Systems and methods for breathing gas supply

Abstract

The invention relates to a system and a method for supplying breathing gas, the system comprising an artificial respiration device (2) and a control device (4), the artificial respiration device having a breathing gas source (3) for generating a breathing gas flow. The control device (4) is suitable for and is designed to generate a defined breathing gas flow for artificial respiration by means of the artificial respiration device (2). In this case, the control device (4) is suitable for and is designed to monitor a variable characterizing pressure by means of a sensor device (5). The variable characterizes the pressure with which the artificial respiration device (2) loads the breathing gas flow to maintain the defined breathing gas flow in order to compensate for the patient's breathing activity. The control device (4) is suitable for and is designed to record the variation curve of the variable over time as a pressure variation curve.

Description

Technical Field

[0001] The invention relates to a system for supplying breathing gas and a method for operating such a system. The system comprises at least one artificial respiration device and at least one control device, the artificial respiration device having at least one breathing gas source for generating a breathing gas flow. The control device generates a defined breathing gas flow for flow-controlled artificial respiration by means of the artificial respiration device. Background Art

[0002] In volume-controlled artificial respiration, a fixed breathing volume is applied to the patient during a predetermined inspiration time. The breathing volume is calculated, for example, from the tidal volume and the respiratory rate. In this form of artificial respiration, the apparatus used therefore essentially attempts to apply a set volume.

[0003] In contrast, in pressure-supported artificial respiration, the respiratory drive of the patient is taken into account. When the patient inhales, the breathing process is supported and the breathing work is thereby facilitated. In pressure-supported artificial respiration, a lower pressure level and an upper pressure level are usually determined. Usually, these two pressures can be set variably. The tidal volume is then obtained from the amount of air expelled when the upper pressure is reached.

[0004] However, it has been found that control or regulation in devices for pressure-controlled or volume-controlled respiration is very complex or worth improving. In pressure-controlled or volume-controlled respiration, the proportion of oscillating air caused by the system is relatively large; oscillating air is air that moves back and forth due to the respiration and does not participate in the gas exchange. Summary of the invention

[0005] In contrast, the flow-controlled artificial respiration according to the invention at least partially rinses the upper airways and thus reduces the proportion of oscillating air.

[0006] In contrast, the object of the present invention is to realize a flow-controlled artificial respiration. Preferably, an improved controllability of the artificial respirator and a more reliable monitoring of the patient's respiratory activity should be achieved. In particular, an improved possibility for preventing mucous membrane drying should be provided.

[0007] This object is achieved by a system according to the invention and by a method according to the invention. Improvements and advantageous configurations are the subject matter of the description. Further advantages and features are apparent from the general description and the description of the exemplary embodiments.

[0008] The system according to the invention is used for supplying breathing gas or artificial respiration to a patient. The system comprises at least one artificial respiration device having at least one breathing gas source for generating a breathing gas flow. The system comprises at least one control device, which is suitable for and configured to generate at least one limited breathing gas flow for artificial respiration by means of the artificial respiration device, and preferably to adjust to a rated value and in particular to a certain flow rate. Here, the control device is suitable for and configured to monitor at least one parameter characterizing pressure by means of at least one sensor device. The parameter characterizes the following pressure, with which the artificial respiration device loads the breathing gas flow to maintain a limited breathing gas flow, in order to compensate and in particular regulate the patient's respiratory activity. Here, the control device is particularly suitable for and configured to record the variation curve of the parameter over time as a pressure variation curve.

[0009] The system according to the invention offers numerous advantages. The monitoring and recording of the variables and, for this purpose, the monitoring of the pressure to which the artificial respiration device must be set in order to compensate for the respiratory activity offer a significant advantage. This makes it possible to monitor the artificial respiration and the respiratory activity of the patient particularly easily and at the same time very reliably. In addition, this provides a particularly reliable and at the same time structurally simple possibility for adjusting the artificial respiration device according to the respiratory activity of the patient.

[0010] Preferably, the control device is suitable for and is designed to determine at least one characteristic parameter that characterizes the patient's respiratory activity from the pressure change curve (taking into account the pressure change curve). Such a characteristic parameter can be, for example, the tidal volume, the duration of a breath, the respiratory rate or the like. The characteristic parameter can also be an apnea-hypopnea index (AHI). Particularly preferably, the characteristic parameter is a respiratory phase, so that exhalation and inhalation are preferably identified and distinguished from each other. This provides particularly reliable monitoring of artificial respiration. In addition, such a characteristic parameter can be particularly advantageously used to regulate artificial respiration.

[0011] Preferably, the control device is suitable for and is designed to identify inspiration (inspiratory breathing phase) in that the pressure required to maintain a defined breathing gas flow decreases over time and in particular decreases by a defined amount and / or changes a defined amount. In particular, the pressure change curve for identifying inspiration shows a negative slope. It is possible to consider evaluating the derivative of the pressure change curve and / or other analysis techniques for the function for this purpose. It is also possible that the pressure required to maintain a defined breathing gas flow drops and / or must drop below a defined threshold value in order to identify inspiration. In particular, the pressure drops by a certain amount relative to at least one previously recorded value and / or a previously recorded pressure change curve. It is possible that the pressure change curve must have a defined pressure difference in order to identify inspiration.

[0012] It is also preferred that the control device is suitable and configured to identify exhalation (breathing phase of exhalation) in that the pressure required to maintain a defined breathing gas flow decreases over time and in particular increases by a defined amount and / or changes a defined amount. In particular, the pressure variation curve for identifying exhalation shows a positive slope. It is possible to evaluate the derivative of the pressure variation curve for this purpose and / or to take into account other analysis techniques for the function. It is also possible that the pressure required to maintain a defined breathing gas flow must increase and / or increase above a certain threshold value in order to identify exhalation. In particular, the pressure rises by a certain amount relative to at least one previously recorded value and / or a previously recorded pressure variation curve for this purpose. It is possible that the pressure variation curve must have a defined pressure difference in order to identify exhalation.

[0013] This configuration provides a particularly reliable and at the same time simple possibility in terms of sensors for identifying the breathing phase or inhalation or exhalation. In addition, the identification of inhalation or exhalation is particularly decisive for the targeted regulation of the artificial respiration device taking into account the patient's respiratory condition.

