Methods and breathing equipment for determining respiratory gas content in the airway during artificial respiration

Abstract

This invention relates to a method for determining the respiratory gas content in the airway, wherein the method includes quantitatively detecting inspiratory and expiratory respiratory gas flows using at least one respiratory gas flow sensor and summing the detected inspiratory and expiratory flow values ​​to the respiratory gas content, wherein determining the respiratory gas content in the airway for the subsequent breath begins with an initial respiratory gas content value, and the initial respiratory gas content value is set based on the respiratory gas volume difference between the inspiratory respiratory gas volume delivered to the patient during the earlier breath and the expiratory respiratory gas volume output by the patient during the earlier breath: a reset initial value closer to zero than a difference that quantitatively describes the respiratory gas volume difference; or a continuous initial value closer to the difference than zero.

Description

Technical Field

[0001] This invention relates to a method for determining the respiratory gas content in the airway of a patient undergoing at least partial artificial respiration after multiple breaths administered by a breathing device, wherein the multiple breaths have at least one earlier respiratory volume or at least one subsequent breath following the earlier respiratory volume. The earlier respiratory volume comprises one earlier breath or multiple earlier breaths following each other. The method includes quantitatively detecting inspiratory and expiratory respiratory gas flows using at least one respiratory gas flow sensor, and the method further includes summing the detected inspiratory and expiratory flow values ​​to obtain the respiratory gas content.

[0002] The present invention also relates to a breathing apparatus for at least partially performing artificial respiration on a patient, the breathing apparatus constituting a method for implementing the presently described method. Background Technology

[0003] In principle, the volume of respiratory gas in a respiratory device is obtained by integrating the detected respiratory gas flow over the time of interest (based on digital data processing using conventional digital integration). Therefore, the volume of inspiratory gas administered at the respiratory device is determined by integrating the detected inspiratory gas flow—that is, the flow of respiratory gas toward the patient—from the beginning to the end of the inspiratory process. Similarly, the volume of expiratory gas exhaled by the patient can be determined by integrating the detected expiratory gas flow over the duration of the expiratory process—that is, from the beginning to the end of the expiratory process.

[0004] Understanding, for example, the volume of inspiratory gas is crucial for controlling a respiratory device in order to determine whether the tidal volume (which, in volume-related respiratory control, is the amount of inspiratory gas to be administered per breath) has been delivered to the patient as determined by the therapist. If so, the respiratory device, operating in a volume-related controlled breathing mode, will switch from inspiratory to expiratory.

[0005] The respiratory gas flow is typically monitored and integrated continuously to determine the amount of respiratory gas present or remaining in the patient's airway at any given time point. Here, the inspiratory and expiratory respiratory gas flows are distinguished by different mathematical symbols due to their opposite directions—one towards the patient and the other away. Therefore, when integrating the respiratory gas flow, the amount of inspiratory gas in the patient is first numerically accumulated during inspiration and then numerically reduced again during the subsequent expiratory phase.

[0006] Ideally, during the exhalation phase, the amount of respiratory gas flowing away from the patient should be the same as the amount flowing towards the patient during the inhalation phase. However, whether due to calibration defects or manufacturing inaccuracies that can manifest in asymmetric detection accuracy in the direction of flow, flow sensors in respiratory devices can detect respiratory gas flow with varying degrees of accuracy in opposite flow directions. For example, calibration defects can arise because the flow sensor is subjected to a moisture load from the respiratory gas that condenses in the sensor's region. With increasing or altered moisture loads, the flow sensor deviates from its calibration more and more, or by altered degrees. Moisture can condense to varying degrees upstream and downstream of the flow sensor, especially differential pressure flow sensors, thus contributing to the asymmetric detection characteristics in the direction of respiratory gas flow.

[0007] The result was then observed as a drift in the sensor signal, representing the respiratory volume, over multiple breaths. Due to this drift, the sensor signal deviated numerically from the theoretically error-free sensor signal over time.

[0008] To avoid this drift, some existing respiratory devices are configured to determine the respiratory gas content in the patient's airway individually for each breath, independent of the detection results for the respiratory gas content used in the previous breath (respiratory gas - respiratory gas content). In the case of continuous detection of respiratory gas content, this corresponds to resetting the detected respiratory gas content to zero at the end of an earlier breath, so that the detection of respiratory gas content for subsequent breaths begins at zero.

[0009] While this avoids the described drift, it presents the following danger: the periodic reset of the detection of the sum of inspiratory and expiratory respiratory gas volumes is crucial for assessing other events important to the respiratory process, such as so-called "breath stacking," triggered, for example, by "double triggering" or by a short expiration, which can be understood in German as "Atemstapelung" (breath stacking). In this event, no or only incomplete expiration occurs between two triggered inspiratory processes, such that in subsequent breaths following the incomplete expiration, the tidal volume preset at the respiratory device is reapplied to the apparent residual respiratory gas content remaining in the patient's airway. Because the residual respiratory gas content in the patient's airway at the end of the earlier incomplete expiration is not identified due to the reset to zero when detecting respiratory gas volume, undesirably high respiratory gas pressure and undesirably high respiratory gas volume are generated in the patient's airway in subsequent breaths by the application of tidal volume, which is rarely uncomfortable for the patient but implies undesirable medical risks.

[0010] Different methods for inferring the occurrence of a double triggering of an inspiratory process based on respiratory parameters of the current respiratory process are known from US 8757152 B1. However, these methods affect the determination of the respiratory gas content in subsequent breaths following the earlier breath. Summary of the Invention

[0011] Therefore, the object of the present invention is to improve the method for determining respiratory gas-respiratory gas content mentioned at the beginning and to construct a respiratory device for implementing the method, so as to safely avoid drift of the sensor signal representing the respiratory gas-respiratory gas content of the patient, thereby not obscuring the medically important respiratory superposition.

[0012] The present invention achieves the aforementioned objective through the method described at the beginning by setting an initial value for the respiratory gas content to a reset initial value closer to zero than a value that quantitatively describes the difference in respiratory gas volume delivered to the patient during an earlier respiratory period and the amount of expiratory respiratory gas output from the patient during an earlier respiratory period, or setting it to a continuous initial value closer to the difference than zero, based on the difference in respiratory gas volume. The determination of the respiratory gas content for subsequent breaths begins with this initial value. Therefore, for example, when the respiratory gas volume difference is numerically small, e.g., less than a difference threshold, a reset initial value can be set as the initial value for the respiratory gas content. This should be the typical case for artificial respiration, allowing the described drift to be prevented by using a reset initial value. Furthermore, when the respiratory gas volume difference is numerically large, e.g., greater than a difference threshold, a continuous initial value can be set as the initial value for the respiratory gas content. This achieves the observation of abnormal respiratory events reflected in the respiratory gas volume received and output by the patient, while still avoiding unwanted signal drift.

[0013] Therefore, small numerical deviations between the inspiratory and expiratory gas volumes can be leveled off or hidden, while sufficiently large deviations are used as initial values ​​in determining the respiratory gas content for subsequent breaths. Thus, when determining the respiratory gas content for subsequent breaths, it is considered that the patient's airway is already partially filled with respiratory gas at the start of the subsequent breath.

[0014] The term "respiratory tract" refers to a patient's upper and lower respiratory tracts. The body organ commonly referred to as the "lungs" belongs to the lower respiratory tract.

