smaller than the minimum gas flow to be achieved, which is determined by the medical device or by the operator of the medical device. Respectively, the control algorithm reduces the nasal gas pressure if the measured, minimum internal gas flow is higher than the minimum flow determined by the medical device or by the operator of the medical device, with the internal cascaded flow control reducing the minimum All gas flow is not limited. Dam it always regulates the medical device to an optimal nasal gas pressure.

The minimum internal gas flow of the gas in the medical device can be determined by measuring this gas flow with an internal flow measurement sensor in the medical device for a defined period of time. This time period is typically in a range between 0.5 seconds and 50 seconds, in particular in a range between 2 seconds and 30 seconds.

The final nasal gas pressure is preferably regulated on the basis of a blood gas value. For example, the blood gas value is measured beforehand. Depending on the fleas of the measured blood gas value, the final nasal gas pressure is increased or decreased. The nasal gas pressure can be adjusted to each individual patient.

In particular, the blood gas value is a carbon dioxide value - for example a transcutaneous carbon dioxide value or an arterial carbon dioxide partial pressure value - or an oxygen saturation value - for example a blood oxygen saturation value. This means that common blood gas values can be used to regulate the nasal gas pressure.

The nasal gas pressure is preferably limited to a value between 0.1 mbar and 20 mbar, so that the gas consumption is kept low.

The control device preferably creates a suitable control command for the actuator on the basis of the previously determined nasal gas flow, so that the actuator releases the conditioned gas accordingly to the hose system. This will optimize gas consumption in the medical device. The control command is not finally listed a voltage value, a speed value or a current value or is specified on the basis thereof. Alternatively or additionally, the control device creates a suitable control command for the actuator based on the previously determined nasal gas pressure, so that the actuator releases the conditioned gas accordingly to the hose system. This not only optimizes gas consumption in the medical device, it also ensures increased patient comfort.

Another aspect of the invention relates to a device for executing a nasal flow therapy application, comprising an actuator, a hose system connection for connecting a hose system to the actuator, and at least a measuring transducer, which provides measurement signals from at least one pressure measuring sensor. There is also a control device with a pressure regulator for regulating a nasal gas pressure.

The pressure control in the device, for example in a medical device, enables a patient to do less of his own breathing work during a nasal flow therapy application. The pressure control is configured so that the gas pressure is constant. In the application, the required peak flows of the gas or respiratory gas can be covered and a lower gas consumption can be achieved in the medical device, whereby the applied oxygen concentration can remain unchanged.

Typically, an actuator described here at least comprises a blower for conditioning the gas, as a result of which the medical device is used in a private household.

Alternatively or in addition, an actuator described here at least comprises a gas source with a valve for conditioning the gas. This means that the existing infrastructure in a hospital can be used. Alternatively, when using a blower and a gas source with a valve, the existing infrastructure in the hospital can have a supporting effect in the medical device. Furthermore, different oxygen concentrations can be set directly on the medical device.

A computing system is preferably present, the actuator being connected to the computing system and the computing system being configured to at least provide a pressure approximation based on the internal pressure measurement value and to be calculated on the basis of an approximate differential pressure value in the hose system. At the same time, an internal pressure measurement value can be determined with a pressure measurement sensor in the medical device, which is arranged in the area of the hose system connection. Som it is not necessary to have an additional pressure measurement sensor on the hose system. Typically there is - preferably between the computing system and the actuator - a digital-to-analog transducer in the device, the digital-to-analog transducer converting the values calculated in the computing system into control commands for the actuator.

In particular, the computing system has a computing algorithm which is configured to carry out the method described here. The method described here can therefore be carried out fully automatically.

The computing system preferably has a storage unit. This means that the values that can be used for pressure control, such as the internal pressure measured value or the pressure differential approximation value, can be stored in the memory unit so that they can be called up easily when required.

The pressure control is preferably configured to control the nasal gas pressure on the basis of the at least one pressure approximation value. With pressure control based on at least one pressure approximation value, a nasal pressure measurement can be omitted, as a result of which the nasal cannula can be manufactured more cost-effectively and the medical device can be operated with different hose systems or hose system accessories and therefore more universally.

