Devices, systems and methods for supporting detection of return of spontaneous circulation during cardiopulmonary resuscitation

Abstract

The present invention relates to a device, system and method for providing quantitative support for the detection of the restoration of spontaneous circulation during cardiopulmonary resuscitation. Photoplethysmography measurement is used to trigger blood pressure measurement for the purpose of assessing the restoration of spontaneous circulation and thus for guiding the user to perform CPR. The present invention can prevent ineffective interruptions during compressions and re-arrest of the heart due to unnecessary compressions.

Description

Technical Field

[0001] The present invention relates to a device for providing quantitative support for detecting the return of spontaneous circulation during cardiopulmonary resuscitation. The present invention also relates to a system incorporating the aforementioned device and a corresponding method. Background Art

[0002] Detecting the return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR) is challenging. High-quality CPR requires minimizing interruptions in chest compressions. Typically, during CPR, chest compressions need to be interrupted to perform a pulse check (in most cases by manually palpating the arterial pulse). Ineffective pulse checks can lead to unnecessary interruptions in chest compressions. In addition, it is known that pulse checks by manual palpation are time consuming, especially when there is no spontaneous pulse. This can result in prolonged interruptions in compressions, which in turn can lead to a decrease in the quality of the CPR delivered. In fact, interruptions in chest compressions reduce blood flow, which can reduce the chances of obtaining ROSC. In addition, manual palpation is known to be unreliable, even when performed by expert clinicians.

[0003] Furthermore, it is known that delivering compressions to a beating heart may cause the heart to stop beating again. Therefore, it is important to know when the heart is strong enough and no longer needs additional support so that compressions can be stopped.

[0004] Alternatively, a reliable and objective measurement for supporting ROSC detection is an invasive arterial blood pressure measurement, which can be interpreted as indicating ROSC when systolic blood pressure (SBP) is above, for example, 60 mmHg. Monitoring of end-tidal CO2 or central venous oxygen saturation for ROSC detection may also be considered. However, these measurements require the placement of a catheter or a secured airway. Therefore, they are invasive measurements and are therefore generally neither desirable nor available.

[0005] Transthoracic impedance (TTI) measurement and near-infrared spectroscopy (NIRS) are noninvasive methods that can provide pulse detection support during CPR, but TTI is greatly affected by chest compressions and NIRS has a slow response to ROSC.

[0006] US 2007 / 191688 A1 discloses embodiments of systems and methods for detecting a patient's response to an external stimulus. An exemplary method includes the following actions: generating at least one time series of at least one physiological parameter; detecting an external stimulus; detecting at least one response associated with the stimulus, the response including at least one of a pattern and a value; and outputting an indication of the response.

[0007] US 2014 / 323846 A1 discloses a system for determining the hemodynamic state of an individual, which system may include a photoplethysmography (PPG) subsystem and a response trigger module, wherein the PPG subsystem is configured to detect a PPG signal, and the response trigger module is configured to analyze the PPG signal and output one or more response triggers based on the change characteristics of the PPG signal within a time window. Each of the one or more response triggers may involve an instruction for initiating detection of at least one physiological characteristic of the individual. A blood pressure (BP) variability index determination module is configured to determine a BP variability index related to the hemodynamic state of the individual based on the frequency or pattern of the one or more response triggers. Summary of the invention

[0008] It is an object of the present invention to provide a device for supporting the detection of return of spontaneous circulation during cardiopulmonary resuscitation which is non-invasive and capable of preventing unnecessary interruptions of chest compressions.

[0009] In a first aspect of the invention, a device for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation is proposed, the device comprising:

[0010] a PPG input configured to obtain one or more photoplethysmographic (PPG) signals of a patient;

[0011] a BP output unit configured to provide a BP control signal, wherein the BP control signal is used to control the BP sensor to start measuring the blood pressure BP of the patient;

[0012] a BP input (35) configured to obtain one or more BP measurements; and

[0013] a processing unit configured to analyze one or more predefined PPG signal attributes of the one or more PPG signals and generate the BP control signal if one or more of the PPG signal attributes satisfy a predefined condition, wherein the one or more PPG signal attributes correspond to one or more of the following: detected pulse presence, pulse rate, duration of a predefined pulse rate level, variation of an inter-pulse interval over time, pulse strength, duration of presence of the pulse of the patient, and a number of cardiac-induced harmonics,

[0014] Therein, the processing unit (40) is configured to evaluate a state of an indicator of a cardiogenic output indicative of restoration of spontaneous circulation based on the BP measurement and / or a combination of the one or more PPG signals and the BP measurement.