[0015] Preferably, the summation of the inspiratory and expiratory gas flows over multiple breaths is a bilanzielle summation, in which oppositely oriented gas flows with different mathematical signs are considered. For example, all gas flows delivered to the patient can be positive, while all gas flows flowing away from the patient can be negative. The continuous summation of gas flows with different signs results in the summation of gas flows with the same orientation in the same respiratory segment, such as the inspiratory process, yielding a numerically increasing inspiratory gas volume, which decreases again numerically in subsequent expiratory processes as another respiratory segment, having gas flows with the same orientation to each other during expiration but opposite to the orientation of the previous inspiratory process, through the continued summation of gas flows with opposite signs. At any point during respiration, the gas volume thus determined is sufficiently accurate to indicate the patient's current respiratory gas content. If the determination of the respiratory gas content begins with an initial respiratory gas content at the start of the first breath assisted by the respiratory device, then the respiratory gas content obtained over the multiple respiratory processes experienced so far represents the change relative to the initial respiratory gas content. Because determining the respiratory gas content present in the patient's airway other than artificial respiration is significantly costly, the initial respiratory gas content mentioned is usually zero. Therefore, the respiratory gas content determined by the currently proposed method is preferably a respiratory gas content other than the generally unknown initial respiratory gas content. That is, the respiratory gas content represents the portion of the total amount of respiratory gas that moves through the respiratory device during respiratory therapy, which is currently remaining in the patient's airway.

[0016] The difference quantitatively indicates the difference in respiratory gas volume between the total inspiratory respiratory gas delivered in an earlier respiratory volume and the total expiratory respiratory gas volume out of the patient in the same earlier respiratory volume. This corresponds, neglecting possible leakage losses, to the respiratory gas content present in the patient's airway at the end of the earlier respiratory volume in the valves of the breathing device and the tubing that guides the respiratory gas, and optionally also in the area of ​​the airway itself.

[0017] For clarification, breathing according to this application includes at least one inhalation process, and usually also includes an exhalation process. As mentioned above, due to overlapping or double triggering of breathing, the exhalation process can be incomplete, wherein complete cessation of the exhalation process also constitutes an incomplete exhalation process.

[0018] In principle, it is possible to consider selecting a reset initial value from a predetermined range of values ​​that are closer to zero than the difference. The corresponding case, after necessary modifications, applies to continuous initial values, which can be selected from a predetermined range of values ​​that are closer to the difference than zero. To completely and safely avoid drift, the initial reset initial value is preferably zero. Alternatively or additionally, the continuous initial value is preferably a difference to ensure that the determination of the initial value of the respiratory gas content for subsequent breaths begins with the respiratory gas content minus the respiratory gas volume at the end of the earlier breath for the subsequent breath. The integration of the respiratory gas flow through the breathing limit ensures that the determination of the initial value of the respiratory gas content for subsequent breaths begins with the respiratory gas content minus the respiratory gas volume at the end of the earlier breath for the subsequent breath; in this application, the initial value of the respiratory gas content is set to a difference.

[0019] Preferably, the initial value of the respiratory gas content is repeatedly determined during a uniform and continuous respiratory therapy for the patient in order to hide drift error over the longest possible period of artificial respiration, but without hiding respiratory superposition.

[0020] In principle, it is also possible to consider correcting possible drift only after a predetermined number of breaths, so that earlier breaths can include multiple earlier breaths that follow each other. Subsequent breaths follow earlier breaths, and an initial value for the respiratory gas content should be determined for each subsequent breath. However, if the earlier breaths contain too many breaths, the drift error summed over these many breaths can be difficult to distinguish, and thus can only be distinguished by an undesirably high error rate, when detecting respiratory gas content without drift in the case of breath superposition.

[0021] To ensure that the drift error used to determine the initial value of the respiratory gas content for subsequent breaths is sufficiently distinguishable from the effects of breath superposition, according to a preferred improvement of the invention, for a plurality of sequential breaths, an earlier breath volume comprises exactly one earlier breath. This achieves another advantageous improvement: for each of the plurality of earlier breaths, an initial value of the respiratory gas content for the corresponding subsequent breath is determined based on the difference in respiratory gas volume. In this case, the breaths that are considered as subsequent breaths in the determination of the initial value of the respiratory gas content are respectively earlier breaths in the subsequent determination of the initial value of the respiratory gas content.

[0022] In a simple yet robust design of the method, the difference itself can be used as a criterion to determine whether to set a reset initial value or a continuity initial value as the initial value for the respiratory gas content. The greater degree of freedom in determining the initial value for the respiratory gas content, resulting in higher accuracy in determining the respiratory gas content, can be achieved by the method additionally including obtaining a determination value, where the determination value represents the difference in respiratory gas volume.

[0023] Here, it is sufficient for the determination value to qualitatively or indirectly represent the difference in respiratory volume. For example, the determination value can assess the difference in respiratory volume based on the difference between the duration of at least one inspiratory phase and the duration of at least one expiratory phase of an earlier respiratory volume, and infer the difference in the respiratory volume of the corresponding inspiratory and expiratory phases from the difference in the mentioned durations. The determination value can be a predetermined function of the duration of at least one inspiratory phase and the duration of at least one expiratory phase of an earlier respiratory volume. The determination value can, for example, be proportional to the quotient of the duration of at least one inspiratory phase and the duration of at least one expiratory phase of an earlier respiratory volume.

[0024] When the determination value represents a difference, it is possible to make a particularly precise determination of one or another initial value for the respiratory gas content. The determination value can be a predetermined function of the difference. Advantageous designs for the determination value are discussed below. Thus, when determining the initial value for the respiratory gas content, a reset initial value or a continuous initial value can be determined as the initial value for the respiratory gas content based on the determination value.

[0025] Therefore, if, as described above, the earlier breath volume comprises exactly one earlier breath, then a determination value can be obtained for each of the earlier breaths and an initial value for the breath gas content can be determined for each subsequent breath following one of the earlier breaths, based on the corresponding determination value.

[0026] Using a determination value that is numerically different from the difference but represents the difference, for example, to correlate the difference with the overall volume of respiratory gas movement during the earlier respiratory phase in a manner persuasive to the determination value. This is because a given absolute parameter of respiratory therapy, such as the partial respiratory duration in seconds or the difference in volume, mass, or weight, is medically assessed differently depending on whether said parameter is present in children receiving artificial respiration or adults receiving artificial respiration.

[0027] Preferably, the determination value relates the difference to the amount of inspiratory gas delivered to the patient during the earlier respiratory phase. Therefore, the determination value can be proportional to the quotient of the difference and the amount of inspiratory gas delivered to the patient during the earlier respiratory phase when the respiratory device is involved. The proportionality factor can be selected based on the characteristics of the respective respiratory device used, for example, taking into account leakage losses occurring in each breath. However, a value of 1 for the proportionality factor is sufficient, such that the determination value equals the quotient mentioned above. Its reciprocal, which also applies as the quotient, has the same informational content and thus the same persuasiveness. As already indicated above, the determination value could be the difference itself, although this is not preferred for the reasons stated above.

[0028] Determining the initial value of respiratory gas content based on the decision value can advantageously include comparing the decision value with a predetermined decision threshold, wherein the initial value of respiratory gas content is determined based on the result of the comparison. The decision threshold can be selected according to the experimental sequence at the breathing device used, such that the error rate of undesirably falsely identified but actually absent respiratory superpositions and / or undesirably falsely retained actual respiratory superpositions is kept as low as possible.

[0029] When the initial value of the respiratory gas content is preferably determined repeatedly during artificial respiration, artifacts can occur that depict increasingly unrealistic images of the actual amount of respiratory gas moving during artificial respiration over time.

[0030] For example, the applicant learned from medical observation that respiratory superposition cannot occur arbitrarily frequently because the limited airway volume in the patient's body makes it impossible to frequently administer the tidal volume set at the breathing device to a patient with incomplete exhalation. Therefore, the proposed method suggests that if a continuous initial value is set as the initial value of the respiratory gas content each time the initial value of the respiratory gas content is determined sequentially for a predetermined first number of times, then when determining the initial value of the respiratory gas content multiple times for different breaths, a reset initial value is set as the initial value of the respiratory gas content, independent of the difference in respiratory gas volume, and especially independent of the determined value. In studies to date, 4 has proven to be a suitable predetermined first number, although the first number could also be 3, 5, or even 6.

