VENTILATOR

Description

[0001] The present invention relates to a ventilator with at least one ventilation device for generating a respiratory gas flow for ventilation and with at least one monitoring device for monitoring at least one characteristic parameter of the respiratory gas flow.

[0002] Sometimes, such ventilators can be used for ventilation during cardiopulmonary resuscitation (CPR). By having the device take over ventilation, the doctor or rescuer is significantly relieved of this task, allowing them to better concentrate on chest compressions and other measures.

[0003] In the current state of the art, ventilators are known that can not only provide ventilation during CPR but also assist with chest compressions. To this end, the ventilator uses sensors to monitor pressure and flow changes in the patient's lungs during chest compressions. By evaluating the sensor signals, the device recognizes how often and how forcefully the rescuer is performing chest compressions. For example, after detecting 30 compressions, the device can prompt the rescuer to pause chest compressions so that two more compressions can be delivered by the device or the rescuer. Detection of (the onset of) cardiac activity is achieved via an additional ECG.

[0004] A ventilator of this type is known from EP 3 254 617 A1 and from US 2010 / 0036266 A1.

[0005] In contrast, the object of the present invention is to improve the technical devices for supporting CPR. In particular, a device is to be provided which can be used in the context of CPR and provides reliable and helpful information about the patient or the success of the CPR, especially without requiring an additional ECG.

[0006] This problem is solved by a ventilator according to claim 1. Further developments and advantageous embodiments are the subject of the dependent claims. Further advantages and features will become apparent from the general description and the description of the exemplary embodiments.

[0007] The present invention offers many advantages. A significant advantage is the detection mode for recognizing heartbeats based on an evaluation of the recorded parameters. This enables technically simple yet highly reliable and automated heartbeat detection. The device or system can thus detect heartbeats and optionally inform the rescuer whether and when the patient's heart has started beating again. Accordingly, the rescuer is informed whether or not CPR or chest compressions need to be continued.

[0008] During CPR, it is crucial to detect the return of cardiac activity as early as possible in order to react accordingly and initiate further important measures. Until now, detecting the return of cardiac activity has often been very difficult, as the rescuer's concentration is focused on CPR and, in particular, chest compressions. With the present invention, the rescuer can now concentrate fully on the necessary measures without having to constantly check whether the heart is beating again.

[0009] The technical and constructive implementation of the invention offers a particular advantage, as it enables heartbeat detection to be provided economically and with meaningful medical information. Since heartbeats are detected by evaluating a parameter that is often recorded during ventilation anyway, retrofitting existing devices is particularly easy.

[0010] According to the invention, at least one characteristic parameter is a measure of the flow of the breathing gas.

[0011] In particular, the key parameter is the respiratory gas flow rate. It is possible that at least two parameters are recorded, comprising at least the respiratory gas flow rate and the respiratory gas pressure. In the present technical field, the (respiratory gas) flow rate is also frequently referred to as flow. Therefore, the terms (respiratory gas) flow rate and flow rate can be used synonymously within the scope of the present invention. The (respiratory gas) flow rate is, in particular, a volumetric flow rate. For the purposes of the invention, the respiratory gas is, in particular, respiratory gas that is supplied to the patient by the ventilator and / or respiratory gas that escapes from the patient's lungs and / or, more generally, respiratory gas that enables the detection of the heartbeat signals according to the invention.

[0012] Preferably, at least one characteristic of the trend structure is a change in the parameter over time.

[0013] In particular, a condition is to include at least one measure of similarity to a temporal change in the parameter caused by heartbeats. Specifically, the trend characteristic describes how quickly, strongly, and / or frequently the parameter changes over time. Using such parameters offers a particularly reliable and technically simple method for detecting heartbeats.

[0014] Alternatively or additionally, at least one trend structure feature can describe a geometric structure of the parameter's time course. In this case, a condition is provided, in particular, for at least one measure of similarity to a predefined geometric structure of the parameter's time course, generated by heartbeats. Such structures include, for example, symmetry properties, slopes, inflection points, zeros, maxima, and minima. Other features identifiable within the framework of a functional analysis or curve sketching of the parameter's time course can also be used. The condition is then, in particular, a similarity of such a feature to at least one predefined feature.

[0015] In a preferred and advantageous further development, at least one feature of the flow structure describes or is itself a temporal flow change. In particular, the condition is then at least that the temporal flow change exhibits a defined similarity to a temporal flow change caused by heartbeats. Since specific flow changes and pressure changes occur very reliably together with heartbeats, such a design offers a particularly reproducible detection of heartbeats.

