Filter assembly and method for filtering a gas from a gas mixture

Abstract

The invention relates to an assembly and a method for filtering at least one gas out of a gas mixture. A filter unit (4) of the filter assembly comprises an inlet and an outlet and is capable of filtering the gas out of the gas mixture during the flow of the gas mixture through the filter unit (4). The filter unit (4) receives the gas and heats up here. A filter temperature sensor (46, 46.2) of the filter assembly is capable of measuring at least once a measure for the temperature within a first measuring region (MP, MP.2) inside the filter unit (4). A notification is generated depending on the measured temperature and is outputted in a form which can be perceived by a person. The notification comprises information about the current state of the filter unit (4).

Description

Technical Field

[0001] The present invention relates to a filter assembly and a method for filtering at least one gas from a gas mixture. Background Technology

[0002] The task of filtering gases from a gas mixture occurs, for example, in hospitals. This involves performing artificial respiration on a patient, or sedating or anesthetizing them with at least one anesthetic. During artificial respiration, the anesthesia machine performs a series of breathing cycles, delivering a specific amount of a gas mixture, including oxygen and at least one anesthetic, to the patient in each cycle. The air exhaled by the patient then typically contains traces of this anesthetic.

[0003] Exhaled anesthetic should be prevented from reaching the surrounding environment of the anesthesia machine. A breathing circuit must be established to resupply the exhaled air to the anesthesia machine. The air exhaled by the patient is then supplied to the anesthesia machine.

[0004] Excess gas is typically generated in this breathing circuit between the patient and the anesthesia machine and must be removed from the breathing circuit. In one design, the excess gas is delivered to a fixed fluid receiver. Exhaled anesthetic should be prevented from reaching the fluid receiver as part of the excess gas and potentially entering the hospital's supply system.

[0005] In this application, the excess gas acts as a gas mixture, and each or every anesthetic in the gas mixture acts as the gas to be filtered out. It is possible that the excess gas contains at least two different anesthetics, all of which are to be filtered out.

[0006] The known process involves guiding a gas mixture, specifically excess gas, through a filtration unit. During this flow, the filtration unit filters out the gas that should be removed from the mixture—in this case, the anesthetic. The filtration unit necessarily receives the filtered-out anesthetic and therefore can only filter out a specific amount. Consequently, it is frequently necessary to replace used filtration units with new ones.

[0007] US 2001 / 0 025 640 A1 proposes the use of an indicator material to detect anesthetics in a gas mixture, wherein the indicator material reacts chemically with the anesthetic and changes the color of the anesthetic as a result of the reaction. The user can visually perceive the color change and then replace the filter unit, see paragraph

[0015] .

[0008] In WO 2019 / 038 566 A1 Figure 1The diagram depicts a breathing circuit in which a gas mixture containing an anesthetic is supplied to a patient. The gas mixture exhaled by the patient (exhaust gas 38) may contain the anesthetic and is guided through a filter unit having a housing (canister 208) and filter material 210. The housing 208 includes an inlet 203 and outlets 211, 311. The filter material 210 binds the anesthetic. In addition, ambient air (general theater air 206) and air cooled by passing through inlet 204 (cold airflow 204a) are guided into the filter units 208, 210. Thus, the airflow exiting from the filter units 208, 210 is cooled. A control device 301 receives a signal from a sensor (thermostat or thermocouple 303) in outlet 311 of housing 208 and regulates the delivery of cold air through inlet 204. If the anesthetic is found in outlet 211, the gas mixture is guided through a filter 214 containing activated carbon. Summary of the Invention

[0009] The object of the present invention is to provide a filter assembly and a method that filters at least one gas from a gas mixture by means of the filter unit during the flow of a gas mixture through the filter unit, and in many cases prevents undesirable events such as the appearance of gas that should have been filtered out by the filter unit downstream with greater reliability than known filter assemblies and methods.

[0010] The present invention is achieved by a filter assembly having the features of claim 1 and by a method having the features of claim 16. Advantageous designs are described in the dependent claims. Wherever it makes sense, the advantageous designs of the filter assembly according to the invention are also advantageous designs of the method according to the invention, and vice versa.

[0011] The filter assembly and method according to the invention are capable of filtering at least one gas from a gas mixture. The gas mixture is, for example, breathing air exhaled by the patient or excess air in a breathing circuit, and the gas to be filtered is an anesthetic.

[0012] The filter assembly includes a filter unit having an inlet and an outlet. The filter assembly is designed such that the gas mixture flows through the inlet into the filter unit, passes through the filter unit at least once, optionally multiple times, and flows out of the filter unit again through the outlet. The filter unit is capable of filtering the gas from the gas mixture during its flow through the filter unit.

[0013] The filter unit is capable of receiving the filtered gas. As a result of the process of receiving the filtered gas, the filter unit becomes hot.

[0014] The filter assembly further includes a sensor assembly having a first filter temperature sensor and optionally at least one second filter temperature sensor. The first filter temperature sensor is designed to measure, at least once, the temperature inside the filter unit, i.e., a measure of the temperature within a first measurement region. Preferably, it measures the instantaneous temperature within the first measurement region. The second filter temperature sensor is also designed to measure, at least once, the temperature inside the filter unit, preferably a measure of the temperature in a second measurement region spatially spaced from the first measurement region and particularly preferably located upstream of the first measurement region.

[0015] The filter assembly according to the invention is designed to automatically perform the following steps: The filter assembly generates a notification, and more precisely, based on the temperature measured in the first measurement area, or more precisely, based on at least one measured value of said temperature. This notification includes information about the current state of the filter unit. This information may consist, for example, a message that the filter unit should be replaced as soon as possible, a prediction of how much longer the filter unit can be used, or a message that the filter unit does not currently need to be replaced.

[0016] - In one alternative, the filter assembly outputs a notification carrying this information in a form perceptible to a person, particularly by sight, hearing, and / or touch (via vibration), for example, on an externally visible wall of the filter unit's housing. In another alternative, the filter assembly causes this notification to be output in a human-perceptible form, and more precisely, by a spatially distant receiver. Preferably, this receiver is at least temporarily connected to the filter assembly via a wired or wireless data connection.

[0017] The method according to the invention is implemented using the filter assembly according to the invention. The method includes the following steps: The gas mixture flows into the filter unit through the inlet. The gas mixture flows through the filter unit at least once, and multiple times in one design configuration.

[0018] - During the flow of the gas mixture through the filtration unit, the filtration unit filters out gas or at least a portion of the gas from the gas mixture.

[0019] The gas mixture then flows out of the filter unit through the outlet.

[0020] The filter unit receives the gas that has been filtered out of the flowing gas mixture. The filter unit is designed such that, as a result of the gas receiving process, it becomes hot.

[0021] - The first filter temperature sensor measures the temperature in the first measurement area at least once.

[0022] - A notification is automatically generated based on at least one measured temperature value in the first measurement area. This notification includes information about the current status of the filtering unit.

[0023] - This prompts the notification to be output in a form that is perceptible to humans.

[0024] According to the invention, a filter unit is used that receives the gas to be filtered and becomes heated therein. Preferably, an exothermic chemical reaction occurs within the filter unit. Many known filter materials become heated when they receive gases, such as anesthetics or other long-chain hydrocarbons. One example is a filter material comprising activated carbon. In one design, the filter unit comprises a cylinder and a loose material inside the cylinder, wherein the loose material comprises activated carbon or other absorbent material. In one design, it is possible to reuse the cylinder and replace only the loose material. In another design, the cylinder can only be replaced as a whole with the loose material.

[0025] This invention utilizes the heat generated by the filter unit during use to ascertain its current state and inform the user of this state. Because the internal temperature of the filter unit is measured, although possible, it is unnecessary in many designs due to this invention for the sensor to come into contact with the filter material inside the filter unit. In particular, it is unnecessary for the sensor to chemically react with the filter material and / or chemically determine the amount of gas that the filter material has received. More specifically, this invention allows, in many designs, the temperature of the filter unit to be determined from the outside without contact, thus revealing its current state. In many cases, this effect facilitates monitoring of the filter unit and also enables remote monitoring. Furthermore, if the internal temperature of the filter unit is measured without contact, the risk of leakage of the gas mixture or loose material due to gaps in the filter unit is reduced.