[0031] In the same context where tidal volumes cannot be administered too frequently physiologically and sufficient exhalation is not possible during this period, if the number of determinations of continuous initial values ​​has reached or exceeded a predetermined proportion threshold within the previously determined second number of initial values ​​for respiratory gas content, the initial value can be reset to the initial value of respiratory gas content independently of the difference in respiratory gas volume, especially independent of the determined value, wherein the proportion threshold is less than the second number. Similarly, the second number is preferably greater than the first number. The proportion threshold can be a percentage threshold or an absolute threshold. For example, the proportion threshold can be 50%, or the proportion threshold can be 5 determinations when the determined second number is 10. In the case of a percentage-defined proportion threshold, the determined second number as a reference variable can be changed in the data processing procedure that causes the implementation of the proposed method with less effort than an absolutely defined proportion threshold.

[0032] Similarly, alternatively or preferably additionally, it can be proposed that if, within a predetermined number of previously implemented breaths, the frequency at which the quotient of the first breath gas content difference and the second breath gas content difference (different from the first breath gas content difference) reaches or exceeds a predetermined quotient threshold reaches or exceeds a frequency threshold, then the initial value is reset as the initial value of the breath gas content, independent of the breath gas volume difference and, in particular, independent of the determination value. The first breath gas content difference is preferably the difference between the breath gas content at the end of the determined breath and the breath gas content in the airway at the end of an earlier breath volume occurring before the determined breath. The second breath gas content difference is preferably the difference between the breath gas content in the airway at the end of the inspiratory phase of the determined breath and the breath gas content in the airway at the end of an earlier breath volume occurring before the determined breath. Expressed as an equation, this means for the preferred embodiment:

[0033]

[0034] The increment or counter symbol 'i' refers to the subsequent breath under consideration, that is, the breath determined within a predetermined number of previously performed breaths in the above terminology. The determined breath is freely chosen, however, it should not be the first breath in the breathing process, as a breath must precede it. Preferably, the determined breath is the breath that occurs moment before the subsequent breath.

[0035] Therefore, the increment or count symbol i-1 refers to the earlier respiratory volume occurring just before the determined respiration, especially the earlier respiration occurring just before the determined respiration. In Equation 1, V endexp,i V represents the respiratory gas content at the end of a defined breath, i.e., at the end of the expiratory phase of the defined breath; endexp,i-1V represents the respiratory volume occurring earlier than the defined breath, especially at the end of the earlier breath, i.e., at the end of the expiratory phase; endinsp,i This represents the respiratory gas content at the end of the inspiratory phase of the subsequent breath, and QS is the quotient threshold. The quotient threshold can be determined based on experimental studies. The quotient threshold is preferably between 0.1 and 0.3, more preferably between 0.15 and 0.25, and particularly preferably 0.2.

[0036] As a percentage threshold, the frequency threshold can be approximately 40% to 80%. Preferably, the frequency threshold is in the range of 40% to 60%, and particularly preferably 50%.

[0037] The predetermined frequency can be between 5 and 20 breaths, preferably between 8 and 15 breaths, and particularly preferably 10 breaths.

[0038] Another feasible approach to misjudging respiratory gas content could be based on positive end-expiratory pressure (PEEP) during artificial respiration. P ositive E nd- E xpiratory P Changes in positive end-expiratory pressure (PEEP). Due to the known relationship between gas pressure and volume, changes in PEEP also imply changes in the end-expiratory respiratory gas content. To advantageously avoid erroneous assessments of respiratory gas content caused by changes in PEEP, within the scope of the proposed method, it can be proposed that if a quantitative change in PEEP has been detected within a predetermined time period prior to the current determination of the initial respiratory gas content, then the initial value is reset and determined as the initial respiratory gas content value, independent of the difference in respiratory gas volume, and especially independent of the determination value. The predetermined time period can be relatively defined with respect to a reference time period. The predetermined time period and / or the reference time period can be absolutely defined as a time period in units of seconds, minutes, etc. However, the predetermined time period and / or the reference time period can also be functionally defined, for example, by the duration of a predetermined number of earlier breaths or respiratory segments. A respiratory segment can be, for example, the inspiratory or expiratory phase of breathing.

[0039] Furthermore, during artificial respiration, especially after respiratory superposition, but also occasionally, deep expiratory processes exceeding the average occur, in which the patient delivers more expiratory gas than the respiratory gas received during the preceding inspiratory phase. Following such a deep expiration with an above-average expiratory gas volume, the patient's airway is highly likely not medically critically filled with respiratory gas. Therefore, if, for at least one of two earlier respiratory volumes occurring just before the current subsequent breath (with respect to its already determined initial respiratory gas content), the expiratory gas volume of the earlier breath volume obtained from the detected expiratory gas stream is numerically greater than the inspiratory gas volume obtained from the inspiratory gas stream of the same earlier breath volume, then the reset initial value is determined as the initial respiratory gas content, independent of the difference in respiratory gas volume, and especially independent of the determination value. In a preferred embodiment, this means, on the one hand, that the determination of respiratory gas content can begin with a reset initial value at the moment following the deep exhalation mentioned above, because there is no respiratory superposition in this case. In another preferred embodiment, this means, on the other hand, that the determination of respiratory gas content can only begin with a reset initial value at the moment following the incomplete exhalation if a deep exhalation has occurred prior to the incomplete exhalation itself. Although respiratory superposition occurs in the second case mentioned, it occurs in the airway following the previous overexhalation, so that there is no concern about excessive airway load even after an incomplete exhalation due to respiratory superposition.

[0040] To simplify the monitoring of the breathing process, the respiratory gas content in the respiratory tract can be graphically output to the output device as a function of time.

[0041] The objective technical objective mentioned above is also achieved by a respiratory device for at least partially performing artificial respiration on a patient, said respiratory device comprising:

[0042] - A breathing gas source device that provides inhaled breathing gas for artificial respiration of a patient.

[0043] - A flow-changing device configured to generate and numerically modify the inspiratory respiratory gas flow.

[0044] - A breathing gas tubing device having a longitudinal end that is closer to the patient during operation and a longitudinal end that is further away from the patient during operation, so as to deliver an inspiratory breathing gas flow from the breathing gas source device toward the patient.

[0045] - A flow sensor device configured to numerically detect the inspiratory and expiratory respiratory gas flows.

[0046] - A control device having a data storage memory, wherein the control device is connected to the data storage memory and a flow sensor device via signal transmission, and the control device is configured to control the flow-changing device's operating power to alter the inhaled respiratory gas flow.

[0047] The control device is configured to implement the methods described above and their advantageous improvements. The control device can have a processor with integrated circuitry and a data memory with a program stored thereon that can be invoked and processed by the processor, wherein the processor executes the program to perform the aforementioned methods.

[0048] The respiratory gas source device of a respiratory apparatus can have a suction opening through which ambient air or gas can be drawn from a predetermined gas reservoir. The respiratory gas source device can additionally or alternatively have a gas reservoir as a respiratory gas source, for example, as a reservoir container or as a connecting component for connecting a supply line that connects the respiratory apparatus to a locally installed gas reservoir, as is often the case in a clinic. To provide the feasibility of mixing different gases into a respiratory gas, the respiratory gas source device can have multiple individual respiratory gas sources, as mentioned above. Here, different gases to be mixed can have different temperatures and / or different humidity levels due to their individualized supply and depressurization. To ensure that the inhaled respiratory gas actually reaches the patient at a one-time set humidity, it is particularly preferable that no respiratory gas components are added to the respiratory gas stream flowing from the humidifier downstream of the preferred humidifier in the inspiratory direction.