[0014] In particular, the respiratory rate is measured and / or the oxygen mixing is controlled (in particular more inhalation than exhalation) and / or the humidification and heating of the respiratory gas is controlled (in particular more inhalation than exhalation) and / or the respiratory gas flow is controlled (in particular more inhalation than exhalation (Bilevel High Flow)) as a function of the detected respiratory phase. For the use of Bilevel High Flow, the control is performed in such a way that a higher flow (for example in the range of 40-60 l / min) is predefined during inspiration in order to increase the tidal volume. Similarly, during exhalation, the control is performed at a lower flow (preferably in the range of 10-40 or 5-38 l / min) in order to ensure flushing of the dead space of the upper respiratory tract.

[0015] According to the invention, the control device is also suitable and designed to detect a disconnection (port disconnected from the nose or port disconnected from the hose or hose disconnected from the device). The control device detects a disconnection either by the occurrence of a long apnea (e.g. longer than one minute or preferably longer than two minutes) and / or by a reduction in the speed / pressure required to achieve the set flow rate. When a disconnection is detected, the control device is suitable and designed to trigger a disconnection alarm and / or to switch off the oxygen mixing and / or to reduce the flow rate.

[0016] According to the invention, it is also provided that the high flow mode is applied not by a nasal cannula but by a common breathing mask. In this application, the ventilation device reacts to the patient's respiratory activity (the ventilation device attempts to produce a constant flow). This can be used as a training program for the respiratory muscles. The higher the set flow, the greater the resistance (training) the patient bears when exhaling. The lower the set flow, the greater the resistance (training) the patient bears when inhaling. According to the invention, the total difficulty of the training can be set by the control device (via the regulator coefficient of the high flow regulator). The more sluggish / cautious the regulation, the lower the resistance during breathing (both inhalation and exhalation). The more dynamic / aggressive the regulation, the higher the resistance. The daily duration of the respiratory muscle training can be detected by remote monitoring.

[0017] In a particularly advantageous development, the control device is suitable and designed to determine at least one respiratory event as a function of the pressure. The respiratory event is determined in particular by comparison with a stored pressure curve. Such respiratory events are, for example, snoring, bradypnea and / or obstructive pressure peaks, apnea, hypopnea or other corresponding events.

[0018] It is possible and preferred that the control device is suitable and configured to determine at least one breathing pattern based on the pressure change curve. Preferably, the control device is suitable and configured to study the breathing pattern with respect to at least one breathing event. The study of the breathing pattern is carried out in particular by comparison with at least one stored breathing pattern and / or with the aid of at least one (learning) algorithm. The breathing pattern corresponds in particular to a characteristic time curve of the breathing and preferably to a characteristic time curve of the breathing events occurring in the breathing. For example, wakefulness recognition or sleep recognition can be carried out by studying the breathing pattern. The breathing pattern is represented, for example, by a sequence of apneas and / or hypopneas.

[0019] It is possible that the control device is suitable and designed to evaluate the calculated pressure curve and / or the calculated breathing pattern and / or the identified breathing events with respect to a confidence level. For this purpose, methods known in the field of artificial respiration for evaluating pressure curves or events can be considered. For example, a predetermined significance level must be reached, whereby a certain breathing event and / or breathing pattern is identified.

[0020] In particular, the control device is suitable and designed for controlling the artificial respiration device according to the pressure curve, as is known, for example, from pressure-supported or pressure-controlled artificial respiration. In particular, at least one of the following settings or adjustments can be performed according to the pressure curve: automatic start, automatic stop, ramp, awakening detection, event detection, statistics, frequency, breathing volume, apnea, hypopnea, event control, saturation control, automatic flow control, remote monitoring, short-range monitoring, control or setting of PSG and / or SpO2 and / or TcCO2, Soft-PAP, oxygen mixing. In particular, at least one control known from CPAP, IPAP or BiPAP artificial respiration can be implemented according to the pressure curve.

[0021] The control device can be suitable and designed to output at least one user interaction and, for example, an alarm as a function of the pressure curve. It is also possible that the control device is suitable and designed to transmit the pressure curve and, in particular, the respiratory events and / or the respiratory pattern identified by the pressure curve to at least one network device. In particular, the system is designed for remote monitoring. In particular, the control device can set and / or transmit treatment statistics as a function of the pressure curve.

[0022] It is particularly preferred that the control device is suitable for and configured to set at least one instrument parameter of the artificial respiration device according to the pressure variation curve and / or to set at least one artificial respiration parameter by means of the artificial respiration device. In particular, the artificial respiration device can be controlled according to the pressure variation curve. In particular, the control device is suitable for and configured to set the instrument parameter and / or artificial respiration parameter as a reaction to a respiratory event and / or a breathing pattern. The instrument parameter, for example, includes a ventilator speed, a humidifying power, a heating power or the like. The instrument parameter may also include the switching on and / or shutting off and / or pausing of the artificial respiration device. The instrument parameter may also be related to software settings. The artificial respiration parameter is preferably a flow rate or a flow rate and / or a pressure and / or other parameter characterizing artificial respiration. The instrument parameter and the artificial respiration parameter may be coupled and / or may influence each other. It is possible to set the instrument parameter for realizing a determined artificial respiration parameter.

[0023] Preferably, the instrument parameters and / or the artificial respiration parameters are set as a function of at least one identified breathing pattern and / or at least one breathing event. In particular, the flow rate of the breathing gas flow is set as a function of the identified breathing pattern and / or breathing event.

[0024] In an advantageous embodiment, the control device is suitable and designed to set at least one flow rate of the breathing gas flow by means of the artificial respiration device as a function of the oxygen saturation of the breathing gas flow. It is also possible that at least one further artificial respiration parameter can be set as a function of the oxygen saturation. In particular, the oxygen saturation is monitored with a sensor. It is also possible that the flow rate of the breathing gas flow can be set as a function of an oxygen mixture that is provided by the system and / or that is fixedly set.

[0025] Preferably, the control device is suitable for and is configured to set the oxygen mixture mixed into the breathing gas flow according to the pressure variation curve. Preferably, the control device is suitable for and is configured to modulate the oxygen mixture according to the breathing phase, and in particular modulate according to the pressure variation curve according to the breathing phase. In particular, the oxygen mixture can be increased and / or reduced in a targeted manner according to the pressure variation curve. In particular, for the oxygen mixture, at least one oxygen source that can be opened or closed in a targeted manner is provided. The oxygen mixture can be up to 100%. It is also possible that the oxygen mixture is deactivated or is 0%. The oxygen mixture can be, for example, up to 300 l / min.

