Respiratory devices with condensation protection in the patient interface

Abstract

The invention relates to a respiratory device (10) for artificial respiration of a patient (12), the respiratory device comprising: a respiratory gas source device (15, 62), a flow changing device (16), a humidifying device (38), the humidifying device being designed to numerically increase the absolute humidity of the inhaled respiratory gas flow (AF), wherein the humidifying device (38) has a liquid reserve (40) and a power-variable evaporating device (76) for this purpose, and a respiratory gas line device (30) in order to convey the inhaled respiratory gas flow (AF) from the humidifying device (38) toward the patient (12). , a flow sensor (44) which detects the respiratory gas flow (AF) in numerical terms, a control device (18) which is designed to control the operating power of the evaporation device (76) in dependence on a preset desired humidity of the respiratory gas and in dependence on a signal of the flow sensor (44), wherein the respiratory gas line device (30) has a coupling component (44a) at its proximal end (30a) which is used to couple the respiratory gas line device (30) to a patient interface (31) which transmits the respiratory gas to the patient (12). According to the present invention, the control device (18) is designed to determine a subsequent state of a respiratory situation downstream of the coupling component (44a) in the inhalation direction in dependence on operating parameters of the respiratory device (10) and to change the operating power of the evaporation device (76) in dependence on the determination result.

Description

Technical Field

[0001] The present invention relates to a breathing apparatus for artificial respiration of a patient, comprising:

[0002] a breathing gas source device which provides inspiratory breathing gas for artificial respiration of a patient,

[0003] a flow changing device, which is designed to generate an inspiratory breathing gas flow and to change the amount of the inspiratory breathing gas flow,

[0004] a humidifier, which is designed to increase the absolute humidity of the inspired breathing gas flow, wherein the humidifier has a liquid reservoir and a variable-power evaporator for this purpose,

[0005] a breathing gas line device having a proximal longitudinal end which is closer to the patient during operation and a distal longitudinal end which is further away from the patient during operation, in order to convey an inspiratory breathing gas flow from the humidification device towards the patient,

[0006] a flow sensor which is designed to be able to detect the breathing gas flow in numerical terms,

[0007] - a control device, which is designed to control the operating power of the evaporation device as a function of a preset desired humidity of the breathing gas and as a function of the signal of the flow sensor, wherein the breathing gas line device has a coupling component at its proximal end, which is used to couple the breathing gas line device to a patient interface, such as an endotracheal tube, a laryngeal mask or a combination tube, which transmits breathing gas between the breathing gas line device and the patient. Background Art

[0008] A similar breathing apparatus is known from US 2013 / 0073013 A1. The known breathing apparatus uses ambient air as a breathing gas source and a combination of a fan and a valve in order to numerically vary the flow of the breathing gas stream in the breathing apparatus. An evaporator humidifier is provided in order to humidify the breathing gas if necessary. The water reservoir present in the evaporator humidifier overflows with the breathing gas stream and, in the process, carries away the water vapor present at the water level of the water reservoir.

[0009] The breathing apparatus known from US 2013 / 0073013 A1 also comprises a heatable breathing gas line arrangement in order to avoid undesired condensation of humidity in the breathing gas by supplying heat to the breathing gas line arrangement.

[0010] Downstream of the humidifying device of the known breathing device, but before the start of the heating section of the breathing gas line device, i.e. in the region of the distal end of the breathing gas line device, a flow sensor for determining the breathing gas flow, a temperature sensor for detecting the temperature of the breathing gas, and a humidity sensor for detecting the humidity of the breathing gas are provided. Furthermore, sensors for detecting the ambient temperature and the ambient air humidity are provided.

[0011] A doctor or nursing staff can set the operating parameters of the respiratory device via the input / output device.

[0012] A control device of a known breathing device controls the breathing device in a manner not described in detail. The control device determines a desired temperature for the heating operation of the breathing gas line device based on a detected ambient temperature and a detected ambient air humidity, a detected temperature of the breathing gas flow and a detected humidity of the breathing gas flow, and also in relation to operating data and structural data of the breathing gas line device. In this case, the desired temperature is selected so that the temperature in the breathing gas line device is higher than the corresponding dew point temperature. The control device controls the heating of the breathing gas line device as a function of the selected desired temperature. According to the disclosure of US2013 / 0073013 A1, the dew point temperature is obtained from available data related to hygrometry, i.e., from the detected temperature and the detected relative humidity of the breathing gas flow.

[0013] A breathing device of this type is known from EP 2 143 459 B1. It also discloses a breathing gas line device having a breathing gas source and a fan as a flow changing device. The breathing device known from EP 2 143 459 B1 also has an evaporator humidifier. The evaporator humidifier also has a water reserve, which is overflowed by the breathing gas flow during operation, wherein the breathing gas flow is humidified during the overflow.

[0014] The section of the breathing gas line device of the known breathing apparatus extending from the humidifier device to the proximal longitudinal end of the breathing gas line device is heatable. In the section, a flow sensor and a temperature sensor for determining the temperature and the numerical flow of the breathing gas are arranged in the longitudinal end region of the breathing gas line device closer to the humidifier device. A proximal temperature sensor is also arranged at the proximal longitudinal end of the breathing gas line device, to which a patient interface for connecting the breathing gas line device to a patient to be ventilated can be coupled.

[0015] At the control device of the known respirator, the operator can set a desired respirator gas temperature or a desired humidity level of the respirator gas provided by the respirator. The control device is connected to the two temperature sensors and to the flow sensor in a data transmission manner, thereby obtaining their detected values.

[0016] Using a table, a formula or a characteristic curve stored in a data memory, the control device controls the energy supply to the heating plate of the humidification device as a function of the required breathing gas humidity and the breathing gas flow determined by sensor means and the breathing gas temperature determined by sensor means, in order to provide a breathing gas flow with the desired breathing gas humidity and the desired breathing gas temperature. The required breathing gas humidity is either a humidity set by an operator or a humidity previously stored in the data memory.