[0049] A flow sensor device can have one or more flow sensors, for example, for inspiratory and expiratory respiratory gas flows respectively. Preferably, the flow sensor device includes only one flow sensor to detect both inspiratory and expiratory respiratory gas flows. The flow sensor is preferably located proximally between the respiratory gas tubing device and the patient interface, but it can also be housed distally within the housing of the respiratory device, which may also house flow-modifying devices. For higher process reliability, the respiratory device can also have multiple flow sensors, such as a distal flow sensor within the housing of the respiratory device and a proximal flow sensor near the patient, which detect inspiratory and expiratory respiratory gas flows respectively.

[0050] Preferably, the breathing device has a pressure sensor device, which may also have one or more pressure sensors to measure the pressure of inhaled and / or exhaled breathing gases.

[0051] Preferably, the flow sensor device includes a differential pressure flow sensor, enabling the detection of the corresponding respiratory gas pressure at the location where the respiratory gas flow is detected. Particularly preferably, the flow sensor device is a proximal flow sensor device located close to the patient. For example, the proximal flow sensor device used to detect the respiratory gas flow to determine the initial value of the respiratory gas content is located no more than 80 cm, preferably no more than 50 cm, away from the patient's mouth. A proximal flow sensor device provides better synchronization than a distal flow sensor device located far from the patient, thereby allowing for more accurate detection of patient-induced triggering of the inspiratory process, i.e., the patient's inspiratory effort.

[0052] Preferably, the respiratory device, especially the control device, also includes a time measuring device so as to determine the duration of the process and sub-process during respiratory therapy.

[0053] To achieve a graphical output of the determined respiratory gas content as a function of time, the breathing device preferably has a graphical output device, such as a monitor or touch screen. The control device is then preferably configured to graphically output the determined respiratory gas content as a function of time at the output device.

[0054] To provide therapists accompanying patients on artificial respiration with a simple and feasible method for quickly and reliably identifying potential critical respiratory superpositions, if the continuity initial value is set as the initial value of the respiratory gas content, then the graphical output of the respiratory gas content in the airway as a function of time at the output device can include measures to change the graphical output of the respiratory gas content as a function of time.

[0055] Changes in the graphical output can be changes in the graph of the respiratory gas content as a function of time, such as line color and / or line width, such as changes between thinner and thicker line widths, and / or line type, such as changes between dotted lines and / or dashed lines and / or solid lines.

[0056] Additionally or alternatively, the change in the graphic output can be a change in at least one segment of the background, on which a graph of the respiratory gas content as a function of time is output. For example, the color and / or texture of the background can be changed, such as changing between a shaded line and a monochrome. Here, either the entire background can be changed, or only the graphic and a reference line, such as a zero line for the respiratory gas content, can be changed.

[0057] In principle, changes to the graphic output can be made to the entire graphic output, or they can be made to a portion of the output that describes the temporal changes in respiratory gas content. This applies, in particular, but not only to changes in the background.

[0058] Simplified identification of respiratory superposition and when it occurs can be advantageously achieved for the accompanying therapist by ensuring that changes in the graphical output are implemented only from the point in time when the continuity initial value is selected as the initial value for the respiratory gas content, and that the already output graphical content remains unchanged. The breathing device is correspondingly configured to execute the graphical output for these changes.

[0059] For inputting data and, more generally for outputting data, the respiratory device preferably includes input / output devices controllable by a control device, including the graphical output devices mentioned above. Input / output devices may include multiple buttons, rotary switches, touchscreens, speakers, light-emitting mechanisms, etc. Similarly, the respiratory device may have a data interface and / or data transmission lines to obtain data from other devices and / or transmit data to said other devices. The data interface may be a socket, radio antenna, plug, etc.

[0060] In principle, the respiratory device is preferably configured to provide artificial respiration to a patient according to different breathing modes, from which the treating physician can select when setting up the respiratory device. For example, the respiratory device can provide artificial respiration to the patient in a volume-dependent or pressure-dependent manner. Because respiratory superposition or dual triggering mainly occurs when performing assisted or supplemental breathing modes, in which the patient can trigger subsequent artificial respiration assisted by the respiratory device through inspiratory effort, the respiratory device is preferably configured to: perform artificial respiration in assisted breathing modes, in which control devices detect the inspiratory effort of the patient performing artificial respiration and manipulate flow-changing devices based on the detection of inspiratory effort; and administer an inspiratory volume of respiratory gas to the patient via a breathing gas tubing device. For example, inspiratory effort can be detected by monitoring sudden, typical changes in the breathing gas flow and / or breathing gas pressure in the breathing gas tubing device.

[0061] To mitigate the effects of unwanted respiratory overlap or double triggering, the control device is preferably configured to identify incomplete exhalations based on an initial value of respiratory gas content determined according to the method and / or based on the determined respiratory gas content in the airway. If a continuity initial value is set as the initial value of respiratory gas content, incomplete exhalations can be easily and safely identified by exceeding one or more thresholds of respiratory gas-respiratory gas content during subsequent inspiration. Preferably, the control device is configured to change the breathing pattern, particularly switching between a volume-dependently controlled breathing pattern and a pressure-dependently controlled breathing pattern, when the control device identifies an incomplete exhalation. Of particular interest here is the switching from a volume-dependently controlled breathing pattern to a pressure-dependently controlled breathing pattern, wherein the volume-dependently controlled breathing pattern would face “overfilling” of the airway with incomplete exhalations, while the pressure-dependently controlled breathing pattern is controlled, for example, to a respiratory gas pressure value to be reached during inspiration and not to the delivery of a predetermined tidal volume.

[0062] The previously mentioned amount of respiratory gas can be the mass, weight, or volume of the respiratory gas. Preferably, the amount of respiratory gas is the volume of respiratory gas, as is preferred and commonly used in medical respiratory techniques. Attached Figure Description

[0063] The invention will now be described in detail with reference to the accompanying drawings. The drawings show:

[0064] Figure 1 A schematic diagram of a breathing apparatus arranged for artificial respiration of a patient according to the present invention is shown, and

[0065] Figure 2 The graphical output shows the time-varying curves of respiratory gases and respiratory gas content for patients undergoing artificial respiration, created once using a conventional determination method and once using the proposed method.

[0066] Figure 3 A flowchart illustrating the process of the currently proposed method according to an embodiment of the present invention is provided. Detailed Implementation

[0067] exist Figure 1 In this context, the respiratory device according to an embodiment of the invention is generally designated as 10. In the example shown, the respiratory device 10 is used to perform artificial respiration on a preferred human patient 12.

[0068] The respiratory device 10 has a housing 14 in which a suction opening 15 is formed, and (not visible from the outside due to the opaque housing material) houses a flow-changing device 16 and a control device 18. The suction opening 15 allows the flow-changing device 16 to draw ambient air from the external environment U of the respiratory device and deliver it as breathing gas to the patient 12 after being cleaned by a substantially known filter. Therefore, the suction opening 15 is, in this application, a breathing gas source device.

[0069] An ambient temperature sensor 17 can be located in the suction opening 15. The ambient temperature sensor measures the temperature of the air in the environment U and transmits it to the control device 18.

[0070] The flow-changing device 16 is constructed in a substantially known manner and is capable of having a pump and / or a compressor and / or a fan and / or a pressure vessel and / or a pressure reducing valve, etc. The breathing device 10 also has an inspiratory valve 20 and an expiratory valve 22 in a substantially known manner.

[0071] Control device 18 is typically implemented as a computer or microprocessor. The control device includes... Figure 1 The data storage device 19, denoted by 19, is used to store and retrieve data necessary for the operation of the respiratory device 10 when needed. The data storage device 19 can also be located outside the housing 14 during network operation and connected to the control device 18 via a data transmission connection. This data transmission connection can be formed via cable or radio link. However, to prevent interference with the data transmission connection from affecting the operation of the respiratory device 10, the data storage device 19 is preferably integrated into the control device 18 or at least housed in the same housing 14 as the control device.