[0026] In particular, the oxygen mixing is performed according to at least one of the following provisions: maintaining the oxygen content, maintaining the absolute flow of oxygen, and demand control based on measured or estimated patient needs. In particular, at least one sensor-based control device is provided for the oxygen mixing. Such sensor-based control devices include, in particular, control devices based on SpO2 and / or TcCO2 and / or other control provisions.

[0027] Particularly preferably, when the flow rate of the breathing gas flow increases, the oxygen mixing and / or the oxygen content in the breathing gas flow decreases by a certain amount. This inverse matching has been shown to be particularly advantageous based on clinical experience. Due to the correspondingly large flow rate in flow-controlled artificial respiration, better oxygen absorption is achieved, so that the mixing can be reduced accordingly. In particular, an increase in the flow rate of the breathing gas flow is accompanied by a decrease in the oxygen mixing or the oxygen content in the breathing gas flow. In particular, at least one distribution function is stored, which describes the inverse proportionality between the oxygen mixing and the flow rate.

[0028] In particular, oxygen mixing takes place only during inspiration. In particular, oxygen mixing does not take place during exhalation. It is possible and preferred that oxygen mixing is increased during inspiration relative to exhalation. In this case, inspiration and exhalation are preferably identified as described above based on the pressure curve. This enhanced mixing during inspiration offers many advantages. However, sensor-based regulation is also possible.

[0029] The applicant claims a system for the supply of breathing gas or artificial respiration of a patient. Such a system comprises at least one artificial respiration device having at least one breathing gas source for generating a breathing gas flow. The system comprises at least one control device, which is suitable and configured to generate at least one limited breathing gas flow for volume-controlled artificial respiration by means of the artificial respiration device and preferably regulate it to a rated value and in particular to a certain flow rate. In this case, the system comprises at least one humidifying device for humidifying the breathing gas flow in a particularly targeted manner and / or at least one heating device for heating the breathing gas flow in a particularly targeted manner. Such a system is preferably configured as the aforementioned system. Preferably, the aforementioned system is also configured in this manner.

[0030] The humidification device comprises, for example, a nebulizer and / or a humidifier and / or a humidifier and / or an evaporator. It is possible that the heating device is also suitable for cooling the breathing gas flow. It is possible that the humidification device is also suitable for dehumidifying the breathing gas flow.

[0031] In particular, the control device is suitable for and is configured to set the humidification and / or heating of the breathing gas flow according to the pressure variation curve, and in particular adjust the target temperature and / or target humidity of the breathing gas flow. The target temperature and / or target humidity are measured in particular at the patient and / or in the vicinity of the patient. For example, the target temperature and / or target humidity are measured at the output area of ​​the hose connected to the patient and / or in the area of ​​the breathing interface. The measurement can also be performed at other locations, for example at the outlet of the instrument or the outlet of the artificial respiration device. In particular, at least one sensor device with a corresponding sensor is provided for detecting the target temperature and / or target humidity. In particular, humidification is performed using the aforementioned humidification device. In particular, heating is performed using the aforementioned heating device.

[0032] Preferably, the control device can be used to set a breathing phase-controlled humidification and / or heating. In this case, the breathing phase is preferably determined as described above based on the pressure curve.

[0033] In particular, the control device is suitable and configured to set the humidification and / or heating as a function of the flow rate of the respiratory gas flow. Such an adaptation of the humidification or heating to the flow rate is particularly advantageous, since dry or cold flow is often perceived as particularly uncomfortable at correspondingly high flow rates of high flow rates.

[0034] Preferably, the control device is suitable for and is configured to set humidification and / or heating according to at least one parameter detected by a sensor. In this case, the parameter is preferably extracted from a parameter group, wherein the parameter group includes at least: ambient temperature, ambient humidity, temperature in the system, humidity in the system, hose temperature, temperature at the patient interface, humidity at the hose end and / or at the patient interface. The temperature or humidity in the system can be captured, for example, in the region of the heating device, in particular at the heating rod and / or plate and / or sensor. The temperature or humidity in the system can also be captured in the humidifying device and / or in the housing and / or at the housing and / or at the ventilation device and in particular at the ventilator outlet.

[0035] In a particularly advantageous embodiment, the control device is suitable and designed to at least approximately compensate for flow errors and / or other deviations caused by humidification and / or heating by means of the artificial respiration device. In particular, flow errors between 0.1% and 10% can be compensated. In particular, flow errors of a few percent can be compensated. In particular, flow errors caused by humidification or water evaporation can be compensated.

[0036] In a particularly advantageous development, the control device is suitable and designed to reduce the flow rate of the breathing gas flow provided for artificial respiration until a measure of the humidity of the breathing gas flow reaches a threshold value and / or until the temperature of the breathing gas flow reaches a threshold value. Here, the flow rate of the breathing gas flow provided for artificial respiration can in particular be reduced by a stored value and / or reduced to a stored value. The flow rate provided for artificial respiration is then fully provided, in particular when the threshold value is reached and / or exceeded. Particularly preferably, the flow rate of the breathing gas flow provided for artificial respiration is provided only when the value of the humidity of the breathing gas flow and / or the temperature of the breathing gas flow reaches a threshold value. Preferably, a humidity-controlled ramp is stored for the flow rate of the breathing gas flow.

[0037] In a particularly advantageous refinement, the system comprises a humidifying device for humidifying the breathing gas flow and at least one heating device for heating the breathing gas flow, wherein the heating device is suitable for and is configured to heat the breathing gas flow (at least during inhalation) to 36-38° C., wherein the humidifying device is suitable for and is configured to humidify the breathing gas flow with a relative humidity in the range of 90-100%, preferably 95-99%.

[0038] This configuration provides particularly comfortable artificial respiration, since humidification and heating have a significant influence on the comfort of artificial respiration. The flow rate set for artificial respiration is only particularly advantageous if humidification is reliably provided, since high-flow artificial respiration can be painful without adequate humidification. It is advantageous to first carry out heating at a lower flow rate and the highest possible humidity or 100% humidity and only then increase the flow rate.

