Method and apparatus for separating carbon dioxide from a respiratory gas mixture

Abstract

The invention relates to a method and a device for separating carbon dioxide from a breathing gas mixture. The separation is performed by means of a membrane sheet which acts as a molecular filter.

Description

Technical Field

[0001] This invention relates to a method and apparatus for separating at least carbon dioxide (CO2) from a respiratory gas mixture. Separation is performed, for example, by means of a membrane used as a molecular filter. Background Technology

[0002] Separating CO2 from a mixture of gases containing carbon dioxide (as it does during artificial respiration or under anesthesia) is a highly demanding task.

[0003] It is known that, for economic and safety reasons, the administered breathing gas circulates in a closed loop, in which oxygen and / or CO2 and / or anesthetic gas are replenished according to consumption and carbon dioxide is removed from the loop. Generally, carbon dioxide enrichment in artificial respiration systems should be avoided. A concentration of 0.5% is typically considered a limit that should not be exceeded.

[0004] The amount of carbon dioxide that must be removed depends on the application. Exhaled breathing air contains approximately 5% carbon dioxide. This concentration should be reduced to 0.5% or lower in the breathing circuit.

[0005] Typically, CO2 combines with breathing lime (Atemkalk) and is thus extracted from the circuit. However, the breathing lime cannot be reused and must be removed. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a cost-effective and practical method for separating a defined respiratory gas. The object of the present invention is also to provide an adjustment of the proportion of a defined respiratory gas concentration in a respiratory gas mixture.

[0007] The present invention includes a method for separating a respiratory gas mixture comprising at least O2 and CO2 and at least one volatile anesthetic and flowing in a respiratory gas path, wherein the respiratory gas mixture is directed to a first separating material at a first flow rate, wherein the first separating material separates at least oxygen O2 and carbon dioxide CO2 from the at least one volatile anesthetic, wherein the at least one volatile anesthetic is then delivered to the respiratory gas path or retained in the respiratory gas system, wherein the separated residual respiratory gas mixture having at least oxygen O2 and carbon dioxide CO2 is directed to a second separating material at a second flow rate, wherein at least carbon dioxide CO2 is separated from the respiratory gas mixture by the second separating material, wherein the separated carbon dioxide CO2 is at least temporarily separated out or released into the environment or into the respiratory gas continuing conduction system, wherein the remaining portion of the respiratory gas mixture, which is essentially oxygen O2, is then delivered to the first separating material.

[0008] Additionally, the method is characterized in that the first separating material selectively allows smaller molecules, namely oxygen (O2) and carbon dioxide (CO2), to pass through, while blocking at least one volatile anesthetic.

[0009] Additionally, the method is also characterized in that the first separating material is a diffusion filter.

[0010] Additionally, the method is also characterized in that the breathing gas is separated via a diffusion filter due to the concentration gradient.

[0011] Additionally, the method is also characterized in that the second separating material is a diffusion filter.

[0012] Alternatively or additionally, the present invention relates to a method (or an apparatus) wherein a second separating material selectively allows smaller molecules, namely nitrogen N2 and / or oxygen O2, to pass through, and at least to a large extent blocks at least carbon dioxide CO2.

[0013] Additionally, the method is characterized in that the second separating material is a diffusion filter having a permeability ratio of at least 50:1 for N2 and / or O2 to CO2.

[0014] Additionally, the method is characterized in that the second separating material is a diffusion filter having a permeability ratio of at least 100:1 for N2 and / or O2 to CO2.

[0015] Furthermore, the method is characterized in that the first flow rate is 4 to 25 L / min.

[0016] The method is also characterized in that the first flow rate is 3 to 18 L / min.

[0017] Additionally, the method is also characterized in that the first flow rate is generated by a fan, a compressed gas source, or a pump.

[0018] The method is also characterized in that the first flow rate at least in stages includes a breathing gas with 10% to 30% oxygen.

[0019] The method is further characterized in that the second flow rate is 4 to 25 L / min.

[0020] Additionally, the method is also characterized in that the second flow rate is 6 to 18 L / min.

[0021] The method is also characterized in that the second separating material is a diffusion filter having a permeability ratio of O2 to CO2, preferably such that the CO2 flow rate released into the environment or into the respiratory gas conduction system is less than the flushing flow rate of the first separating material.

[0022] The method is also characterized in that the second flow is generated by a fan, a compressed gas source, or a pump.

[0023] Additionally, the method is characterized in that the respiratory gas mixture is at least partially or completely derived from the expiratory respiratory gas pathway.

[0024] The method is also characterized in that the first separation material is connected to the inspiratory breathing gas path via a first output end in a manner that conducts breathing gas, wherein a breathing gas source is arranged downstream of the first separation material and upstream of the inspiratory patient connection.

[0025] Additionally, the method is characterized by having a fresh gas supply (of oxygen) and an anesthetic gas supply arranged downstream of the first separating material and upstream of the breathing gas source.

[0026] Furthermore, the method is characterized in that an oxygen sensor and / or a flow sensor and / or a CO2 sensor are arranged downstream of the respiratory gas source.

[0027] The method is also characterized in that the respiratory gas mixture contains at least nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and at least one volatile anesthetic.

[0028] The method also achieves the adjustment of a defined proportion of respiratory gas in the respiratory gas mixture. To this end, according to the invention, the feeding or supply of respiratory gas (especially O2, CO2, and / or anesthetic gas) is arranged. Similarly, the separation or removal of at least a defined proportion of respiratory gas from the respiratory gas mixture is arranged. The necessary adjustments, in particular the control of the required actuators, are performed by a control unit, which can also be divided into multiple sub-control units.