[0072] In order to input data into the breathing device 10, or more precisely, into the control device 18, the breathing device 10 may have an input device 24, which inputs data into the control device 18. Figure 1 The example shown uses a keyboard. As will be explained below, the keyboard is not necessarily the only data input for the control device 18. In fact, in addition to or alternative to the keyboard, the control device 18 can obtain data via different data inputs, such as via network lines, radio links, or via sensor interface 26.

[0073] In order to output data to the therapist performing the treatment, the breathing device 10 may have an output device 28, which is a monitor in the example shown.

[0074] For artificial respiration, patient 12 is connected to breathing equipment 10, more specifically to flow-changing device 16 in housing 14, via breathing gas tubing device 30. Patient 12 is intubated using an endotracheal tube serving as patient interface 31. The proximal longitudinal end 31a of patient interface 31 delivers inspiratory respiratory gas flow AF into the airway 12a of patient 12. Expiration respiratory gas flow EF also flows into breathing gas tubing device 30 via the proximal longitudinal end 31a.

[0075] The patient's respiratory tract 12a includes its upper respiratory airway 12a1 and its lower respiratory airway 12a2. The body organ commonly referred to as the "lung" belongs to the lower respiratory airway 12a2.

[0076] The distal longitudinal end 31b of the patient interface 31 is configured for connection to the breathing gas tubing device 30. The patient interface is surrounded by the body of the patient 12 from its downstream position 31c along the inspiratory direction to its proximal longitudinal end 31a. This implies that the patient interface 31 is exposed to the external environment U from its distal longitudinal end 31b to its position 31c, and is in a primarily convective heat transfer connection with the external environment.

[0077] The breathing gas tubing device 30 has an inspiratory hose 32 through which fresh breathing gas can be guided from the flow alteration device 16 into the airway 12a of the patient 12. The inspiratory hose 32 can be interrupted and has a first inspiratory hose 34 and a second inspiratory hose 36. A humidifier 38 can be provided between the first and second inspiratory hoses for targeted humidification and optionally also for temperature regulation of the inspiratory gas delivered to the patient 12. The humidifier 38 can be connected to an external liquid reservoir 40 through which water for humidification or medications, such as those for suppressing inflammation or widening the airway, can be delivered to the humidifier 38. When using the current breathing device 10 as an anesthesia breathing device, volatile anesthetics can be delivered to the patient 12 in a controlled manner via the breathing device 10 in the manner described above. The humidifier 38 ensures that fresh breathing gas is delivered to the patient 12 at a predetermined humidity (optionally with the addition of a drug aerosol) and at a predetermined temperature.

[0078] In this example, the second intake hose 36 can be electrically heated by the in-line heating device 37. The in-line heating device 37 can be operated by the control device 18. Unlike the above, the first intake hose 34 can also be heated, and / or at least one hose 34 or / and 36 can be heated by a device other than the electric in-line heating device 37, such as by flushing with a heat exchange medium.

[0079] In addition to the already mentioned inspiratory valve 20 and expiratory valve 22, the respiratory gas tubing device 30 also has an expiratory hose 42 through which metabolic respiratory gases are blown out of the patient 12’s airway 12a into the external environment U as an expiratory respiratory gas flow EF.

[0080] At the distal longitudinal end 30b of the breathing gas tubing device 30, the inhalation hose 32 is coupled to the inhalation valve 20, and the expiration hose 42 is coupled to the expiration valve 22. Preferably, only one of these two valves is open simultaneously to allow airflow. The operation and control of valves 20 and 22 are also performed via control device 18.

[0081] During the respiratory cycle, initially during the duration of the inspiratory phase, the expiratory valve 22 is closed and the inspiratory valve 20 is opened, allowing fresh inhaled respiratory gas to be guided from the housing 14 to the patient 12. This flow of fresh respiratory gas is caused by a targeted increase in the pressure of the respiratory gas via the flow-changing device 16. Due to the increased pressure, the fresh respiratory gas flows into the airway 12a of the patient 12, where it overcomes the individualized elasticity of the body parts adjacent to the airway and expands the body region adjacent to the airway, particularly the thoracic cavity. Consequently, the air pressure within the airway 12a of the patient 12 also increases.

[0082] At the end of the inspiratory phase, the inspiratory valve 20 is closed and the expiratory valve 22 is opened. The expiratory phase begins. Due to the increased gas pressure of the respiratory gas present in the patient's airway 12a until the end of the inspiratory phase, the respiratory gas flows into the external environment U after the expiratory valve 22 is opened, wherein the gas pressure in the patient's airway 12a decreases as the flow continues. If the gas pressure in the airway 12a reaches the positive end-expiratory pressure (PEEP) set at the breathing device 10, which is a pressure slightly higher than atmospheric pressure, then the expiratory phase ends with the closure of the expiratory valve 22 and is followed by another respiratory cycle.

[0083] During the inspiratory phase, exemplarily in a volume-dependent controlled assisted breathing mode, a set tidal volume, i.e., the volume of air per breath, is delivered to patient 12. The tidal volume is multiplied by the number of respiratory cycles per minute, i.e., by the respiratory rate, to obtain the minute volume of the currently performed artificial respiration.

[0084] Preferably, the respiratory device 10, and especially the control device 18, is configured to repeatedly update or obtain respiratory operation parameters characterizing the respiratory operation of the respiratory device 10 during respiratory operation, so as to ensure that the respiratory operation is as optimally matched as possible to the patient 12 who is to be breathing at any given time. Particularly advantageously, one or more respiratory operation parameters are determined by means of respiratory rate, so that current respiratory operation parameters best matched to the patient 12 can be provided for each respiratory cycle.

[0085] For this purpose, the respiratory device 10 can be connected to one or more sensors that monitor the patient's condition and / or the operation of the respiratory device 10 via data transmission. As such a sensor, the respiratory device 10 has a proximal differential pressure flow sensor 44 that numerically detects the respiratory gas flow present in the respiratory gas tubing device 30, more specifically the inspiratory respiratory gas flow AF and the expiratory respiratory gas flow EF. The proximal differential pressure flow sensor 44 is coupled to the data input terminal 26 of the control device 18 by means of a sensor wiring device 46. The sensor wiring device 46 may, but is not necessarily, include electrical signal transmission lines. The sensor wiring device may also have a flexible hose line that transmits the gas pressure present on both sides of the flow resistance of the differential pressure flow sensor 44 in the flow direction to the data input terminal 26, where the gas pressure is quantified by a pressure sensor 27.

[0086] More specifically, in the preferred embodiment, the breathing gas tubing device 30 has a separately formed Y-shaped tubing section 47 at its proximal longitudinal end region 30a, which is connected to the second inhalation hose 36 and the expiration hose 42 at its distal end region and to the proximal flow sensor 44 at its proximal end region.

[0087] The proximal flow sensor 44 has a coupling component 44a at its proximal end region, which can also be a patient interface 31 for a mask rather than a tube, and can be coupled to the breathing gas tubing device 30 by means of the coupling component and the proximal flow sensor 44.

[0088] The second inspiratory tubing 36 is equipped with a proximal temperature sensor 48 in its longitudinal end region, which measures the temperature of the respiratory gas flow AF as close as possible to the patient 12 in the second inspiratory tubing 36 and transmits it to the control device 18.

[0089] For the sake of completeness only, it should be noted that the breathing device 10 according to the invention can be housed as a mobile breathing device 10 on a rollable support 50.