[0039] In an advantageous embodiment, at least one drying mode can be carried out after the artificial respiration. In particular, the hose arrangement and in particular the artificial respiration hose are dried. In particular, condensed water is removed in a targeted manner. The drying mode can be carried out by means of a heating device and / or a humidifying device.

[0040] It is possible to provide at least one condensation protection device. For this purpose, for example, a relative humidity of 95% is maintained at 37° C. Other combinations of humidity and temperature are also possible.

[0041] In particular, the humidification device is suitable for and is configured to be used for taking water provided for humidification from at least one reservoir before heating and heating it separately from the reservoir. Here, water is understood synonymously with other liquids suitable for humidification. For example, the isolation of water can be achieved with the scheme of a bird waterer. In particular, the capillary effect is used for isolation. It is possible that the heating device includes at least one heating plate, which includes at least one heating element and a heating plate, for example, arranged in a float with a small basin. The water provided for humidification can also be atomized. For this purpose, for example, a mesh atomizer and / or a nozzle atomizer and / or a rotary atomizer and / or an atomizer with a heating hose are provided. Here, it is preferred to construct a corresponding regulating device or a safety device, which ensures that no mist enters the patient.

[0042] The applicant claims a system for the supply of breathing gas or artificial respiration of a patient. Such a system comprises at least one artificial respiration device, which has at least one breathing gas source for generating a breathing gas flow. The system comprises at least one control device, which is suitable and configured to generate at least one defined breathing gas flow for volume-controlled artificial respiration by means of the artificial respiration device and preferably regulate it to a setpoint value and in particular to a certain flow rate. In this case, the system comprises at least one hose device, which has at least one artificial respiration hose that can be coupled to the artificial respiration device and by means of which the breathing gas flow can be conveyed to a patient interface. Such a system is preferably configured as one of the above-described systems. Preferably, the above-described system is also configured in this way.

[0043] The hose arrangement can include at least one heatable artificial breathing hose. In particular, the heatable artificial breathing hose includes at least a part of a sensor unit for detecting at least one parameter characterizing humidity and / or temperature. In particular, this part of the sensor unit is arranged inside the breathing hose and / or integrated into the breathing hose. This part of the sensor unit can also be arranged at least partially or completely outside the artificial breathing hose. Then, this part of the sensor unit is preferably arranged externally on the breathing hose. The parameter that can be detected by means of the sensor unit can be used in particular to control or regulate the heating of the hose. In particular, the heating of the hose is regulated by the parameter detected in this way. It is possible to take into account at least one other parameter for the heating of the hose.

[0044] Preferably, the hose arrangement comprises at least one respiration hose which can be heated gradually over its length. In particular, a heating gradient or temperature gradient can be set over the length of the hose. In particular, the respiration hose has at least one first, more strongly heatable section which is suitable and designed for evaporating water. In particular, the respiration hose comprises at least one second section which is heated less than the first section, so that a targeted compensation of heat losses with respect to evaporated water is achieved in the second section.

[0045] In a particularly advantageous embodiment, the hose arrangement comprises at least one heatable artificial respiration hose, which has at least one heater that can be separated from the artificial respiration hose. Here, the heater can be equipped with a new artificial respiration hose as required when the hose is replaced and can continue to be used. It is also possible that the sensor unit of the artificial respiration hose can be separated from the artificial respiration hose and can continue to be used as required after the hose is replaced.

[0046] The hose arrangement preferably has at least one artificial respiration hose made of a water-repellent material. For example, this material is similar to the air conditioning membrane (Klimafolie) in house construction and / or the air conditioning fabric (Klimatextil) of functional clothing.

[0047] The hose arrangement can include at least one thermally insulating artificial respiration hose. In particular, the artificial respiration hose is double-walled. In particular, an air layer and / or a vacuum region is provided between at least two walls. It is also possible that the artificial respiration hose is surrounded by a thermally insulating material. In particular, a thermal insulation relative to the surrounding environment is provided.

[0048] In all embodiments of the system, it is particularly preferred that the control device is suitable and configured to apply at least one fixed breathing volume within a predetermined inspiration time by means of an artificial respiration device via a defined breathing gas flow. In particular, minute ventilation is calculated from tidal volume and respiratory rate.

[0049] Preferably, the control device is suitable and configured to take into account at least one stored maximum pressure for a defined breathing gas flow. This maximum pressure can be fixedly predetermined and / or can be dynamically adapted. In particular, the maximum pressure is dynamically adapted according to the pressure variation curve. The maximum pressure can also be set manually. It is possible that this maximum pressure can only be exceeded under special safety measures (for example by entering a password or user identification code or the like). Since the artificial respiration device first attempts to apply the set volume in artificial respiration with controlled airflow, high peak pressures sometimes occur in this artificial respiration method. Therefore, this configuration is a particularly safe possibility for reliably preventing unfavorable peak pressures. In particular, at least one maximum pressure is stored as an alarm limit.

[0050] In particular, the defined breathing gas flow has a flow rate in the range of 0 to 90 l / min, preferably in the range of 1 to 80 l / min, particularly preferably in the range of 2 to 60 l / min. Other flow rates are also possible. In particular, the artificial respiration device can be set to such a flow rate. By means of a selectable presetting, the defined breathing gas flow can have a flow rate for infants in the range of 1-10 l / min. In particular, artificial respiration can be carried out in accordance with regulations with such a flow rate. In particular, a breathing gas flow with a flow rate of 0 to 300 l / min can be set.

[0051] In all configurations, the system is suitable and designed for operation according to regulations with a nasal cannula as a patient interface. In particular, an open nasal cannula is provided. In particular, a breathing gas flow can be applied to the patient using the nasal cannula. In particular, at least one nasal cannula can be connected to an artificial respiration device. In particular, the nasal cannula can be connected to a hose device. It is also possible that the hose device is fixedly and / or detachably connected to the nasal cannula. In particular, an artificial respiration hose can be coupled to the nasal cannula. In particular, the system comprises at least one nasal cannula. Such a nasal cannula is particularly advantageously suitable for high-flow artificial respiration and provides a particularly high level of comfort for the patient. It is also possible that the system can be operated using another suitable patient interface and, for example, using a tracheostomy connector.