[0017] As is generally known, it is particularly important to deliver a breathing gas flow with the correct humidity to the patient during artificial respiration. If the delivered breathing gas is too dry, the patient becomes dehydrated during the artificial respiration. If the delivered breathing gas is too humid, the water in the breathing gas is in danger of condensing and reaching the patient's lungs in liquid form, where it impedes the desired metabolic gas exchange.

[0018] Even if water condensed from the respiratory gas does not reach the lungs of the patient, it may condense on the walls of the respiratory gas line arrangement and / or on the walls of the sensor, for example the proximal flow sensor, and thus reduce the measuring accuracy of the sensor.

[0019] What is decisive here is the relative humidity of the breathing gas, not its absolute humidity. The absolute humidity indicates how much water is dissolved in a reference volume of air. The relative humidity is a measure of how much moisture a predetermined reference volume of air can still absorb and, for example, can be extracted from a patient, or how close the breathing gas is to its humidity saturation. In the case of breathing gases that are close to humidity saturation, even small changes in the temperature of the breathing gas can lead to very undesirable condensation of liquid in the breathing gas (also referred to in the art as "rain out").

[0020] In order to adapt the delivery of breathing gas from the breathing apparatus to the respective patient to be ventilated as required to the needs of the patient, the breathing gas line device has a coupling component at its proximal end, which is used to couple the breathing gas line device to a patient interface that transmits breathing gas between the breathing gas line device and the patient. Such a patient interface is, for example, an endotracheal tube, a laryngeal mask or a combination tube or the like.

[0021] Even if the breathing gas line set is partially or completely heatable, the patient interface that can be coupled to the breathing gas line set is usually not heatable. As a result, the temperature of the patient interface and the temperature of the breathing gas flow in the patient interface can fluctuate more drastically than the temperature of the breathing gas line set and the breathing gas flow therein.

[0022] Regardless of whether the patient interface is a tube or a mask, the section of the patient interface directly connected to the coupling component of the respiratory gas line device is always surrounded by ambient air and can be influenced by the ambient temperature.

[0023] In the above-described emergency transport situations, in which the above-mentioned breathing apparatus is used in a transport vehicle or a transport helicopter in winter and / or at high altitudes, the ambient temperature can be significantly lower than the patient's body temperature and thus significantly lower than the desired temperature of the breathing gas flow. As a result, condensation of moisture can occur at or in the patient interface, for example because the dew point temperature of the breathing gas flow is not exceeded at the walls of the patient interface that are cooled by the ambient air. Since the patient interface is arranged particularly close to the patient and, in the case of an endotracheal tube, is even introduced into the patient's body, condensation of liquid in the area of ​​the patient interface is particularly dangerous for the patient who is to breathe.

[0024] Condensation can occur at the walls of the patient interface which are strongly cooled by the ambient air. Additionally or alternatively, condensation can occur as atomization directly in the breathing gas flow.

[0025] Not only are patient interfaces usually not heated, but as a single-use or disposable item, they are usually not equipped with sensors. This makes it very difficult to identify and suppress condensation in the patient interface. Summary of the invention

[0026] The object of the present invention is therefore to improve a respiratory device of the type mentioned at the outset so that it can enable the patient to breathe as precisely and as stably as possible with correctly humidified breathing gas over a longer breathing period even under extreme external conditions, without condensation forming in the patient interface.

[0027] With regard to a respiratory apparatus of the type mentioned at the outset, the invention achieves the object as follows: the control device is designed to avoid undesired condensation of moisture in the breathing gas flow in the patient interface, in order to ascertain a subsequent state of the breathing situation in the inhalation direction downstream of the coupling arrangement as a function of operating parameters of the respiratory apparatus, in particular operating parameters of the breathing gas flow, such as temperature, mass or volume flow and / or relative humidity, and to change the operating power of the evaporation device as a function of the ascertained result.

[0028] If the control device detects a critical subsequent state with regard to condensation in the patient interface, the change usually reduces the operating power of the evaporation device, thereby reducing or even eliminating the risk of condensation in the patient interface.

[0029] For example, operating parameters of the respiratory device that are important for determining the subsequent state can include: the temperature of the breathing gas flow in the proximal longitudinal end region of the breathing gas line arrangement, as detected by a proximal temperature sensor and transmitted to the control device; and the ambient temperature, as detected by an ambient temperature sensor and transmitted to the control device. Additionally or alternatively, the value of the breathing gas flow determined by a flow sensor can be used to determine the subsequent state. Another important operating parameter can be the type of patient interface and its structural design.

[0030] The respiratory apparatus therefore preferably has a proximal temperature sensor which is designed and arranged to detect the temperature of the inspiratory breathing gas flow in the proximal longitudinal end region of the breathing gas line device.

[0031] The respirator preferably also has an ambient temperature sensor which is designed to detect the temperature of the surroundings of the respirator.

[0032] In a data memory that can be queried by the control device, at least one subsequent data relationship, preferably determined empirically, can be stored, which links a set of operating parameters of the respiratory device - this can be multiple or all of the operating parameters mentioned above - to a subsequent parameter, which indicates the occurrence of condensation of respiratory gas moisture in the patient interface.

[0033] The subsequent parameter can be a binary parameter which can either adopt a first value, which indicates that no condensation has occurred in the patient interface, or a second value, which indicates the opposite, namely that condensation has occurred in the patient interface.

[0034] In conjunction with subsequent data relationships stored in a data memory, for example using an analytically or numerically manageable modeled description of the breathing situation at the patient interface, subsequent parameters can indicate the probability with which condensation of liquid from the breathing gas flow is expected to occur in the patient interface.

[0035] Additionally or alternatively, such a probability value can be realized in that, when the data relationship is empirically determined for the operating parameters relevant to the current respiratory situation, condensation occurs only in a portion of the cases where the parameters are identical according to the empirical investigation; or such a probability value can be realized in that the data relationship does not exist for all operating parameter values ​​described for the current respiratory situation, for example because the data relationship is defined in a table according to grid points. In this case, the missing values ​​can be obtained from the existing values ​​by interpolation and / or extrapolation. In this case, in the case of complex multidimensional relationships between operating parameters and subsequent parameters, inaccuracies may occur when determining the subsequent parameters, which inaccuracies can be appropriately reproduced or interpreted as probabilities.