[0016] Preferably, at least one condition is specified, specifying how frequently and / or regularly the at least one trend feature occurs in the time course of the parameter. This allows, for example, noise-induced changes in the parameter to be discriminated against cardiogenic changes.

[0017] At least one characteristic of the trend describes, or is at least one such characteristic, the occurrence of (local) maxima and / or (local) minima in the time course of the parameter. As a condition, at least one maximum limit for a value of the parameter at a maximum or minimum is specified. Such a design is particularly advantageous because, although significant changes occur in heartbeats, the maxima and minima typically only assume small values.

[0018] In particular, a minimum limit for the value and / or magnitude of the parameter is also specified as a condition, defined as a maximum and / or minimum. This allows negligible changes or noise to be filtered out. It is possible that at least one filter is provided for the data for this purpose.

[0019] Alternatively or additionally, at least one characteristic of the pattern can describe at least one of the following characteristics in the temporal course of the parameter: frequency of maxima and / or minima per unit of time (frequency); number of maxima and / or minima in a period; temporal regularity of occurrence; (geometric) shape of the maxima and / or minima. In particular, the control device is suitable and designed to detect the cardiac activity at least as a function of the frequency and / or value and / or geometric shape of the maxima and / or minima.

[0020] According to the invention, at least one flow structure feature describes or is a maximum and / or minimum flow. As a condition, the invention provides at least one upper limit for the magnitude of the flow. This allows the specific, but correspondingly weak, flow changes to be reliably detected.

[0021] At maximum flow, there is a positive flow, i.e., a flow of respiratory gases towards the patient or into the patient's lungs. At minimum flow, there is a negative flow, i.e., a flow of respiratory gases in the opposite direction.

[0022] According to the invention, at least one upper limit for the flow rate of the breathing gas is provided as a condition. This upper limit lies between 0.01 l / s and 0.3 l / s, and preferably between 0.02 l / s and 0.15 l / s. In particular, it is provided as a condition that the maximum flow rate does not exceed 0.3 l / s. In particular, it is provided as a condition that the minimum flow rate is not less than 0.02 l / s. Additionally or alternatively, an upper limit for the magnitude of another parameter, and preferably the pressure of the breathing gas, can also be provided as a condition. This allows the flow changes specific to heartbeats to be identified particularly well.

[0023] It is possible that a condition is stipulated that at least one sign change occurs between a maximum and a minimum in the time course of the parameter. In particular, at least one sign change, and preferably only one sign change, occurs between a maximum and a minimum in the time course of the flow and / or pressure of the respiratory gas. Such a sign change is caused in particular by the contraction and relaxation of the beating heart and its effect on the lungs or the thoracic cavity.

[0024] It is also possible that a condition is stipulated, at least, that changes in the parameter over time, and preferably the occurrence of maxima and / or minima, occur with a defined frequency and / or regularity. Frequency describes, in particular, the number of changes within a defined time period and can also be referred to as the rate of change. Regularity describes, in particular, the time intervals between the changes, and preferably between the maxima and minima.

[0025] As a condition, it can also be stipulated that temporal changes in the parameter, and preferably the occurrence of maxima and / or minima in the temporal course of the parameter, occur at a frequency of at least ten per minute, and preferably 20 per minute, and particularly in the range of 30 to 200 per minute. In particular, the frequency corresponds to at least a very low heart rate. In particular, the frequency is a maximum of 180 per minute, for example, due to the administered resuscitation medication. In particular, the maximum frequency corresponds to a high heart rate. It can be provided that the control device determines the frequency by querying the patient's age. Thus, a higher (maximum and / or minimum) frequency can be set for younger people, and especially for babies, than for older people.

[0026] In an advantageous further development, the control device is suitable and configured to examine the temporal profile of the parameter for at least one stored heartbeat-related pattern. In particular, the control device is suitable and configured to detect heartbeats at least by the fact that the pattern occurs at least approximately over time. Specifically, the pattern is defined by repetitions of at least one, and preferably at least two, structural features of the parameter. Particularly preferably, the pattern describes repeating geometric structures of the temporal profile of the parameter. Particularly preferably, the pattern defines a temporal and / or geometric regularity of flow changes and / or pressure changes over time. The condition is then, in particular, a similarity between the temporal profile of the parameter and at least one stored pattern.

