DE102014001218A1 - Cost and space optimized realization for mixing of ventilation gases in blower units - Google Patents

Abstract

The method and the device are used to ventilate a patient taking into account a Atemgasadditivbeimischung. It is a respiratory device essentially consisting of a base unit, a breathing tube and a contact device proposed in which a provided by an external breath gas additive source breathing gas additive flow is introduced into the base unit and at least partially mixed with the provided respiratory gas volume flow. By the valve-controlled supply of Atemgasadditiv-volume flow directly into the Atemgasstrang and an additive depot and thus in the cyclically delivered to the patient lung respiratory gas volume flow, it is possible to enrich the additive concentration during the expiration, in which the respiratory gas volume flow in idealized consideration is zero, in any concentration or completely replace.

Description

The invention relates to a method and a device for ventilating a patient, in which a base unit for supplying respiratory gas for patient ventilation and a running within the base unit Atemgasstrang is used with at least one additive depot to which a Atemgasadditivvolumenstrom is supplied.

It is known in the prior art that devices are used for the ventilation of a patient, which have a function which in an additive manner enrich the breathing gas to be supplied to the patient with another component.

Such devices follow the basic structure consisting of a base unit, a fixed to the base unit breathing tube and in turn fixed to the breathing tube contact device which connects the breathing tube with the patient. Basically, the base unit has a suction device for the intake of ambient air, which is optionally provided inside the device as a breathable gas purified by a filter the specified on the base unit breathing tube available.

The breathing gas can be added in the device further inside, in particular additional gaseous components in an additive manner. In particular, oxygen is often mixed with the respiratory gas in order to supply this food to patients in emergency situations in the true sense. Other gaseous components may be, for example, nitrous oxide (nitrous oxide), which has long been used in medicine as a narcotic.

The DE 10 2009 015 928 A1 shows a device for the enrichment of breathing gas with oxygen and discloses a corresponding method for the application of the device for patient ventilation. The device realizes the supply of the oxygen additive into the respiratory gas to be inhaled by the patient via a connection valve and a corresponding supply line into the respiration device.

The sequence valve can be arranged either inside or outside this known device. The mixing takes place independently of the internal or external Zuschaltventilanordnung always inside the device in that the dosed oxygen supplied is added to the breathing gas route. Within this device according to the prior art, a blower box is installed, which is flowed through by the breathing gas and into which the oxygen supply flows, so that at this point in the device, the oxygen is added.

In addition to the Zuschaltventil a check valve is further arranged arranged such that at corresponding pressure conditions breathing gas pressure greater than the oxygen supply pressure, the check valve is closed and thereby the Sauerstoffzuführschlauch can not be flooded with breathing gas.

For the metering of the oxygen as admixing component to the respiratory gas, a method for controlling the Zuschaltventils is disclosed. In addition to the oxygen supply in a device-internal fan box is also known that the oxygen supply takes place at a point of the breathing tube within the device.

A disadvantage of these devices according to the prior art is that the oxygen concentration in the respiratory gas is adjustable exclusively by admixing the oxygen additive. For this reason, a high, up to 100% oxygen concentration can not be provided due to the required volume flow conditions of the respiratory gas volume flow and the oxygen additive volume flow. Another disadvantage is the fact that very high oxygen additive volume flows of up to 150 l / min are required in order to mix the oxygen concentration within the breathing gas to be enriched to desired values.

An additional and serious disadvantage is that although the fans operating within the devices for generating breathing gas volume flow generally operate continuously, they are usually due to the interplay between inhalation and exhalation, ie. H. natural pulmonary function of pulmonary breaths, a discontinuous flow of respiratory gas flow through the device must be provided.

In the exhalation phase, no respiratory gas volume flow takes place within the device and through the fan. The result is that both the blower itself is not flowed through with cooling breathing gas flow as well as other components such as electronic components, which are also cooled by the respiratory gas volume flow are uncooled in this phase. Damage, component failure or shortened service life of these components are possible consequences.

Object of the present invention is to construct a device of the aforementioned type, which provides the patient as accurate as possible, possibly also maximum high concentration of additive in the breathing air available.

It is another object of the invention to improve the cooling of the base unit components in each operating condition. The improvement of Cooling should have no or only insignificant influence on the additive concentration of the respiratory gas volume flow.