[0090] exist Figure 2The example shows a graphical output of the respiratory gas volume balance of patient 12 during multiple breaths. Figure 2 The horizontal axis of the coordinate system represents time in seconds, and the vertical axis represents the current amount of respiratory gas remaining at the patient's 12th position, i.e., respiratory gas content, expressed as respiratory gas volume in milliliters.

[0091] Figure 52 illustrates the results of a conventional method for determining the amount of respiratory gas remaining as the respiratory gas content at patient 12 as the respiratory gas volume balance. In the conventional determination of the respiratory gas content at patient 12, the initial value of the respiratory gas volume balance is reset to zero by control device 18 before each breath to prevent drift of signal 52. This drift can be caused by incorrect calibration and / or manufacturing tolerances of the differential pressure flow sensor 44. Manufacturing tolerances can have the effect that the differential pressure flow sensor 44 outputs numerically identical respiratory gas flows or produces flow signals that are numerically slightly different from each other for inspiratory and expiratory phases.

[0092] To determine the respiratory gas content, control device 18 integrates the flow rate detected by differential pressure flow sensor 44 with respect to the duration of respiration. Figure 2 In the diagram, the upper peak of each local part of graph 52 is associated with a different respiration, where the rising edge is generated by the inspiratory process of the respiration, and the falling edge is generated by the expiratory process of the same respiration. Because in conventional determination, the respiratory gas volume balance or respiratory gas-respiratory gas content starts at zero at the beginning of each respiration, the respiratory gas flow with positive inspiratory values ​​and the respiratory gas flow with negative expiratory values ​​are integrated. The respirations are then addressed by consecutive numbering starting with respiration number 1 at 0 seconds. To simplify orientation, some respirations are identified by their numbers within circles.

[0093] Line 54 indicates the expected respiratory gas volume or expected respiratory gas-to-breath gas content at the end of the inspiratory phase of each breath. The expected respiratory gas-to-breath gas content corresponds to the tidal volume mentioned above.

[0094] Line 56, parallel to line 54, indicates the first limit of 1.5 times the expected value of the respiratory gas-to-respiratory gas content corresponding to the tidal volume of artificial respiration. Line 58 indicates the second limit of twice the expected value of the respiratory gas-to-respiratory gas content corresponding to the tidal volume of artificial respiration.

[0095] exist Figure 2 The respiratory volume balance shown is a theoretically generated respiratory volume balance, used to illustrate the currently applied method. This respiratory volume balance is not derived from actual patient data.

[0096] exist Figure 2 Hyperexhalation occurs during breaths 2 and 4, during which the patient 12 outputs more respiratory gas than previously administered during the inspiratory phase. This can occur, for example, through a slight cough at the end of exhalation or through the spontaneous cancellation of flow obstructions, such as mucus buildup in the airways. It is clear how the subsequent breath 3 is forcibly set to zero by the control device during the subsequent breath 3 relative to the earlier breath 2 when the respiratory gas content is determined to begin, as seen in segment 60 of the vertical line connecting the end of exhalation of breath 2 to the beginning of inhalation of breath 3. The same applies to the subsequent breath 5 relative to its preceding earlier breath 4.

[0097] In the illustrated excessive exhalation, the respiratory volume balance becomes negative, as shown graphically. This excessive exhalation can occur, for example, by the integral of the respiratory gas flow occurring during the duration of each breath pair starting at zero and not integrating after the end of the breath. However, it is important to remember that although breath number 1 begins at a respiratory volume of zero, at that time point there is a non-zero positive respiratory gas volume in the patient's airway 12a as the initial respiratory gas content.

[0098] In the example shown, the breathing device 10 operates in a volume-dependent controlled assisted breathing mode, according to which the set tidal volume is applied to the patient 12 either when PEEP is detected in the breathing gas line (which indicates the end of inspiration) or when the patient 12 exhibits spontaneous breathing, i.e., makes an inspiratory effort or triggers inspiration.

[0099] As in Figure 2 As can be clearly seen, the exhalation process in breath 6 is incomplete and ends by triggering the inhalation process at approximately 15 seconds (dashed line 62). Due to the convention of avoiding signal drift in the conventional method used to determine the respiratory gas-to-respiratory gas content of patient 12, for subsequent breaths 7 following the earlier breath 6, the initial value of the respiratory gas-to-respiratory gas content, or respiratory volume balance, is set to zero, from which the inhalation process of breath 7 begins, as recorded in graph 52.

[0100] Due to the permanent reset of the respiratory gas content in patient 12 at the start of respiration, respiration number 7 in Figure 52 also appears to deliver only the prescribed tidal volume to patient 12. As a consequence of the airway 12a being actually overfilled with respiratory gas during respiration number 7, a sharp and obvious over-emptying of the patient's airway 12a occurs at the end of respiration number 7 when the conventional method is applied in Figure 52.

[0101] In fact, the excessive emptying shown in Figure 52 at the end of breath 7 did not occur. Passive exhalation only caused an excessive output of respiratory gas content due to the previous incomplete exhalation in breath 6 after the end of the inspiratory process of breath 7. This passive exhalation was generally driven only by the overpressure of the ambient atmosphere generated in the patient's airway during inspiration as a sinking of respiratory gas for exhalation.

[0102] Figure 2 Figure 64 shows the respiratory gas content determined according to the method of the present invention as described herein. This is in the control device 18 according to... Figure 3 The flowchart shown has been completed.

[0103] Control device 18 queries the respiratory gas flow value detected by differential pressure flow sensor 44 at a frequency f. Therefore, control device 18 obtains a new respiratory gas flow value after time Δt = 1 / f has elapsed.

[0104] exist Figure 3 In step S10, the control device 18 queries the differential pressure flow sensor 44 and obtains the breathing gas flow value F in response.

[0105] In the subsequent step S20, the control device 18 checks whether the respiratory gas flow value F is detected at the start of a new breath, i.e. at the start of a new inspiratory phase, because in general it is only necessary to check at the start of a new breath whether the respiratory gas-respiratory gas content of the earlier breaths obtained so far should be updated by setting an initial value accordingly to determine the respiratory gas-respiratory gas content for the subsequent breaths that are starting anew, or whether the determination of the respiratory gas-respiratory gas content should start at zero.

[0106] If the obtained respiratory gas flow value F has been detected at the start of subsequent breathing, the method proceeds to step S30, in which a decision value is obtained and the decision value is compared with a decision threshold.

[0107] The determining value is, for example, the difference between the amount of inhaled air in an earlier breath and the amount of inhaled air in a previous earlier breath, which quantifies the difference between the inhaled and expired air volumes of the earlier breath.

[0108] Because the earlier respiration #6 started with an initial value of 0 ml, therefore in Figure 2At point 66, according to graph 52 (and also according to graph 64, which is still superimposed on graph 52 in the same location), the respiratory volume deficit is the difference between the inhaled respiratory volume in the earlier breath 7 and the expired respiratory volume in the same breath 7, where the exhalation in the earlier breath 6 ends prematurely and the subsequent breath 7 begins at point 66. The difference is approximately 220 ml. The inhaled respiratory volume of the earlier breath 6 is a local peak in graph 52, at which the slope of graph 52 flips. The local peak is approximately 340 ml.

[0109] Therefore, the decision value is 220ml / 340ml = 0.65. Based on previous experiments and checks, a value of 0.25 is selected as the decision threshold. Since the decision value exceeds the decision threshold, the method continues to step S40.

[0110] In step S40, it is checked whether the incremental count variable is less than or equal to a predetermined limit value, wherein the frequency of occurrence of consecutive occurrences of decision values ​​exceeding a decision threshold is counted using the incremental count variable, the limit value indicating the maximum permissible number of consecutive occurrences exceeding the decision threshold. In this case, the predetermined limit value is 3.

[0111] Because in the earlier breaths 1 through 6, the essentially complete exhalation has not yet exceeded the determination threshold, and this exceedance only occurs for the first time at the start of the subsequent breath 7, the method continues to step S50.