[0036] Thus, the control device can change the operating power of the evaporation device as a function of the subsequent parameter, in particular reduce the operating power of the evaporation device, in order to avoid condensation in the patient interface. For example, in the case of the simple binary subsequent parameter mentioned above, one value can lead to a reduction in the operating power of the evaporation device, while another value cannot lead to a reduction in the operating power of the evaporation device. In the case of the described subsequent parameter in the form of a probability value, i.e. a value between 0 and 1 or between 0% and 100%, a threshold probability value of condensation in the patient interface, for example a probability of 40% or more, can be predetermined, the subsequent parameter exceeding which leads to a reduction in the operating power of the evaporation device by the control device. In this case - with or without the threshold probability value - the numerical value of the reduction in the operating power can be related to the numerical value of the probability that the subsequent parameter expects condensation in the patient interface. The correlation of the numerical value of the reduction in the operating power with the probability value of the subsequent parameter can be linear or can be progressive, so that starting from the existing operating power, the reduction in the operating power with an increase in the probability of condensation according to the subsequent parameter is much stronger than the probability of condensation.

[0037] In a preferred application case which is computationally simple to use but nevertheless highly efficient, the subsequent state or subsequent parameter of the respiratory condition can include the subsequent temperature of the line wall of the patient interface and / or the subsequent temperature of the breathing gas flow in the patient interface.

[0038] On the one hand, a first advantage of using the subsequent temperature to describe the subsequent state is that, in a known structural design of the patient interface together with the material used to produce the patient interface and in known ambient and operating conditions, based on the last sensor-detected operating state, for example in the region of the coupling component at the proximal longitudinal end of the respiratory gas circuit device, the subsequent temperature in the inhalation direction downstream of the coupling component can be calculated with good accuracy according to a thermodynamic model. Thus, either the subsequent temperature in the patient interface can be calculated according to a thermodynamic model based on parameters detected by measurement technology, in particular closest to the patient interface, or the subsequent temperature can be read based on the aforementioned parameters based on an empirically determined characteristic curve, or a combination of model prediction and reading from empirical data relationships can be used to determine the subsequent temperature.

[0039] A second advantage of using the subsequent temperature for describing the subsequent state is that the subsequent temperature alone is sufficient to predict condensation of liquid in the breathing gas flow. If the absolute humidity of the breathing gas flow is known, then the dew point temperature of the breathing gas flow is known or can be determined based on a known dew point curve, whether by directly measuring the absolute humidity or by measuring the relative humidity or temperature of the breathing gas flow. If the subsequent temperature is below the dew point temperature determined for the respective breathing gas flow, then condensation of humidity in the breathing gas in the patient interface, i.e., undesired "rain out", is likely to occur.

[0040] Preferably, the respiratory device has a moisture sensor device, which is designed to detect a moisture state value of an inhaled breathing gas flow, the moisture state value representing at least one relative humidity of the inhaled breathing gas flow. Preferably, the moisture sensor device is also designed to detect the breathing gas temperature at the detection location of the moisture state value, so that the control device can determine the absolute humidity and / or dew point temperature of the breathing gas flow at the detection location of the moisture state value, for example based on dew point data stored in a data memory. Alternatively or additionally, the moisture sensor device can be directly designed to detect the absolute humidity of the breathing gas as the moisture state value.

[0041] As already indicated above, a respiratory device for predicting a subsequent temperature in a patient interface can have a data memory that can be queried by a control device, in which operating parameters detectable by the respiratory device, such as the ambient temperature or / and operating parameters of the breathing gas flow detectable in the breathing gas line arrangement, are correlated in a measurement-technical manner with the subsequent temperature of the line wall of the patient interface or / and the breathing gas flow. For the sake of completeness and clarity, it should be noted that, for the purposes of this application, values ​​interpolated or extrapolated based on operating parameter values ​​detected in measurement technology are also considered to be detected in measurement technology.

[0042] By means of the data relationships stored in the aforementioned data memory, whether now as empirically determined data tables or data characteristic curves or as analytical or numerical calculation models, the control device can determine the subsequent state with good accuracy, depending on the temperature of the breathing gas flow in the proximal longitudinal region of the breathing gas line arrangement detected by the proximal temperature sensor, on the value of the breathing gas flow detected by the flow sensor, and on a predefined expected humidity of the breathing gas. The probability of undesired condensation in the patient interface can thus be predicted very quickly with good accuracy by means of quantitatively verifiable known or measurement-detectable parameter values.

[0043] If the control device determines the subsequent state as a function of the ambient temperature detected by the ambient temperature sensor, an undesired condensation of humidity in the breathing gas in the patient interface can be predicted particularly accurately. The ambient temperature acting externally on at least one section of the patient interface is a factor that strongly influences the temperature of the breathing gas flowing in the patient interface and thus any condensation in the patient interface.

[0044] Because for the patient, the more downstream the condensation in the breathing gas in the patient interface occurs, that is, the closer it occurs to the patient, the more adverse the effect may be, so that there is a need to worry about liquid in the patient interface, an advantageous improvement scheme of the present invention proposes that the control device determines the subsequent state for the following determination location, which is closer to the proximal end of the patient interface than the distal end, wherein the control device preferably determines the subsequent state for the proximal end of the patient interface.

[0045] Additionally or alternatively, the control device can determine a subsequent state for a section of the patient interface that is between the coupling component and the entry point of the patient interface into the patient's body. The subsequent state, in particular the subsequent temperature, can then be determined for a section of the patient interface that is directly exposed to environmental influences and thus to the ambient temperature, which in extreme operating situations can differ greatly from the desired temperature of the breathing gas flow.

[0046] In addition, if the inspiratory line section of the breathing gas line device can be heated by a line heater, the control device can change, in particular increase, the operating power of the line heater as a function of the ascertainment result. In the trade-off between supplying the patient with slightly superheated breathing gas for a short period of time or supplying breathing gas with a liquid phase fraction, an increased breathing gas temperature is preferably selected.