[0027] It is possible and advantageous for the control device to be suitable and configured to determine the frequency of at least one trend feature over the time course of the parameter and to derive a number of heartbeats and / or a heart rate from this frequency. The number of heartbeats and / or the heart rate can also be determined from the pattern. This allows for a better assessment of cardiac activity after it has resumed.

[0028] In a preferred and advantageous embodiment, the control unit is suitable and configured to detect heartbeats, taking into account whether at least one structural feature of the respiratory gas flow has occurred with a minimum quality and / or minimum number in the recorded temporal profile of the parameter. The minimum number refers in particular to the number of maxima and / or minima. It is also possible to detect heartbeats by considering whether the temporal profile of the respiratory gas flow parameter was recorded for a minimum duration and / or whether the temporal profile of the respiratory gas flow parameter was recorded with a defined minimum signal quality. The minimum quality defines, in particular, whether the structural feature of the respiratory gas flow is recognizable and evaluable as such.In particular, the control unit is suitable and designed to reject and / or weight or verify the result of the heartbeat detection, depending on the aforementioned requirements.

[0029] In particular, the minimum duration is at least 2 or 3 seconds, and preferably at least 5 seconds, and most preferably at least 10 seconds.

[0030] In a particularly advantageous embodiment, the monitoring device can detect at least one further parameter: the carbon dioxide content of the blood and / or the respiratory gas, and / or the blood pressure, and / or the oxygen concentration of the blood. Preferably, the control unit is designed and configured to record the time course of the at least one further parameter and to take at least part of it into account for the detection of heartbeats. Preferably, the control unit is designed and configured to perform a plausibility check, taking the further parameter into account, in order to verify the result of the detection of cardiac activity or the detected heartbeats. The examination of the at least one further parameter is preferably carried out in the same way as described above for the parameter.In particular, the detection of heartbeats involves a weighted consideration of the key parameter and another key parameter. The carbon dioxide content of the blood is described, in particular, by a carbon dioxide partial pressure. Specifically, the monitoring device includes suitable sensor means and / or is operatively connected to at least one external sensor means. Preferably, the monitoring device includes at least one sensor means for detecting the carbon dioxide content of the respiratory gas. Preferably, the onset of cardiac activity is detected by a rising carbon dioxide content of the blood. The carbon dioxide content of the blood would subsequently decrease again.

[0031] In all embodiments, it is particularly preferred that the further parameter is a plethysmogram wave, detected in particular by pulse oximetry, and / or an oxygen concentration detected or measured by pulse oximetry. In particular, the monitoring device is suitable and configured to detect the further parameter by means of pulse oximetry. For this purpose, the monitoring device can be operatively connected to at least one pulse oximeter or itself include a pulse oximeter.

[0032] In a particularly advantageous embodiment, the monitoring device can detect at least one further parameter: a plethysmogram waveform measured by pulse oximetry and / or oxygen saturation measured by pulse oximetry. Preferably, the control unit is designed and configured to record the temporal profile of the at least one further parameter and to at least partially consider it for heartbeat detection. The at least one further parameter is preferably analyzed in the same way as described above for the parameter itself. In particular, the parameter and the further parameter are weighted for heartbeat detection. Specifically, the monitoring device includes suitable sensor means and / or is operatively connected to at least one external sensor.In particular, the onset of cardiac activity is detected by an increasing oxygen saturation and / or by a recurring plethysmogram wave.

[0033] The control device may be designed and configured to monitor cardiac compressions by recording the temporal profile of a characteristic parameter, preferably a flow and / or pressure of the respiratory gas, at least during the compressions, and to evaluate the effectiveness of the compressions based on whether the temporal profile exhibits a defined change in flow and / or pressure. In particular, the quality (especially the applied pressure and / or the stroke length) and / or the quantity (especially the number of strokes) are evaluated.

[0034] The quality is preferably determined based on the amplitude of the pressures and / or flows detected by the sensors of the control unit. The quantity is preferably determined based on the frequency of the pressures and / or flows detected by the sensors of the control unit.

[0035] In all embodiments, it is particularly preferred that the control unit is suitable and configured to issue at least one indication during the detection mode, or for the detection of heartbeats, that chest compressions should be suspended and / or restarted. Preferably, an indication is issued at the beginning of the detection mode, or before the heartbeat detection is performed, that chest compressions should be suspended. If chest compressions are continued, preferably at least one further indication is issued and / or the detection result is discarded. In particular, an indication is issued at the end of the detection mode, or after the heartbeat detection has been performed, that chest compressions should be restarted. The suspension and / or resumption of chest compressions is monitored by the monitoring device.