There is preferably a pressure measuring device for recording at least one nasal pressure measurement, the pressure control regulating the nasal gas pressure according to the hose system on the basis of the at least one nasal pressure measurement. Dam it, nasal pressure measurement is used to automatically detect a change in the tube system - for example, changing the nasal cannula on the tube system - which makes an adjustment step unnecessary.

A flow measurement sensor for measuring an internal gas flow is preferably present in the medical device. The flow measurement sensor m preferably measures the internal gas flow emitted by the actuator, as a result of which the gas consumption can be optimized and the carbon dioxide leaching can be ensured. A humidifier is preferably present, the humidifier preferably being arranged on the hose system. The humidified high-flow oxygen therapy is successfully used in patients with COPD, bronchiectasis, end-stage cancer and in non-intubated patients who need an optimally humidified gas.

In particular, the humidifier is designed to adjust the temperature of the gas. This means that humidification in the gas can be further optimized.

Preferably, a temperature control system for temperature control of the conditioned gas is present, thereby preventing condensation of the humidified air and increasing the partial pressure of the water vapor reaching the patient.

The temperature control system for tempering the conditioned gas is preferably arranged in the hose system, as a result of which the temperature control is adapted to the hose system and an optimized gas is provided.

Alternatively, a humidifier and a temperature control system are available, providing an optimally conditioned gas. The humidifier and the temperature control system are preferably combined in one system.

Alternatively, the humidifier and / or the temperature control system is arranged in the device. A humidifier installed in the device is on the

Device parameters dimensioned so that the device can be manufactured inexpensively and the user does not need any additional devices.

A flow control for regulating a nasal gas flow is preferably present. In addition to regulating the pressure, it also regulates the flow, which ensures gas consumption, carbon dioxide leaching and humidification.

In particular, there is a cascaded control structure, the pressure control for regulating the nasal gas pressure forming an outer cascade and the

Flow control to regulate a nasal gas flow forms an inner cascade. This means that the minimum gas flow through the hose system described here cannot be fallen short of, or that which is present here The described maximum gas flow through the hose system is not exceeded, which subsequently ensures that the carbon dioxide content in the gas is washed out, that the gas is adequately humidified and that gas consumption is optimized.

An oxygen metering device is preferably provided, as a result of which an oxygen concentration can be set on the device.

An input device is preferably provided, so that the user of the device can manually set or enter settings such as, for example, the nasal gas pressure and / or the oxygen concentration.

In particular, the input device has a display unit. The settings specified by the user are typically displayed, as a result of which the user can easily visually check the settings on the device.

The input device is preferably a touchscreen, with which the device is easy to operate and has a particularly compact input device.

The input device preferably has at least one switching device for selecting between automatic pressure control or constant pressure control. With automatic pressure control, the user cannot set a nasal gas pressure, but the medical device independently calculates the optimal nasal gas pressure. The switching device is integrated in the touchscreen. As a result, the input can easily be entered by the operator of the medical device. Alternatively, the switching device is designed as a mechanical switch. This enables the operator to recognize the position of the mechanical switch from a distance, for example.

A measuring device for blood gas measurement is preferably present. Based on the blood gas measurements extracted from it, the nasal gas pressure can be automatically controlled.

A carbon dioxide measurement is preferably present. The carbon dioxide measured values are taken into account in the pressure control, so that on the one hand a sufficiently high gas pressure and a sufficiently high gas flow are provided. Alternatively or in addition, an oxygen measurement is available. The oxygen measurement is connected to the device or integrated in the device. The measured oxygen values are taken into account so that sufficient oxygen levels are provided.

The method described here is preferably a computer-implemented method for operating an actuator. The control device and the computing system in the medical device are configured such that the method described here is carried out automatically. This reduces the manufacturing costs.

The computer implemented method disclosed here is preferably stored in a storage medium. The storage medium can, on the one hand, be integrated in the device or be a mobile storage medium. A mobile storage medium can optionally be connected to different devices, so that the method disclosed here can be used at different locations.