[0026] In many designs, this invention also eliminates the need to house the sensor inside the filter unit. When a filter unit is depleted and replaced by a new one, this sensor, along with the filter unit, often must be discarded or removed. Instead, in many designs, this invention allows the same sensor for filter temperature to be reused sequentially in multiple filter units.

[0027] The first filter temperature sensor and optionally at least one second filter temperature sensor each measure, at least once, the temperature occurring in a corresponding measurement region within the filter unit. This temperature in the measurement region within the filter unit is a measure of how much gas to be filtered has been received by the filter unit up to this point in the measurement region.

[0028] Typically, the filter unit receives the gas to be filtered unevenly across its entire extent. More precisely, at any given moment, only one region within the filter unit typically filters the gas, absorbs the gas, and heats up in the process. If this region can no longer absorb other gases, the gas mixture flows through this region without being absorbed, and the gas is only filtered out in a downstream region. Therefore, an absorption region is formed within the filter unit, which is the area currently absorbing the gas. This absorption region thus flows along the flow direction of the gas mixture from the inlet through the filter unit to the outlet. The invention utilizes the fact that gas absorption results in heating, and that the absorption region, and thus the region with the elevated temperature, frequently moves through the filter unit.

[0029] According to the invention, the gas mixture flows from the inlet through the filter unit to the outlet at least once. The first filter temperature sensor measures the temperature of a first measuring area at least once, which can be located near the outlet of the filter unit. Therefore, if the aforementioned absorption area has reached this first measuring area near the outlet, the filter unit can only absorb a small amount of other gas because only a small amount of filter material remains downstream of the first measuring area and before the outlet. The event of this absorption area (first measuring area) near the outlet becoming hot is detected. This event serves as an indication that the filter unit should be replaced.

[0030] Furthermore, when the first measuring area is located near the outlet, in many cases, the filter unit is replaced only when it actually needs to be replaced, rather than being replaced prematurely. Therefore, the location of the first measuring area near the outlet reduces the consumption of the filter unit compared to a location further upstream. On the other hand, the first measuring area can be located with a sufficiently large safety distance relative to the outlet. This reduces the risk that a significant amount of the gas to be filtered will leave the filter unit through the outlet due to delayed replacement. Moreover, this safety distance often allows sufficient time for filter unit replacement after the appropriate notification has been issued.

[0031] In many cases, the present invention achieves the objective of generating a timely, but not significantly premature, notification that a filter unit must now be replaced, and outputting this notification in a human-perceptible manner. The filter unit can then be replaced promptly without jeopardizing, for example, ongoing medical treatment for an anesthetized patient.

[0032] This invention allows the filter unit to be replaced based on the actual amount of gas received, i.e., on an event-based basis. This invention avoids the need to replace the filter unit on a time-based basis, i.e., at regular time intervals, regardless of how much gas the filter unit has actually received.

[0033] This invention can be used in conjunction with a sensor capable of detecting, at a measurement location downstream of the filter unit, whether the gas mixture exiting the filter unit still contains the gas to be filtered. This sensor, positioned downstream of the filter unit, for example, detects anesthetics in the exiting gas mixture. However, this invention avoids the need for such a sensor and the necessity of replacing the filter unit only when the sensor actually detects the gas to be filtered downstream of it. That is, such a sensor can only detect, after the fact, an undesirable event such as filter breakdown. When the filter breaks down, the filter unit is no longer able to completely filter the gas from the gas mixture. After filter breakdown, a considerable amount of gas often flows out of the outlet and then frequently reaches the surrounding environment or a fluid receiving section. While a sensor with a measurement area downstream of the filter unit can detect such filter breakdown, in many cases it detects it too late to prevent further breakdown.

[0034] Furthermore, it is sometimes impossible to immediately replace the filter unit after a filter breakdown is discovered, especially when medical treatment is being administered to anesthetized patients. This invention reduces the risk of such an undesirable event. In many cases, this invention allows for timely replacement of the filter unit without compromising medical treatment.

[0035] This invention can be used in conjunction with a quantity sensor that determines, from the moment the filter unit is first used, what amount of gas to be filtered, as a component of the gas mixture, has flowed into and been received by the filter unit through the inlet. However, this invention avoids the need to replace the filter unit based on the results of such a quantity sensor. In many cases, such a quantity sensor can only measure, relatively unreliably, the amount that the filter unit has at least received.

[0036] This invention allows for the detection, in a relatively simple manner and more precisely in many cases, of when the filter unit must be replaced before filter breakdown occurs. Relatively simple and reliable temperature sensors are commercially available and can also be used in some designs of the filter assembly according to this invention.

[0037] According to the present invention, the first filter temperature sensor measures a measurement of the current temperature in a first measurement region inside the filter unit. The measured temperature in the first measurement region is used to generate the notification and can be used to determine whether the filter unit can continue to be used or has instead been depleted. In one design, the generation of this notification is based on the measured temperature in the first measurement region and optionally on the measured temperature in a second measurement region.

[0038] In one design, the filter assembly according to the invention further includes a measurement unit for processing signals. The measurement unit is spatially located away from the filter unit. The measurement unit receives signals from a first filter temperature sensor and from at least one optional second filter temperature sensor. Using this signal or these signals, the measurement unit automatically determines whether a pre-defined criterion is met. This criterion depends on at least one temperature value in the first measurement area and optionally additionally on at least one temperature value in the second measurement area. If the criterion is met, the measurement unit generates a notification containing information about the current state of the filter unit. The measurement unit causes this notification to be output in a human-perceptible form, preferably by a spatially located receiver. Preferably, the notification includes information that the filter unit has been depleted or is about to be depleted and therefore must be replaced. The notification may also include a prediction of how long the filter unit can be used until it must be replaced.

[0039] Preferably, the method according to the invention includes the following steps: automatically determining whether the pre-given criteria are met. If the criteria are met, a notification containing information about the current state of the filtering unit is generated.

[0040] According to the present invention, the first filter temperature sensor measures the temperature in the first measurement region at least once. In a preferred design, the first filter temperature sensor measures the temperature in the first measurement region multiple times sequentially, i.e., at multiple consecutive scan times, during the flow of the gas mixture through the filter unit. Using the signal from the first filter temperature sensor, the evaluation unit processing the signal determines the temporal variation curve of the measured temperature in the first measurement region. Of course, the evaluation unit can only approximately determine this temporal variation curve. According to the present invention, the evaluation unit generates a notification when a predetermined criterion is met. According to the preferred design just described, this criterion depends on the determined temporal variation curve of the temperature in the first measurement region.

[0041] During the period when the filter unit receives the gas to be filtered in the first measurement zone, the filter unit heats up in the first measurement zone. The design of the time-varying temperature curve allows for predictions with greater reliability than predictions based solely on measured values: when the filter unit will no longer be able to receive other gases in the first measurement zone. The aforementioned absorption zone then passes through the first measurement zone and moves further towards the outlet. Often, the evaluation unit makes this prediction automatically. This prediction allows for timely replacement of the filter unit with greater reliability. "Timely" means before filter breakdown, i.e., before the gas to be filtered is discharged from the filter unit's outlet. Furthermore, the design with the time-varying temperature curve allows for, in some cases, a greater reliability in distinguishing between the process of the filter unit receiving gas and thus heating up, and the process of the filter unit heating up due to sufficiently large or elevated ambient temperatures or other external influences.

[0042] According to the present invention, the first filter temperature sensor measures at least once a measure of the temperature in a first measurement region inside the filter unit. In a preferred design, the sensor assembly includes at least one second filter temperature sensor. The first or each second filter temperature sensor is also capable of measuring a measure of the temperature inside the filter unit, preferably the same measure as the first filter temperature sensor. However, the two filter temperature sensors can also measure different measures of temperature. The first filter temperature sensor is capable of measuring a measure in the first measurement region, and the first or each second filter temperature sensor is capable of measuring a measure in a corresponding second measurement region inside the filter unit. Viewed along the flow direction of the gas mixture through the filter unit, the first measurement region is downstream of the first or each second measurement region. Therefore, the first measurement region is located between the first or each second measurement region and the outlet of the filter unit. It is possible that multiple second measurement regions are spatially spaced apart from each other between the inlet and the first measurement region.

[0043] The design with multiple filter temperature sensors can be combined with a design for the filter assembly that includes a testing unit. Alternatively, the design with multiple filter temperature sensors can be implemented without a testing unit.