[0015] In a further aspect of the invention, a system for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation is provided, the system comprising:

[0016] one or more PPG sensors configured to measure one or more PPG signals;

[0017] A device as disclosed herein, configured to generate a BP control signal by using the one or more PPG signals; and

[0018] a BP sensor configured to perform BP measurement based on the BP control signal;

[0019] Therein, the device is configured to assess a state of an indicator of a cardiogenic output indicative of restoration of spontaneous circulation based on the BP measurement and / or a combination of the one or more PPG signals and the BP measurement.

[0020] In another aspect of the present invention, a corresponding method, a computer program and a non-volatile computer-readable recording medium are provided, wherein the computer program includes a program code unit, and when the computer program is executed on a computer, the program code unit is used to enable the computer to perform the steps of the method disclosed in this document, and the non-volatile computer-readable recording medium stores a computer program product therein, and when the computer program product is run by a processor, it will enable the method disclosed in this document to be executed.

[0021] Preferred embodiments of the invention are defined in the dependent claims. It should be understood that the claimed method, system, computer program and medium have similar and / or identical preferred embodiments as the claimed device, in particular similar and / or identical preferred embodiments as defined in the dependent claims and disclosed herein.

[0022] The present invention is based on the idea of ​​providing a device for guiding a user, in particular a clinician, in CPR using PPG-triggered BP measurements that indicate restoration of spontaneous circulation. This can prevent unnecessary interruptions during compressions and prevent too long compressions being delivered to a beating heart, which could result in another arrest. Furthermore, the present invention can support the determination of when to administer vasopressors. The present invention is particularly intended to improve both in-hospital CPR and out-of-hospital CPR by medical professionals. The present invention can also be used in public AEDs using on-board PPG and blood measurements.

[0023] Currently, there is no noninvasive, blood pressure-related, quantitative indicator of ROSC.

[0024] PPG is able to detect the presence or absence of a spontaneous pulse non-invasively during CPR. Photoplethysmography is an optical measurement technique that is able to evaluate the changes in the light reflectance or light transmittance of a region or volume of interest over time. PPG is based on the principle that blood absorbs more light than the surrounding tissue, so that changes in blood volume with each heartbeat affect the transmittance or reflectance accordingly. PPG measurements can be performed non-invasively at the skin surface, wherein a light source and a detector in contact with the patient's skin constitute the PPG sensor of the system. However, PPG measurements can also be performed by arranging the PPG sensor at a distance from the tissue, wherein the light source and / or the detector are not in contact with the tissue, as is the case, for example, in camera-based measurements.

[0025] The presence of a spontaneous pulse may be observed in the PPG signal during a few seconds pause in compressions and during ongoing compressions after a defibrillation shock. During ongoing compressions, the increased complexity of the PPG waveform indicates spontaneous cardiac activity underlying the chest compressions. In addition, a decrease in the baseline of the PPG signal may also be considered an indicator of cardiogenic output, i.e., the presence of a heartbeat or the viability of the heart. Furthermore, spectral analysis of the PPG signal during ongoing compressions can show the presence of a second harmonic series, wherein the first harmonic series in the PPG signal spectrum is generated due to chest compressions, and the second harmonic series in the PPG signal spectrum is generated due to spontaneous cardiac activity. The presence of a spontaneous pulse during CPR can be confirmed by an increase in the simultaneously measured invasive arterial blood pressure (iABP).

[0026] However, PPG does not provide a quantitative measure of the state of the circulatory system. In fact, PPG can detect the presence of a spontaneous pulse at sub-life-sustaining blood pressures. PPG does not give the direct blood pressure data that a clinician needs to decide whether to continue CPR or to stop CPR.

[0027] The device according to the invention solves these problems by providing an additional means to assess the adequacy of the spontaneous pulse in the PPG signal and thus assess in a reliable manner the indicator of cardiogenic output corresponding to ROSC.In the present invention, a device combining PPG measurement with blood pressure measurement is described.