[0047] Preferably, the coupling formation is formed at the proximal longitudinal end of the Y-shaped line section of the breathing gas line device, wherein an inhalation hose and an exhalation hose are each connected to the two distal longitudinal ends of the Y-shaped line section.

[0048] The flow sensor can be a distal flow sensor, which is accommodated in the operating housing of the respiratory device. Additionally or alternatively, the flow sensor can be a proximal flow sensor, which is preferably replaceably arranged at the proximal longitudinal end of the respiratory gas pipeline device. The proximal flow sensor can be arranged between the coupling component and the patient interface. When this proximal flow sensor is configured as a pressure difference-flow sensor, it can provide high measurement accuracy and is still low-cost despite this. The proximal flow sensor can be a part of the coupling component, and it itself can be configured for coupling the patient interface.

[0049] The coupling assembly can be formed on a proximal flow sensor which is arranged at a longitudinal end of the breathing gas line device in order to be able to detect at least the inspiratory breathing gas flow and preferably also the expiratory breathing gas flow in terms of value.

[0050] The evaporation device preferably has a heating device, by means of which the liquid reserve is heated and evaporated. The control device is then preferably designed to reduce the heating power of the heating device if the above-mentioned ascertainment indicates that condensation of the liquid in the patient interface is certain or very likely or is above a predefined probability threshold value, or if the ascertainment indicates that the subsequent temperature is above a predefined subsequent temperature threshold value.

[0051] Alternatively or additionally, the evaporation device can have an ultrasonic atomizer. In this case, the operating power that can be changed by the control device in dependence on the ascertainment result is the operating power of the ultrasonic atomizer. The conditions for reducing the atomization power are the conditions mentioned above for reducing the heating power.

[0052] For the purposes of the present application, the sensory ascertainment of a given parameter is equivalent to the direct ascertainment of a further variable which is different from the given parameter if the further variable represents the given parameter based on a known relationship, for example a calibration relationship.

[0053] In the present application, the terms “moisture” and “humidity” are used synonymously.

[0054] Although the empirical determination of data relationships is laborious, since in the laboratory the influencing parameters mentioned are varied in a controlled manner within the scope of their expected operating value range and must be checked for their influence on the target parameters, this effort must only be incurred once for a respiratory device of identical construction. The data relationship thus determined for the design of a respiratory device can then be used for a large number of respiratory devices of identical construction. It is then sufficient to randomly check whether the data relationship that has been determined is suitable for a specific respiratory device.

[0055] The flow sensor can detect at least one value of an inspiratory breathing gas flow in the proximal longitudinal end region of the breathing gas line device, just as the proximal temperature sensor detects the temperature, so that the breathing gas is humidified according to parameters that are as close as possible to the patient.

[0056] In order to define the desired breathing conditions, the respiratory device can have an input device for inputting at least one desired temperature of the breathing gas flow in the proximal longitudinal end region of the breathing gas line arrangement and / or at least one desired humidity of the input breathing gas and / or at least one desired breathing gas flow. It is also possible for only some of the parameters mentioned to be input at the input device, while other parameters of the parameters mentioned can be determined based on empirically determined data relationships based on the input parameters and / or other parameters.

[0057] For example, in order to simplify the operation of the breathing apparatus, the breathing apparatus can have an input device for inputting a desired temperature of the breathing gas flow in the proximal longitudinal end region of the breathing gas line device, and the breathing apparatus can also have a data memory that can be queried by the control device, in which a preferably empirically determined relationship between the temperature values ​​of the breathing gas flow in the proximal longitudinal end region of the breathing gas line device and the associated desired humidity values ​​of the breathing gas is stored. It is then sufficient to input only the proximal breathing gas flow temperature, from which the control device can determine the associated desired humidity of the breathing gas.

[0058] In order to avoid the undesired condensation of liquid at the wall of the breathing gas pipeline device, at least one inhalation pipeline section of the breathing gas pipeline device can have a pipeline heating device. The pipeline section of the inhalation can be heated by means of the pipeline heating device. It is thus possible to prevent the temperature of the wall of the pipeline section of the inhalation from dropping below the dew point temperature of the breathing gas flowing in the pipeline section. The control device can then be configured to control the operating power of the pipeline heating device in relation to the preset desired temperature of the breathing gas flow in the longitudinal end region of the proximal end of the breathing gas pipeline device. When determining the energy or power to be supplied to the pipeline heating device, the control device can also take into account the detected ambient temperature. This significantly simplifies the control circuit for heating the pipeline section, because the breathing gas pipeline device is usually moistened by ambient air with ambient temperature at its outer side. If the ambient temperature is taken into account when heating the pipeline section, it is possible to avoid the undesired temperature fluctuations at the heated wall of the pipeline section of the inhalation. Therefore, the temperature of the heated pipeline section can be maintained with better constancy.

[0059] The breathing gas source device can have a suction opening as a breathing gas source, through which ambient air or gas from a predetermined gas reserve can be sucked. Additionally or alternatively, the breathing gas source device can have a gas reserve as a breathing gas source, for example as a reserve container or as a connecting component for connecting a supply line, which connects the breathing device to a locally installed gas reserve, as is usually the case in a clinic. In order to provide the feasibility of mixing different gases into breathing gas, the breathing gas source device can have a plurality of separate breathing gas sources as mentioned above. Here, different gases to be mixed can have different temperatures and / or different humidity due to the supply and decompression. In order to ensure that the moisture sensor device detects the humidity of the breathing gas actually delivered to the patient, the moisture sensor device is preferably arranged downstream of the breathing gas source device along the inhalation direction of the breathing gas flow. For the reasons mentioned, it is particularly preferred that no breathing gas components are added to the breathing gas flow leaving the humidification device downstream of the humidification device along the inhalation direction.