[0036] In particular, an audible and / or visual and / or haptic indication is given. For example, a beep can be accompanied by a text message. Preferably, at least one voice message is given indicating whether chest compressions should be stopped or restarted.

[0037] It is also possible and advantageous that, in detection mode or for heartbeat detection, at least an indication is given that ventilation should be suspended and / or restarted. The control unit can be suitable and configured to interrupt ventilation at least temporarily in detection mode. It is also possible that ventilation can be continued at least temporarily in detection mode. The suspension can occur depending on the signal quality. For example, ventilation is interrupted when particularly weak pressure and / or flow changes need to be detected, or when the pressure and / or flow signals are unclear and, for example, too small or noisy.

[0038] Preferably, heartbeat detection can also take place during ventilation or chest compressions. The control unit then specifically detects the pressure and / or flow signals in the breathing gas generated by the (onset of) cardiac activity.

[0039] Preferably, the control device is suitable and designed to provide at least one acoustic and / or visual and / or haptic support cue for chest compressions and preferably for their rhythm.

[0040] In particular, the control unit is suitable and designed to output at least one indication depending on the result of the heartbeat detection and preferably to signal the presence of heartbeats acoustically and / or visually and / or haptically. This allows it to be perceived that the heart is beating again, even under difficult conditions.

[0041] Particularly preferably, the ventilation device can be operated by means of the control unit in at least one operating mode for use in combination with (separately performed) chest compressions. In such an operating mode (here referred to as CPR operating mode), the ventilation device provides at least one ventilation specific to cardiopulmonary resuscitation (CPR). This configuration is particularly advantageous because, in addition to monitoring cardiac activity, it provides further support to the rescuer by also taking over ventilation from the ventilator. For such ventilation, the ventilation device is preferably controlled by the control unit taking into account the characteristic parameter. The acquisition and evaluation of the characteristic parameter preferably takes place as described above. In particular, ventilation is dependent on chest compressions.For example, after 30 chest compressions, two ventilation breaths are administered by the ventilation device.

[0042] The control unit is preferably designed and configured to (selectively) suspend ventilation in CPR mode during detection mode and preferably to (selectively) resume ventilation in CPR mode after detection mode, depending on the detection result. In particular, the control unit is designed and configured to perform an automatic and / or adaptive switch between detection mode and CPR mode. Specifically, the heartbeat detection result is discarded if ventilation and / or respiratory activity is present during detection. However, it is also possible for ventilation in CPR mode to be at least partially continued during detection mode. For this purpose, for example, an adjusted pressure and / or flow rate for the ventilation device can be provided. It is also possible for the CPR mode and the detection mode to be active in parallel, at least temporarily.When ventilation is stopped, the previously described instruction to stop chest compressions should preferably also be given.

[0043] The monitoring device is preferably suitable and configured to record the characteristic parameter even during CPR operating mode and, in particular, during the execution of an HDM. The control device is preferably suitable and configured to record and analyze the characteristic parameter even during CPR operating mode and, in particular, during the execution of an HDM.

[0044] Preferably, a condition is stipulated that a temporal change in the characteristic parameter, preferably a change in flow and / or pressure, has an amplitude of at least half, preferably at most one-quarter, of the amplitude of at least one amplitude exhibited by the temporal change in the characteristic parameter during the performance of CPR. In particular, the amplitude during the performance of CPR is at least twice as large as the amplitude of a heartbeat. A further condition is stipulated that such an amplitude occurs within a defined period and / or with a defined frequency and / or regularity. In such a configuration, temporal changes in the characteristic parameter and, for example, amplitude, are specifically meant, which are caused by the performance of CPR, i.e., by externally applied pressure on the chest or the heart.

[0045] Preferably, a condition is stipulated that a temporal change in the characteristic parameter, preferably a change in flow and / or pressure, has an amplitude of at least half, preferably at most one-third, of the amplitude of at least one amplitude that is provided or set for the pressure and / or flow of the breathing gas for ventilation during CPR operation. In particular, the amplitude during ventilation in the context of CPR is at least three times greater than the amplitude of a heartbeat. In particular, a condition is stipulated that such an amplitude occurs within a defined period and / or with a defined frequency and / or regularity.