[0044] The evaluation unit preferably determines, at least once, the spatial variation curve of the temperature along the path from the inlet to the outlet of the filter unit. This spatial variation curve relates to a single moment. To determine this spatial variation curve, the evaluation unit uses the signal from the first filter temperature sensor and the corresponding signal from the one or at least one second filter temperature sensor. According to the invention, the evaluation unit generates a notification if a pre-defined criterion is met. According to the design just described, the criterion depends on the spatial variation curve of the temperature along the path. Preferably, the evaluation unit determines the current spatial variation curve multiple times sequentially.

[0045] The design with multiple filter temperature sensors provides redundancy and allows continued use of the filter assembly according to the invention even if the filter temperature sensors fail. Sensors using different measurement principles for filter temperature can be used. This also improves reliability.

[0046] If the gas mixture flows through the filter unit and the filter unit receives the gas to be filtered, the filter unit often heats up unevenly throughout its entire extent. More precisely, it heats up at each moment in a corresponding absorption region inside the filter unit, and over time this absorption region moves across the filter unit from the inlet to the outlet until the filter unit can no longer receive other gases. A design in which the first measuring region is positioned downstream of the second measuring region allows full utilization of this just described fact. Typically, the second filter temperature sensor first measures the increased temperature, and then the first filter temperature sensor measures the increased temperature. This design, with two distinct measuring regions inside the filter unit, allows for predictions with even greater reliability as to when the filter unit is depleted or will be depleted. This advantage is particularly achieved if the evaluation unit at least once determines the spatial variation curve of the filter temperature.

[0047] Possibly, the sensor assembly includes a third and optional fourth filter temperature sensor, wherein these additional sensors measure the temperature at one or more scales within a third or optional fourth measurement region inside the filter unit. Viewed along the flow direction of the gas mixture through the filter unit, the first measurement region is arranged downstream of the second measurement region, the second measurement region is arranged downstream of the third measurement region, and the third measurement region is arranged downstream of the optional fourth measurement region.

[0048] In a preferred design, the determination is additionally based on the ambient temperature, such as the temperature of the room where the filter assembly is used. This is because the internal temperature of the filter unit typically depends not only on the amount of gas received but also, additionally, on the ambient temperature. The evaluation unit of the sensor assembly, which processes the aforementioned signals, compares at least one temperature measurement for the first measurement area with the measured ambient temperature. The evaluation unit automatically generates a notification with information about the current state of the filter unit based on the comparison result. Therefore, the pre-defined standard depends on the difference between the temperature in the first measurement area and the ambient temperature. This notification is output in a human-perceptible form. Optionally, the evaluation unit compares the temporal variation curve of the temperature in the first measurement area with the ambient temperature. In many cases, the ambient temperature can be considered constant over time. It is also possible to measure the ambient temperature multiple times sequentially. In one design, the evaluation unit compares the spatial variation curve of the filter temperature with the ambient temperature at least once, wherein, preferably, the spatial variation curve and the ambient temperature refer to the same moment.

[0049] In one implementation of this design, the sensor assembly includes an ambient temperature sensor. This ambient temperature sensor is capable of measuring a measure of the temperature in the environment in which the filter assembly is located. In another implementation, the sensor assembly is capable of receiving a signal containing a measure of the ambient temperature. This measure of the ambient temperature is measured by an external ambient temperature sensor. "External" means that the ambient temperature sensor is spatially located away from the filter assembly and is not necessarily part of the filter assembly.

[0050] In some cases, designs that measure and use ambient temperature allow for faster detection of events indicating that the filter unit is about to need replacement. That is, in some situations, this event can be detected without knowing the temporal or spatial variation curves of the temperature.

[0051] The following describes several possible design schemes for the first filter temperature sensor. Optional second and third filter temperature sensors can also be designed according to one of these design schemes, respectively. These design schemes can also be combined, that is, the first filter temperature sensor is implemented according to a first design scheme and the second filter temperature sensor is implemented according to a different second design scheme. It is also possible that at least two filter temperature sensors of the filter assembly are implemented according to the same design scheme.

[0052] In a preferred design, the filtration unit includes a filter housing and a filter. During operation, the filter is inserted into the filter housing. The filter includes filter media capable of filtering out and receiving gas and becoming heated. The gas mixture flows into the filter housing through an inlet opening, into the filter through an inlet, passes through the filter at least once, exits the filter through an outlet, and exits the filter housing through an outlet opening. When a filter is inserted, preferably, the inlet and outlet of the filter are located within a space enclosed by the filter housing. The filter can be removed from the filter housing and replaced by a new filter. Preferably, multiple filters are sequentially housed within the same filter housing.

[0053] Typically, when the filter is replaced, the rest of the filter assembly remains unchanged. In particular, it is not necessary to interrupt the fluid connection between the filter housing and the medical device or fluid housing to replace the filter. The gas containing the gas mixture to be filtered is directed to the filter housing, then flows through the filter and exits again from the filter housing, where the filter is installed.

[0054] In one implementation, the first filter temperature sensor is installed within the wall of the filter housing. A gap exists between the first filter temperature sensor in the wall and the filter installed in the filter housing. Therefore, the first filter temperature sensor is also spatially separated from the first measurement area.

[0055] This design eliminates the need to equip the filter itself with a filter temperature sensor. More precisely, the same filter temperature sensor located in the wall of the filter housing can be used sequentially for multiple filters. This reduces the required material costs. Furthermore, compared to the case where the filter temperature sensor is part of the filter being used, it is easier to establish a wired data connection between the first filter temperature sensor in the wall and the evaluation unit that processes the signal.

[0056] A gap exists between the first filter temperature sensor in the wall of the filter housing and the first measuring area. When the filter receives the gas to be filtered from the flowing gas mixture, the filter becomes hot, and more precisely, it also becomes hot in the first measuring area. Therefore, compared to other states, during the period when the first measuring area receives gas and thus becomes hot, the first measuring area radiates a greater amount of electromagnetic radiation in the infrared range.

[0057] In one implementation, the first filter temperature sensor located in the wall of the filter housing is designed as an infrared sensor or includes at least one infrared sensor. The infrared sensor or each infrared sensor is capable of measuring the amount and / or intensity of infrared radiation emitted by the filter and incident on the infrared sensor. Other embodiments of a sensor for non-contact measurement of filter temperature located in the wall are also possible.

[0058] The design scheme of having a filter temperature sensor in the wall eliminates the necessity in many cases that the actual size of the filter and / or filter housing precisely matches a pre-given size and that the filter is correctly positioned within the filter housing. More specifically, in many cases, if the distance between the first measuring area and the infrared sensor varies from filter to filter, the infrared sensor can also reliably measure the temperature in the first measuring area.

[0059] In another implementation of the first filter temperature sensor located within the wall of the filter housing, a thermal sensor establishes thermal contact between the filter and the first filter temperature sensor. The sensor extends into a first measurement area. The sensor bridges the gap between the filter and the filter housing and transfers heat generated by the filter to the first filter temperature sensor. Furthermore, the first filter temperature sensor includes a transducer. This transducer is capable of generating a signal, preferably an electrical signal, based on the current temperature of the sensor, and more precisely, based on the temperature of the thermal sensor.

[0060] The design scheme with thermal contact in some cases results in a particularly simple mechanical implementation and in others is more robust to environmental impacts, such as pollution, than other possible implementations.

[0061] In another design, the first filter temperature sensor includes a measuring element and a receiver. The measuring element is disposed inside the filter. The receiver is placed within the wall of the filter housing. The measuring element is capable of generating a signal that depends on the temperature in the first measuring region. If the filter is installed in the filter housing, a data connection is established at least temporarily between the measuring element and the receiver, preferably via radio waves. Through this data connection, the signal from the measuring element is transmitted to the receiver.

[0062] The design of having a measuring element in the filter allows the measuring element to be positioned in a first measuring region or at least very close to the first measuring region. In some cases, this also allows for reliable and / or rapid measurement of only relatively small temperature rises in the filter. In some cases, the design of having a measuring element is less dependent on environmental conditions, especially on ambient temperature and humidity.

[0063] Another design approach eliminates the need for detecting and processing electrical measurements or signals in many cases. Therefore, this alternative design typically eliminates the need for a signal processing evaluation unit for the filter assembly. The design approach described below can also be used in conjunction with an evaluation unit.