This object is achieved in that the supply of Atemgasadditives within the base unit at a point of the flow-guiding device components in the flow direction of the respiratory gas takes place behind the blower and between the blower and the Additiveinspeisungsstelle an additive depot is provided.

By supplying the breathing gas additive within the base unit at a point of the flow-guiding device components in the flow direction of the respiratory gas behind the blower, it is possible to realize a cooling of the blower. By a correspondingly positioned and configured cooling air bypass line, it is possible that both the component cooling ensured in each operating condition and the respiratory gas additive concentration is not adversely affected.

Target group of the device according to the invention and methods for the enrichment of breathing gas with additives are preferably human patients. The operation of the lung as oxygen catalyst is clocking and thus discontinuous. An interplay consists of inhaling and exhaling. In the inhalation cycle breathing air is sucked in by expansion of the lungs, in the exhalation cycle, recovered breathing air is expelled as exhaust gas by contraction of the lung.

Inhalation and exhalation are commonly called inspiration and expiration in medicine. Because of these all mammals to own working way of the lung also a ventilator must realize this interplay. Respirators are principally used when the patient's lungs do not or do not adequately perform the interplay or when a breathing air composition other than the normal ambient air, which is the breathing air, is required.

An application of the device can be done in patients with different clinical pictures of ventilatory insufficiency. Typical applications are obstructive ventilation disorders, e.g. As COPD, disorders of respiratory mechanics, such as scoliosis, neuromuscular disorders, central respiratory regulatory disorders or obstructive sleep apnea syndrome. It is possible to use the device as a mobile emergency ventilator. Due to the technical design with device-internal additive storage by the additive depot, the device is suitable as a stationary device, for continuous ventilation or mobile ventilation.

Because of these relationships, the device according to the invention is designed such that, within an interplay of inspiration and expiration, first a respiratory gas volume flow is administered from the base device via the breathing tube or patient tube and the contact device into the lung of the patient to be ventilated.

Upon completion of the inspiration, expiration, i. E., By a patient valve disposed within the contact device. H. exhaled the respiratory gas used by the lung. For this purpose, the patient valve is designed in such a way that a volumetric flow of the recycled respiratory gas directed against the respiratory gas volume flow direction during inspiration is delivered to the environment via the patient valve.

Due to the interplay and function of the patient valve to direct the respiratory gas utilized by the lung into the environment and not into the patient tube, the flow within the patient tube and the base unit does not alternate. The respiratory gas volume flow within the device is thus unidirectional and clocked in devices according to the prior art. This fact makes the teaching of the invention own, in order to increase the proportion of preferably gaseous additive to the breathing gas considerably up to a 100% enrichment.

As a result of the switchable and / or adjustable delivery of the respiratory gas additive via a first wiring harness within the base unit at a point of the flow-guiding device components in the flow direction of the respiratory gas behind the fan and thus in the respiratory gas volume flow to be delivered cyclically to the patient lung, it is possible to control the additive concentration during the expiration process. in which the respiratory gas volume flow in Idealized consideration is zero, to enrich in any concentration or replace completely.

This is possible because both the additive feed lines and the patient tube and the lines and hoses present within the base unit, located downstream of the pressure-generating fan in the respiratory gas flow direction, can be partially or completely flooded with the additive. An additive reservoir located in the breathing gas flow direction downstream of the blower and upstream of the additive feed point increases the available storage volume. As a result, the additive concentration can be enriched or completely replaced during the expiration process in which the respiratory gas volume flow is zero on an idealized basis.

Thus, while in an apparatus according to the prior art, the additive is admixed with the breathing gas during the flow of volumetric flow, the device of the invention causes the respiratory gas volume flow arrest caused by the expiration process to replace the respiratory gas partially or completely in the additive depot and replace the respiratory gas due to corresponding additive overpressure via a bypass line. Thus, the respiratory gas volume flow is no longer only unidirectional but rather bidirectional, it is realized an alternating Atemgasvolumenstromrichtung within the base unit and the patient tube.

At the same time, the bypass line also serves as fan-cooling air line in that in the expiration phase, d. H. in the phase without breathing gas volume flow in the direction of the patient connection, the breathing gas delivered by the fan is introduced into this fan cooling air line. As a result, a breathing gas volume flow is maintained as a secondary strand in the expiratory phase. The intake of the blower and the blower itself are thus constantly flowed through by a breathing gas volume flow, which cools the blower and its power components as a result of the heat exchange. In the intake region, a heat exchanger device for cooling other base unit components, such as power devices or electronics can be provided.