[0046] In particular, the control device is suitable and designed to monitor cardiac compressions by recording a temporal profile of the flow and / or pressure of the respiratory gas, at least during cardiac compressions (CCT), and to evaluate the effect of the cardiac compressions depending on whether the temporal profile exhibits a defined temporal change in CCT flow and / or pressure, wherein changes in flow and / or pressure caused by a beating heart can also be detected, and wherein the control device is suitable and designed to recognize the heartbeat-related changes in flow and / or pressure as heartbeats in a recorded temporal profile of the flow and / or pressure.Preferably, the control device is suitable and designed to distinguish the HDM flow change and / or pressure change from the heartbeat flow change and / or pressure change by having an amplitude at least twice as large as the heartbeat flow change and / or pressure change.

[0047] In particular, the control device is suitable and configured to record the temporal profile of the flow and / or pressure of the respiratory gas, at least during ventilation, for the purpose of monitoring ventilation. Furthermore, it is capable of detecting flow and / or pressure changes caused by a beating heart, and the control device is suitable and configured to recognize these heartbeat-related flow and / or pressure changes as heartbeats within a recorded temporal profile. Preferably, the control device is suitable and configured to distinguish the ventilation-related flow and / or pressure change from the heartbeat-related flow and / or pressure change by ensuring that the ventilation-related flow and / or pressure change has an amplitude at least three times greater than that of the heartbeat-related flow and / or pressure change.

[0048] Further advantages and features of the present invention will become apparent from the description of the exemplary embodiments, which are explained below with reference to the accompanying figures.

[0049] The figures show: Fig. 1 is a purely schematic representation of a monitoring system according to the invention in a perspective view; Fig. 2 is a highly schematic diagram of a time course of a characteristic parameter to illustrate the detection of heartbeats by means of the invention; and Fig. 3 is a highly schematic diagram of a time course of another characteristic parameter to illustrate the detection of heartbeats by means of the invention.

[0050] The Figure 1Figure 1 shows a ventilator 1 according to the invention, which is equipped with a monitoring system 10 and a monitoring device 3. The monitoring system 10 can alternatively also be used as a separate device outside the ventilator 1.

[0051] The ventilator 1 has an internal ventilation unit 2, which is equipped with a fan 12 to generate a flow of breathing gas. The breathing gas is delivered to the patient via a tubing assembly 32 connected to the ventilation unit 2 and a breathing mask 22. Alternatively, other patient interfaces can be used instead of the breathing mask 22. A pressurized gas source can also be provided, either in addition to or as an alternative to the fan 12.

[0052] The monitoring device 3 serves to monitor characteristic parameters of the respiratory gas flow. The ventilation device 2 is then controlled by a control unit 4, taking into account the characteristic parameter and, if applicable, other ventilation parameters.

[0053] The ventilator 1 comprises an output unit 6 with a display and an operating unit 7. Combinations of the operating unit 7 and output unit 6 are also possible, for example, in the form of a touch-sensitive display area or a touchscreen. The output unit 6 also serves to output instructions or signals within a later-described detection mode or CPR operating mode. The output unit 6 can also display its information or instructions on other display devices not shown here, such as a computer display, tablet, smartphone, or the like.

[0054] The ventilation device 2 is here connected to a sensor device 5, which has several sensors for recording the characteristic parameters of the respiratory gas flow and, if necessary, other parameters characteristic of ventilation.

[0055] For example, the sensor means 5 includes a pressure sensor (not shown in detail here) which detects the pressure conditions of the breathing gas flow, and a flow sensor (also not shown in detail) which detects the flow conditions of the breathing gas flow.

[0056] The sensor 5 is operatively connected to the monitoring device 3 and the control device 4, so that the detected quantities can be at least partially processed by them. The sensor 5 can be located in the ventilator 1, in the tubing, or at the patient interface.

[0057] The control unit 4, located inside the housing but not visible here, controls the fan unit 12, enabling, for example, CPAP, APAP, or bilevel ventilation. For ventilation, the ventilation unit 2 is set to a defined respiratory gas flow and / or pressure. The control unit 4 can provide a necessary minimum pressure and / or compensate for pressure fluctuations caused by the user's breathing. For example, the monitoring unit 3 uses the sensor 5 to detect the current pressure at the patient interface 22 and adjusts the fan unit 12 accordingly until the desired ventilation pressure is reached.