[0064] According to this alternative design, the first filter temperature sensor includes a chemical indicator element. This chemical indicator element is in thermal contact with the filter. For example, the chemical indicator element may be externally applied to the filter. The chemical indicator element is either in a first state or at least in a second state, wherein whether the chemical indicator element is in the first state or in one of the second states depends on the temperature in the first measurement area. Whether the chemical indicator element is in the first state or the second state can be perceived visually. These two states are distinguished from each other in a visually perceptible manner. For example, an increase in temperature in the first measurement area causes a color change. Therefore, when using the chemical indicator element, the filter assembly visually outputs a notification with information about the current state.

[0065] In one implementation, an observation window is placed within the filter receiving section, allowing a user to determine the current state of the chemical indicator element from the outside through the observation window. This design leads to a particularly simple implementation that does not require a signal processing evaluation unit. In another implementation, the sensor assembly includes a color sensor, such as a camera, wherein the color sensor is capable of automatically determining the state of the chemical indicator element. The implementation with the observation window and the implementation with the color sensor can be combined, for example, by the color sensor determining the state of the chemical indicator element through the observation window.

[0066] In one implementation, the chemical indicator element covers the entire perimeter of the filter. If the filter has a cylindrical shape, the chemical indicator element may have, for example, a stripe shape on its circumference. This design, where the chemical indicator element covers the entire perimeter of the filter, eliminates the need to insert the filter into the filter housing at specific rotational positions. More precisely, the chemical indicator element can be seen through an observation window in every position of the inserted filter.

[0067] Possibly, the filtration unit includes at least two chemical indicator elements, wherein one chemical indicator element is arranged downstream of the other. The sequence of chemical indicator elements visually indicates how the absorption zone described above moves from the inlet through the filtration unit to the outlet.

[0068] According to the present invention, the filtration unit is capable of filtering out at least one gas from a gas mixture. In one design, the gas to be filtered out is an anesthetic, also known as a poison. Many anesthetics have boiling points between 25°C and 50°C and therefore often evaporate at room temperature.

[0069] In one application, the filter assembly according to the invention is used for artificial respiration of a patient. The filter assembly filters out a gas, such as an anesthetic or carbon dioxide, from a gas mixture, which is then directed to or away from the patient.

[0070] Furthermore, the present invention relates to a system capable of providing artificial respiration to a patient. The system includes a ventilator, a fluid delivery unit, and a filter assembly according to the invention. Tubes, such as double-lumen tubes and tubing, are two examples of the fluid delivery unit. For example, the patient-side coupling unit includes a breathing mask or a tube or catheter.

[0071] The fluid delivery unit establishes at least a temporary fluid connection between the ventilator and the patient-side coupling unit. The patient-side coupling unit is located within or on the patient's body, or may be located there. The ventilator is capable of delivering a gas mixture through the fluid delivery unit and thereby through the established fluid connection to the patient-side coupling unit. This gas mixture includes oxygen and at least one other gas, such as breathing air or an anesthetic. The gas mixture reaches the patient's respiratory system via the patient-side coupling unit. In one design, the ventilator is capable of performing a series of breathing cycles, wherein a certain amount of the gas mixture is delivered through the fluid connection to the patient-side coupling unit in each breathing cycle.

[0072] The filter assembly according to the invention is temporarily in fluid connection with a fluid delivery unit located between the ventilator and the patient side. The filter assembly according to the invention filters out at least one gas from a gas mixture flowing through the fluid delivery unit and through the filter unit of the filter assembly. Such gas may be, for example, carbon dioxide or an anesthetic.

[0073] In a preferred design, the respirator is designed as an anesthesia machine. Preferably, the respirator designed as an anesthesia machine includes an anesthetic vaporizer or anesthetic vaporizer capable of feeding at least one gaseous anesthetic into a carrier gas flow. The anesthesia machine delivers a gas mixture to a coupling unit on the patient side, wherein the gas mixture includes oxygen and at least one anesthetic and is generated by the anesthetic vaporizer or anesthetic vaporizer. This gas mixture sedates or anesthetizes the patient.

[0074] A preferred ventilation circuit is established, wherein the anesthesia machine delivers a gas mixture to a coupling unit on the patient side and the air exhaled by the patient flows back to the anesthesia machine. This exhaled air contains carbon dioxide and typically contains the anesthetic agent, or each of the delivered agents. Preferably, a CO2 absorber filters the carbon dioxide from the exhaled air.

[0075] If the breathing circuit just described is established, in one implementation, the filter assembly according to the invention is arranged in the section of the breathing circuit that guides exhaled air from the patient side coupling unit back to the anesthesia machine. The exhaled air is guided through the filter unit. In another implementation, a certain amount of gas mixture branches off from the breathing circuit, is guided to the filter assembly according to the invention, is guided through the filter unit, and is guided back to the breathing circuit.

[0076] The air exhaled by a patient typically contains an anesthetic. An anesthetic and a carrier gas are usually mixed into the breathing circuit, thus requiring the excess of the gas mixture to be removed from the breathing circuit. The filter assembly according to the invention reduces the risk that anesthetic contained in the excess gas mixture may escape into the environment and affect personnel within the breathing circuit or impact fixed hospital infrastructure. Alternatively, the filter assembly according to the invention may filter out carbon dioxide from the exhaled air. It is also possible that the filter assembly according to the invention filters out not only at least one anesthetic but also carbon dioxide. Attached Figure Description

[0077] The invention will now be described with the aid of embodiments. Here: Figure 1 A respiratory system with an anesthesia machine and a filtration unit is shown; Figure 2 An exemplary filter unit is shown in a side view, wherein the filter inlet and outlet are arranged near the bottom; Figure 3 Another exemplary filter unit with a forced guidance mechanism for excess gas is shown in top view; Figure 4 An exemplary diagram illustrates the spatial variation curve of temperature in the filter unit, i.e., the correlation between temperature and location; Figure 5 A first design for a filter temperature sensor with a sensor located inside the filter element is shown; Figure 6 A second design for a filter temperature sensor with a thermal contact element on the outer surface of the filter cartridge is shown; Figure 7 A third design for a filter temperature sensor with a non-contact infrared sensor is shown. Figure 8 A fourth design for a filter temperature sensor with multiple chemical indicating elements located on the filter cartridge is shown. Detailed Implementation

[0078] In this embodiment, the invention is used to perform artificial respiration on patient P and, in this case, to deliver at least one anesthetic to the patient. When artificial respiration is performed on patient P, for example, in a hospital lobby or on a vehicle or airplane, the patient is in a space that is at least partially enclosed.

[0079] Figure 1 A medical system 100 is schematically illustrated for anesthetizing or sedating a patient P and for performing artificial respiration. A patient-side coupling unit 39, such as a breathing mask, tube, or catheter, is schematically positioned on or within the patient P's body. A gas mixture is supplied to the patient P via an inspiratory gas line 27, which flows to the patient-side coupling unit 39. This gas mixture contains oxygen and is mixed with at least one anesthetic to keep the patient P sedated or anesthetized. The oxygen content in the gas mixture may be higher than the oxygen content in the breathing air. The breathing air exhaled by the patient P contains carbon dioxide (CO2) and may also contain traces of the administered anesthetic. The exhaled breathing air is expelled via an expiratory gas line 28, which in this embodiment is inhaled. Two gas lines 27, 28 are connected to a medical device in the form of an anesthesia machine 1, which maintains gas flow in the breathing circuit to supply the patient P with breathing air and anesthetic and to inhale and receive the exhaled air. This breathing circuit includes gas lines 27 and 28 and a patient-side coupling unit 39, and is guided through the anesthesia machine 1. The two gas lines 27 and 28 together form the fluid delivery unit of this embodiment, which at least temporarily establishes a fluid connection between the anesthesia machine 1 and the patient-side coupling unit 39.

[0080] The anesthesia machine 1 is supplied with pressurized breathing air, pure oxygen (O2), and nitrous oxide (N2O) from the hospital infrastructure, generating a gas mixture. In this embodiment, the anesthesia machine 1 includes the following components: - Gas mixer 29, which generates a mixture from at least two or three delivered gases, namely breathing air, O2, and N2O, which is used as a carrier gas for an anesthetic, wherein the gas mixer 29 can be constructed as described in DE 10 2008 057180 B3. - A fluid delivery unit 5, such as a blower, pump, or piston-cylinder unit, wherein the fluid delivery unit 5 moves the gas mixture through the breathing circuit and thereby maintains the airflow in the breathing circuit. -Anesthetic vaporizer 2, which includes a tank for liquid anesthetic and a vaporizer unit, and - Preferably, a filter unit 3 with a lime filter is installed inside the device, wherein the filter unit 3 filters out CO2 from the breathing air exhaled by the patient P and exited via the exhalation gas tubing 28.