In the drawings, embodiments of the invention are shown schematically. Show it:

1 in a perspective view of the general structure of a ventilator consisting of base unit, patient or breathing tube and contact device and

2 a pneumatic plan according to the invention.

1 shows the basic structure of a device for ventilation and enrichment of breathing gas with additives ( 100 ). To the base unit ( 110 ) is connected via a patient connection ( 17 ) the patient tube ( 23 ) connectable. In the area of the base unit ( 110 ) facing away from the patient's hose ( 23 ) is a contact device ( 120 ) and a patient valve ( 12 ) arranged. It is also possible that contact device ( 120 ) and patient valve ( 12 ) are made in one piece.

2 shows the pneumatic plan according to the invention with the resulting system function. Basically, the pneumatic equipment of the base unit ( 110 ) of four corresponding strands, the additive string, the breathing gas string, the emergency breathing string and the bypass or cooling air string. In particular, the breathing gas train forms the primary flow-leading base device component.

The additive stream is essentially passed through a filter ( 3 ), an additive metering valve ( 2 ) as well as corresponding pneumatic lines and in the area of the additive feed point ( 24 ) fluidly connected to the breathing gas line.

The breathing gas line extends from the base of an intake area with a filter ( 6 ) and optional heat exchanger ( 13 ) of the blower ( 7 ) via the additive store ( 10 ), the volume flow sensors ( 4 . 11 ) and the check valve ( 14 ) to the patient connection ( 17 ) and further basic devices through the breathing tube ( 23 ) as well as a volume flow sensor ( 22 ) to the patient. The applied patient pressure behind the patient valve ( 12 ) through a branch line and the PAW nozzle ( 18 ) by means of basic device-internal airway pressure sensor ( 5 ) certainly.

The emergency respiratory tract is formed by a pneumatic line arrangement comprising a check valve ( 16 ). In terms of flow technology, the emergency breathing line is connected to the breathing gas line between the filter ( 6 ) and blower ( 7 ) as well as check valve ( 14 ) and patient connection, wherein the check valve ( 16 ) is oriented in such a way that a respiratory gas flow in the direction of the patient valve ( 12 ) is possible. In the event of a malfunction in the device, it is possible for the patient to aspirate filtered breathing air via the emergency breathing line.

The multi-function string is the bypass or cooling air string consisting of a pneumatic line assembly comprising a check valve ( 9 ) and a throttle valve ( 8th ) is formed, wherein the check valve ( 9 ) is arranged such that a breathing gas flow is supported in the direction of environment to the outside of the base unit. In case of failure, the check valve prevents ( 9 ) In addition, the penetration of (unfiltered) outside air. Due to the supply of breathing gas during the expiration phase, the respiratory gas can be partially or completely filled in the lines and the additive reservoir ( 10 ) are replaced and the replaced breathing gas are discharged as a result of appropriate additive overpressure on the bypass strand. Depending on the size of the additive depot ( 10 ) the throttle ( 8th ) and the valve ( 2 ) adjusted such that a passage of additive flow through the bypass line is largely avoided.

Via an external, to the additive connection ( 1 ) connectable additive source is the additive in the base unit ( 110 ). In a preferred embodiment, the additive source is an oxygen source which delivers gaseous oxygen at a pressure of 2.7 to 6 bar. The additive is passed through the filter ( 3 ) to the additive valve ( 2 ). The additive valve ( 2 ) can, depending on the desired feed characteristic as a switching valve for switching on and off of the additive feed or control valve, z. B. Proportional valve to control the feed behavior may be formed. Also, the electrical control of the additive valve ( 2 ) in any design via a microcontroller ( 21 ) in order to be able to exert targeted influence on the additive volume flow and that at the additive feed point ( 24 ) to regulate or control amount of additive introduced.

The breathing gas line extends from the base of an intake area with a filter ( 6 ) and optional heat exchanger ( 13 ) of the blower ( 7 ) via the additive store ( 10 ), the volume flow sensors ( 4 . 11 ) and the check valve ( 14 ) to the patient connection ( 17 ) and further basic devices through the breathing tube ( 23 ) as well as a volume flow sensor ( 22 ) to the patient. The blower ( 7 ) generates both the suction pressure required for the aspiration of the respiratory gas in the intake area and the respiratory gas transport within the base unit ( 110 ) and breathing tube ( 23 ) as well as contact device ( 120 ) required pressure increase of the respiratory gas. The gas flow to the patient is only by a positive pressure difference between blower ( 7 ) and patient valve ( 12 ) possible.