[0058] Ventilator 1 can be operated in a cardiac activity detection mode. In this mode, automatic heartbeat detection takes place. This allows ventilator 1, for example, during CPR, to determine if and when the heart starts beating again.

[0059] An exemplary sequence of the recognition mode will now be described with reference to the Figure 2 As described. In detection mode, the control unit 4 evaluates a time profile 201 of the parameter 200 of the breathing gas flow, which the monitoring unit 3 previously detected (as pressure, flow, or volume) and which was recorded by the control unit 4. Profile 201 corresponds here to a plot of the parameter 200 over time 203, which is specified in seconds. The profile 201 shown here represents a 10-second window of a flow recording.

[0060] The control unit 4 then examines the temporal sequence 201 for one or more sequence structure features 202. If the examined sequence structure features 202 then fulfill at least one condition stored in the control unit 4 and, for example, correspond to or resemble stored heartbeat-specific sequence structure features 202, the control unit 4 interprets this as the presence of a heartbeat.

[0061] In the example shown here, the parameter corresponds to the flow rate of the respiratory gases. To detect heartbeats, a time-dependent profile 201 of the flow rate is used. The flow rate is given here in liters per second. For evaluation, the control unit 4 analyzes the profile 201 for specific flow rate changes, defined as a profile structure feature 202, which are caused by the beating heart. Alternatively or additionally, the pressure of the respiratory gases can also be recorded as a parameter and analyzed accordingly.

[0062] In the example shown here, maxima 212 and minima 222 occurring over time 203 are used as trend features 202. This allows those flow changes specifically caused by the beating heart to be detected particularly reliably. A superimposition or comparison of the trend shown here 201 with an electrocardiogram (ECG) (not shown) illustrates the relationship between the pressure changes and the heartbeats particularly clearly. The ECG only shows the electrical activity of the heart, whereas the present invention makes it possible to also detect the heart's pumping activity. It can be clearly seen here that a maximum flow value corresponds to approximately 0.1 l / s. Such a rather low peak flow is characteristic of the flow changes caused by heartbeats.The amplitude of heartbeat-related flow signals ranges from 0.5 L / min to 3.5 L / min, for example, from 0.6 to 2.3 L / min. The amplitude of heartbeat-related pressure signals ranges from 0.2 cm H₂O to 3.0 cm H₂O, for example, from 0.4 to 2.2 cm H₂O.

[0063] Additionally or alternatively, the control unit 4 can also perform pattern recognition for the waveform 201 to detect heartbeats. For this purpose, waveform 201 is examined for the occurrence of a specific pattern 232. In the waveform 201 shown here, for example, a pattern 232 is particularly evident, characterized by regularly occurring geometric structures with associated maxima 212 and minima 222, as well as the characteristic slopes between them. The specific small, rhythmic oscillations in the respiratory gas flow are particularly visible in this pattern.

[0064] The previously described detection mode can also be performed without the ventilator 1 using the monitoring system 10. The monitoring system 10 comprises the monitoring device 3 and the control unit 4. To detect the parameter 200 of the respiratory gas flow, the monitoring device 3 is connected to the patient via a suitable respiratory interface.

[0065] The monitoring system 10 can then be used, for example, as a standalone system during CPR to enable automated heartbeat detection. Ventilation during CPR is then performed manually or using a separate ventilator (not shown here). The monitoring system 10 can also be coupled with or integrated into an existing ventilator 1 to extend its functionality to include the heartbeat detection mode.

[0066] Ventilator 1 offers an operating mode for using it in combination with (separately performed) chest compressions. In this CPR operating mode, ventilation unit 2 provides ventilation specific to CPR. This allows ventilator 1 to take over ventilation, enabling the rescuer to concentrate on chest compressions. For example, after 30 chest compressions, ventilation unit 2 delivers two ventilation breaths.

[0067] An example of how ventilator 1 is used during CPR is described below. First, the patient is connected to ventilator 1 as intended. Ventilator 1 is then switched to CPR mode so that the ventilation unit 2 provides ventilation specifically suited for CPR. Chest compressions are performed by the rescuer either concurrently with or alternately with ventilation.

[0068] The ventilator 1 can assist the rescuer during chest compressions (CCF) by, for example, providing audible and visual signals regarding the rhythm and number of CCFs. It can also output signals indicative of CCF quality, such as whether chest pressure is sufficient. For this purpose, pressure and flow changes are detected and evaluated by the control unit 4 based on signals acquired by the monitoring unit 3. Since chest pressure causes characteristic pressure and flow changes in the patient's lungs, this provides reliable monitoring.