[0060] In order to detect and control the energy or power supplied to the evaporation device, the control device can be connected to the evaporation device in a signal transmission manner. Additionally or alternatively, the control device can be connected to the energy supply of the evaporation device in a signal transmission manner. For example, the control device can be directly designed to detect the current supplied to the evaporation device and the voltage applied thereto. If a control device directly designed to detect energy, in particular electrical energy, would mean too much expenditure, the control device can be connected in a signal transmission manner to at least one energy sensor, which is designed to detect the energy supplied to the evaporation device. The energy and / or power currently supplied to the evaporation device can then be determined by the control device from the signal transmitted to the control device via the signal transmission connection. Here, the determination of energy and power differs only in that power is a detection of energy over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention will be described in detail below with reference to the accompanying drawings. The accompanying drawings show:

[0062] Figure 1 a schematic diagram showing a breathing apparatus according to the invention ready for artificial respiration of a patient, and

[0063] Figure 2 Show Figure 1 Rough schematic diagram of the breathing gas circuit branching for inspiratory air of a breathing apparatus.

[0064] Specific implementation form

[0065] exist Figure 1 In the embodiment of the present invention, a respiratory apparatus is generally indicated at 10. In the example shown, the respiratory apparatus 10 is used for artificial respiration of a human patient 12.

[0066] The respirator 10 has a housing 14 in which a suction opening 15 is formed and - due to the opaque housing material not visible from the outside - accommodates a flow changing device 16 and a control device 18. The suction opening 15 allows the flow changing device 16 to draw in ambient air from the external environment U of the respirator and, after cleaning known per se, to pass it as breathing gas to the patient 12. For the purposes of the present application, the suction opening 15 is therefore a breathing gas source device.

[0067] Located in the intake opening 15 is an ambient temperature sensor 17 which measures the temperature of the air of the environment U and transmits it to a control device 18 .

[0068] The flow changing device 16 is constructed in a manner known per se and can have a pump, a compressor, a fan 52, a pressure accumulator, a pressure reducing valve 54 (see Figure 2) etc. Furthermore, the respiratory device 10 has an inhalation valve 20 and an exhalation valve 22 in a manner known per se.

[0069] The control device 18 is usually implemented as a computer or a microprocessor. The control device includes Figure 1 In the embodiment of the present invention, a data memory 19 is provided in the housing 14 so that data required for the operation of the respiratory device 10 can be stored and can be called up when necessary. The data memory 19 can also be located outside the housing 14 in network operation and connected to the control device 18 via a data transmission connection. The data transmission connection can be formed by a cable link or a radio link. However, in order to prevent interference with the data transmission connection from possibly affecting the operation of the respiratory device 10, the data memory 19 is preferably integrated into the control device 18 or is at least accommodated in the same housing 14 as the control device.

[0070] In order to input data into the respiratory device 10 or more precisely into the control device 18, the respiratory device 10 has an input device 24 which is connected to the control device 18. Figure 1 In the example shown, this is represented by a keyboard. As will be explained further below, the keyboard is not the only data input of the control device 18. In fact, the control device 18 can obtain data via different data inputs, such as via a network line, a radio link or via a sensor interface 26, which will be discussed in detail below.

[0071] In order to output data to the treating physician, the respiratory device 10 can have an output device 28 , in the example shown, a screen.

[0072] For artificial respiration, the patient 12 is connected to the respirator 10, more precisely to the flow changing device 16 in the housing 14, via a breathing gas line arrangement 30. For this purpose, the patient 12 is intubated by means of an endotracheal tube as a patient interface 31. The proximal longitudinal end 31a of the patient interface 31 outputs the inspired breathing gas flow AF into the lungs of the patient 12. The expiratory breathing gas flow also flows into the breathing gas line arrangement via the proximal longitudinal end 31a.

[0073] The distal longitudinal end 31b of the patient interface 31 is designed for connection to the breathing gas line device 30. From point 31c downstream in the inhalation direction to the proximal longitudinal end 31a, the patient interface is surrounded by the body of the patient 12. This in turn means that the patient interface 31 is exposed to the external environment U from its distal longitudinal end 31b to point 31c and is connected to the external environment mainly by convection in a heat transfer manner.

[0074] The breathing gas line device 30 has an inhalation hose 32, via which fresh breathing gas can be conducted from the flow-changing device 16 into the lungs of the patient 12. The inhalation hose 32 can be discontinuous and has a first inhalation hose 34 and a second inhalation hose 36, between which a humidifier 38 can be arranged, which is used to specifically humidify the inhaled breathing gas delivered to the patient 12 and possibly also to control its temperature. The humidifier 38 can be connected to an external liquid reservoir 40, via which water for humidification or drugs, for example for suppressing inflammation or for dilating the respiratory tract, can also be delivered to the humidifier 38. Thus, when the present respirator 10 is used as an anesthesia respirator, volatile anesthetics can be output to the patient 12 in a controlled manner via the respirator 10. The humidifier 38 ensures that fresh breathing gas is delivered to the patient 12 at a predetermined humidity, possibly with the addition of a drug aerosol, and at a predetermined temperature.

[0075] In the present example, the second suction hose 36 can be electrically heated by a line heating device 37. The line heating device 37 can be controlled for operation by the control device 18. In contrast to what has been mentioned, the first suction hose 34 can also be heatable, or / and at least one hose 34 and / or 36 can be heated by a device other than the electrical line heating device 37, for example by a flushing device with a heat exchange medium.

[0076] In addition to the already mentioned inhalation valve 20 and exhalation valve 22 , the breathing gas line arrangement 30 also has an exhalation hose 42 , via which metabolized breathing gases are blown out of the lungs of the patient 12 into the external environment U.

[0077] At the distal longitudinal end 30b of the breathing gas line device 30, the inhalation hose 32 is coupled to the inhalation valve 20, and the exhalation hose 42 is coupled to the exhalation valve 22. Preferably, only one of the two valves is opened at the same time for the passage of the gas flow. The actuation of the valves 20 and 22 is likewise controlled by the control device 18.

[0078] During the breathing cycle, firstly for the duration of the inspiration phase, the exhalation valve 22 is closed and the inspiration valve 20 is opened, so that freshly inhaled breathing gas can be conducted from the housing 14 to the patient 12. The flow of fresh breathing gas is caused by the targeted increase in the breathing gas pressure by the flow changing device 16. Due to the increased pressure, the fresh breathing gas flows into the lungs of the patient 12 and there expands the body region near the lungs, i.e., in particular the thorax, overcoming the individual elasticity of the body part near the lungs. As a result, the gas pressure inside the lungs of the patient 12 also increases.