The breathing gas is released from the blower ( 7 ) first into the additive depot ( 10 ) or, depending on the operating state and in particular in the expiratory phase, through the bypass line and thus via the throttle valve ( 8th ) and check valve ( 9 ) transported back to the environment. The bypass strand is used, inter alia, to the blower ( 7 ) Respiratory gas volume flow generated in the expiratory phase, in which no respiratory gas volume flow is conveyed to the patient, to maintain and thereby realize a respiratory gas flow in the intake continuously.

The breathing gas flow in the intake area is also called cooling air flow for the fan ( 7 ) and for the operation of the heat exchanger ( 13 ) used. Both the blower ( 7 ) as well as the optional heat exchanger ( 13 ) obtained by the realized constant breathing gas volume flow in the intake continuously cooling power. The bypass strand is between the blower ( 7 ) and the additive depot ( 10 ) Contact with the breathing gas line fluidically. As a result, it is largely prevented that respiratory gas additive can flow off via the bypass strand. Thus, it is possible to realize the cooling air flow practically without additive loss. Even if the additive flow rate through valve ( 2 ) is controlled overshadowing is not to be expected with additive loss, additive depot in addition to its memory function also works balancing and can compensate for fluctuations.

The device for ventilation and enrichment of respiratory gas with additives ( 100 ) realizes different device-internal functions as a function of the breathing game consisting of expiration and inspiration. In the inspiratory phase, the device ( 100 ) to the patient to be respirated breathing gas with breathing gas additive via the breathing gas line available. In this phase, no or only excess breathing gas flows through the bypass strand into the environment.

The additive concentration in the respiratory gas volume flow is determined by two technical effects correlations within the base unit ( 110 ). On the one hand, depending on the circuit position of the additive valve (coming from the additive stream ( 2 ) via the additive feed point ( 24 ) Additive are introduced into the respiratory gas volume flow of Atemgasstranges. On the other hand, during the expiration phase, in which no respiratory gas volume flow flows in the breathing gas line, via the additive feed point ( 24 ) Additive in the breathing gas line and in the additive storage ( 10 ) are introduced.

The additive storage ( 10 ) is in 2 idealized and can be formed in practice by different components or their combination. Conceivable components are hoses with the appropriate length or diameter, spatial structures such as tanks, pressure bottles or the like.

The additive depot ( 10 ) stores the through the valve ( 2 ) influenceable amount of additive in the expiratory phase, so that this additive is present in the inspiratory phase directly in the breathing gas line and directly enriches the respiratory gas. As a result and depending on the proportion of additive to be achieved, the control speed of the valve ( 2 ) and reduce the amount of additive to be added during the inspiratory phase. Even with a high additive requirement, the maximum flow rate of the valve ( 2 ), because in the additive depot ( 10 ) stored additive additionally supports the breathing gas enrichment.

As a rule, the respiratory gas additive is gaseous and is preferably formed by oxygen. In the case of a gaseous additive may be in the Additive depot (( 10 ) and the lines involved practically form a gas column highly concentrated or pure additive, since the mixing can be realized only with moving breathing gas volume flow. Using the volume flow sensor ( 4 ), which is preferably designed as a bidirectionally operating sensor, the loading and unloading of the additive depot ( 10 ) measure up. Depending on this and for setting a desired additive content in the respiratory air, the valve ( 2 ) and the additive volume flow can be adjusted.

Via the second, arranged in the breathing gas flow meter flow sensor ( 11 ) can be measured to the patient enriched by the additive portion of the respiratory gas volume flow. Within the base unit ( 110 ) is a control electronics, preferably a microcontroller ( 21 ) arranged either through the heat exchanger ( 13 ) or directly in the respiratory gas flow is coolable. The same applies to the optional electronic power components such. B. the exemplified supercaps ( 20 ).

Via the check valve ( 16 ), the patient may be in case of a malfunction, for example in case of failure of the blower ( 7 ), suck in filtered ambient air as breathing gas. The check valve ( 16 ) is adjustable so that the suction with low airway resistance is possible.