In particular, control commands for the actuator are stored in the storage medium. The storage medium is inserted into the medical device so that it can be called up immediately and the actuator is driven with these control commands.

Further advantages, features and details of the invention result from the following description, in which exemplary embodiments of the invention are described with reference to the drawings.

Like the technical content of the claims and figures, the list of reference symbols is part of the disclosure. The figures are described coherently and comprehensively. The same reference symbols mean the same components, reference symbols with different indices indicate functionally identical or similar components.

It shows:

1 shows a system for executing a nasal flow therapy application,

Fig. 2 shows a first embodiment of an inventive device for

Running a nasal flow therapy application, 3 shows a further embodiment of a device according to the invention for carrying out a nasal flow therapy application,

4 shows a flowchart m for a first embodiment of the method according to the invention without a pressure measuring device, and

5 shows a flow diagram m for a further embodiment of the method according to the invention with a pressure measuring device.

1 shows a system 15 for performing nasal flow therapy on a patient. The system 15 comprises a hose system 17 and a medical device 20 with an actuator 22. The hose system 17 comprises a hose 18 and a nasal cannula 16, and is connected to the actuator 22 of the medical device 20. A humidifier 19 is arranged along the hose 18. The actuator 22 provides the tube system 17 or the nasal cannula 16 with conditioned gas which is supplied by the tube system 17 or by the

Nasal cannula 16 is given to the environment or to a patient. Depending on the composition of the gas, it is z. B. a breath gas, which is administered to a patient to assist breathing.

FIG. 2 shows a first embodiment of the medical device 20 according to the invention from FIG. 1 and comprises a hose system connection 23 for connecting the hose system 17. The actuator 22 in the medical device 20 has a digital-analog transducer 24 and is with the hose system connection 23 connected. The actuator 22 consists, not exhaustively, of a blower and / or an oxygen connection and a valve and in particular a humidifier (not shown).

The medical device 20 has a control device 28 which contains a computing system 30, a storage unit 32 and a cascaded control structure 36. The control system 28 connects the computing system 30, the storage unit 32 and the cascaded control structure 36 to one another for the exchange of data. The storage unit 32 has a table 33 for storing gas pressure data and gas flow data. The control device 28 has a pressure control 35 for regulating a nasal gas pressure P _nasai , which is connected to the flow control 40 for exchanging data. The pressure control 35 is configured so that the actuator 22 regulates the gas to a constant nasal gas pressure Pnasai. The control device 28 has a flow control 40 for regulating the nasal gas flow F _na sai, which is electrically connected to the digital-analog transducer 24 of the actuator 22. Pressure control 35 and flow control 40 are connected to one another by means of a cascaded control structure 36, pressure control 35 forming an outer cascade and flow control 40 forming an inner cascade.

The medical device 20 has an internal pressure measuring sensor 38 for measuring internal gas pressures P _in t, which are determined or generated by the actuator 22. These are made available to the control device 28 with the aid of an analog-digital transducer 39 as pressure measurement signals.

The medical device 20 has a flow measurement sensor 41 for measuring internal gas flows F _int , which are determined or generated by the actuator 22. These are made available to the control device 28 with the aid of an analog-digital transducer 42 as flow measurement signals.

On the medical device 20 there is an input and output device 45 which is provided with a display unit 46 and with a touchscreen 47 for entering and displaying gas pressure values and / or gas flow values or gas pressure data and / or gas flow data. The input and output device 45 further comprises a switching device 48 for selecting between an automatic pressure control and a constant pressure control. The input and output device 45 is connected to the control device 28 for data exchange.

The medical device 20 has a connecting strip 49 for connecting measuring devices or metering devices. The terminal block 49 is connected to the control device 28. For example, a list of measuring devices for blood gas measurement, such as a carbon dioxide measurement and / or an oxygen measurement, an oxygen metering device with an oxygen connection and a valve (not shown) can be connected (not shown). The medical device 1 20 shown in FIG. 3 essentially corresponds to the medical device 20, as is described in connection with FIG. 2. The medical device 120 differs in that there is a pressure measuring device 160 for recording nasal pressure measured values P _me s and the medical device 120 is preferably a respirator. The medical device 120 has a control device 128, which has the components described in FIG. 2 and their technical functions. Furthermore, the medical device 120 has an input and output device 145, which has the components described in FIG. 2 and their technical functions.