[0081] The anesthetic vaporizer 2 incorporates anesthetic from the anesthetic tank into the carrier gas. For example, the vaporizer unit of the anesthetic vaporizer 2 vaporizes the anesthetic in the tank and / or sprays it into the carrier gas.

[0082] The anesthesia machine 1 delivers gas to the breathing circuit. The filtration unit 3 extracts gas, particularly CO2, from the breathing circuit. At equilibrium, more gas is delivered to the breathing circuit than is extracted. Therefore, the excess gas needs to be expelled from the breathing circuit. This excess gas is hereinafter referred to as "excess gas" and acts as a gas mixture. This excess gas typically contains traces of the exhaled anesthetic. The anesthetic or each anesthetic should be filtered out from this gas mixture. In this embodiment, the anesthetic or each anesthetic acts as the gas to be filtered out.

[0083] The excess gas branches off from the breathing circuit at branch point 24, and more precisely, branches off via delivery line 6 and subsequently, downstream, discharge line 8. This branching is achieved in two different ways: on one hand, the fluid delivery unit 5 discharges gas and delivers the discharged excess gas into delivery line 6, wherein the volumetric flow rate of the discharged excess gas varies over time, and the idealized time-varying curve of the volumetric flow rate has, for example, a half-sine curve shape. On the other hand, the discharged excess gas is guided through discharge line 8 and, in one design, is inhaled.

[0084] In this embodiment, the discharge line 8 leads to a fixed fluid receiving section 7, which is placed within the wall W. The fluid receiving section 7 is preferably part of a fixed hospital infrastructure that receives and delivers gases discharged from various medical devices. An inhalation pump 10 draws the gas into the discharge line 8 and delivers it to the fluid receiving section 7. The inhalation pump 10 can be positioned in front of or behind the wall W.

[0085] An optional volumetric flow sensor 9 measures the volumetric flow rate, i.e., the volume per unit time, flowing through the discharge line 8. For example, the volumetric flow sensor 9 measures the pressure difference between two measuring points in the discharge line 8, where one measuring point is located downstream of the other. In one design, the suction pump 10 is controlled based on the signal from the volumetric flow sensor 9, with an adjustment target such that the actual volumetric flow rate through the discharge line 8 equals a desired, predetermined volumetric flow rate. This automatically adjusts the actual volumetric flow rate in the discharge line 8.

[0086] The delivery line 6 guides excess gas from the anesthesia machine 1 to the filter unit 4, which will be further described below and is part of the filter assembly according to the invention. The excess gas flows through the filter unit 4 at least once, and optionally multiple times. In this case, the filter unit 4 filters out the anesthetic or at least one, preferably each, anesthetic from the flowing excess gas. The excess gas purified of the anesthetic flows into the discharge line 8.

[0087] The ambient temperature sensor 21 measures the ambient temperature in the surrounding environment of the filter unit 4.

[0088] Figure 2 An exemplary design of the filter unit 4 is shown. The filter unit 4 includes a filter element 11 for an anesthetic and a cylinder 20 in the form of a cylinder or truncated cone, wherein the cylinder 20 surrounds the filter element 11. Preferably, the cylinder 20 completely and airtightly surrounds the filter element 11, except for the openings described below. In a preferred design, the filter element 11 includes loose material surrounded and held by the cylinder 20 from all sides. Preferably, the loose material includes activated carbon. The cylinder 20 prevents the loose material from escaping. Alternatively, instead of activated carbon or in addition to activated carbon, the filter element 11 may include zeolite, organometallic filters, and / or Kieselgene. In this embodiment, a surrounding protrusion 12 is mounted on the upper part of the cylinder 20. The filter element 11, the cylinder 20, and the optional protrusion 12 together constitute the filter of this embodiment.

[0089] Furthermore, the filter unit 4 includes a filter housing in the form of a can 13, wherein the can 13 is rotationally symmetrical about a central axis, which is vertically arranged and positioned during use. Figure 2 and Figures 5 to 8 The drawing plane shows the can 13, which preferably has a circular bottom perpendicular to the central axis and a tubular circumferential surface surrounding the central axis. The can can also have a cylindrical or truncated cone shape. Two openings 22.1 and 22.2 are inserted into the circumferential surface of the can 13, and more precisely, in the illustrated embodiment, are placed near the upper edge of the circumferential surface.

[0090] A surrounding seal 41 is fitted onto the upper edge of the circumference of the canister 13. Approximately cylindrical filters 11, 20, and 12 can be inserted into and removed from the canister 13 from above. The surrounding protrusion 12 is supported on the seal 41 at the upper edge of the circumference. Due to the protrusion 12 and the seal 41, the risk of a considerable amount of gas mixture leaking from the canister 13 into the surrounding environment is minimal. Optionally, a cap (not shown) can be fitted onto the canister 13 from above and removed again.

[0091] A tubular gap 19 appears between the circumferential surface of the tank 13 and the cylinder 20, see [reference]. Figure 3 The tank-to-transport line 16 in tank 13 is fluid-tightly connected to the transport line 6, guiding the transported excess gas from opening 22.1 toward the bottom of tank 13 and terminating in the discharge opening 14. The tank-to-discharge line 32 in tank 13 is fluid-tightly connected to the discharge line 8, guiding the excess gas flowing from filters 11, 20, 12 toward the discharge line 8, starting at the entry opening 35 or at the height of the bottom of cylinder 20 and leading to opening 22.2.

[0092] If the cylinder 20 is correctly, and particularly in the correct rotational position, inserted into the tank 13, in one design, the discharge opening 14 of the tank-to-conveyor line 16 overlaps with the inlet opening 25 in the cylinder 20. The inlet opening 35 of the tank-to-discharge line 32 overlaps with the outlet opening 34 in the cylinder 20. The two openings 14 and 35 are located near the circumference of the cylinder 20 and near the bottom of the tank 13, while the two openings 25 and 34 are located in the middle of the circumference of the cylinder 20 and near the bottom.

[0093] In the illustrated example, excess gas is introduced into filters 11, 20, and 12 from below through inlet opening 25. The arrows in filter element 11 exemplarily illustrate the direction in which excess gas flows through filter element 11, see [reference needed]. Figure 2 .

[0094] It is also possible that the discharge opening 14 of the tank-transfer line 16 is located near the lid of the tank 13 and / or the inlet opening 25 in the cylinder 20 is located near the surrounding protrusion 12.

[0095] Figure 3 A design is shown in which excess gas is forcibly guided as it flows through filter unit 11 and thus flows through filter unit 11 twice. Figure 3 The drawing plane is horizontal and perpendicular to Figure 2The drawing plane, and the central axis of the tank 13 and filters 11, 20, 12 is perpendicular to the plane. Figure 3 The drawing plan shows a circular gap 19 between the filters 11, 20, 12 and the tank 13.

[0096] In this implementation, wall 38 is installed inside the filters 11, 20, and 12, and this wall is impermeable to the fluid. Wall 38 extends parallel to the central axis of filter 11, which is perpendicular to... Figure 3 The wall, preferably spaced from the central axis and preferably having a flat or curved surface along the vertical axis, is the plan view of the drawing. The wall 38 divides the cylinder 20, and thus the filter element 11 within the cylinder 20, into an ascending region Au and a descending region Ab for the flow of the gas mixture. See [reference needed] Figure 3 Viewed from a direction parallel to the central axes of filters 11, 20, and 12, both the rising region Au and the falling region Ab have cross-sections in the form of arc segments. The rising region Au is in fluid connection with the inlet opening 25.

[0097] In all designs, the filter element 11 filters out at least one anesthetic from the excess gas. The excess gas flows through the delivery line 6 into the tank-to-delivery line 16 and through the tank-to-delivery line 16, entering the filter element 11 through the inlet opening 25 in the cylinder 20. Ideally, all anesthetic is extracted from the excess gas in the filter element 11. Subsequently, the excess gas is discharged from the filter element 11 through the outlet opening 34, flows through the inlet opening 35 into the tank-to-discharge line 32, and through the tank-to-discharge line 32 into the discharge line 8.