[0052] In an advantageous development, the system has a nasal cannula with a connecting piece for each nostril, wherein each connecting piece can be at least partially inserted into the respective nostril, wherein each connecting piece has a diameter which is dimensioned such that the respective nostril is not sealed when the connecting piece is inserted.

[0053] For example, each nozzle has a diameter that is smaller than 9 / 10, preferably smaller than 8 / 10 and larger than 6 / 10 of the diameter of the corresponding nostril.

[0054] The method according to the invention is used to operate the aforementioned system. In particular, the aforementioned system is suitable and designed for operation according to the method according to the invention.

[0055] The parameter is in particular pressure. The parameter monitored by the sensor device is in particular the following pressure, with which the artificial respiration device must load the breathing gas flow, in order to maintain a limited breathing gas flow relative to the patient's breathing activity, and in particular to keep it at a certain flow rate or rated flow rate and / or to keep it at at least one other characteristic parameter characterizing the breathing gas flow. The parameter describes in particular the breathing gas flow pressure in the artificial respiration device and / or at the outlet of the artificial respiration device and in particular at the interface for connecting to the hose device and / or the patient interface. The parameter describes in particular a pressure matching, which is necessary in order to bring the actual value of the breathing gas flow to the required rated value. It is also possible that the parameter represents at least one other parameter characterizing pressure. Then, the parameter is, for example, a ventilator rotation speed or the like.

[0056] The sensor device comprises in particular at least one sensor for detecting a variable. The sensor device comprises in particular at least one pressure sensor and / or at least one rotational speed sensor and / or at least one flow sensor and / or other suitable sensors.

[0057] In particular, the control device is suitable for and is configured to obtain the following pressure, which the artificial respirator must apply in order to keep the limited breathing gas flow constant. In particular, the control device is suitable for and is configured to obtain the following pressure, which the artificial respirator must apply in order to keep the breathing gas flow affected by the respiratory activity at a limited rated value. In particular, the control device is suitable for and is configured to be used to adjust the limited breathing gas flow to a certain flow rate in the following manner, that is, by means of the artificial respirator, pressure matching and / or at least one rotation speed matching of the ventilation device. The pressure of the breathing gas flow is especially set by the rotation speed of the ventilation device. It is also possible to set the pressure by opening or closing a compressed gas source in a targeted manner. In particular, the control device is suitable for and is configured to be used to adjust the limited breathing gas flow by means of pressure matching. The control device can especially perform pressure matching in order to keep the limited breathing gas flow at a certain flow rate and preferably adjust the compensation patient's respiratory activity at this time.

[0058] With the system according to the invention, flow-controlled artificial respiration or high-flow artificial respiration can be performed in particular. In particular, the artificial respiration device can be controlled by means of a control device. In particular, the artificial respiration device can be controlled by means of a control device for presetting a defined breathing gas flow.

[0059] The defined breathing gas flow is in particular a persistent flow. The defined breathing gas flow is in particular defined by a predetermined flow rate. The defined breathing gas flow can also be defined by at least one other characteristic parameter characterizing the volume flow. Within the scope of the present invention, the flow rate is also referred to as flow rate or flow. The breathing gas flow can also be referred to as flow or breathing gas flow. The defined breathing gas flow describes in particular the amount of breathing gas provided to the patient or flowing into the patient over time. Here, flow-controlled artificial respiration and high-flow artificial respiration are used as synonyms. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Further advantages and features of the invention emerge from the description of exemplary embodiments which are explained below with reference to the drawings.

[0061] The accompanying drawings show:

[0062] Figure 1 A purely schematic illustration of a system according to the invention is shown in a perspective view;

[0063] Figure 2 A highly schematic diagram of the way the system functions; and

[0064] Figure 3 Another highly schematic diagram of the way the system functions. DETAILED DESCRIPTION

[0065] Figure 1 The system 1 according to the invention for supplying breathing gas or artificial respiration is shown, which has at least one artificial respiration device 2, which is provided here by a ventilator 11. The system 1 shown here is operated according to the method according to the invention. The artificial respiration device 2 is equipped with a breathing gas source 3 for generating a breathing gas flow, which is provided here by a ventilation device 13 in the housing interior.

[0066] The ventilation device 13 generates a breathing gas flow by means of a ventilator, which is delivered to the patient via a hose device 8 coupled to the artificial respiration device 2. For example, an electric motor with a ventilator impeller is provided. Additionally or alternatively, a compressed gas source can also be provided as the breathing gas source 3.

[0067] The ventilator 11 comprises an operating device 10 and a display device 20. A combination of an operating device 10 and a display device 20 can also be provided, for example in the form of a touch-sensitive display surface or a touch screen.

[0068] The system 1 is configured for flow-controlled artificial respiration or high-flow artificial respiration. The artificial respiration device 2 is controlled by a control device or control unit 4 which is arranged invisibly in the housing. For flow-controlled artificial respiration, the control device 4 sets the artificial respiration device 2 to a defined breathing gas flow. Thus, a fixed breathing volume is applied to the patient within a predetermined inspiration time. In one configuration, the system 1 can also be used for pressure-supported or pressure-controlled artificial respiration at a defined flow rate.

[0069] Here, the system 1 is equipped with a hose device 8 adapted or optimized for flow-controlled artificial respiration. For example, the breathing gas flow is set to have a flow rate of 0 to 300 l / min. For this purpose, an artificial respiration hose 18 is provided, which is coupled to the breathing gas source 3 and the patient interface or patient port 28.

[0070] The patient interface 28 is designed here as an open nasal cannula 38. The nasal cannula 38 is also called a nasal cannula. Advantageously, the hose device can also be used in conjunction with a tracheostomy connector. Such a nasal cannula 38 is generally significantly more comfortable for the patient than, for example, a fixed breathing mask and is a particular advantage of flow-controlled artificial respiration. Here, the nasal cannula 38 is loosely suspended in the nose and flushed with a correspondingly high predefined breathing gas flow (high flow or continuous flow). As a result, carbon dioxide is washed out of the upper respiratory tract before inspiration and a small positive overpressure is generated, so that inspiration can be particularly comfortably supported. A nasal cannula allows continuous leakage, while a breathing mask substantially avoids leakage.