[0029] The present invention also relates to an apparatus for separating a respiratory gas mixture comprising at least O2 and CO2 and at least one volatile anesthetic and flowing in a respiratory gas path, wherein the respiratory gas mixture is directed to a first separating material at a first flow rate, wherein the first separating material separates at least oxygen O2 and carbon dioxide CO2 from the at least one volatile anesthetic, wherein the at least one volatile anesthetic is then delivered to the respiratory gas path or retained in the respiratory gas system, wherein the separated remaining respiratory gas mixture having at least oxygen O2 and carbon dioxide CO2 is directed to a second separating material at a second flow rate, wherein at least carbon dioxide CO2 is separated from the respiratory gas mixture by the second separating material, wherein the separated carbon dioxide CO2 is at least temporarily separated out or released into the environment or into the respiratory gas continuation system, wherein the remaining portion of the respiratory gas mixture, which is essentially oxygen O2, is then delivered to the first separating material.

[0030] Optionally, the device is also characterized in that the respiratory gas mixture is directly or forcibly conducted through the patient or by means of a pump or turbine to a first separating material, wherein the first separating material is configured and constructed to separate at least oxygen O2 and / or carbon dioxide CO2 from at least one volatile anesthetic, wherein the at least one volatile anesthetic is then delivered to or retained in the respiratory gas path, wherein the respiratory gas path has a respiratory gas pump (which can be a valve, a turbine, or a respiratory gas source), wherein the respiratory gas is conducted to the patient via a patient interface.

[0031] Optionally, the device is also characterized in that the first separating material can be configured as a diffusion filter in a branch of the breathing gas tubing or implemented as a filter housing having an inlet for breathing gas, an upper chamber, an outlet for breathing gas to the patient, a diffusion filter, a lower chamber and an outlet (for breathing gas from the lower chamber, leading to the breathing gas path in the direction toward the second separating material) and an inlet from the tubing of the second separating material into the lower chamber.

[0032] The device is also characterized in that the remaining respiratory gas mixture (containing at least nitrogen N2, oxygen O2, and carbon dioxide CO2) is guided via a pipeline to a second separation material at a second flow rate, and at least carbon dioxide CO2 is separated from the respiratory gas mixture by the second separation material, wherein the separated carbon dioxide CO2 is at least temporarily separated out or released into the environment or into the respiratory gas continuation system, wherein there is a device that regulates the flow rate of the separated carbon dioxide.

[0033] Furthermore, the device is characterized in that the remainder of the breathing gas mixture, which is essentially (nitrogen N2 and) oxygen O2, is transported via a pipeline to a first separation material, wherein a breathing gas pump / turbine is arranged in or connected to the pipeline in a gas conduction manner for this purpose, the breathing gas pump / turbine generating the necessary flushing flow rate of the breathing gas, which can also be simply a volume displacement.

[0034] The device is also characterized in that a check valve is arranged in the pipeline between the first separation material and the second separation material, the check valve selectively blocking the flow of breathing gas in one direction.

[0035] According to the invention, the separating materials 1 and 2 may be identical or different. This is particularly applicable to the selection of filters. For example, filters may have different selectivity for oxygen and carbon dioxide and / or anesthetics.

[0036] Additionally, the device is characterized in that the second separating material is implemented as a filter having an upper portion and a lower portion, wherein a diffusion filter is arranged between the portions, wherein the upper portion has an inlet for a breathing gas mixture (from the first separating material) and an outlet to the environment, wherein the lower portion has an outlet leading to a breathing gas path in a direction toward the first separating material, wherein a pump / turbine is arranged in the breathing gas path between the outlet and the inlet, the pump / turbine generating a flushing flow rate for the breathing gas.

[0037] Optionally, the device is also characterized in that the diffusion filter is steam sterilizable, i.e., thermally stable up to 134°C.

[0038] Optionally, the device is also characterized in that the two diffusion filters are constructed as membrane filters / surface filters or as tubes (hollow fibers), wherein the size of the face and channel cross-section is configured such that a flow rate of 60 L / min is achieved in the flow direction and a maximum pressure drop of no more than 2 cmH2O (==mbar,==hPa) is achieved in the flow direction and / or diffusion direction.

[0039] Optionally, the device is also characterized in that the permeability ratio of the N2 and / or O2 to CO2 diffusion filters is configured to substantially block CO2, wherein the permeability ratio is preferably such that the CO2 flow rate released into the environment or into the breathing gas continuation system is less than the flushing flow rate in the separation material during the first stage.

[0040] The device is also characterized in that the first flow rate entering the separation material is 4 to 30 L / min, and the second flow rate entering the separation material is 1 to 35 L / min.

[0041] Optionally, the device is also characterized in that it can adjust the flushing flow rate between the first chamber and the subsequent chamber as needed, so that the CO2 content leaving the first stage is adjustable.

[0042] The device is also characterized in that a breathing gas pump is arranged downstream of the first separating material and upstream of the inspiratory patient connection.

[0043] Optionally, the device is also characterized in that a fresh gas supply (of oxygen) and / or an anesthetic gas supply are arranged downstream of the first separating material and upstream of the breathing gas pump.

[0044] The device is also characterized in that an oxygen sensor and / or a flow sensor and / or a CO2 sensor are arranged downstream of the breathing gas pump.