[0098] The filter element 11 absorbs the anesthetic or each of the anesthetics. In many cases, the filter material binds to the molecules of the anesthetic. This process is exothermic for each filter material used in the filter element 11 of this embodiment. Therefore, heat is released when anesthetics are absorbed. The present invention utilizes this fact. If activated carbon is used as the filter material, then the filter material will, in many cases, heat up by at least 4°C at the usual concentration of the anesthetic until the filter element 11 is completely incorporated and can no longer absorb other anesthetics. In many cases, a temperature rise of at least 4°C can be reliably detected.

[0099] Figure 4An exemplary diagram illustrates how the internal temperature of the filter element 11 at a given moment varies with location, i.e., spatially. In this schematic, excess gas flows into the filter element 11 from above through inlet opening 25, flows through the filter element 11, and exits the filter element 11 through outlet opening 34, which is located at the bottom of the filter element 11. Note: Because the excess gas contains an anesthetic, it is typically heavier than air and sinks.

[0100] The diagram to the left of the filter unit 4 shows the position x along the flow direction of excess gas on the x-axis (from top to bottom). L represents the length of the filter element 11 along the flow direction, i.e., in... Figure 4 The vertical extension is shown. Position x = 0 represents the inlet opening 25 of the filter element 11, and position x = L represents the outlet opening 34 of the filter element 11. The temperature Temp at a specific moment, depending on the position, is plotted on the y-axis. It can be seen that in x... max The maximum value at x. The filter element 11 is currently orbiting this maximum value x. max The area receives the anesthetic. From x=0 to x=x max The subsequent areas have been largely infused with anesthetics.

[0101] The peak temperature x max The absorption area where the filter element 11 currently receives the anesthetic moves over time from the inlet opening 25 through the filter element 11 toward the outlet opening 34. Therefore, the first measuring position MP is preferably located near the outlet opening 34, at which the current internal temperature of the filter element 11 is measured according to the invention. By measuring the temperature at this first measuring position MP, the following event can be identified: the temperature peak x max It has almost reached the outlet opening 34 and the filter element 11 can only receive a small amount of other anesthetics.

[0102] It is possible that the corresponding current temperature can be additionally measured at other measurement locations MP.2, MP.3, ..., MP.n, wherein these additional measurement locations MP.2, MP.3, ..., MP.n are located between the inlet opening 25 and the first measurement location MP. Typically, at any given time, the corresponding current temperature in the filter element 11 depends on the measurement location MP, MP.2, ... where that temperature was measured. The temperature peak value x max Over time, the temperature peak moves from inlet opening 25 towards outlet opening 34. Here, the temperature peak successively passes through measurement positions MP.n, ..., MP.2, MP. In many cases, from the temperature peak x... maxThe time-varying curve, i.e., the movement, can predict when the filter element 11 will be depleted and therefore must be replaced.

[0103] The signal processing evaluation unit 26 receives signals from at least one filter temperature sensor described below and preferably from the ambient temperature sensor 21, see [link to relevant documentation]. Figure 2 and Figures 5 to 7 The measured ambient temperature serves as a reference value and can affect the temperature of the filter element 11. Each filter temperature sensor measures the internal temperature of the filter element 11 at measurement positions MP, MP.2, ..., MP.n. The evaluation unit 26 receives signals from each filter temperature sensor and from the ambient temperature sensor 21, and determines the current state of the filter element 11 based on the measured internal temperature of the filter element 11 and the measured ambient temperature.

[0104] The evaluation unit 26 can control the status display 17. If the filter element 11 has received so much anesthetic that the filters 11, 20, and 12 must be replaced, a notification, such as an alarm, is output on the status display 17 in a human-perceptible form. This notification includes information about the current status of the filter element 11. The alarm can also indicate a time period after which the filters 11, 20, and 12 must be replaced.

[0105] The following reference Figures 5 to 8 This section describes four possible design schemes for a filter temperature sensor. It is possible that the filter assembly includes multiple filter temperature sensors, where using multiple designs from these schemes introduces redundancy and, in some cases, improves reliability compared to a single measurement principle. Alternatively, it is possible that the filter assembly includes multiple filter temperature sensors constructed in the same manner, i.e., using the same measurement principle.

[0106] exist Figure 5In the illustrated embodiment, the measuring element 15 measures the temperature inside the filter element 11 and at a first measuring position MP near the outlet opening 34 in the cylinder 20. This measuring element 15 is positioned inside the filter element 11 at the first measuring position MP. If excess gas has reached this first measuring position MP, it has already traversed most of its path through the filter element 11. The measuring element 15 is in data connection via a signal line 18 to a filter-side contact element 44 inside the cylinder 13, which bridges the gap 19 between the filters 11, 12, 20 and the cylinder 13. The signal line 18 is positioned inside the filter element 11. A cylinder-side contact element 45 is inserted into the circumference of the cylinder 13. The filter-side contact element 44 establishes a data connection between the measuring element 15 and the cylinder-side contact element 45, and is preferably also mechanically connected to the cylinder-side contact element 45.

[0107] In one design, the filter-side contact surface 47 is inserted into the cylinder 20, and this contact surface makes electrical contact with the signal line 18 on its inner surface and with the filter-side contact element 44 on its outer surface. This filter-side contact surface 47 can include a ring or annular segment, such that electrical contact between the signal line 18 and the contact element 44 is established in many or even all possible rotational positions of the filters 11, 20, 12 relative to the tank 13.

[0108] Elements 18, 47, and 44 establish a data connection between measuring element 15 and contact element 45. The signal from measuring element 15 is transmitted to contact element 45 via this data connection and from there further to evaluation unit 26. Furthermore, evaluation unit 26 obtains a measurement value from ambient temperature sensor 21. Evaluation unit 26 compares the signal from measuring element 15 with the measured ambient temperature and determines whether the filter unit 11 can still receive other anesthetics.

[0109] It is possible that another sensor (not shown) is arranged at at least one additional measurement location MP.2, ..., MP.n. The measurement values ​​of said or each additional sensor are also transmitted to the evaluation unit 26 via signal lines and contact elements.

[0110] Figure 6 and Figure 7A preferred design is shown in which the measuring element 15 and signal line 18 are not required for the filter element 11. Instead, the temperature sensor for each filter is located entirely outside the filters 11, 20, and 12. Thus, the same filter temperature sensor can be reused sequentially to monitor multiple filters 11, 20, and 12. No special treatment is required for the measuring element 15 and signal line 18 when reprocessing or cleaning used filters 11, 20, and 12.

[0111] In accordance with Figure 6 In the design, the filter-side contact element 49 is arranged inside the tank 13 and bridges the gap 19 between the cylinder 20 and the tank 13. The filter-side contact element 49 is in thermal contact with the outer surface of the cylinder 20 and is preferably positioned as close as possible to the measurement position MP. (This is similar to...) Figure 5 As in the design, the annular filter-side contact surface 47 can be inserted into the cylinder 20 and as close as possible to the first measurement position MP. However, this filter-side contact surface 47 is used to establish thermal contact. Elements 47 and 49 together function as sensors.

[0112] The contact element 49 on the filter side transfers heat from the filter element 11 to the measuring element 48 on the tank side. The measuring element 48 on the tank side acts as a transducer and generates an electrical signal based on the heat transferred by the contact element 49 on the filter side. Examples of implementations of this measuring element 48 are thermocouples, PTC sensors, or NTC sensors.

[0113] It is possible that at least one additional sensor is located near another measurement location, MP.2, ..., MP.n. Figure 6 In this example, a second measuring element 48.2 on the can side is additionally inserted into the circumferential surface of the can 13. A second contact element 49 on the filter side bridges the gap 19 between the inserted filters 11, 20, 12 and the circumferential surface of the can 13. Another contact surface 47.2 on the filter side can be inserted into the cylinder 20 and, more precisely, near the second measuring position MP.2.

[0114] Figure 7A design is shown in which a filter temperature sensor 46 measures the temperature at a measurement location MP inside the filter element 11 without contact. This design depends less on the relative position of the installed filters 11, 20, 12 with respect to the tank 13 and also less on the actual maximum diameter of the filters 11, 20, 12, which may vary from filter to filter. The filter temperature sensor 46 is preferably placed within the circumferential surface of the tank 13 and as close as possible to the measurement location MP. It is possible that at least one additional filter temperature sensor 46.2 measures the temperature at other measurement locations MP.2, ..., MP.n without contact.