The pressure measuring device 1 60 is connected to the connection bar 149. The nasal pressure measured values P _me s measured by the pressure measuring device 160 are transmitted to the control device 128 with the aid of the analog-digital measuring transducer 150. The measured nasal pressure measurement values P _mes are converted into control commands in the pressure control 135 of the control device 128 for regulating the actuator 122. The control device 128 has a flow control 140 for regulating the nasal gas flow F _na sai, which is electrically connected to the digital-analog transducer 124 of the actuator 122. Pressure control 135 and flow control 140 are connected to one another by means of a cascaded control structure 136, pressure control 135 forming an outer cascade and flow control 140 forming an inner cascade. The control commands are transferred to the actuator 122 by means of the digital-to-analog transducer 124.

FIG. 4 shows a first embodiment of the method according to the invention for operating the previously described actuator 22 in a medical device 20 according to FIGS. 1 and 2. In advance, the hose system connection 23 is connected to the hose 18 of the hose system 17 and the nasal cannula 16 provided or arranged on the tube system 17 (step 70; step a)). It is then ensured that the nasal cannula 1 6 is not arranged on a patient (step 71). This is followed by several steps for adjusting the medical device 20 together with the hose system 17, the internal gas flow F _{int of} the gas being increased linearly from 0 liters per minute to 100 liters per minute within a period of 10 seconds (step 72). During this period, the internal gas pressure values Pnt and the internal gas flow values Fmt with the internal pressure measurement sensor 38 and the internal flow measurement sensor 41 and transmitted to the control device 28. The respective differential _{pressure approximation} values dP _SCh are then calculated on the basis of the measured internal gas pressure or the measured internal gas pressure value Pnt and on the basis of the pressure approximation value P _n in the computing system 30, whereby

D - p _ _r ] p

^G h 'int ^u - ^r sch and with P _n = 0, equal to dP _SCh = Pnt applies.

The several internal gas pressure measured values R _nt thus correspond to the differential pressure approximation values dP _SCh in the hose system 17. These are stored in table 33 of the storage unit 32 together with the associated measured internal gas flow values F _in t (step 73), wom The medical device 20 is adjusted with the connected hose system.

Alternatively, the respective differential pressure approximation values dP _SCh can be calculated with mathematical functions, for example polynomial functions, such as dPs _ch = R ₀ + R * Fin _t + R * Ff _nt + for adjustment. The constants R ₀ , Ri, ... are then determined using a least square method. Further functions for determining the differential _{pressure approximation values} dP _SCh based on the internal gas flow F _int are not exhaustively enumerated linear functions or quadratic functions.

In a further step (step 74), the maximum, average gas flow F _max through the hose system 17 is set at 100 liters per minute.

An ideal body weight of a patient (I BW) (or the body size and sex of the patient) and an oxygen concentration HO2 in the medical device 20 are then determined at the input and output device 45 45 and a measured, effective, internal, maximum Gas flow F _in t, max and an expiration time T _e are calculated in the computing system 30 (step 75). Furthermore, the dead space V _{d is} calculated with the aid of the ideal body weight (I BW) and a Radford constant, the Radford constant typically being 2.2 ml / kg (Vd = 2.2 ml / kg ^* I BW) (step 76).

The respective pressure approximation value P _n is then determined using the measured internal gas pressure measured values R _nt and the differential pressure approximation values dP _SCh stored in table 33 in the computing system 30, the differential _{pressure approximation value} dP _{SCh being} determined using the measured internal gas flow R _nt ( Step 77).

A further consequence is that a minimum gas flow F _m m is determined through the hose system (step 78).

The minimum gas flow F min _in is 30 m in the computing system calculated, where V _{d is} the previously determined dead space, k is 0.33 and T _{e is} the previously calculated expiration time.