[0045] Optionally, the device is also characterized by having a cascaded flushing flow treatment via a separating material, wherein the second separating material is implemented as a dual or multiple diffusion filter.

[0046] The device is also characterized in that the second separating material separates at least carbon dioxide (CO2) from the respiratory gas mixture and separates it from the upper chamber via the output end into the respiratory gas continuation system, wherein the pump guides the separated carbon dioxide (CO2) through a pipeline to the input end of the second separating material.

[0047] The device is also characterized in that the remainder of the breathing gas mixture, diffused through the diffusion filter, namely essentially nitrogen (N2) and oxygen (O2), is conducted from the lower chamber through an opening to the second separating material and enters here through an inlet, wherein the remainder here still contains, for example, 6% CO2.

[0048] The device is also characterized in that the inlet of the second filter is supplied by the outlet of the first filter, wherein the further reduced CO2 content dominates in the lower portion of the second separation material, wherein the breathing gas thus treated is then conveyed to the first separation material.

[0049] The present invention also includes a hose system having a device according to the invention.

[0050] The present invention also includes a ventilator having the device according to the invention.

[0051] The present invention also includes a ventilator configured and constructed for carrying out the steps of the method.

[0052] The present invention also includes a ventilator comprising a device for separating a respiratory gas mixture, said respiratory gas mixture containing at least O2 and CO2 and flowing in a respiratory gas path. - In the breathing gas path, the breathing gas mixture is guided to the first separation material at a first flow rate. - Wherein, the first separating material separates at least oxygen (O2) and carbon dioxide (CO2), and - Of these, oxygen and a reduced share of CO2 are either delivered to the respiratory gas pathway or retained in the respiratory gas system. - Wherein, the remaining respiratory gas mixture separated, having at least oxygen and an increased share of carbon dioxide (CO2), is directed to the second separation material at a second flow rate. - Wherein, at least carbon dioxide (CO2) is separated from the respiratory gas mixture by a second separating material, and - Wherein, the separated carbon dioxide (CO2) is at least temporarily separated and released into the environment or into the respiratory gas conduction system, and - The remaining portion of the respiratory gas mixture, which is essentially oxygen (O2) and a reduced share of CO2, is then transported to the first separation material.

[0053] Alternatively or additionally, the present invention comprises a method and apparatus for separating CO2 from a respiratory gas mixture, wherein the respiratory gas mixture is guided along one side of a special semi-permeable membrane through which components of the gas mixture can be delivered, wherein the membrane is selected such that the delivery of CO2 and / or at least one volatile anesthetic through the membrane is significantly less efficient than the delivery of other gas components of the respiratory gas mixture, wherein two membranes are used.

[0054] It should be noted that the features individually listed in the claims can be combined with each other in any technically meaningful manner and illustrate other configurations of the invention. Additionally, the invention is described and described in detail, particularly in conjunction with the accompanying drawings.

[0055] Furthermore, it should be noted that the conjunction “and / or” used herein, which refers to the existence of two features and the connection between them, is always interpreted as: in the first configuration of the subject matter according to the invention, only the first feature can exist; in the second configuration, only the second feature can exist; and in the third configuration, both the first feature and the second feature can exist.

[0056] The dependent claims relate to various independent and advantageous extensions of the invention, the features of which can be freely combined by those skilled in the art within a technically meaningful scope. This also applies in particular to extensions beyond the limitations of different claim types.

[0057] In the sense of this invention, a respiratory gas mixture is any respirable gas mixture containing oxygen (O2) and carbon dioxide (CO2) and / or at least nitrogen (N2) and / or at least one anesthetic gas (e.g., nitrofluoride, desflurane, nitrous oxide, xenon, etc.).

[0058] The filters used according to the present invention are chemically resistant to the gases and vapors used. The filter module as a whole is configured and constructed to be cleaned and / or sterilized. Therefore, the filter or filter module has the necessary heat resistance of at least 134°C.

[0059] It is particularly advantageous if multiple methods for reducing CO2 partial pressure or CO2 fraction are combined, i.e., by flushing the membrane with gas on the side away from the breathing gas mixture and by reducing the total pressure on the side of the membrane away from the breathing gas mixture.

[0060] A key advantage of the membranes used is their high tolerance to halogenated hydrocarbons. For this reason, they are particularly suitable for long-term use in anesthesia or artificial respiration systems where the noteworthy application of these substances can be anticipated.

[0061] According to the present invention, sensors can be used to provide information about respiratory gas values ​​or respiratory gas parameters, such as information about carbon dioxide.

[0062] According to the present invention, the ventilator is a non-invasive device for home use or an invasive clinical ventilator or anesthetic ventilator, and thus a device or application in which carbon dioxide can be an important guiding parameter for the success of artificial respiration or the patient's condition. Detailed Implementation

[0063] Figure 1 An apparatus and method according to the invention are shown for separating a respiratory gas mixture 3. The respiratory gas mixture 3 contains at least oxygen (O2) and carbon dioxide (CO2), and optionally nitrogen (N2) and / or at least one volatile anesthetic.

[0064] The respiratory gas mixture 3 flows through the respiratory gas path 4 and is directed to the first separation material 1 at a first flow rate. The respiratory gas mixture 3 flows through the respiratory gas path 4 at least segmentally through at least one line 8. The line 8 can be at least divided into lines 8a and 8b. Here, the respiratory gas mixture 3 is brought to the separation material 1 directly or by force (by the patient or with the aid of a pump or turbine).