[0115] In a preferred implementation, the filter temperature sensor 46 measures the intensity and / or amount of infrared radiation emitted by the filter element 11 and penetrating outward through the cylinder 20. The measurements from the filter temperature sensors 46, 46.2 are transmitted to the evaluation unit 26. Examples of filter temperature sensors 46, 46.2 used for measuring the amount of infrared radiation are thermoelectric sensors, CCD cameras, thermal imaging cameras, multiple infrared thermocouples, or multiple thermopile systems. Alternatively, an infrared camera (thermal imaging camera) may be used as the filter temperature sensor 46.

[0116] Figure 8A design is shown that does not require a measurement unit 26 for data transmission and signal processing, but can be used in combination with such a measurement unit 26. At least one chemical indicator element 50, preferably additionally at least one other chemical indicator element 50.2, ..., 50.n, and particularly preferably a series of chemical indicator elements 50, 50.2, ..., 50.n, are applied to the outer surface of the filter cartridge 20, wherein the series extends parallel to the central axis of the filter cartridge 20. Each chemical indicator element 50, 50.2, ..., 50.n is located near a measurement position MP, MP.2, ..., MP.n, respectively. Each chemical indicator element 50, 50.2, ..., 50.n has a visually perceptible first state when the temperature at the measurement position MP, MP.2, ..., MP.n is below a predetermined temperature limit, and a visually perceptible second state when the cartridge temperature exceeds this temperature limit, wherein the second state is optically different from the first state. Each measuring position MP, MP.2, ..., MP.n is located on the cylinder 20 and around or near the corresponding chemical indicator element. For example, when the cylinder temperature exceeds a temperature limit, the indicator elements 50, 50.2, ..., 50.n change their color, i.e., show a color change. The temperature limit is selected such that when the filter element 11 has not yet received an anesthetic at the corresponding measuring position MP, MP.2, ..., MP.n, the cylinder temperature is below the temperature limit, and when the filter element 11 can no longer receive other anesthetics at the measuring position MP, MP.2, ..., MP.n, the cylinder temperature is above the temperature limit.

[0117] exist Figure 8 In the example, the indicator element 50.n, located at the furthest downstream end, already has a second state, which is outlined by a shading line, while the remaining indicator elements 50.3, 50.2, and 50 still have a first state outlined by white.

[0118] The observation window 37 is placed into the circumference of the can 13, and the observation window is... Figure 8 The diagram is schematically shown. Each of the indicator elements 50, 50.2, ..., 50.n is visible from the outside through the viewing window 37. The user can clearly see the current state of each of the indicator elements 50, 50.2, ..., 50.n from behind the viewing window 37. Alternatively, the camera and image evaluation unit (neither shown) may automatically determine whether the indicator elements 50, 50.2, ..., 50.n are currently in a first state or a second state. In one design, the camera is placed inside the tank 13, and in another design, the viewing window 37 is positioned between the camera and the indicator elements 50, 50.2, ..., 50.n.

[0119] List of reference numerals in the attached diagram: 1 Anesthesia machine, including anesthetic vaporizer 2, gas mixer 29, CO2 lime filter 3 and fluid delivery unit 5. 2 The anesthetic vaporizer in the anesthesia machine 1 includes an anesthetic tank 49. 3 A lime filter that filters CO2 from exhaled air. 4 The filtration unit, which filters the anesthetic from the gas output from the anesthesia machine 1, includes a filter element 11 in a cylinder 20, a cylinder 20 with protrusions 12, and a canister 13, which is connected to the delivery line 6 and the discharge line 8. 5 The fluid delivery unit of the anesthesia machine 1 that moves gas in the breathing circuit, for example, in the form of a pump. 6 The delivery tubing runs from the anesthesia machine 1 to the filter unit 4. 7 The hospital infrastructure has a fixed gas containment section, enclosed by a wall W, connected to a filter unit 4 via an exhaust pipe 8. 8 The discharge pipe leads from the filter unit 4 to the gas container 7. 9 Volumetric flow sensor in discharge pipe 8 10 The suction pump, located at the discharge line 8 or in the fluid receiving section 7, is in fluid connection with the discharge line 8. 11 The cylindrical activated carbon filter of filter unit 4 acts as a filter element and is surrounded by cylinder 20. 12 The circumferential protrusion of the cylinder 20 rests on the upper edge of the can 13, preferably on the circumferential seal 41. 13 A tank, into which a delivery pipe 6 is introduced and out of which a discharge pipe 8 is led, the tank having a cylindrical or truncated conical shape and serving as a filter housing. 14 The discharge opening of the tank conveying pipeline 16 is located at the lower end of the tank conveying pipeline 16, and overlaps with the inlet opening 25 when the cylinder 20 is loaded. 15 The measuring element measures the temperature of the filter element 11 at a first measuring position MP inside the filter element 11 and is connected to the signal line 18. 16 The tank delivery pipeline inside tank 13 forms a fluid-sealed continuation of delivery pipeline 6, guides gas from delivery pipeline 6 to the bottom of tank 13, and terminates in discharge opening 14. 17 The status display for filter element 11 is controlled by evaluation unit 26 and is capable of outputting alarms. 18 The signal line inside the filter element 11 runs from the measuring element 15 to the contact surface 47. 19 The circumferential gap between filters 11, 20, 12 and the inner wall of tank 13 20 A cylindrical tube surrounds the filter element 11, including surrounding protrusions 12, and in one design includes indicator elements 50, 50.2, ... 21 An ambient temperature sensor measures the temperature in the environment used for filter components. 22.1 The delivery pipeline 6 terminates in the opening on the circumferential surface of the tank 13. 22.2 The discharge pipe 8 begins in the opening on the circumferential surface of the tank 13. 24 A branch point in the breathing circuit, where excess gas branches out of the breathing circuit and where the delivery line 6 begins. 25 The inlet opening at the bottom or near the cover of cylinder 20 overlaps with the outlet opening 14 when filters 11, 20, and 12 are installed. 26 The evaluation unit that processes the signal receives measured values ​​from the temperature sensor 21 of each filter and the ambient temperature sensor 21 and determines the current state of the filter element 11. 27 Inspiratory gas tubing, used to supply breathing air to patient P. 28 The expiratory air tubing is used to draw in the breathing air exhaled by patient P. 29 The gas mixer of anesthesia machine 1 produces a carrier gas for the anesthetic agent. 32 The tank discharge pipe inside tank 13, starting from the inlet opening 35, guides gas from the bottom of tank 13 to the discharge pipe 8. 34 The discharge opening near the bottom of cylinder 20 overlaps with the inlet opening 35 when filters 11, 20, and 12 are installed. 35 The inlet opening of the tank discharge pipe 32 is in fluid connection with the outlet opening 34 when filters 11, 20, and 12 are installed. 37 Observation window on the periphery of tank 13 39 The coupling unit on the patient side is located inside or on the patient P's body. 41 The surrounding seal on the upper edge of can 13 44 The contact element on the filter side electrically bridges the gap 19 between the canister 13 and the filters 11, 20, and 12. 45 The contact element on the tank side of the wall of tank 13 makes thermal contact with the contact element 44 on the filter side, generates measurement values, and transmits these measurement values ​​to the evaluation unit 26. 46 A non-contact filter temperature sensor measures the amount of infrared radiation generated by the filter element 11 at the measurement position MP. 46.2 A second filter temperature sensor, operating without contact, measures the amount of infrared radiation generated by the filter element 11 at measurement position MP.2. 47 The contact surface located in the cylinder 20 and near the first measurement position MP contacts the signal line 18 (only in designs with measuring element 15) and the contact elements 44 and 49 on the filter side. 47.2 The contact surface located in the cylinder 20 and near the first measuring position MP is in contact with the contact element 49.2 on the filter side. 48 The measuring element on the tank side of the circumference of tank 13 makes thermal contact with the contact element 49 on the filter side, transmitting the measured value to the evaluation unit 26. 48.2 The measuring element on the other side of the circumference of tank 13 makes thermal contact with the contact element 49.2 on the filter side, transmitting the measured value to the evaluation unit 26. 49 The internal contact element of the can 13 contacts the contact surface 47 and thermally bridges the gap 19 between the can 13 and the cylinder 20. 49.2 Another contact element inside the can 13 contacts the contact surface 47.2 and thermally bridges the gap 19 between the can 13 and the cylinder 20. 50 The chemical indicator element near the first measurement position MP displays a first state (low temperature) or a second state (high temperature) based on the temperature of the filter element 11. 50.2、…、50.n Additional chemical indicator elements near the measurement locations MP.2, ..., MP.n 100 A medical system for providing artificial respiration to patient P includes an anesthesia machine 1, a filter unit 4, tubing 6 and 8, a volumetric flow sensor 9, and an ambient temperature sensor 21. This medical system can be connected to a coupling unit 39 and a gas container 7 on the patient side. L Length of filter element 11 MP A first measuring position is used to measure the temperature in the filter element 11, and this first measuring position is located near the outlet opening 34. MP.2、...、MP.n Other measurement locations inside the filter element 11 are arranged upstream of the first measurement location MP. P The patient, connected to the anesthesia machine 1 via a coupling unit 39 on the patient side, inhales at least one anesthetic agent. Temp The internal temperature of filter unit 11 W The wall of the fixed gas container 7 <![CDATA[x max ]]> The location of the temperature peak, that is, the location of the maximum temperature inside the filter element 11.