The check valve ( 14 ) closes when exhaling the patient due to the then check valve ( 14 ), so that the respiratory gas volume flow to the patient valve ( 12 ) is stopped. By means of a PEEP control panel ( 15 ) adjustable, reduced pressure of the blower ( 7 ) is controlled by the PEEP control panel ( 15 ) and the PEEP nozzle ( 19 ) the patient valve ( 12 ) and allows the exhalation, ie the exhalation into the environment. The adjustable PEEP control panel ( 15 ) serves to optimize the control characteristics of the patient valve ( 12 ). In this way, the patient pressure control is realized in an advantageous manner.

The interaction of the additive train and the breathing gas line enables both pressure-dependent and volume-flow-dependent ventilation controls to be realized. While the blower ( 7 ) is available as a controllable pressure source within the overall system and in whose dependence the ventilation control can be carried out by the valve ( 2 ) controlled additive volume flow in the dependence of a ventilation control conceivable. These two basic control characteristics can be used individually or superimposed by independent controllers.

In order to be able to realize an additive concentration in the breathing gas volume flow of 21% to 100%, the volume flows of the valve ( 2 ) and the blower ( 7 ). Due to the arrangement of the volumetric flow sensors ( 4 . 11 ), the additive concentration can be calculated using the sum or difference value formation of the volumetric flow sensor measured values. The calculation may preferably be performed within the microcontroller ( 21 ) respectively. The prerequisite for the correct determination of the volume flow is the precise adjustment of the flow rate sensors ( 4 . 11 ) to each other.

The absolute measurement accuracy does not play the dominant role, but their vote to the effect that both volume flow sensors ( 4 . 11 ) in the zero point and in the scaling provide as identical as possible values. Is the additive volume flow by closing the valve ( 2 ) can be adjusted by varying the speed of the blower ( 7 ) Within the blower parameter limits steplessly almost any breathing gas volume flows through both volume flow sensors ( 4 . 11 ) so that the volumetric flow sensors ( 4 . 11 ) can be precisely calibrated at zero point as well as in the scaling without further aids. This makes it possible to measure the inspiratory additive concentration via the volumetric flow measurement alone, and via the control of valve ( 2 ) and or the speed of the blower ( 7 ) to adjust.

The throttle valve ( 8th ) can be active or passive.

Another advantage of the depot is that the valve ( 2 ) can be made relatively small.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009015928 A1 [0005]

Claims (23)