In a further step (step 79), a query is made in the medical device 20 as to whether the nasal gas pressure P _n se _{t should be set} automatically on. The query takes place on the basis of the position of the switching device 48 on the medical device 20 or via a setting defined in the control device 28.

In the case of a non-automatic determination of the nasal gas end pressure P _n s _et , a nasal gas end pressure P _n s _t that is set by the user by hand is read in by the input and output device 45 on the medical device 20 (step 80; step b)) ,

The final gas flow F _n se _t is then determined as a function of the difference between the specified nasal final gas pressure P _n se _t and the previously determined pressure approximation values P _n , so that the difference just mentioned is converted to 0 (zero adjustment)

_Use it to calculate F _nSet : P _nSet - P _n -> 0, whereby the gas pressure P nasal _na sai toward the nasal allowable gas P _n set is controlled (step 81; step c)). Thus, pressure control 35 is carried out first as an outer cascade of the cascaded control structure.

Furthermore, the gas end flow F _n se _t determined in step 81 is limited upwards according to the previously determined maximum average gas flow F _max and downwardly limited according to the previously determined minimum gas flow F _min (step 82).

As an alternative to the directly mentioned steps (steps 80 to 82), an automatic determination of the nasal gas pressure Pnse _t , a measurement of a measured, effective, internal, minimum gas flow F _mt.min (step 83) and a query as to whether the calculated minimum gas flow F _{min is} less than the determined measured effective internal minimum gas flow F _int, min (step 84).

If the calculated minimum gas flow F _{min is} smaller than the determined, effective, internal, minimum gas flow F _mt.min , the control device 28 reduces the nasal gas pressure P _n se _t and defines it (step 85; step b)).

If the calculated minimum gas flow F _{min is} greater than the determined, effective, internal, minimum gas flow F _mt.min , the control device 28 increases the nasal gas pressure P _n se _t and determines it (step 86; step b)).

In both cases, the final nasal gas pressure P _n _{t is} limited to a value between 0 mbar and 10 mbar (step 87).

In step 88, the pressure control is then carried out as an outer cascade of the cascaded control structure.

The final gas flow F _n se _t is limited in accordance with the previously determined maximum, average gas flow F _max and is limited to the value zero (step 89).

The measured, internal gas flow Fm _t is then regulated with the aid of the flow control 40 and subsequently with the aid of the actuator 22 to the calculated gas end flow F _n se _t . (Step 90). In other words, it is easy to do according to FnSet Fint 0, so that the nasal gas flow F _na sai is regulated towards the calculated gas end flow F _n set. The flow control is thus executed as an inner cascade of the cascaded control structure.

The control device 28 then creates a suitable control command for the actuator 22 on the basis of step 90 and transmits it to the actuator 22, so that the actuator 22 releases the conditioned gas to the hose system (step 91; step d)).

Subsequently, steps 75 to 82 and step 89 to step 91 can be carried out several times.

Alternatively, steps 75 to 79 and steps 83 to 91 can be carried out several times.

FIG. 5 shows a further embodiment of the method according to the invention for operating the previously described actuator 122 in a medical device 20 according to FIG. 1 and in a medical device 120 according to FIG. 3, the medical device 120 comprising a pressure measuring device 160 or being connected to it which is designed to record pressure measurements P _me s.

In a first step (step 170), a maximum average gas flow F _max through the hose system is set at 100 liters per minute.

An ideal body weight of a patient (IBW) (or the size and sex of the patient) and an oxygen concentration (F1O2) are then determined in the medical device 120, a measured, effective, internal, maximum gas flow P _{nt, max} and an expiration time T _{e are} calculated (Step 171).

Furthermore, the dead space V _{d is} calculated using the ideal body weight (IBW) and a Radford constant, the Radford constant typically being 2.2 ml / kg (Vd = 2.2 ml / kg * IBW) (step 172).

A minimum gas flow F _m m through the hose system is subsequently determined (step 173). The minimum gas flow F _{m in} is included in the computing system calculated, where V _{d is} the previously determined dead space, k is 0.33 and T _{e is} the previously calculated expiration time.