[0112] In step S50, it is checked whether the probability of satisfying Equation 1 given above for the last 10 breaths is no more than 50%, where the quotient threshold is 0.2 due to experimental and medical examinations.

[0113] Since there were no previous 10 breaths until the subsequent breath on the 7th, step S50 is performed for the existing number of previous 6 breaths.

[0114] The use of Equation 1 is illustrated below using breath number 4 (i=4) as an example: Referring to point 68, the end-expiratory gas volume of breath number 4 is approximately -30 ml. Referring to point 70, the previous breath (i-1=3) was approximately 0 ml. The end-inspiratory gas volume of breath number 4 is slightly lower than the expected tidal volume, approximately 350 ml. Using Equation 1, the value -0.08 is derived from the value on the left-hand side of Equation 1, which is already certain to be no greater than the quotient threshold of 0.2 simply because of the negative sign. For the remaining breaths numbered 1 through 6, the results appear similar, not exceeding the quotient threshold. Therefore, for less than half of the breaths preceding breath number 7, Equation 1 is satisfied, thus failing to reach the frequency threshold of 50% as exemplarily. The method then proceeds to step S60.

[0115] In step S60, it is checked whether an excessively large exhalation occurred in the earlier 5th breath relative to the previous 6th breath. In a large exhalation, the amount of respiratory gas exhaled from patient 12 is greater than the amount of respiratory gas previously inhaled by the patient, resulting in a negative end-expiratory volume. The criterion for not having an excessively large exhalation is whether the end-expiratory volume of the earlier 6th breath is greater than the negative end-expiratory volume of the earlier 5th breath (see Equation 2).

[0116] V endexp，i >-V endexp，i-1 Equation 2

[0117] Although the end-expiratory gas volume of breath #5 is negative, approximately -25 ml, it is negligible. The end-expiratory gas volume of breath #6, approximately 220 ml, is greater than the end-expiratory gas volume of breath #5 multiplied by -1. Therefore, the method continues to step S70.

[0118] In step S70, it is checked whether PEEP has increased during the predetermined time period prior to the subsequent breath 7, for example, during the last two breaths prior to 5 and 6. This is not the case. Therefore, the method continues to step S80.

[0119] If step S80 is reached, it is clear that all criteria for identifying incomplete exhalations and thus identifying respiratory superposition are met. In step S80, the breathing pattern is changed from the currently implemented volume-dependent controlled assisted breathing to pressure-dependent controlled assisted breathing. Furthermore, it is preferable to set the pressure value for the changed breathing pattern to a pressure assist value derived from a predetermined number of breaths passed in the previous moment, such as the average end-inspiratory gas pressure of the last 10 breaths minus PEEP. This should prevent the reapplication of tidal volume after the identified incomplete exhalation. The method then proceeds to step S90.

[0120] Step S80, which involves changing the breathing pattern, is merely one possible variation of the method. Typically, therapists performing treatment do not expect to independently change the breathing pattern using a breathing device. The method can also proceed directly from step S70 to step S90.

[0121] In a graphical way Figure 2 During the breathing process shown, no change in breathing pattern occurred.

[0122] In step S90, the count variable representing the frequency of incomplete exhalations occurring one after another is incremented by 1. The method then continues to step S100.

[0123] In step S100, the end-expiratory gas volume of the previous earlier breath #6 is set as a continuity initial value to determine the respiratory gas content during subsequent breaths #7. The method then proceeds to step S110.

[0124] In step S110, the volume of breathing gas flowing to date is calculated by digitally integrating the breathing gas flow obtained in step S10. It is assumed here that the detected breathing gas flow F flows until the next breathing gas flow is detected, i.e., within a duration Δt. In other words, the breathing gas content AL of the kth detected breathing gas flow, which consists of a total of n breathing gas flows from the considered subsequent breaths, obtained in step S110, corresponds to the following equation 3:

[0125]

[0126] Among them, V Anfangswert This is an initial value used to determine the respiratory gas content in subsequent breaths. As described above, after the method branch including step S100, the initial value is a continuous initial value, that is, the end-expiratory respiratory gas volume in the patient's airway during the earlier breath that occurs just before the subsequent breath.

[0127] After performing digital integration in step S110, the method returns to step S10, where the next respiratory gas flow is detected.

[0128] Because the method is only used to determine the initial value to determine the respiratory gas content of patient 12, if the detected respiratory gas flow is not at the start of breathing, the method proceeds directly to the digital integration in step S110 after step 20.

[0129] Steps S40 to S70 are not mandatory, but they improve the accuracy of the method. The method can also cause a process branch with steps S100 or S140 only in step S30 based on the formation of the decision value and its comparison with the decision threshold.

[0130] If, in one of the steps S30 to S70, one of the mentioned criteria is not evaluated as described above, then the process flow does not proceed to step S80 or S90, but instead proceeds to an alternative branch, where the next processing step S120 is taken.

[0131] The not necessarily existing step S120 confirms the continuation of the selected volume-related controlled, assisted breathing mode.

[0132] In any case where the standard evaluation in any of steps S30 to S70 deviates, an alternative step S130 corresponding to the previously described step S90 is reached, in which the count variable used to count the frequency of consecutive breaths, i.e. incomplete exhalations, is reset to zero because the previous earlier breath did not have a breath superposition.

[0133] The method then proceeds to step S140, in which the initial value used to determine the respiratory gas content for subsequent respirations is reset to a reset initial value of zero. This means that if the method branch with step S140 is executed, then V Anfangswert It equals 0.

[0134] The method then proceeds to step S110, which has already been described above, in which the digital integration of the detected type stream F(k) is performed.

[0135] For a better overview, Figure 2 Figures 52 and 64 are repeatedly labeled with reference numerals. Figure 52 conventionally shows the respiratory gas content of patient 12 by resetting the initial value to zero before each breath, while Figure 64 shows the respiratory gas content of patient 12 calculated according to the currently proposed method. In principle, it applies that... Figure 2 In the diagram, the portion of the figure significantly below the zero line belongs to figure 52, while the peak that approaches or fully reaches line 56 belongs to figure 64. Between the point where figure 64 enters figure 52 and the point where figure 64 and figure 52 are separated again, the two figures 64 and 52 extend along a common line, which is explained by a common integration rule.

[0136] To enable therapists observing the graphical output of respiratory gas content to identify incomplete exhalations and subsequent tidal volume reapplication as easily, quickly, and reliably as possible, the control device 18 is configured to change the graphical representation of respiratory gas content as a function of time, starting from a point in time where a continuity initial value is set as an initial value for the respiratory gas content. This change in the graph can, for example, continue until a respiratory gas content at the end of exhalation is reached that is below a predetermined graphical change threshold or whose numerical difference from the average respiratory gas content at the end of exhalation over the last n breaths is no more than a predetermined graphical change amount, where n can, for example, be 5, 10, or other integers.

[0137] For breath #7, the graphical output of the breath gas content is exemplarily changed by altering the line style and line color. For breath #9, the graphical output of the breath gas content is exemplarily changed by increasing the line width from thin to thick.

[0138] In breath 7, following the incomplete exhalation of breath 6, the conventional determination of the respiratory gas-respiratory gas content differs for the first time from the determination based on the method discussed here. This is followed by breath 8 with an incomplete exhalation, a normal breath 9, a breath 10 with an incomplete exhalation, and then an even number of breaths up to breath 30 with an incomplete exhalation, followed by an odd number of breaths with incomplete exhalations. Breath superposition ceases from breath 32 (including that breath itself).