[0065] The first separating material 1 is provided and configured to separate at least oxygen O2 and / or carbon dioxide CO2 from at least one volatile anesthetic (A).

[0066] The at least one volatile anesthetic is either delivered to or retained in the breathing gas path 4. The breathing gas path 4 has a breathing gas pump 5 (which can be a valve, a turbine, or a breathing gas source), which can be implemented as a turbine. Breathing gas is delivered to the patient 7 via the patient interface 6.

[0067] The first separating material 1 can simply refer to a diffusion filter in a branch of the breathing gas tubing (e.g., expiratory type), or the separating material 1 can be implemented as a filter housing having an inlet 111 for breathing gas, an upper chamber 11, an outlet 112 for breathing gas to the patient, a diffusion filter 12, a lower chamber 13 and an outlet 132 for breathing gas from the lower chamber 13 and an inlet into the lower chamber 131.

[0068] The remaining respiratory gas mixture (containing at least nitrogen (N2), oxygen (O2), and carbon dioxide (CO2)) is directed via line 8a to the second separation material 2 at a second flow rate. At least carbon dioxide (CO2) is separated from the respiratory gas mixture by the second separation material 2. The separated carbon dioxide (CO2) is either temporarily released into the environment 25 or into the respiratory gas continuation system 25.

[0069] Here, there is a device 24 that regulates the flow rate of the separated carbon dioxide.

[0070] The remainder of the breathing gas mixture, which is essentially (nitrogen N2 and) oxygen O2, is then transported via line 8b to the first separation material 1. For this purpose, a breathing gas pump / turbine 10 is arranged in line 8b, or connected to lines 8a and / or 8b in a gas-conducting manner, which generates the necessary flushing flow rate of the breathing gas (this flushing flow rate can also be simply volume displacement). In line 8a, a check valve 9 can be arranged between the first separation material 1 and the second separation material 2, which selectively blocks the flow of breathing gas in one direction, specifically from the second separation material 2 to the first separation material 1.

[0071] The first separating material 1 is configured to selectively allow smaller molecules, namely nitrogen (N2), oxygen (O2), and carbon dioxide (CO2), to pass through, while blocking larger molecules, such as volatile anesthetics. The first separating material 1 is implemented here as a filter having an upper portion 11 and a lower portion 13, wherein a diffusion filter 12 is arranged between these portions. The upper portion 11 has an inlet 111 for the respiratory gas mixture 3 and an outlet 112 leading to the respiratory gas path 4 in the direction toward the patient 7.

[0072] The lower portion 13 has an inlet 131 and an outlet 132 leading toward the breathing gas path 8a in the direction toward the second separating material 2. The second separating material is configured to selectively allow smaller molecules, namely nitrogen (N2) and oxygen (O2), to pass through, while at least largely blocking carbon dioxide (CO2). The second separating material 2 may include a diffusion filter 22.

[0073] Here, the second separating material 2 is implemented as a filter having an upper portion 21 and a lower portion 23, wherein a diffusion filter 22 is arranged between these portions. The upper portion 21 has an inlet 211 for the breathing gas mixture 3 (which comes from the first separating material) and an outlet 212 leading to the environment 25.

[0074] The lower portion 23 has an outlet 231 leading to the breathing gas path 8b in the direction toward the first separating material 1. Between the outlet 231 and the inlet 131, a pump / turbine 10 is arranged in the breathing gas path, generating a flushing flow rate for the breathing gas. A narrow section 24 is arranged between the outlet 212 and the environment, which regulates the flow of CO2-containing breathing gas. The breathing gas is separated via diffusion filters 12 and 22 due to a concentration gradient.

[0075] The first separation material 1 includes, for example, a diffusion filter 12. The diffusion filter 12 is contaminated by patient gases (at least in the upper chamber 11) and therefore must be treatable (sterilizable and washable). The diffusion filter 12 must be steam sterilizable, i.e., thermally stable up to 134°C. Today's chemical absorbents are consumed after a relatively short period (e.g., 4 to 10-hour work shifts) and subsequently become special waste because they subsequently contain chlorofluorocarbons (volatile anesthetics). Therefore, the diffusion filter must withstand approximately 50 autoclave cycles over a one-year service life and under weekly handling conditions.

[0076] The two diffusion filters 12 and 22 are configured as membrane filters / surface filters or as tubes (hollow fibers). Here, the dimensions of the face and channel cross-section are configured to achieve a flow rate of 60 L / min in the flow direction and a maximum pressure drop not exceeding 2 cmH2O (= mbar, = hPa) in the flow direction and / or diffusion direction. If necessary, a number of membranes or a number of hollow fibers can be parallelized.

[0077] Diffusion filters 12 and 22 can be made of various plastics, ceramics, pressed glass beads, or sintered or rolled metals (or combinations thereof). Commonly used materials include: polysulfone, polyethersulfone (PES), cellulose, cellulose esters (cellulose acetate, cellulose nitrate), regenerated cellulose (RC), silicone, polyamide ("nylon", more precisely: PA 6, PA 6.6, PA 6.10, PA 6.12, PA 11, PA 12), polyamide-imide, polyamide-urea, polycarbonate, ceramics, stainless steel, silver, silicon, zeolite (aluminosilicate), polyacrylonitrile (PAN), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), and piperazine amide.

[0078] The combination of these materials is used to manufacture thin films (TFs), which typically consist of a support layer (e.g., cellulose acetate) and a cover layer (e.g., polyamide).