[0079] At the end of the inhalation phase, the inhalation valve 20 is closed and the exhalation valve 22 is opened. The exhalation phase begins. Due to the increase in the gas pressure of the respiratory gas in the lungs of the patient 12 until the end of the exhalation phase, the respiratory gas flows into the external environment U after opening the exhalation valve 22, wherein the gas pressure in the lungs of the patient 12 decreases as the flow duration continues. If the gas pressure in the lungs 12 reaches the positive end-expiratory pressure (PEEP) set at the respiratory device 10, that is, a pressure slightly above the atmospheric pressure, the exhalation phase ends with the closing of the exhalation valve 22 and another breathing cycle follows.

[0080] During the inspiration phase, the so-called tidal volume, ie the volume of breathing gas per breathing process, is delivered to the patient 12. Multiplying the tidal volume by the number of breathing cycles per minute, ie by the breathing frequency, yields the minute volume of the currently performed artificial respiration.

[0081] Preferably, the ventilator 10, in particular the control device 18, is designed to repeatedly update or determine breathing operation parameters representing the breathing operation of the ventilator 10 during the breathing operation in order to ensure that the breathing operation is optimally adapted to the respective patient 12 to be breathed at each point in time. Particularly preferably, one or more breathing operation parameters are determined using the breathing frequency, so that current and therefore optimally adapted breathing operation parameters to the patient 12 can be provided for each breathing cycle.

[0082] For this purpose, the respiratory device 10 can be connected to one or more sensors in a data-transmitting manner, which monitor the patient's condition and / or the operation of the respiratory device 10. Figure 1 In the description, only a proximal flow sensor 44 is mentioned as an example of a series of possible sensors, which detects the breathing gas flow present in the breathing gas line device 30 in terms of value. The proximal flow sensor 44, which is preferably designed as a differential pressure sensor, can be coupled to the data input 26 of the control device 18 by means of a sensor line device 46. The sensor line device 46 can, but does not necessarily, include an electrical signal transmission line. The sensor line device can also have a hose line, which transmits the gas pressure present on both sides of the flow sensor 44 in the flow direction to the data input 26, where the gas pressure is determined by only one of the two sensors. Figure 2 The pressure is quantified by the pressure sensor 27 shown in FIG.

[0083] More specifically, in a preferred embodiment, the breathing gas line device 30 has a separately constructed Y-shaped line section 47 at its proximal longitudinal end region 30a, which is connected to the second inhalation hose 36 and the expiratory hose 42 at its distal end region, and the Y-shaped line section is connected to the proximal flow sensor 44 at its proximal end region.

[0084] The proximal flow sensor 44 has at its proximal end region a coupling component 44 a , by means of which the patient interface 31 , which can also be a mask instead of a tube, can be coupled to the proximal flow sensor 44 and thus to the respiratory gas line device 30 .

[0085] At its proximal longitudinal end region, the second inhalation hose 36 has a proximal temperature sensor 48 which measures the temperature of the breathing gas flow AF in the second inhalation hose 36 as close as possible to the patient 12 and transmits it to the control device 18 .

[0086] It should be pointed out only for the sake of completeness that the respiratory device 10 according to the invention can be accommodated as a mobile respiratory device 10 on a rollable stand 50 .

[0087] exist Figure 2 Shown in Figure 1 A rough schematic diagram of the inspiratory line branching of the respiratory device 10 is shown.

[0088] The flow changing device 16 comprises a fan 52 and a pressure reducing valve 54 downstream of the fan in the suction direction. It is also possible to provide only the fan 52. The control device 18 can control the fan 52 and the pressure reducing valve 54 via lines 56 or 58 for operation.

[0089] The fan 52 can draw in ambient air from the external environment U through the suction opening 15. Additionally or alternatively, gas from a storage container 62, for example pure oxygen, can be used as breathing gas or mixed with the sucked-in ambient air via a valve 60. In the illustrated embodiment, the suction opening 15 and the storage container 62 thus jointly form a breathing gas source device.

[0090] In the respiratory device 10 , the sucked-in ambient air is cleaned in a filter (not shown) in a manner known per se.

[0091] Downstream of the flow-changing device 16 in the suction direction is an intake valve 20 , which can be controlled to open and close by the control device 18 via a line 64 .

[0092] Further downstream in the air intake direction, a first air intake hose 34 is connected to the air intake valve 20 .

[0093] In a narrow sense, the respiratory device 10 has a moisture sensor device 66 downstream of the humidifier device 38 in the inhalation direction, which in the economically preferred case shown comprises a sensor 68 for ascertaining the relative humidity of the inhaled breathing gas flow AF and a temperature sensor 70 for ascertaining the breathing gas temperature in the region where the humidity is detected by the sensor 68. Alternatively, the moisture sensor device 66 can comprise only a sensor for detecting the absolute humidity of the breathing gas, which is however not preferred for cost reasons.

[0094] The moisture sensor device 66 detects the relative humidity and temperature of the breathing gas downstream of the breathing gas sources 15 and 62 but before the humidification measures are introduced by the breathing device 10 by means of the relative humidity and temperature of the breathing gas upstream of the humidification device 38. The moisture sensor device 66 can be arranged at the humidification device 38. Figure 1 In the housing shown in FIG. 3 , however, a humidifying device 38 is arranged upstream, which is formed by a humidifying chamber 72 with a liquid reservoir 74 to which thermal energy can be supplied via a thermal evaporation device 76 in the form of a heating plate for evaporating the liquid.

[0095] The detection values ​​of sensors 68 and 70 can be transmitted to control device 18 via lines 78 and 80 .

[0096] The control device 18 can determine the absolute humidity of the breathing gas from the thus obtained detection values ​​for the relative humidity and the temperature of the breathing gas before reaching the humidification device 38 and compare it with the desired setpoint humidity of the breathing gas.

[0097] The desired humidity of the breathing gas can be derived, for example, from a data relationship stored in the data memory 19, which comes from the proximal temperature sensor 48 and optionally from the signal of the proximal breathing gas flow detected by the proximal flow sensor 44. Alternatively, the desired desired humidity of the breathing gas can also be input manually via the input device 24.