[0028] First, one or more PPG signals are obtained by a PPG input. The PPG input is understood to be a data interface capable of transmitting a PPG signal (ie, PPG data). The PPG input may be an analog interface or a digital interface supporting a wired connection or a wireless connection. PPG signals of one or more wavelengths may be obtained. For example, the incident light may be ambient light, such as sunlight. A pulse oximeter may also be used to obtain the PPG signal (ie, PPG data), which monitors the perfusion of blood to the dermis and / or other tissues of the patient. A typical pulse oximeter includes a red LED and an infrared LED as a light source and a photodiode for detecting light that has been transmitted through the patient's tissue, wherein the LED and the photodetector diode are typically configured to be arranged directly on the patient's skin, typically on a digit (fingers or toes) or an earlobe. Other locations on the patient may also be suitable. The LED may emit light of different wavelengths, which diffuses through the vascular bed of the patient's skin and is received by the photodetector diode. Other simpler versions of the system for obtaining PPG data may also be used, including those with a single light source of one or more wavelengths.

[0029] The obtained one or more PPG signals are then analyzed in a processing unit for one or more features indicative of a spontaneous heart pulse. In particular, the one or more algorithms comprised in the processing unit are configured to detect a spontaneous heart pulse during CPR (either during a pause of a few seconds in compressions or during ongoing compressions), wherein PPG measurements during pauses are more reliable because there are fewer motion artifacts, in particular from chest compressions. The detection of a spontaneous pulse is coupled to a predefined condition on one or more properties of the one or more PPG signals, wherein the properties can be any of the following: the presence of a pulse of the patient detected in the PPG signals, the pulse rate, the duration of a predefined pulse rate level (in particular the duration of a predefined minimum pulse rate level), the variation of the inter-pulse interval over time, the strength of his or her pulse, the duration of (stable) pulse detection and the number of harmonics due to the heart.

[0030] Algorithms for analyzing the PPG signal content to support ROSC detection can be found in US 2016 / 0157739 A1 or WO 2017 / 072055 A1.

[0031] When the recovery of spontaneous pulse is detected in the PPG signal measured (continuously) during CPR, the BP measurement will be triggered. Moreover, different types of algorithms can be used in the processing unit for the BP measurement performed after the spontaneous pulse is detected. The type of algorithm used may depend in particular on the type of PPG sensor and BP sensor used for measurement and the timing of the measurement. According to one of the algorithms, a BP control signal for controlling the BP sensor to measure the patient's blood pressure is generated in the processing unit, and the BP control signal is forwarded to the BP sensor by the BP output unit. The BP output unit is understood as a data interface capable of transmitting a BP control signal. It can be an analog interface or a digital interface supporting a wired connection or a wireless connection. The BP measurement may include one or more of the following: mean arterial pressure, systolic pressure, diastolic pressure, and finger artery pressure. The BP control signal may enable the BP sensor to measure the blood pressure in the form of a continuous blood pressure time trace or in the form of an interval. Then, the BP measurement obtained can provide clinicians with quantitative information about the state of the circulatory system. In fact, it can be used as an indicator of cardiogenic output and subsequently help clinical personnel evaluate the recovery of spontaneous circulation ROSC. ROSC is known in the art and refers to the restoration of a clinically significant pulse, ie, the point at which the heart begins to spontaneously generate life-sustaining blood flow.

[0032] In general, combining a PPG measurement with a BP system has the following advantages: The PPG measurement provides a (continuous) screening for the presence or absence of a spontaneous pulse. Once a spontaneous pulse is detected, a BP measurement can be performed to provide quantitative information about the circulatory system. This can better support the clinician in making decisions than using PPG alone, because it allows the clinician to determine whether the blood pressure is sufficient to stop CPR. In addition to this, there is no need for continuous BP measurements, because in order to detect cardiogenic output and then detect ROSC, it is necessary to know whether the heart is beating before applying BP measurement. This can be determined via PPG. In addition, PPG can further support the clinician in making decisions, because the PPG waveform can include information attributable to other physiological phenomena such as breathing in addition to information about the heart rate. Moreover, by evaluating the transmittance and / or reflectance at different wavelengths (usually red wavelengths and infrared wavelengths), the blood oxygen saturation (SpO2) can be determined. Therefore, the processing unit can also take this information into account to evaluate ROSC.