[0079] The second separating material 22 selectively allows smaller molecules, namely nitrogen (N2) and / or oxygen (O2), to pass through, while at least largely blocking carbon dioxide (CO2). The second separating material 2 includes a diffusion filter 22. The permeability ratio of the diffusion filter 22 to N2 and O2 to CO2 is at least 50:1. The permeability ratio can also be at least 100:1. The permeability ratio should preferably be such that after the second stage, the CO2 flow rate released into the environment or into the breathing gas continuation system 25 is less than the flushing flow rate in the first stage (separating material 1).

[0080] The initial flow rate entering the separation material 1 is, for example, 4 to 25 L / min or 6 to 18 L / min. The released flow rate should be as small as possible. The released flow rate should be as small as possible less than the typical average exhaled patient flow rate.

[0081] On average, adult patients exhale less than 8 L of respiratory gas per minute, which contains an average of <=5% CO2. If the gas in diffusion filter 2 is enriched by a factor of 10 to 12, a flow rate of 0.6 to 0.8 L / min is obtained for the released flow rate (through 212), which is acceptable.

[0082] The first flow rate is generated by a fan, a compressed gas source, or a pump 5, or the first flow rate is directly inhaled by the patient into the separating material 1, for example, when the separating material 1 is in an expiratory tubing. In this embodiment, the breathing gas path 4 is an expiratory breathing gas path 4e.

[0083] The second flow rate 4 entering the separation material 2 is 1 to 25 L / min or 6 to 18 L / min. The flushing flow rate between chamber 13 and the upper chamber 21 and the lower chamber 23 can be adjusted as needed. This allows the CO2 content exiting the first stage at 132 to be set. Although the higher CO2 content at the output end of the first stage (at 132) is not ideal for the patient, it can save energy and extend the operating time when the battery is running.

[0084] The second flow rate is generated by a fan, a compressed gas source, or a pump 10. The respiratory gas mixture 3 is at least partially or completely drawn from the expiratory respiratory gas path 4e. The first separating material 1 is connected to the inspiratory respiratory gas path 4i via a first output end 112 in a conduction manner, wherein a respiratory gas source 5 is arranged downstream of the first separating material 1 and upstream of the inspiratory patient connection 6. A fresh gas supply (oxygen) and an anesthetic gas supply are optionally arranged downstream of the first separating material 1 and upstream of the respiratory gas source 5. A sensor, particularly an oxygen sensor and / or an anesthetic gas sensor, is optionally arranged downstream of the respiratory gas source 5. A flow sensor is optionally arranged downstream of the respiratory gas source 5. A CO2 sensor (carbon dioxide measurement, Kapnometrie) is optionally arranged downstream of the respiratory gas source 5. Sensors can also be arranged in the respiratory gas path before and / or after the first separating material 1. Sensors can also be arranged in the respiratory gas path before and / or after the second separating material 2.

[0085] The method and apparatus also achieve the adjustment / control of a defined proportion of respiratory gas in a respiratory gas mixture. To this end, according to the invention, the feeding or supply of respiratory gas (especially O2, CO2, and / or anesthetic gas) is arranged. Similarly, the separation or removal of at least a defined proportion of respiratory gas from the respiratory gas mixture is arranged. The necessary adjustments, particularly the control of the required actuators, are performed by a control unit, which can also be divided into multiple sub-control units.

[0086] In particular, the actuators for controlling flow (i.e., especially pumps / turbines 5, 10, 26), the device 24 for removing breathing gas (parts), the check valve 9, the supply of fresh gas (oxygen) and the supply of anesthetic gas.

[0087] To regulate / control a specific proportion of respiratory gas in the respiratory gas mixture, the control unit takes into account user specifications and / or stored instructions and / or sensor signals. In particular, this is achieved through at least one flow sensor and / or CO2 sensor and / or O2 sensor and / or anesthetic gas sensor.

[0088] Figure 2 An apparatus and method according to the invention are shown for separating a respiratory gas mixture 3. The respiratory gas mixture contains at least oxygen (O2) and carbon dioxide (CO2), and optionally nitrogen (N2) and / or at least one volatile anesthetic (A). Figure 2 Showing according to Figure 1 The device, however, features cascaded flushing flow treatment via separating material 2. This device can be used if the diffusion coefficient is significantly less than 100 or gas losses should be further reduced. Theoretically, any number of stages can be cascaded. Each stage requires a pump. However, due to the very small flow rate, the pumps can also be set up and constructed in a small and cost-effective manner. As a result, a small amount of gas rich in high concentrations of CO2 can be released via cascaded flushing flow treatment.

[0089] The remaining breathing gas mixture, separated after passing through the first diffusion filter 12 and containing at least oxygen (O2) and carbon dioxide (CO2), is directed via line 8a at a second flow rate to a second separating material 2, where the remaining breathing gas mixture contains, for example, 60% CO2. The second separating material is configured to selectively allow smaller molecules, i.e., nitrogen (N2) and / or oxygen (O2), to pass through, and to at least largely block at least carbon dioxide (CO2). The second separating material 2 is implemented as a dual or multiple diffusion filter 2.

[0090] At least carbon dioxide (CO2) is separated from the respiratory gas mixture by the second separating material 2 and discharged from the upper chamber 21 via the output end 212. The separated CO2 is either temporarily discharged or released into the environment 25 or into the respiratory gas continuation system 25. The respiratory gas continuation system 25 may optionally include a pump 26 that guides the separated CO2 back to the input end 211 of the second separating material 2 via a line 27.