Contraption ( 100 ) for ventilating a patient, comprising a base unit ( 110 ) for the supply of breathing gas for patient ventilation, and a within the base unit ( 110 ) extending breathing gas line with at least one additive depot ( 10 ), characterized in that a respiratory gas additive can be fed into the breathing gas line in such a way that the additive depot ( 10 ) is at least partially filled with breathing gas additive. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that the additive depot ( 10 ) during the expiratory phase at least partially filled with breathing gas additive. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that the supply of the respiratory gas additive within the base unit at an additive feed point ( 24 ) of the Atemgasstranges seen in Atemgasvolumenstromrichtung behind the additive depot ( 10 ) lies. Contraption ( 100 ) for ventilating a patient according to claim 3, characterized in that in front of and behind the additive feed point ( 24 ) each have a volume flow sensor ( 4 . 11 ) is provided in the breathing gas line. Contraption ( 100 ) for ventilating a patient according to claim 4, characterized in that the in Atemgasvolumenstromrichtung before the additive feed point ( 24 ) of the breathing gas line provided volume flow sensor ( 4 ) can measure a volume flow in both possible flow directions. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that the supply of the respiratory gas additive within the base unit ( 110 ) at an additive feed point ( 24 ) of the Atemgasstranges is formed by an additive strand. Contraption ( 100 ) for ventilating a patient according to claim 6, characterized in that the additive strand at least one additive valve ( 2 ), which is designed as a switching and, or control valve. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that the breathing gas line is a blower ( 7 ) for breathing gas volume flow generation, wherein the additive depot ( 10 ) within the Atemgasstranges seen in Atemgasvolumenstromrichtung behind the blower ( 7 ) is arranged. Contraption ( 100 ) for ventilating a patient according to claim 8, characterized in that the breathing gas line in the intake of the blower ( 7 ) a heat exchanger ( 13 ), so that the respiratory gas volume flow flowing in the intake region can be used as cooling air. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized by a bypass strand having at least one throttle valve ( 8th ) and a check valve ( 9 ), wherein the bypass strand seen in Atemgasvolumenstromrichtung behind the blower ( 7 ) is fixed to the breathing gas line, which is at least a portion of the respiratory gas volume flow into the environment can be conducted. Contraption ( 100 ) for ventilating a patient according to claim 10, characterized in that the throttle valve ( 8th ) is adjustable such that in the expiratory phase of the respiratory gas volume flow through the intake of the respiratory tract and the fan ( 7 ) and the bypass strand can flow, so that at the heat exchanger ( 13 ) A continuous breathing gas volume flow can be used as cooling air. Contraption ( 100 ) for ventilating a patient according to claim 10, characterized in that the bypass strand seen in Atemgasvolumenstromrichtung behind the blower ( 7 ) and in front of the additive depot ( 10 ) is fixed to the breathing gas line, that the respiratory gas volume flow can be conducted into the environment when the additive depot ( 10 ) is at least partially filled with breathing gas additive. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that an emergency respiratory tract comprising at least one check valve ( 16 ) seen in Atemgasvolumenstromrichtung behind a filter ( 6 ) and in front of the blower ( 7 ) at the breathing gas line is determined that a breathing gas flow consisting of filtered breathing gas in the direction of patient valve ( 12 ) is supported. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that at least one contact device ( 120 ) for connection to at least one patient to be ventilated with the base unit ( 110 ) via a patient connection ( 17 ) is coupled, so that the respiratory gas between the base unit ( 110 ) and contact device ( 120 ) can flow. Contraption ( 100 ) for ventilating a patient according to claim 1, characterized in that a microcontroller ( 21 ) for recording the measured values of the airway pressure sensor ( 5 ), the volumetric flow sensors ( 4 . 11 ) and the position of the adjustable throttle valve ( 8th ) as well as for controlling or regulating or adjusting the speed of the Blower ( 7 ), the valve ( 2 ) and the throttle valve ( 8th ) is provided. Method for ventilating a patient, comprising the steps of: a) providing a pressurized respiratory gas volume flow within the base unit ( 110 ) a device ( 100 ) for ventilating a patient according to one of claims 1 to 15, b) providing a pressurized breathing gas additive volume flow within the base unit ( 110 ), characterized in that the provision of the pressurized respiratory gas volume flow and respiratory gas additive volume flow at the additive feed point ( 24 ) takes place in such a way that during the expiration phase the respiratory gas additive volume flow at least partially into the additive depot ( 10 ) flows. A method of ventilating a patient according to claim 16, characterized in that during the inspiration phase, a respiratory gas volume flow and respiratory gas additive volumetric flow flows into the lungs of the patient to be ventilated. A method for ventilating a patient according to claim 17, characterized in that the proportion of the flowing into the patient lung Atemgasadditiv-volume flow is up to 100% of the total respiratory gas volume flow. A method for ventilating a patient according to claim 16, characterized in that the step ii. through one via a valve ( 2 ) adjustable respiratory gas additive volume flow takes place. A method of ventilating a patient according to claim 16, characterized in that by a Atemgasadditivvolumenstrommessung ( 4 ) during the expiratory phase and the respiratory gas volume flow measurement ( 4 . 11 ) during the inspiration phase, both the average respiratory gas additive concentration and the actually emitted respiratory gas volume flow can be determined by calculating the volumetric flow measured values. Method for ventilating a patient according to claim 20, characterized in that the adjustment of the volumetric flow sensors required for the determination of the mean respiratory gas additive concentration and the actually delivered respiratory gas volume flow ( 4 . 11 ) at zero point and scaling comprises the following steps: a) closing the valve ( 2 ) so that no breathing gas additive volume flow is provided, b) varying the speed of the blower ( 7 ) within the blower parameter limits, so that different breathing gas volume flows through both volume flow sensors ( 4 . 11 ) flow, c) adjustment of the volumetric flow sensors ( 4 . 11 ) based on the different breathing gas volume flows at zero point and scaling. A method for ventilating a patient according to claim 20, characterized in that both pressure-dependent and volume flow-dependent ventilation regulations by the device ( 100 ) can be realized according to claim 15. Method for ventilating a patient according to claim 19, characterized in that the throttle ( 8th ) and the valve ( 2 ) are adjustable so that a passage of additive flow through the bypass line is largely avoided.

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