Claims

1. A filter assembly for filtering gases from a gas mixture, in, The filter assembly includes - Filter unit, and - Sensor assembly with a temperature sensor and a first filter. Among them, the filtering unit -Including entrances and exits, and - Designed to filter gas from the gas mixture as it flows through the filtration unit. The filter unit is capable of receiving the filtered gas. The filtration unit becomes hot as a result of receiving gas. The filter assembly is designed such that the gas mixture -Flows through the inlet into the filter unit. -Flow through the filter unit at least once, and -Flows out of the filter unit through the outlet. The first filter temperature sensor is designed to measure the temperature at least once within a first measurement region inside the filter unit. The filter assembly is designed for, - Automatically generate notifications based on the measured temperature, and - Output the notification in a form that is perceptible to humans, or cause the notification to be output in a form that is perceptible to humans. The notification includes information about the current status of the filtering unit.

2. The filter assembly according to claim 1, Its features are, The filter assembly includes a signal processing evaluation unit. The evaluation unit for the processed signal is designed to automatically... - Determine whether a pre-defined standard is met when using the signal from the temperature sensor of the first filter. The standard depends on at least one value of the temperature in the first measurement area, and If the criteria are met, a notification containing information about the status of the filtering unit is generated.

3. The filter assembly according to claim 2, Its features are, The first filter temperature sensor is designed to measure a quantification of the temperature in the first measurement region at multiple scan times that follow each other. The signal processing evaluation unit is designed to determine the time-varying temperature curve in the first measurement area using the signal from the first filter temperature sensor. The criterion for generating a notification when it is met depends on the time-varying temperature curve in the first measurement area.

4. The filter assembly according to any one of claims 2 or 3, Its features are, The sensor assembly includes at least one second filter temperature sensor. The second filter temperature sensor, or each second filter temperature sensor, is designed to measure the temperature at least once for a second measurement region within the interior of the filter unit. Viewed in the direction along which the gas mixture flows through the filter unit, the first measuring area is arranged downstream of the second measuring area or each of the second measuring areas. The evaluation unit for the processed signal is designed to be used for, When using the signals from the first filter temperature sensor and the second filter temperature sensor, or at least one second filter temperature sensor, respectively. Determine the spatial variation curve of temperature along the path from the inlet to the outlet of the filter unit at a given moment, and The criterion for generating a notification when it is met depends on the detected spatial variation curve of temperature along the path.

5. The filter assembly according to any one of claims 2 to 4, Its features are, The sensor assembly includes an ambient temperature sensor designed to measure a measure of the temperature in the environment surrounding the filter assembly, or The sensor assembly is designed to receive a signal from the ambient temperature sensor that includes a measure of the ambient temperature. The evaluation unit is designed to be used for, - Calculate at least once the difference between the filter temperature measured by the first filter temperature sensor and the measured ambient temperature. The standard depends on the difference between the measured filter temperature and the measured ambient temperature.

6. The filter assembly according to any one of the preceding claims, Its features The filtration unit includes a filter housing and a filter. The filter is installed or can be installed into the filter housing, and The filter assembly is designed such that, when the filter is installed, the gas mixture flows into the filter housing, through the inlet, through the filter, out of the outlet, and out of the filter housing. The first filter temperature sensor is installed in the wall of the filter housing and is separated from the installed filter.

7. The filter assembly according to claim 6, Its features are, The first filter temperature sensor includes an infrared sensor. The infrared sensor is designed to measure the amount or intensity of infrared radiation emitted by the filter as a measure of temperature.

8. The filter assembly according to claim 7, Its features are, The infrared sensor includes - Thermoelectric sensor, and / or - Thermal imaging camera, and / or - Multiple infrared thermocouples, and / or - Multiple thermopile.

9. The filter assembly according to claim 6, Its features are, The first filter temperature sensor includes a thermal sensor and a converter. The thermal sensor establishes thermal contact between the installed filter and the converter, and The converter is designed to generate a signal based on the temperature of the thermal sensor.

10. The filter assembly according to any one of claims 6 to 9, Its features are, The first filter temperature sensor includes -The internal measuring elements of the filter and - The receiver in the wall of the filter housing The measuring element is designed to generate a signal based on the temperature in the first measuring region, and Specifically, when the filter is installed, a data connection is established between the measuring element and the receiver.

11. The filter assembly according to any one of claims 6 to 10, Its features are, The first filter temperature sensor includes a chemical indicating element. The chemical indicator element -In thermal contact with the filter, and -Depending on the temperature in the first measurement area, the filter is in either a visually perceptible first or second state. The second state is different from the first state.

12. The filter assembly according to any one of the preceding claims, Its features are, The filtration unit is designed to filter out at least one anesthetic from the gas mixture.

13. An application of a filter assembly according to any one of the preceding claims, Used for artificial respiration on patients.

14. A system for performing artificial respiration on a patient. in, The system includes -Respirator - Fluid guiding unit, and - The filter assembly according to any one of claims 1 to 12, The fluid guiding unit is designed to establish a fluid connection, at least temporarily, between the ventilator and the coupling unit on the patient side. The coupling unit on the patient side is connected to or can be connected to the patient. The respirator is designed to deliver a gas mixture including oxygen through the fluid guide unit to the coupling unit on the patient side, and Among them, the filter assembly -At least temporarily in fluid connection with the fluid guiding unit, and - Designed to filter at least one gas from a gas mixture being guided through the filter unit of the filter assembly.

15. The system according to claim 14, Its features are, The respirator was designed as an anesthesia machine. The anesthesia machine is designed to deliver a gas mixture comprising oxygen and at least one anesthetic agent through the fluid guide unit to the coupling unit on the patient side. The filter assembly is designed to filter out anesthetics or each type of anesthetic from a gas mixture that is guided through the filter unit of the filter assembly.

16. A method for filtering a gas from a gas mixture, When using a filter assembly, the filter assembly includes - Filter unit, and - Sensor assembly with a temperature sensor and a first filter. in, The filtration unit includes an inlet and an outlet. The method includes the following steps: The gas mixture flows through the inlet into the filtration unit. The gas mixture flows through the filter unit at least once. -The filtration unit filters out gas from the gas mixture as it flows through it. The filtration unit receives the filtered gas. - The filter unit becomes hot as a result of receiving gas and The gas mixture flows out of the filter unit through the outlet. The method includes the following additional steps: - The first filter temperature sensor measures the temperature at least once in a first measurement area inside the filter unit. - Automatically generate notifications based on the measured temperature, and - Output the notification in a form that can be perceived by humans. The notification includes information about the current status of the filtering unit.

17. The method according to claim 16, Its features are, The method includes the following additional automatically implemented steps: - Determine whether a pre-given standard is met, wherein the standard depends on the temperature in the first measurement area, and If the criteria are met, a notification containing information about the status of the filtering unit is generated and output.

18. The method according to claim 17, Its features are, The method includes the following additional steps: - The first filter temperature sensor measures the temperature in a first measurement region inside the filter unit at multiple scan times that follow each other. - Determine the time-varying curve of the measured temperature in the first measurement area, and The criterion for generating a notification when it is met depends on the temperature change curve in the first measurement area.

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