[0033] In particular, based on the BP measurement results, the clinician can determine that when the blood pressure is high enough, such chest compressions can be stopped to further evaluate potential ROSC; and when the blood pressure is low, such chest compressions need to continue to provide additional support to the beating heart. The evaluation of whether CPR actions can be stopped based on the BP measurement can be linked to predefined conditions regarding the patient's blood pressure. In addition to the blood pressure value, the condition can also include a threshold value regarding the duration that the patient is at a specific blood pressure. For example, if the diastolic blood pressure (DBP) is measured to be equal to or higher than 40 mmHg for at least 30 seconds, the processing unit can only evaluate indicators of cardiogenic output.

[0034] In addition, the assessment of the cardiogenic output may also be based on a combination of BP measurements and PPG measurements. That is, the indicator of the cardiogenic output may be provided by a BP signal attribute alone or in combination with a PPG signal attribute such as pulse rate. In fact, the indicator of the cardiogenic output may also be provided by other appropriate vital signs (e.g., a PPG signal attribute alone or a combination of an ECG signal attribute and a PPG signal attribute). The state of the indicator represents a measure of the probability of ROSC.

[0035] In an embodiment of the device, the predefined condition comprises one or more of: a threshold, a range, an item in a lookup table, and a position in a graph.

[0036] For example, detection of a spontaneous pulse is provided only if the patient's pulse is detected to be at a pulse strength of at least 0.1% of the patient's average PPG signal level (at the moment of measurement) for at least 30 seconds, at a rate of at least 30 beats per minute. That is, the predefined conditions define thresholds for pulse strength, pulse rate, and pulse duration. In addition, the predefined conditions can include PPG signal characteristics, such as the number of harmonics caused by the heart detected in the PPG signal. Similarly, the processing unit can compare the detected pulse rate data with data in a lookup table, for example, of a memory of the device. If the measured data matches the data of the table, the processing unit can determine that a spontaneous pulse has been detected and trigger a BP measurement. The processing unit can also track the PPG signal over time and compare the signal with a PPG signal waveform stored in the memory. In this case, the predefined condition can be represented by the matching of the two signals with a predefined range. In addition, the processing unit can calculate the probability of ROSC based on the measured and / or derived PPG signal parameters.

[0037] In another embodiment, the device further comprises an ECG input configured to obtain one or more electrocardiogram (ECG) signals, wherein the processing unit is configured to analyze the one or more predefined PPG signal properties using the one or more ECG signals.

[0038] The ECG input is understood to be a data interface capable of transmitting one or more ECG signals (i.e., ECG data) respectively. The ECG input may be an analog interface or a digital interface supporting a wired connection or a wireless connection. The (organized) ECG signal may facilitate the search for a pulse in a PPG signal. When the ECG signal has an organized appearance, a QRS complex can be distinguished in the signal. This indicates that the electrical activity of the heart has been restored again, which is called cardiac rhythm restoration (ROR). However, ROR does not provide information about the mechanical activity of the heart. When observing ROR, the myocardium may still be unable to contract, which occurs in large numbers in patients undergoing CPR in hospitals. Therefore, additional measurements reflecting the mechanical activity of the heart are still needed. PPG is an easy-to-use non-invasive method that can show whether the heart has resumed beating again. The QRS complex in the ECG signal analyzed by the processing unit can facilitate the detection of the pulse caused by the heart in the PPG signal, because when the heart is beating, the PPG pulse caused by the heart should follow these QRS complexes.

[0039] Advantageously, the device further comprises a chest compression signal input unit, which is configured to obtain a chest compression signal indicating one or more of the following: transthoracic impedance, chest compression rate, length of inter-compression interval, chest compression force, chest compression depth, chest compression acceleration and chest compression speed, wherein the processing unit is configured to: analyze the chest compression signal, and identify and process or remove artifacts of the chest compression signal from the one or more PPG signals and / or the ECG signals.