[0069] After a certain number of breaths, for example, 30, ventilator 1 prompts the rescuer to interrupt chest compressions. A further specific number of breaths, for example, two, are then delivered using ventilator 2. Following these breaths, or concurrently, control unit 4 activates the detection mode for cardiac activity. For this purpose, the temporal profile 201 of parameter 200 is evaluated as described above. For example, cardiogenic pressure changes and / or flow changes are detected over time 201 and, if they meet certain conditions, identified as heartbeats.

[0070] It may be planned that ventilation by the ventilation device 2 takes place during the recording of the parameter 201 for the time course under investigation. However, it may also be planned that ventilation is deliberately suspended, for example, to avoid influencing the recording of parameter 200. This is advantageous when the measurement conditions are difficult or the signal quality of the measurement data is critical. The monitoring device 3, sensors, and control unit 4 shown here are designed and configured to record the heartbeat-related signals even during ventilation and / or during CPM (cardiac monitoring). When plotted against flow or pressure signals, these heartbeat-related signals can then be identified as oscillating fluctuations of the corresponding signals.

[0071] If control unit 4 does not detect any heartbeats, the rescuer receives a message indicating that chest compressions should be continued. Chest compressions are then performed as previously described and accompanied by ventilator 1 until the next detection mode occurs, and so on. If control unit 4 detects heartbeats, it then issues a corresponding message to the rescuer.

[0072] Another exemplary sequence of the recognition mode will now be described with reference to the Figure 3 described. In addition to what is described, this also includes the information relating to the Fig. 2 The described procedure includes a plausibility check to verify the result of the heartbeat detection.

[0073] For this purpose, the control unit 4 evaluates a time-lapse 303 profile 301 of a further parameter 300. The further parameter 300 is here a carbon dioxide partial pressure of the breathing gas, which the monitoring unit 3 has recorded with its own or an external sensor.

[0074] It has been shown that at time 302, when circulatory activity resumes, a significant increase in the partial pressure of carbon dioxide in the breathing gas also occurs. Therefore, the control unit 4 checks the curve 301 of the further parameter 300 for such an increase in the partial pressure of carbon dioxide. If the increase is present, a notification can be issued, for example. If no increase occurs, a warning can be issued, the detection mode can be continued, or the result can be discarded.

[0075] Alternatively or additionally, a pulse oximetrically recorded plethysmogram wave and / or a pulse oximetrically measured blood oxygen concentration can also be used as a further parameter 300. In this case, the monitoring device 3 is, for example, connected to a pulse oximeter. Thus, for example, a significant change in oxygen concentration can be used to determine whether circulatory activity has resumed. Reference symbol list:

[0076] 1 Ventilator 2 Ventilation device 3 Monitoring device 4 Control device 5 Sensor device 6 Output device 7 Operating device 10 Monitoring system 12 Fan device 22 Breathing mask 32 Tubing device 200 Parameter 201 Trend 202 Trend structure feature 203 Time 212 Maximum 222 Minimum 232 Pattern 300 Parameter 301 Trend 302 Time point 303 Time

Claims

1. A ventilator (1) comprising at least one ventilation apparatus (2) for generating a respiratory gas flow for ventilation, and comprising at least one monitoring apparatus (3) for monitoring at least one characteristic parameter (200) of the respiratory gas flow, wherein the at least one characteristic parameter (200) is a measure of a flow of the respiratory gas, and comprising at least one control apparatus (4) which is suitable and designed to carry out at least one detection mode for cardiac activity and, for this purpose, to register a time profile (201) of the characteristic parameter (200) of the respiratory gas flow and to examine the time profile (201) of the characteristic parameter (200) for at least one profile-structure feature (202), and to detect heartbeats at least in that the profile-structure feature (202) at least partially satisfies at least one stored condition for a heartbeat-related profile-structure feature (202), characterized in that the at least one profile-structure feature (202) describes an occurrence of maxima (212) and / or minima (222) in the time profile (201) of the flow, and in that at least one maximum limit for an amount of the flow at a maximum (212) and at a minimum (222) is provided as a condition, and in that at least one upper limit between 0.01 liters per second and 0.3 liters per second for an amount of the flow is provided as a condition.