[0091] The remainder of the breathing gas mixture, diffused through diffusion filter 22, which is essentially nitrogen (N2) and oxygen (O2), is conducted from the lower chamber 23 through opening 231 to the second separation material 2' and enters here through inlet 211', where the remainder still contains, for example, 6% CO2.

[0092] The first filter is implemented having an upper portion 21 and a lower portion 23, wherein a diffusion filter 22 is arranged between these portions. The upper portion 21 has an inlet 211 for the breathing gas mixture 3 and an outlet 212 leading to the environment 25. A narrow section 24 is arranged between the outlet 212 and the environment, which regulates the flow of breathing gas containing CO2.

[0093] The lower portion 23 has an outlet portion 231 in the direction toward the second filter 2'.

[0094] The inlet 211' of the second filter 2' is supplied using the outlet of the first filter 231. The upper portion 21' has an outlet 212' leading to a pump 26, which conducts breathing gas containing CO2 (with 6% CO2) via a line 27 to the inlet 211 of the first filter 2. Thus, in this embodiment, the CO2 content in the lower portion 23' of the second separation material 2' is reduced to 0.6%. The breathing gas thus treated is then conveyed to the first separation material 1. Between the outlet 231' of the second filter and the inlet 131 of the first filter, a breathing gas pump 10 is arranged in the breathing gas path, which generates a flushing flow rate for the breathing gas.

[0095] and Figure 1 Accordingly, in accordance with Figure 2 In this embodiment, a respiratory gas pump 5 can also be arranged downstream of the first separating material 1 and upstream of the inspiratory patient connection 6. A fresh gas supply (for oxygen) and an anesthetic gas supply can optionally be arranged downstream of the first separating material 1 and upstream of the respiratory gas pump 5. A sensor, particularly an oxygen sensor and / or an anesthetic gas sensor, can optionally be arranged downstream of the respiratory gas pump 5. A flow sensor can optionally be arranged downstream of the respiratory gas pump 5. A CO2 sensor (carbon dioxide measurement) can optionally be arranged downstream of the respiratory gas pump 5. Sensors can also be arranged in the respiratory gas path before and / or after the first separating material 1. Sensors can also be arranged in the respiratory gas path before and / or after the second separating material 2, or they can also be arranged in the pipeline 2.

[0096] The method and apparatus also achieve the adjustment / control of a defined proportion of respiratory gas in a respiratory gas mixture. To this end, according to the invention, the feeding or supply of respiratory gas (especially O2, CO2, and / or anesthetic gas) is arranged. Similarly, the separation or removal of at least a defined proportion of respiratory gas from the respiratory gas mixture is arranged. The necessary adjustments, particularly the control of the required actuators, are performed by a control unit, which can also be divided into multiple sub-control units.

[0097] In particular, the actuators for controlling flow (i.e., especially pumps / turbines 5, 10, 26), the device 24 for removing breathing gas (parts), the check valve 9, the supply of fresh gas (oxygen) and the supply of anesthetic gas.

[0098] To regulate / control a specific proportion of respiratory gas in the respiratory gas mixture, the control unit considers user specifications and / or stored instructions and / or sensor signals. In particular, this includes sensor signals from at least one flow sensor and / or CO2 sensor and / or O2 sensor and / or anesthetic gas sensor.

[0099] Figure 3 The application of the teachings (device and method) according to the invention in a ventilator according to the invention and the meaning of the teachings are shown. Figure 3 This demonstrates the importance of alveolar ventilation (VA) in hemodynamically stable, anesthetized patients under CO2-free conditions. Figure 3 The changes in different patient-specific physiological parameters are shown using volumetric carbon dioxide analysis during alveolar ventilation monitoring. In (B), changes in alveolar ventilation (VA) in hemodynamically stable patients are presented by (A) reducing respiratory rate (RR) from 15 breaths per minute to 10 breaths per minute (i), by increasing (ii) and decreasing (iii) tidal volume (VT) under controlled artificial respiration.

[0100] The elimination of carbon dioxide (VCO2) (shown in D) and the partial pressure of CO2 in the alveoli (PACO2) (shown in C) exhibit opposite behavior. The partial pressure of CO2 in the arteries (PaCO2) is shown in (C) through the PACO2 in the alveoli (the upper line in C).