Subsequently, a nasal gas final pressure Pnse _t that is set by the user by hand is read in by the input and output device 145 on the medical device 120 (step 174; b)).

Subsequently, the nasal pressure measurement value (P _me s) is measured with the pressure measuring device 160 and transferred to the pressure control 135 of the control device 128 via the analog-digital measuring transducer 150 (step 175).

The final gas flow F _n se _{t is then determined} as a function of the difference between the specified first nasal final gas pressure P _n s _et and the previously measured nasal pressure measured value P _me s, so that the difference just mentioned is converted to 0 (zero adjustment) according to

_Use this to calculate F _nSet : P _nSet - P _mes -> 0, whereby the nasal gas pressure P _me s is regulated towards the first nasal gas pressure P _n se _t (step 176; step c)). Pressure control is thus carried out first as an outer cascade of the cascaded control structure.

Furthermore, the gas end flow F _n se _t determined in step 176 is limited upwards according to the previously determined maximum average gas flow F _max and downwardly limited according to the previously determined minimum gas flow F _min (step 177).

The measured internal gas flow Fm _t is then regulated with the aid of the actuator 122 towards the calculated gas end flow F _n se _t . (Step 178). In other words, a zero adjustment takes place, according to so that the nasal gas flow F _na sai is regulated towards the calculated gas flow F _n set. Dam flow control is implemented as an inner cascade of the cascaded control structure.

The control device 128 then creates a suitable control command for the actuator 122 on the basis of step 78 and transmits this to the actuator 122, so that the actuator 22 releases the conditioned gas to the hose system (step 179; step d)).

Subsequently, steps 170 to 179 can be carried out more than once.

Reference numerals list

system

nasal cannula

hose system

tube

humidifier

medical device

actuator

Hose system at the end

Digital-to-analog transducers from 22

control device

computing system

storage unit

table

pressure control

cascaded control structure internal pressure measurement sensor

Analog-digital transducer

flow control

internal flow measuring sensor

Analog-digital transducer from 41

Input and output device

display unit

touchscreen

switching device

Terminal strip with medical device

actuator

Digital-to-analog transducer from 122 control devices

pressure control

cascaded rule structure 145 input and output device

140 flow control

149 Terminal block

150 analog-digital transducers

160 pressure measuring device

70-91 procedural steps

170-179 procedural steps

P nSet first nasal gas pressure

P nasal nasal gas pressure

Pmes pressure reading

Pn pressure approximation

dPsch first differential pressure approximation

Pint first internal pressure reading

Fm in minimal gas flow

F nasal nasal gas flow

Fmax maximum mean gas flow

Fint.max effective internal maximum gas flow Fint internal gas flow

Fnt.min minimal internal gas flow

F nSet nasal gas flow

Claims

claims

1. A method for operating an actuator (22; 122) in a medical device (20; 120), the actuator (22; 122) being connected to a hose system (17), and the medical device being a control device (28; 128) with a pressure regulator (35; 135) for regulating a gas pressure and has a computing system (30), the method comprising the following steps:

a) providing a nasal cannula (16) on the tube system (17);

b) determining a nasal gas pressure (Pnset) on the pressure control (35;

135);

c) regulating a nasal gas pressure (P _na sai) on the actuator (22; 122) using the pressure control (35; 135), in particular towards the nasal gas pressure

(P nSet);

d) dispensing a conditioned gas from the actuator (22; 122) to the hose system (17).

2. The method according to claim 1, characterized in that the pressure control (35; 135) takes place on the basis of at least one nasal pressure measurement value (Pmes) or on the basis of at least one pressure approximation value (P _n ), in particular a change in a nasal gas flow (F _na sai ) takes place in the hose system (17), which is preferably carried out before the nasal gas pressure (Pnset) is set at the pressure control (35; 135) (step b)).

3. The method according to claim 2, characterized in that the at least one pressure approximation value (P _n ) is calculated on the basis of at least one internal pressure measurement value (P _in t) and on the basis of at least one differential pressure approximation value (dPsch) in the hose system (17).