[0098] Based on the desired humidity of the breathing gas and also in dependence on the signal of the proximal temperature sensor 48 transmitted to the control device 18 via the line 82, the signal of the moisture sensor device 66 and the signal of the proximal flow sensor 44, the control device 18 determines the operating power to be supplied to the evaporation device 76 in the form of a hot plate. The control device 18 controls the energy supply device 86 of the evaporation device 76 via the line 84 in accordance with the determined operating power. The control device 18 receives information about the operating power output to the evaporation device 76 via the line 84, for example, in the form of a voltage applied to the evaporation device 76 and a current intensity flowing into the evaporation device. The energy supply device 86 can output a variable power to the evaporation device 76, for example, by pulse width modulation. In pulse width modulation, the voltage applied to the evaporation device 76 is a temporally averaged voltage.

[0099] The liquid emerging from the liquid reservoir 74 is evaporated by the evaporation device 76 and conducted along with the breathing gas flow AF which overflows the liquid reservoir 74 .

[0100] In order to take into account heat losses of evaporation device 76 into environment U, control device 18 ascertains the amount of energy to be supplied to evaporation device 76 via energy supply device 86 per time, also taking into account the ambient temperature ascertained by ambient temperature sensor 17 .

[0101] In order to determine the operating power to be supplied to the evaporation device 76 as a function of the desired humidity of the breathing gas and also as a function of the proximal breathing gas temperature, the absolute humidity detected indirectly by the moisture sensor device 66, the proximal breathing gas flow detected by the proximal flow sensor 44, and also as a function of the ambient temperature, corresponding data relationships are stored in the data memory 19, which data relationships were previously determined in the laboratory by varying parameters under controlled conditions for respiratory devices 10 of identical construction.

[0102] It is therefore assumed that the inspiratory breathing gas flow AF leaves the humidification device 38 with the desired humidity content due to the operation of the evaporation device 76 controlled by the control device 18 according to the mentioned parameters. The inspiratory breathing gas flow then enters the second inspiratory hose 36, which can be heated by the line heating device 37. The operation of the line heating device 37 can be controlled by the control device 18 by means of the line 88 according to the temperature detected by the proximal temperature sensor 48, so that the proximal breathing gas temperature detected by the proximal temperature sensor 48 is above the dew point temperature of the humidified inspiratory breathing gas flow AF.

[0103] The dew point temperature can be determined based on the proximal breathing gas temperature detected by the proximal temperature sensor 48 and also based on the dew point temperature curve in the data storage memory 19 based on the assumption that the breathing gas has a desired humidity after passing through the humidification device 38. Therefore, the dew point temperature curve results in a desired temperature, which should not be dropped below the proximal temperature sensor 48, preferably even with a certain safety margin.

[0104] The storage of the dew point temperature curve in the data memory 19 does not necessarily mean the storage of a continuously differentiable curve. The dew point temperature curve is stored in an approximation with a sufficient number of control points, for example in the form of a table. It is also possible to store an approximate mathematical function for the dew point temperature, by means of which the dew point temperature can be determined based on the known absolute humidity or based on the known value pair consisting of relative humidity and the associated temperature.

[0105] The problem of properly supplying the patient with adequately humidified but not over-humidified breathing gas lies in the patient interface 31. The patient interface 31 is neither heatable like the second inhalation hose 36 nor provided with any sensor capable of detecting the state of breathing in the patient interface 31. This is due to the usual feature of the patient interface 31 as a disposable or one-time interface.

[0106] Therefore, when the ambient temperature is very low, for example, during emergency use, at least the section between the distal longitudinal end 31b of the patient interface 31 and the inlet of the patient interface 31 into the patient 12 at location 31c that is exposed to the external environment U is strongly affected by the ambient temperature. Here, the patient interface 31 in the section can be strongly cooled by the ambient temperature, so that "rain out" is undesirably caused in the patient interface 31. This undesirable condensation of liquid in the inhaled breathing gas flow AF is usually most likely to occur at the pipeline wall of the patient interface 31 that is cooled by the ambient air. However, it is not excluded that the breathing gas flow AF is cooled in the patient interface 31 under the influence of the ambient temperature to cause atomization in the breathing gas flow AF.

[0107] In order to avoid such undesirable condensation of liquid in the patient interface 31, the control device 18 is designed to determine, based on operating parameters of the respiratory device and in particular operating parameters of the inspiratory breathing gas flow AF transmitted to the control device via available sensors, a subsequent state of the breathing situation that occurs in the patient interface 31 downstream of the coupling component 44a in the inspiratory direction under the influence of the ambient temperature, and to determine, based on the determined subsequent state, whether condensation is to be expected in the patient interface 31.

[0108] For this purpose, either empirically determined data relationships or analytically or numerically solvable equation systems can be stored in data memory 19 as a model description of the thermal state of patient interface 31 during operation in conjunction with operating data of respiratory device 10 and its environment U.

[0109] In a particularly simple and rapidly ascertainable calculation model, the subsequent state of the patient interface 31 is the subsequent temperature of the patient interface 31, which can be ascertained, for example, based on the proximal breathing gas temperature at the temperature sensor 48, further taking into account the structural design of the patient interface 31 together with the materials used therein, and taking into account the ambient temperature measured by the ambient temperature sensor 17. Furthermore, the inspiratory breathing gas flow AF detected by the proximal flow sensor 44 and, if desired, even the expiratory breathing gas flow likewise detected by the proximal flow sensor 44 can be used to ascertain the subsequent temperature.

[0110] Therefore, when the subsequent temperature of the patient interface 31 determined based on empirically determined data relationships or / and determined based on a thermodynamic model at a point upstream of the distal longitudinal end 31 b in the inhalation direction does not exceed the dew point temperature, the control device 18, which already has the dew point temperature of the inhaled breathing gas flow AF due to the above-mentioned control of the respiratory device 10, may proceed from the direct risk of condensation in the patient interface 31. For the safety of the patient, it is preferred not to use the dew point temperature directly, but a threshold temperature, which is the dew point temperature increased by a predetermined safety margin.