[0101] Not all parts of the respiratory tract—from the mouth and nostrils to the alveoli—are actually involved in gas exchange. Information about the fraction of "effective" alveolar ventilation is very helpful in determining and, if necessary, optimizing the "effectiveness" of artificial respiration. CO2, due to its high solubility and the resulting very rapid kinetics, is an ideal indicator of alveolar ventilation (VA). Therefore, measurements and graphical representations of the partial pressure of CO2 (PETCO2) in the exhaled gas mixture, in the form of a carbon dioxide analysis curve, provide for continuous monitoring of ventilation. Examples of qualitative assessments of ventilation using carbon dioxide analysis include: disconnection, apnea, ruling out incorrect intubation, obstruction, ruling out patient-ventilator asynchrony, etc. Furthermore, PETCO2 is used as a quantitative measure (for adjusting ventilation)—a high PETCO2 level indicates underventilation when hemodynamics are stable and metabolism is constant, or a low PETCO2 level indicates overventilation. In practice, both will lead to adjustments in the atemminutenvolumen (VE) at the ventilator. Because ventilatory volume (VE) is the product of tidal volume and respiratory rate, it provides modulation of these two components. In principle, the current goal is to achieve low tidal volume (VT) to avoid volumetric, biological, and barotrauma through lung-protective artificial respiration. However, it is particularly important to consider that dead space is also ventilated with each breath, in addition to the alveoli involved in gas exchange. This proportion of dead space ventilation significantly affects the efficiency of artificial respiration. The following simple formula applies to the respiratory volume per minute, i.e., alveolar ventilation (VA) and dead space ventilation (VD): VE = VA + VD Ventricular ventilation (VE) consists of an effective portion and an ineffective portion. In the effective portion, gas comes into contact with pulmonary capillaries and participates in gas exchange (alveolar ventilation = VA), while in the ineffective portion, gas does not participate in gas exchange (dead space = VD). Therefore, VA and its share of VE are measures of respiratory efficiency, and especially under conditions of respiratory restriction, VA and VD are important characteristic parameters for optimizing artificial respiration settings. Accordingly, VA is calculated as: VA = VE - VD Figure 3 This demonstrates the importance of ventricular tachycardia (VA) in hemodynamically stable, anesthetized patients with CO2 elimination. Changes in respiratory rate and ventricular volume (VT) alter VA, which in turn affect CO2 partial pressure and CO2 elimination (VCO2) in an inverse sense. Higher VCO2 at elevated VA reduces the partial pressure across the alveolar-capillary membrane, leading to hypocapnia. Conversely, lower VA results in less CO2 elimination and consequently hypercapnia.

[0102] Carbon dioxide analysis is a suitable method to determine and graphically represent the amount or fraction of exhaled carbon dioxide (abbreviated as CO2). Here, the CO2 dynamics of mechanically ventilated patients are presented non-invasively and in real-time. In particular, volumetric carbon dioxide analysis demonstrates a suitable method for clinical monitoring of mechanically ventilated patients.

[0103] Using carbon dioxide analysis, the concentration of CO2 in the respiratory gas can be measured during the respiratory cycle. The CO2 concentration is periodically calculated by the absorption of infrared light according to Lambert-Beer's law and is typically expressed as a partial pressure in mmHg. The graphical representation of CO2 elimination during respiration is called a carbon dioxide graph, and the corresponding measuring instrument is called a carbon dioxide concentration monitor (Kapnograph).

[0104] The patient-specific physiological parameter of the amount of CO2 (or, specifically, the volume of CO2 eliminated in a single breath) can be determined non-invasively by volumetric carbon dioxide analysis using the integral of exhaled CO2 over the exhaled tidal volume.

[0105] Therefore, in the process according to the recommended method, CO2 diffusion can be used as a patient-specific physiological parameter representing the success of artificial respiration, so that the conclusion of adjusting at least one technical artificial respiration parameter can be automatically drawn subsequently. Thus, it is possible to ensure physiologically successful artificial respiration without irritating the patient.

[0106] According to another aspect of the teachings, a ventilator for artificial respiration of a patient is proposed. The proposed ventilator includes: a measuring device (sensor) configured to detect at least one patient-specific physiological parameter (such as O2 or CO2); a control device configured to determine at least one technical artificial respiration parameter, wherein artificial respiration of the patient is performed based on the technical artificial respiration parameter, wherein the at least one technical artificial respiration parameter corresponds to at least one of artificial respiration parameters (i.e., respiratory pressure, respiratory volume per minute, tidal volume, respiratory rate, positive end-expiratory pressure, and / or the concentration of inhaled oxygen provided by the ventilator and / or the CO2 fraction or partial pressure provided by the ventilator); and an adjustment unit communicating with the measuring device and the control device. Here, the measuring device is configured to perform repeated measurements of the at least one patient-specific physiological parameter at time intervals. The adjustment unit is configured to perform adjustments to the at least one technical artificial respiration parameter based on the repeated measurements of the patient-specific physiological parameter.

[0107] The artificial respirator provided for artificial respiration of patients is preferably configured to operate by means of the foregoing method and / or when using the device.

[0108] In particular, this understanding is crucial in the context of ventilators: the variable functional state of the lungs during artificial respiration, from one breath to the next, is incorporated into the regulation of the ventilator settings. By simultaneously incorporating both technical and physiological parameters—in the form of technical ventilator parameters and patient-specific physiological parameters—into the regulation of the ventilator, a new dimension of ventilator therapy is achieved. Even under the challenging conditions of modern intensive care, where hospital stays are decreasing despite worsening conditions, this approach ensures reliable control of ventilator therapy.

[0109] The proposed ventilator can automatically observe the patient's condition through specific physiological parameters and automatically adjust the technical artificial respiration parameters at regular time intervals through the proposed regulation / control, so as to achieve successful and non-irritating artificial respiration for the patient.

[0110] According to another advantageous embodiment of the ventilator, the measuring device is configured as a carbon dioxide concentration detector and is configured to perform repeated measurements of at least one patient-specific physiological parameter by means of (preferably volumetric) carbon dioxide analysis, and such that the at least one patient-specific physiological parameter corresponds to at least one parameter that directly represents CO2 gas exchange in the patient's lungs, preferably corresponding to at least one of the following parameters: end-expiratory CO2 partial pressure in the exhaled gas mixture, alveolar CO2 partial pressure, or the volume of CO2 eliminated during a single breath of the patient.