[0139] The following characteristics should be noted: At the end of expiration in breath 15, patient 12 exhales deeply, causing the end-expiratory volume of respiratory gas in patient 12a's airway to become negative. Because the end-inspiratory volume of breath 15 is positive, as is the case with the end-inspiratory volume of each other breath, the decision value obtained in step S30 is also negative, and thus less than the decision threshold. Therefore, the initial value is reset to the airway initial value to determine the respiratory gas content of subsequent breaths 16.

[0140] In breath 16, patient 12 triggers another inspiratory phase immediately after the end of inspiration, resulting in the administration of a second tidal volume directly after the first tidal volume. Following the subsequent expiration in breath 17, due to the high end-inspiratory gas volume of breath 17, the decision value formed in step S30 is less than the decision threshold, causing the initial value to be reset to the initial respiratory gas content value for the subsequent breath 18.

[0141] Through Figure 2 The curve 64 shows the respiratory gas-respiratory gas content table as a function of time. The graphical representation of the respiratory process avoids unwanted drift and still provides a more intuitive and understandable information about the inspiratory and expiratory respiratory gas volumes during the respiratory process.

Claims

1. A method for determining the content of respiratory gas in a respiratory tract, the respiratory gas being present in the airway (12a) of a patient (12) who has at least partially received artificial respiration after a plurality of breaths performed with the assistance of a breathing device (10), wherein the plurality of breaths comprises at least one earlier breath volume and at least one subsequent breath following the earlier breath volume, wherein the earlier breath volume comprises one earlier breath or a plurality of earlier breaths following each other, wherein the method comprises quantitatively detecting inspiratory and expiratory respiratory gas flows by at least one respiratory gas flow sensor (44) and summing the detected inspiratory and expiratory flow values ​​to the respiratory gas content in the airway. The determination of the respiratory gas content in the airway during the subsequent breaths begins with an initial value for the respiratory gas content. This initial value is set based on the difference between the amount of inspiratory respiratory gas delivered to the patient (12) during the earlier breaths and the amount of expiratory respiratory gas delivered by the patient (12) during the earlier breaths. The initial value is set as either a reset initial value closer to zero than a difference that quantitatively describes the difference in respiratory gas volume, or a continuity initial value closer to the difference than zero.

2. The method according to claim 1, Its features are, The reset initial value is zero or / and the continuity initial value is a difference.

3. The method according to claim 1 or 2, Its features are, The initial value of the respiratory gas content was repeatedly determined during artificial respiration of the patient (12) at least partially.

4. The method according to claim 1 or 2, Its features are, The method includes determining a decision value, wherein the decision value represents the respiratory gas volume difference, and wherein the reset initial value or the continuity initial value is determined based on the decision value as the initial value of the respiratory gas content for the subsequent breath.

5. The method according to claim 4, characterized in that, The determination value represents the difference.

6. The method according to claim 4, Its features are, The determined value is proportional to the quotient of the difference and the amount of inspiratory gas delivered to the patient during the earlier breathing period, which is involved in the breathing device (10).

7. The method according to claim 4, Its features are, Determining the initial value of the respiratory gas content based on the determination value includes comparing the determination value with a predetermined determination threshold, wherein the initial value of the respiratory gas content is determined based on the result of the comparison.

8. The method according to claim 3, Its features are, If the initial value of the continuous breathing gas content was determined as the initial value of the breathing gas content each time when the initial value of the breathing gas content was determined sequentially a predetermined first number of times, then the initial value of the reset was set as the initial value of the breathing gas content, independent of the difference in breathing gas volume.

9. The method according to claim 3, Its features are, If the number of times the determination of the continuous initial value has been reached or exceeded within a predetermined second number of the initial value of the respiratory gas content in the respiratory tract, then the reset initial value can be set as the initial value of the respiratory gas content independently of the respiratory gas volume difference, wherein the proportion threshold is less than the second number.

10. The method according to claim 3, Its features are, If the following condition is met within a predetermined number of breaths: the frequency at which the quotient of the first breath gas content difference and the second breath gas content difference, which is different from the first breath gas content difference, reaches or exceeds a predetermined quotient threshold, then the reset initial value is determined as the initial value of the breath gas content, independent of the breath gas volume difference.

11. The method according to claim 10, characterized in that, The first respiratory gas content difference is the difference between the respiratory gas content in the airway at the end of the determined respiration and the respiratory gas content in the airway at the end of an earlier respiratory volume that occurred before the determined respiration, and / or wherein the second respiratory gas content difference is the difference between the respiratory gas content in the airway at the end of the inspiratory phase of the determined respiration and the respiratory gas content in the airway at the end of an earlier respiratory volume that occurred before the determined respiration.

12. The method according to claim 1 or 2, Its features are, If, for at least one of two earlier breaths occurring just before the current subsequent breath for which the initial value of the respiratory gas content is determined, the expiratory respiratory gas volume of the earlier breath from the detected expiratory respiratory gas stream is numerically greater than the inspiratory respiratory gas volume of the same earlier breath from the inspiratory respiratory gas stream, then the reset initial value is determined as the initial value of the respiratory gas content, independent of the difference in respiratory gas volume.

13. The method according to claim 1 or 2, Its features are, If a change in the PEEP quantification has been detected within a predetermined time period prior to the current determination of the initial value of the respiratory gas content, then the reset initial value is determined as the initial value of the respiratory gas content, independent of the respiratory gas volume difference.

14. The method according to claim 1 or 2, Its features are, The respiratory gas content in the respiratory tract is graphically output to the output device as a function of time (28).

15. The method according to claim 14, Its features are, If the initial value of continuity is set as the initial value of the respiratory gas content, then the graphical output of the respiratory gas content as a function of time is changed.

16. A breathing apparatus (10) for at least partially providing artificial respiration to a patient (12), said breathing apparatus comprising: - A breathing gas source device (15) that provides inhaled breathing gas to perform artificial respiration on the patient (12). - A flow-changing device (16), said flow-changing device being configured to generate and numerically change the inspiratory respiratory gas flow, - A breathing gas tubing device (30) having a longitudinal end that is closer to the patient (12) during operation and a longitudinal end that is further away from the patient (12) during operation, so as to deliver an inspiratory breathing gas flow from the breathing gas source device (15) toward the patient (12). - Flow sensor device (44), the flow sensor device being configured to numerically detect the inspiratory respiratory gas flow and the expiratory respiratory gas flow, - A control device (18) having a data storage (19), wherein the control device (18) is connected to the data storage (19) and the flow sensor device (44) by means of signal transmission, and the control device is configured to control the operating power of the flow changing device (16) to change the inhaled respiratory gas flow. The control device (16) is characterized in that it is configured to implement the method according to any one of the preceding claims.

17. The breathing device (10) according to claim 16, Its features are, The breathing device (10) has a graphic output device (28), and the control device (28) is configured to implement the method according to claim 14 or 15.

18. The breathing device (10) according to claim 16 or 17, Its features are, The breathing device (10) is configured to: perform artificial respiration in an assisted breathing mode, wherein the control device (16) detects the inspiratory effort of the patient (12) performing artificial respiration and manipulates the flow-changing device (16) based on the detection of the inspiratory effort; and administer an inspiratory amount of breathing gas to the patient (12) via the breathing gas tubing device (30).

19. The breathing device (10) according to claim 18, Its features are, The control device (18) is configured to identify incomplete exhalation based on an initial value of the respiratory gas content in the airway and / or based on the determined respiratory gas content in the airway, and to change the breathing mode if the control device (18) identifies an incomplete exhalation.

20. The breathing device (10) according to claim 19, characterized in that, If the control device (18) detects an incomplete exhalation, it switches between a volume-dependent controlled breathing mode and a pressure-dependent controlled breathing mode.

21. The breathing device (10) according to claim 16 or 17, Its features are, The flow sensor device (44) that determines the initial value of the respiratory gas content based on its detection value is a proximal flow sensor device (44).

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