[0111] For the case in which the control device 18 ascertains in this way that condensation will certainly or very likely occur in the patient interface 31 or with a probability greater than a predetermined limit, the control device 18 is designed to reduce the operating power supplied to the evaporation device 76. In this case, based on the ascertainment result, the greater the risk of condensation, for example, the greater the value by which the subsequent temperature of the patient interface 31 exceeds the threshold temperature or even the dew point temperature, the higher the value by which the operating power of the evaporation device 76 can be reduced.

[0112] In addition, the control device 18 can also increase the operating power of the line heating device 37 in order to increase the temperature of the inspiratory breathing gas flow AF on the way to the proximal longitudinal end 30a of the breathing gas line arrangement 30. However, since the present control device 18 is also intended to be able to prevent condensation of breathing gas in the patient interface 31 for non-heatable inspiratory hoses, a reduction in the operating power of the evaporation device 76 is performed in any case.

Claims

1. A respiratory device (10) for artificial respiration of a patient (12), the respiratory device comprising: a breathing gas source device (15, 62) which provides breathing gas for inspiration of artificial respiration of the patient (12), a flow changing device (16) which is designed to generate an inspiratory breathing gas flow (AF) and to change the amount of the inspiratory breathing gas flow (AF), a humidifier (38) which is designed to increase the absolute humidity of the inspiratory breathing gas flow (AF) in terms of value, wherein the humidifier (38) has a liquid reservoir (40) and a variable-power evaporator (76) for this purpose, a breathing gas circuit device (30) having a proximal longitudinal end (30a) close to the patient (12) during operation and a distal longitudinal end (30b) remote from the patient during operation, in order to convey the inspired breathing gas flow (AF) from the humidification device (38) towards the patient (12), a flow sensor (44) which is designed to detect the respiratory gas flow (AF) in numerical terms, a control device (18) which is designed to control the operating power of the evaporation device (76) as a function of a predefined desired humidity of the breathing gas and as a function of a signal of the flow sensor (44), The breathing gas line device (30) has a coupling component (44a) at its proximal end (30a), the coupling component being used to couple the breathing gas line device (30) to a patient interface (31) for transmitting breathing gas between the breathing gas line device (30) and the patient (12), It is characterized in that The control device (18) is designed to determine a subsequent state of a breathing situation downstream of the coupling component (44a) in the inhalation direction based on a temperature of the breathing gas flow (AF) in the proximal longitudinal end region (30a) of the breathing gas line device (30) detected by a proximal temperature sensor (48), a value of the breathing gas flow (AF) determined by the flow sensor (44) and a preset desired humidity of the breathing gas, and to change the operating power of the evaporation device (76) based on the determination result. wherein the flow sensor (44) is arranged between the coupling component (44a) and the patient interface (31), and The subsequent state of the respiratory condition includes the subsequent temperature of the tube wall of the patient interface (31).

2. The breathing apparatus (10) according to claim 1, It is characterized in that The subsequent state of the breathing condition includes a subsequent temperature of the breathing gas flow (AF).

3. The breathing apparatus (10) according to claim 2, It is characterized in that The respiratory device has a data memory (19) which can be queried by the control device (18), in which the operating parameter value of the respiratory gas flow (AF) is associated with a subsequent temperature value of the tube wall of the patient interface (31) and / or a subsequent temperature value of the respiratory gas flow (AF).

4. The breathing apparatus (10) according to claim 1, It is characterized in that The control device (18) ascertains the subsequent state as a function of an ambient temperature detected by an ambient temperature sensor (17).

5. A breathing apparatus (10) according to claim 2 or 3, It is characterized in that The control device (18) ascertains the subsequent state as a function of an ambient temperature detected by an ambient temperature sensor (17).

6. The breathing apparatus (10) according to claim 1, It is characterized in that The control device (18) ascertains the subsequent state for an ascertainment location that is closer to a proximal end (31a) of the patient interface (31) than to a distal end (31b) of the patient interface.

7. A breathing apparatus (10) according to claim 2, 3 or 4, It is characterized in that The control device (18) ascertains the subsequent state for an ascertainment location that is closer to a proximal end (31a) of the patient interface (31) than to a distal end (31b) of the patient interface.

8. The breathing apparatus (10) according to claim 6, It is characterized in that The control device (18) determines the subsequent state for a proximal end (31a) of the patient interface (31).

9. The breathing apparatus (10) according to claim 7, It is characterized in that The control device (18) determines the subsequent state for a proximal end (31a) of the patient interface (31).

10. The breathing apparatus (10) according to claim 1, It is characterized in that The control device (18) determines the subsequent state for a section of the patient interface (31) that is located between the coupling component (44a) and an entry point (31c) of the patient interface (31) into the body of the patient (12).

11. A breathing apparatus (10) according to claim 2, 3, 4, 6 or 8, It is characterized in that The control device (18) determines the subsequent state for a section of the patient interface (31) that is located between the coupling component (44a) and an entry point (31c) of the patient interface (31) into the body of the patient (12).

12. The breathing apparatus (10) according to claim 1, It is characterized in that At least one inhalation line section (36) of the breathing gas line device (30) has a line heating device (37), by means of which the inhalation line section (36) can be heated, wherein the control device (18) is designed to change the temperature of the breathing gas at a proximal temperature sensor (48) as a function of the ascertainment result and to change the operating power of the line heating device (37) for this purpose.

13. A breathing apparatus (10) according to claim 2, 3, 4, 6, 8 or 10, It is characterized in that At least one inhalation line section (36) of the breathing gas line device (30) has a line heating device (37), by means of which the inhalation line section (36) can be heated, wherein the control device (18) is designed to change the temperature of the breathing gas at a proximal temperature sensor (48) as a function of the ascertainment result and to change the operating power of the line heating device (37) for this purpose.

14. A breathing apparatus (10) according to claim 1, 2, 3, 4, 6, 8, 10 or 12, It is characterized in that The patient interface is an endotracheal tube, a laryngeal mask or a combination tube.

Images