4. The method according to claim 3, characterized in that the at least one differential pressure approximation value (dPsch) in the hose system (17) is calculated on the basis of an internal gas flow (Fmt), the at least one differential pressure approximation value (dPsch) being calculated in particular with the aid of a mathematical function or preferably from a table (33) is called up in the computing system (30) or is further calculated in particular with the aid of at least one nasal pressure measurement value (P _mes ).

5. The method according to any one of claims 1 to 4, characterized in that a minimum gas flow (F _min ) through the hose system (17) is determined or regulated, the minimum gas flow (F _min ) in the computer system (30) preferably with is calculated, where V _{d is} the dead space, which is calculated in particular using an ideal body weight of a patient and a Radford constant, and k is a factor between 0.05 and 2, preferably 0.33, and T _{e is} an expiration time.

6. The method according to any one of claims 1 to 5, characterized in that a maximum average gas flow (F _max ) through the hose system (17) is provided, the average maximum gas flow (F _max ) preferably to a value between 10 and 200 liters per minute is preferably set to a value of 100 liters per minute.

7. The method according to any one of claims 1 to 6, characterized in that the nasal gas flow (F _nasai ) is regulated, the nasal gas flow (F _nasai ) preferably being regulated as an inner cascade of the nasal gas pressure (Pn _asai ).

8. The method according to any one of claims 1 to 7, characterized in that the determination of the nasal gas pressure (Pnse _t ) (step b)) takes place automatically, this being based in particular on a blood gas measured value, preferably a carbon dioxide value or an oxygen saturation value or a minimal gas flow (F _min ) is regulated.

9. Device for executing a nasal flow therapy application, comprising an actuator (22; 122), a hose system connection (23) for connecting a hose system (17) to the actuator (22; 122) and at least one Measuring transducer (39), which provides measuring signals from at least one pressure measuring sensor (38), characterized in that a control device (28; 128) with a pressure regulator (35; 135) for regulating a nasal gas pressure (P _na sai) is present.

10. The device according to claim 9, characterized in that a computing system (30) is present, the actuator (22; 122) being connected to the computing system (30) and the computing system (30) preferably having a storage unit (32), and the computing system (30) is configured to calculate at least one pressure approximation value (P _n ) based on at least one internal pressure measurement value (Pnt) and on the basis of at least one differential pressure approximation value (dPs _Ch ) in the hose system (17), and preferably the pressure control (35; 135) is configured to regulate the nasal gas pressure (Pnasai) after the tube system (17) on the basis of the at least one pressure approximation value (P _n ).

11. The device according to claim 9 or 10, characterized in that a pressure measuring device (160) for detecting at least one nasal pressure measured value (P _me s) is present, the pressure control (35; 135) the nasal gas pressure (Pnasai) according to the hose system (17) regulates on the basis of the at least one nasal pressure measurement value (Pmes), and preferably a flow measurement sensor (41) for measuring an internal gas flow (Fmt) is present in the medical device (20; 120).

12. Device according to one of claims 9 to 11, characterized in that a humidifier (19) is provided, the humidifier (19) being arranged in particular on the hose system (17), and / or a temperature control system for temperature control of the conditioned gas is present ,

13. Device according to one of claims 9 to 12, characterized in that a flow control (40; 140) for regulating a nasal gas flow (F _na sai) is present, and in particular a cascaded control structure (36; 136) is present, the Pressure control (35; 135) for regulating the nasal gas pressure (Pnasai) forms an outer cascade and a flow control (40; 140) for regulating the nasal gas flow (F _na sai) forms an inner cascade.

14. Device according to one of claims 9 to 13, characterized in that an oxygen metering device is present, and preferably an input and output device (45; 145) is provided, the input and

Output device (45; 145) in particular has a display unit (46) and is preferably a touchscreen (47).

15. Device according to one of claims 9 to 14, characterized in that a measuring device for measuring blood gas is present, preferably for a carbon dioxide measurement and / or for an oxygen measurement.