Claims

1. A method for separating a respiratory gas mixture (3), said respiratory gas mixture comprising at least O2 and CO2 and at least one volatile anesthetic, and flowing in a respiratory gas path (4), - in, The respiratory gas mixture (3) is directed at a first flow rate to a first separation material (1) configured as a diffusion filter. - Wherein, the first separating material (1) separates at least oxygen O2 and carbon dioxide CO2 from the at least one volatile anesthetic, thereby obtaining a separated residual respiratory gas mixture having at least oxygen O2 and carbon dioxide CO2. - Wherein, the at least one volatile anesthetic separated by the first separating material (1) is either delivered to the respiratory gas path (4) or retained in the respiratory gas system. - The remaining respiratory gas mixture separated is guided to the second separation material (2) at the second flow rate. - Wherein, at least carbon dioxide (CO2) is separated from the remaining respiratory gas mixture by the second separating material (2), thereby obtaining the remaining portion of the respiratory gas mixture, which is essentially oxygen (O2), and - Wherein, the carbon dioxide (CO2) separated by the second separating material (2) is released into the environment or into the respiratory gas conduction system, and - Wherein, the remaining portion of the respiratory gas mixture is then transported to the first separating material (1) as the flushing flow rate of the first separating material (1). The flushing flow rate between the first separating material (1) and the second separating material (2) can be adjusted as needed, so that the CO2 content leaving the first stage at the output end of the first stage can be adjusted.

2. The method according to claim 1, characterized in that, The first separating material (1) selectively allows smaller molecules, namely oxygen O2 and carbon dioxide CO2, to pass through, and blocks at least one volatile anesthetic.

3. The method according to claim 1 or 2, characterized in that, The first flow rate or the second flow rate is 4 L / min to 25 L / min.

4. A ventilator for carrying out the steps of the method according to claim 1 or 2, comprising means for separating a respiratory gas mixture (3), said respiratory gas mixture comprising at least O2 and CO2 and at least one volatile anesthetic and flowing in a respiratory gas path (4), - in, The respiratory gas mixture (3) is directed at a first flow rate to a first separation material (1) configured as a diffusion filter. - Wherein, the first separating material (1) separates at least oxygen O2 and carbon dioxide CO2 from the at least one volatile anesthetic, thereby obtaining a separated residual respiratory gas mixture having at least oxygen O2 and carbon dioxide CO2, and - Wherein, the at least one volatile anesthetic separated by the first separating material (1) is either delivered to the respiratory gas pathway (4) or retained in the respiratory gas system. - The remaining respiratory gas mixture separated is guided to the second separation material (2) at the second flow rate. - Wherein, at least carbon dioxide (CO2) is separated from the remaining respiratory gas mixture by the second separating material (2), thereby obtaining the remaining portion of the respiratory gas mixture, which is essentially oxygen (O2), and - Wherein, the carbon dioxide (CO2) separated by the second separating material (2) is released into the environment or into the respiratory gas conduction system, and - Wherein, the remaining portion of the respiratory gas mixture is then conveyed to the first separating material (1) as the flushing flow rate of the first separating material (1). The flushing flow rate between the first separating material (1) and the second separating material (2) can be adjusted as needed, so that the CO2 content leaving the first stage at the output end of the first stage can be adjusted.

5. The artificial ventilator according to claim 4, characterized in that, The first separating material (1) is configured as a diffusion filter in a branch of a breathing gas tubing or as a filter housing having an inlet (111) for breathing gas, an upper chamber (11), an outlet (112) for breathing gas to the patient, a diffusion filter (12), a lower chamber (13) and a lower outlet (132) and a lower inlet (131), the lower outlet being for breathing gas from the lower chamber (13) to a first breathing gas path line (8a) in a direction toward the second separating material (2), and the lower inlet entering the lower chamber (13) from the second breathing gas path line (8b) of the second separating material.

6. The artificial ventilator according to claim 5, characterized in that, The flushing flow rate between the lower chamber (13) and the following chamber (21) can be adjusted as needed so that the CO2 content leaving the first stage at the lower outlet (132) is adjustable.

7. The ventilator according to any one of claims 4 to 6, characterized in that, The remainder of the breathing gas mixture, which is essentially nitrogen (N2) and oxygen (O2), is transported to the first separated material (1) via a second breathing gas path line (8b), wherein a breathing gas pump or turbine (10) is arranged in or connected to the second breathing gas path line (8b) in a gas conduction manner, the breathing gas pump or turbine being used to generate a flushing flow rate for flushing the first separated material (1) or for displacement of the volume of breathing gas.

8. The ventilator according to any one of claims 4 to 6, characterized in that, A check valve (9) is arranged in the first breathing gas path line (8a) between the first separating material (1) and the second separating material (2), the check valve selectively blocking the flow of breathing gas in one direction.

9. The ventilator according to any one of claims 4 to 6, characterized in that, The diffusion filter is constructed as a membrane filter and / or a surface filter or as a tube and / or hollow fiber, wherein the size of the surface and channel cross-section is configured such that, during operation of the device, a flow rate of 60 L / min is achieved in the flow direction and a maximum pressure drop of no more than 2 cmH2O is achieved in the diffusion direction, based on a combination of volumetric flow rate, pressure, temperature and breathing gas mixture.

10. The ventilator according to any one of claims 4 to 6, characterized in that, The device is configured such that, during operation of the device, the first flow rate entering the first separation material (1) is 4 L / min to 30 L / min, and the second flow rate entering the second separation material (2) is 1 L / min to 35 L / min.

11. The ventilator according to any one of claims 4 to 6, characterized in that, A cascaded flushing flow treatment is provided through the second separation material (2), wherein the second separation material (2) is implemented as a double or more filters (22, 22').

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