[0071] In order to prevent the mucous membrane from drying out due to the continuous air flow, the respiratory gas flow is humidified and heated in a targeted manner. For this purpose, the system 1 is equipped with a humidifying device 6 and a heating device 7. The heating device 7 is integrated in the humidifying device 6. The control device 4 additionally activates the humidifying device 6 and / or the heating device 7 at least temporarily for humidifying or heating the respiratory gas.

[0072] The respirator tube 18 is designed in two parts and extends with a first part from the respirator device 2 to the humidifier device 6 . The second part of the respirator tube 18 then extends from the humidifier device 6 to the nasal cannula 38 .

[0073] The humidifying device 6 is equipped here with a reservoir 16 for water. The water is evaporated and / or atomized and mixed with the breathing air flowing through the artificial respiration hose 18. At the same time, the breathing air flowing through the humidifying device 6 is heated in a targeted manner by the heating device 7.

[0074] In order to optimally regulate the humidity and / or temperature of the breathing gas flow, the hose arrangement 8 is equipped with a sensor unit 48. The power of the humidifying device 6 or the heating device 7 is then regulated accordingly via the sensor unit 48.

[0075] In addition or as an alternative to the heating device 7, the hose device 8 can also be designed as a heated hose. For this purpose, the artificial respiration hose 18 has its own heater 58. The heater 58 can be separated from the artificial respiration hose 18 without damage, so that the heater 58 can continue to be used with a new artificial respiration hose 18 after the hose is replaced. The heater 58 can be controlled by the sensor unit 48.

[0076] The system 1 shown here is equipped with a sensor device 5, which is here not visible in the ventilator 11. By means of the sensor device 5, the control device 4 detects the pressure that the ventilator 2 must apply in order to maintain a defined breathing gas flow in order to compensate for the patient's breathing activity. For example, for this purpose, the pressure at the outlet of the measuring instrument is measured, which the ventilator 2 needs to keep the defined breathing gas flow constant. This pressure changes continuously. For example, during inspiration, less pressure is required to maintain a defined breathing gas flow than during exhalation. Conversely, during exhalation, more pressure is required because the patient breathes against the applied breathing gas flow. The sensor device 5 comprises, for example, at least one pressure sensor and / or at least one flow sensor.

[0077] The control device 4 records the detected pressure change curve over time and saves it as a pressure change curve. Through the pressure change curve, the control device 4 can determine the characteristic parameters that characterize the patient's respiratory activity. For example, the control device draws a breathing pattern through the pressure change curve. Then, different breathing events and conditions can be identified from the breathing pattern. For this, for example, corresponding settings can be made to the artificial respiration device and in particular, flow changes can be used to react. In addition, breathing events or breathing patterns can be transmitted through remote monitoring. For example, AHI can be obtained from this.

[0078] The control unit 4 is configured and constructed to detect dyspnea from the pressure signal and / or from the flow signal of the pressure sensor device 5 and / or the flow sensor device 5. In addition, the control unit 4 is configured and constructed to detect periodic breathing or breathing interruptions from the pressure signal and / or from the flow signal of the pressure sensor device 5 and / or the flow sensor device 5.

[0079] The system 1 is also designed and configured, for example, such that an oxygen admixture of up to 300 l / min or more takes place via an internal or external oxygen source (not shown in detail here).

[0080] The system 1 is designed and configured, for example, so that the control unit 4 activates the oxygen source for an oxygen mixture that is modulated as a function of the breathing phase, taking into account the signal of the flow and / or pressure sensor device 5. For example, it is conceivable to control the oxygen mixture in such a way that more oxygen is provided to the patient during the inspiration phase than for exhalation.

[0081] The system 1 is, for example, constructed and configured so that a pulse oximeter or a CO2 meter can be adapted, which then communicates with the system 1 and / or is supplied with energy by the system. With the measurements of these instruments, the user (or an automatic algorithm) can set the correct flow and the correct oxygen mix. For example, the control unit takes into account the measurements of the pulse oximeter and / or the CO2 meter when activating / controlling the oxygen source and / or when activating / controlling the fluidics module.

[0082] Figure 2 A flow rate curve 100 and a pressure curve 101 as well as a speed curve 102 of the speed of the ventilation device 13 are shown, which are recorded during an exemplary breathing activity or an exemplary operation of the system 1. The upper diagram shows the flow rate curve 100, wherein the flow rate is plotted in liters per minute over time. The middle diagram shows the pressure curve 101, wherein the pressure detected by the sensor device 5 is plotted over time. The lower diagram shows the speed curve 102, wherein the speed of the ventilation device 13 is plotted in revolutions per minute over time. These values ​​are recorded during mouth breathing of the patient.

[0083] Here, the set flow rate is 20 liters per minute. As can be seen from the plot, the flow rate fluctuates in the range of 16 to 20 l / min. These fluctuations are explained by the patient's respiratory activity. During inspiration, the flow rate increases. With the start of exhalation, the flow rate decreases again. This can be explained by the back pressure that the patient generates with his exhalation. The flow from the nasal cannula is suppressed by the exhalation. With the start of inspiration, the breathing gases can flow out of the patient interface unhindered.

[0084] It can be seen that the pressure fluctuates between 7.5 and 10 mbar. These fluctuations are caused by the patient's breathing. With inspiration, the breathing gas can flow out of the patient interface more easily and the pressure in the hose system decreases accordingly. With exhalation, the flow of exhaled air opposes the flow of breathing gas. Since the control unit 4 tries to keep the flow constant, it must increase the pressure during exhalation in order to get the same flow rate out of the patient interface.

[0085] It can be seen that the speed fluctuates within a certain range. The fluctuations are related to the fluctuations in the signal of the pressure curve 101. The fluctuations also correspond to the fluctuations in the signal of the flow curve 100. In order to keep the flow constant during inspiration, the control unit 4 must reduce the speed slightly. During exhalation, the control unit 4 tries to keep the flow at a predetermined level. For this purpose, the speed is increased in order to increase the pressure and ensure that the flow remains constant by means of the increased pressure.

[0086] and Figure 2 similar, Figure 3 The upper diagram shows a flow rate curve 100 , the middle diagram shows a pressure curve 101 , and the lower diagram shows a rotational speed curve 102 . Figure 2 Differently, these values ​​are detected during nasal breathing. Here, the mouth is closed and the patient breathes through the nose.