2. The ventilator (1) according to the preceding claim, wherein the at least one profile-structure feature (202) describes a temporal change in the characteristic parameter (200), and wherein at least one measure of a similarity to a temporal change in the characteristic parameter (200) caused by heartbeats is provided as a condition.

3. The ventilator (1) according to one of the preceding claims, wherein the at least one profile-structure feature (202) describes a temporal flow change, and wherein the condition is at least that the temporal flow change has a defined similarity to a temporal flow change caused by heartbeats.

4. The ventilator (1) according to one of the preceding claims, wherein it is at least provided as a condition how often and / or regularly the at least one profile-structure feature (202) occurs in the time profile (201) of the characteristic parameter (200).

5. The ventilator (1) according to one of the preceding claims, wherein the upper limit for the amount of the flow of the respiratory gas is between 0.02 liters per second and 0.15 liters per second.

6. The ventilator (1) according to any of the preceding claims, wherein it is at least provided as a condition that temporal changes in the characteristic parameter (200), and preferably an occurrence of maxima (212) and / or minima (222) in the time profile (201) of the characteristic parameter (200), occur at a frequency of at least 10 per minute and preferably 20 per minute and / or in the range from 30 to 200 per minute.

7. The ventilator (1) according to one of the preceding claims, wherein the control apparatus (4) is suitable and designed to determine a frequency of the at least one profile-structure feature (202) in the time profile (201) of the characteristic parameter (200) and to determine, from the frequency, a number of heartbeats and / or a heart rate.

8. The ventilator (1) according to one of the preceding claims, wherein the control apparatus (4) is suitable and designed to perform the detection of the heartbeats taking into account whether the at least one profile-structure feature (202) has occurred with a minimum quality and / or minimum number in the registered time profile (201) of the characteristic parameter (200) and / or whether the time profile (201) of the characteristic parameter (200) of the respiratory gas flow has been registered for a minimum duration and / or whether the time profile (201) of the characteristic parameter (200) of the respiratory gas flow has been registered with a defined minimum signal quality, and wherein the minimum duration is in particular at least five seconds.

9. The ventilator (1) according to one of the preceding claims, wherein, by means of the monitoring apparatus (3), a carbon dioxide content of the blood and / or of the respiratory gas and / or a blood pressure and / or an oxygen concentration of the blood can be recorded as at least one further characteristic parameter (200) and wherein the control apparatus (4) is suitable and designed to register a time profile (201) of the at least one further characteristic parameter (200) and to at least partially take it into account for the detection of the heartbeats, and in particular wherein the further characteristic parameter is a plethysmogram wave recorded by pulse oximetry and / or an oxygen concentration measured by pulse oximetry.

10. The ventilator (1) according to one of the preceding claims, wherein the control apparatus (4) is suitable and designed to register, in order to monitor chest compressions, a time profile (201) of a flow of the respiratory gas at least during the chest compressions, and to evaluate an effect of the chest compressions depending on the fact that the time profile (201) has a defined temporal flow change.

11. The ventilator (1) according to one of the preceding claims, wherein the control apparatus (4) is suitable and designed to output, for a detection of the heartbeats, at least an indication that chest compressions are to be paused and / or resumed, and / or wherein the control apparatus (4) is suitable and designed to provide at least one acoustic and / or visual and / or haptic support indication for chest compressions and preferably for a rhythm thereof.

12. The ventilator (1) according to one of the preceding claims, wherein the ventilation apparatus (2) is operable by means of the control apparatus (4) in at least one operating mode for use of the ventilator in combination with chest compressions, and wherein the ventilation apparatus (2) in the operating mode provides at least specific ventilation for cardiopulmonary resuscitation (CPR) (so-called CPR operating mode).

13. The ventilator (1) according to the preceding claim, wherein it is at least provided as a condition that a temporal change in the characteristic parameter, preferably a flow change, has at least one amplitude, the magnitude of which is at most half, preferably at most a quarter, of the magnitude of at least one amplitude which the temporal change in the characteristic parameter has during the performance of chest compressions.

14. The ventilator (1) according to either of the two preceding claims, wherein it is at least provided as a condition that a temporal change in the characteristic parameter, preferably a flow change, has at least one amplitude, the magnitude of which is at most half, preferably at most one third, of the magnitude of at least one amplitude which is provided or, respectively, set for the flow of the respiratory gas for the ventilation during the CPR operating mode.