[0087] In order to identify AHI as a characteristic parameter, for example, it is considered to reduce the required pressure fluctuations to compensate the respiratory gas flow by x%. Here, the reduction X of the pressure fluctuation is preferably between 30% and 50% in hypopnea and / or between 70% and 100% in apnea. Alternatively or in addition, the duration of the pressure fluctuation reduction can be considered; for example, the duration is at least 5 seconds, preferably at least 10 seconds. Therefore, the reduction of the pressure fluctuation must last for at least 5 seconds in order to identify apnea or hypopnea. It is also possible to count apnea and hypopnea (AHI) per hour. In particular, at least one AHI value is stored every day. In addition, obstructive and central apnea and hypopnea are distinguished. It is possible to approximately achieve the adjustment compensation of the persistent respiratory gas flow by pressure. Here, the preferred goal is that the respiratory gas flow fluctuates less than 5l / min and / or less than 10%. If the adjustment compensation is achieved only outside the tolerance range, instead of obtaining the respiratory activity, the pressure fluctuation and the respiratory gas flow fluctuation can also be added weightedly. When a persistent apnea and / or hypopnea is detected, it can be provided that the device also detects that the patient port is not worn correctly and then, for example, issues an alarm. For example, a "patient port has slipped" alarm can be issued. In addition, it can be provided that intermittently increased respiratory activity is recognized as a cough. For example, coughs are counted per hour and at least one value is stored per day.

[0088] In an advantageous embodiment, a detection of decompensation is provided (in particular as a characteristic parameter and / or with the aid of a characteristic parameter). This is understood in particular to be the detection of a suspected worsening of the condition. The detection is carried out, for example, in terms of an increase in the respiratory rate, in particular an increase to above 20 bpm or an increase by 20%; and / or a decrease in the oxygen saturation, in particular a decrease to below 90% or 85% or a decrease by 5%; and / or an increase in the pulse rate; and / or an increase in the number of coughs per hour or day; and / or an increase in the number of apneas per hour or day; and / or an increase or decrease in the duration of use.

[0089] In a similarly advantageous configuration, a monitoring interface is provided. The monitoring interface can be designed to monitor in a hospital / nursing home and, for example, includes Bluetooth, a PDMS interface, a LAN, or a WLAN. The interface can be designed to monitor offline at home and, for example, includes an internal instrument memory, a storage medium, or a communication device via Bluetooth and an App. The interface can also be designed to monitor remotely and, for example, be configured as an IoT interface and, for example, include or be suitable for GSM, NB-IoT, LTE-M, 2G, 4G, or 5G. The interface can transmit signals, in particular, transmit breathing gas pressure and breathing gas flow. The interface can transmit stored statistics, and in particular transmit mean values ​​and / or medians and / or percentiles and / or histograms, which preferably relate to or describe breathing frequency, pressure fluctuations, breathing gas flow fluctuations, FiO2 values, pulse frequency values, or FiO2 values. The interface can transmit stored events, and in particular transmit the number of apneas and hypopneas per hour or per day, the number of oxygen desaturations per hour or per day, and the number of coughs per hour or per day. The interface can transmit alarms, and for example port alarms, frequency alarms and / or decompensation alarms. The interface can transmit the duration of use and / or the time of use, in particular together with selected setting parameters. In particular, setting parameters and / or instrument parameters and / or artificial respiration parameters can be changed via the interface. Preferably, the instrument can authenticate itself, preferably using its serial number and / or a security key (e.g. a certificate).

[0090] In the case of the identification of the breathing phase as a characteristic parameter, at least one measurement of the breathing frequency is preferably performed with the aid of this characteristic parameter, in particular by means of the following formula: 60 / duration of a single breath in seconds. In particular, a control of the oxygen mixing is performed as a function of the breathing phase as a characteristic parameter (more inhalation than exhalation). In particular, a control of the humidification and heating of the breathing gas is performed as a function of the breathing phase as a characteristic parameter (more inhalation than exhalation). In particular, a control of the breathing gas flow is performed as a function of the breathing phase as a characteristic parameter: more inhalation than exhalation (bi-level-high flow).

[0091] Reference numerals list

[0092] 1 System

[0093] 2 Artificial respiration device

[0094] 3 Breathing gas source

[0095] 4 Control device

[0096] 5 Sensor device

[0097] 6 Humidification device

[0098] 7 Heating device

[0099] 8 Hose assembly

[0100] 10 Operating device

[0101] 11 Artificial respirator

[0102] 13 Ventilation

[0103] 16 Reserve

[0104] 18 Artificial respiration hose

[0105] 20 Display device

[0106] 28 Patient Interface

[0107] 38 Nasal cannula

[0108] 48 sensor units

[0109] 58 Heater

[0110] 100 Flow rate change curve

[0111] 101 Pressure change curve

[0112] 102 Speed ​​change curve

Claims

1. A system (1) for a flow-controlled breathing gas supply, comprising at least one artificial respiration device (2) and at least one control device (4), wherein the artificial respiration device has at least one breathing gas source (3) for generating a breathing gas flow, wherein: The control device (4) is suitable for and is configured to generate at least one defined breathing gas flow for artificial respiration by means of the artificial respiration device (2), wherein the control device (4) is suitable for and is configured to monitor at least one parameter characterizing pressure by means of at least one sensor device (5), and the parameter characterizing the following pressure, with which the artificial respiration device (2) loads the breathing gas flow to maintain the defined breathing gas flow in order to compensate for the patient's respiratory activity, and the control device (4) is suitable for and is configured to record the time variation curve of the parameter as a pressure variation curve, characterized in that the system comprises at least one humidifying device (6) for humidifying the breathing gas flow and / or at least one heating device (7) for heating the breathing gas flow, wherein the control device (4) is suitable for and is configured to set the humidification and / or heating of the breathing gas flow according to the pressure variation curve and adjust to a target temperature and / or target humidity of the breathing gas flow.

2. The system (1) according to claim 1, wherein: The control device (4) is suitable and designed to determine at least one characteristic parameter that characterizes the patient's respiratory activity as a function of the pressure curve.

3. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to detect inhalation by virtue of the pressure required to maintain the defined breathing gas flow decreasing over time.

4. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to detect exhalation by virtue of a pressure increase over time which is required to maintain the defined breathing gas flow.

5. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to determine at least one respiratory event as a function of the pressure profile.

6. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to determine at least one breathing pattern as a function of the pressure profile and to evaluate the breathing pattern with respect to at least one breathing event.

7. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to output at least one user interaction as a function of the pressure profile and / or to transmit the pressure profile to a network device.

8. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to set at least one device variable of the respirator (2) as a function of the pressure profile and / or to set at least one respiration parameter by means of the respirator (2).

9. The system (1) according to claim 8, wherein: The device parameters and / or artificial respiration parameters are set as a function of the detected breathing pattern and / or breathing events.

10. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to set at least one flow rate of the breathing gas flow as a function of the oxygen saturation of the breathing gas flow by means of the artificial respiration device (2).

11. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to set an oxygen mixture into the breathing gas flow as a function of the pressure profile.

12. The system (1) according to claim 11, wherein: When the flow rate of the breathing gas flow increases, the oxygen mixture and / or the oxygen content in the breathing gas flow decreases by a certain amount.

13. The system (1) according to claim 11, wherein: Oxygen mixing occurs only during inspiration and / or not during exhalation, and / or oxygen mixing is increased during inspiration relative to exhalation.

14. The system (1) according to claim 1 or 2, wherein: The heating device (7) is suitable and designed for heating the breathing gas flow to 36-38° C. at least during inspiration, wherein the humidifying device (6) is suitable and designed for humidifying the breathing gas flow with a relative humidity in the range of 90-100%.

15. The system (1) according to claim 1 or 2, wherein: The control device (4) can be used to adjust humidification and / or heating that is controlled by the breathing phase.

16. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to set humidification and / or heating as a function of the flow rate of the breathing gas flow.

17. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to set the humidification and / or heating as a function of at least one parameter detected by a sensor.

18. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to at least approximately compensate for flow errors and / or other deviations caused by humidification and / or heating by means of the artificial respiration device.

19. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to reduce the flow rate of the breathing gas flow provided for artificial ventilation until a measure of the humidity of the breathing gas flow reaches a threshold value and / or until the temperature of the breathing gas flow reaches a threshold value.

20. The system (1) according to claim 1 or 2, wherein: At least one drying mode can be carried out following the artificial respiration.

21. The system (1) according to claim 1 or 2, wherein: The humidifying device (6) is suitable and designed to remove water provided for humidification from at least one reservoir (16) before heating and to heat the water separately from the reservoir (16).

22. The system (1) according to claim 1 or 2, comprising at least one hose device (8), which has at least one artificial respiration hose (18) that can be coupled to the artificial respiration device (2) for conveying the breathing gas flow to a patient interface (28).

23. The system (1) according to claim 22, wherein: The hose arrangement (8) comprises at least one heatable respiration hose (18), wherein the heatable respiration hose (18) comprises at least a part of a sensor unit (48) for detecting at least one variable characterizing humidity and / or temperature.

24. The system (1) according to claim 22, wherein: The hose arrangement (8) comprises at least one artificial respiration hose (18) which can be heated gradually over its length.

25. The system (1) according to claim 22, wherein: The hose arrangement (8) comprises at least one heatable respiration hose (18) having at least one heater (58) which can be separated from the respiration hose (18), wherein the heater (58) can be equipped with a new respiration hose (18) as required when the hose is replaced and can continue to be used.

26. The system (1) according to claim 22, wherein: The hose arrangement (8) has at least one respiration hose (18) made of a water-repellent material and / or at least one thermally insulated respiration hose (18).

27. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to apply a fixed breathing volume within a predefined inspiration time by means of the artificial respiration device (2) via the defined breathing gas flow.

28. The system (1) according to claim 1 or 2, wherein: The control device (4) is suitable and designed to take into account at least one stored maximum pressure for the defined breathing gas flow.

29. The system (1) according to claim 1 or 2, wherein: The defined breathing gas flow has a flow rate in the range of 0-110 l / min.

30. The system (1) according to claim 1 or 2, wherein: By means of a selectable presetting, the defined breathing gas flow has a flow rate for infants in the range of 1-10 l / min.

31. The system (1) according to claim 1 or 2, which is suitable and designed for operation with a nasal cannula (38) as a patient interface (28) as provided, wherein: The nasal cannula (38) has a connecting piece (38a, 38b) for each nostril, wherein each connecting piece can be at least partially inserted into the respective nostril, wherein each connecting piece has a diameter which is dimensioned such that the respective nostril is not tightly closed when the connecting piece is inserted.

32. The system (1) according to claim 31, wherein: Each tube (38a, 38b) has a diameter that is less than 9 / 10 of the diameter of the corresponding nostril.

33. The system (1) according to claim 1 or 2, which is suitable and designed for operation with a breathing mask as a patient interface (28) as provided, wherein: The respiratory mask is suitable and designed to surround at least the patient's nose and substantially prevent leakage flow, and the control device (4) is suitable and designed to operate the ventilation device so that the ventilation device generates a substantially constant flow that counteracts the patient's respiratory activity.

34. The system (1) according to claim 7, wherein: The at least one user interaction comprises an alert.

35. The system (1) according to claim 7, wherein: The control device (4) is suitable and designed to transmit the respiratory events and / or respiratory patterns identified by the pressure profile to a network device.

36. The system (1) according to claim 9, wherein: The flow rate of the breathing gas flow is set according to the identified breathing pattern and / or breathing events.

37. The system (1) according to claim 11, wherein: The control device (4) is suitable and designed to regulate the oxygen mixture as a function of the breathing phase.

38. The system (1) according to claim 14, wherein: The humidification device (6) is suitable and designed for humidifying the breathing gas flow with a relative humidity in the range of 95-99%.

39. The system (1) according to claim 17, wherein: The parameters are extracted from a parameter group, which includes at least: ambient temperature, ambient humidity, temperature in the system, humidity in the system (1), hose temperature, temperature at the patient interface, humidity at the hose end and / or at the patient interface (28).

40. The system (1) according to claim 29, wherein: The defined breathing gas flow has a flow rate in the range of 1-80 l / min.

41. The system (1) according to claim 29, wherein: The defined breathing gas flow has a flow rate in the range of 2-60 l / min.

42. The system (1) according to claim 31, wherein: Each tube (38a, 38b) has a diameter that is smaller than 8 / 10 of the diameter of the corresponding nostril and larger than 6 / 10 of the diameter of the corresponding nostril.

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