[0040] Although the processing unit may identify and remove chest compression artifacts from the PPG signal and / or ECG signal, it may also process the chest compressions in other ways. For example, in the case where the effect of chest compressions on the PPG signal and / or ECG signal is at most a predefined level, it may not be necessary to remove artifacts of the chest compression signal from the PPG signal and / or ECG signal. On the other hand, if the effect of chest compressions on one or more PPG signals and / or ECG signals is shown to be above the level, compression artifacts may be reduced or removed from the PPG signal and / or ECG signal, for example, by removing all frequency components related to the measured compression rate and its harmonics. In this way, motion artifacts caused by chest compressions are eliminated or at least reduced, which motion artifacts may complicate the detection of the heart pulse in the PPG signal and the detection of the QRS complex in the ECG signal. Furthermore, in addition to explicitly removing the compression components from one or more PPG signals and / or ECG signals, it may also be sufficient to identify only the frequency components related to the compressions. For example, when applying spectral analysis to a PPG signal and / or an ECG signal, it is sufficient to know which frequency components in the spectrum are due to chest compressions, so that these frequency components can be ignored when further analyzing the signal spectrum.

[0041] In further embodiments of the device, the processing unit is configured to analyze the chest compression signal to distinguish pauses in compressions from ongoing compressions and to generate the BP control signal during pauses in compressions or during ongoing compressions.

[0042] When BP measurement is triggered during a pause in compressions, PPG measurement can prevent unnecessary interruptions in compressions and invalid BP measurements. On the other hand, when BP measurement is triggered during ongoing compressions, PPG measurement can determine when a spontaneous pulse occurs and thus BP measurement can be started immediately to prevent compressions on a beating heart (which could cause the heart to stop beating again).

[0043] In another embodiment, the device for supporting the detection of the resumption of spontaneous circulation further comprises a user input configured to obtain user information from a first user interface, wherein the processing unit is configured to generate the BP control signal and / or adjust the predefined condition based on the user information; and / or the device further comprises a user output configured to provide ROSC information to a second user interface. In particular, when the processing unit detects the presence of a spontaneous pulse in the PPG signal, a user input is first required to confirm the start of BP measurement to determine the most appropriate time to start BP measurement.

[0044] The user information may include the patient's BP data and / or other data of the patient, which are related to the state of the indicator for evaluating the cardiogenic output and, therefore, to the assessment of ROSC. In particular, the user information may be used to adjust the threshold or range of the state of the indicator for evaluating the cardiogenic output, which is related to, for example, the BP detected in the PPG signal, the duration of the BP level, the PR, the duration of the (minimum) PR level, the pulse interval, the change in the pulse interval, the presence of the pulse, the duration of the presence of the pulse, the pulse strength, and the number of harmonics caused by the heart. These data may also include end-tidal CO2 data, (central venous) oxygen saturation data and / or NIRS data. The user information may also be information about the CPR protocol used, and therefore may also be information including the rate of chest compressions applied to the patient. In particular, the user information may include an algorithm for analyzing one or more PPG signals and / or BP measurements in the processing unit.

[0045] ROSC information comprises any of the following: information about one or more PPG signals (particularly after removal or reduction of artifacts has been achieved by using compression signals), one or more predefined PPG signal attributes, presence of pulses detected in the PPG signal, pulse rate, duration at a certain (minimum) PR level, variation of the inter-pulse interval over time, pulse strength, duration of presence of a (stable) pulse, number of cardiac-induced harmonics, BP, rate of chest compressions, chest compression fraction, oxygen saturation and any indicator of cardiogenic output and their status, and an estimate of the probability of ROSC (estimated by the processing unit).

[0046] In a preferred embodiment of the system for supporting detection of restoration of spontaneous circulation, the BP sensor comprises a BP cuff, which can be any of the following: a finger cuff, a wrist cuff and an arm cuff, and the one or more PPG sensors are configured to be arranged in one of the cuff, one or more other finger cuffs, wrist cuffs or arm cuffs, or in a finger, earlobe, concha or auricle, forehead, nose wing or nasal septum of the patient, and / or inside the mouth (for example, inside the cheek or tongue).

[0047] In particular, the BP cuff may be an inflatable cuff with an external pressure, i.e., the pressure applied by the cuff to the patient's body depends on the cuff inflation level. The pressure provided by the cuff is then measured by a BP sensor included in the cuff. The measured external pressure is used to determine blood pressure, e.g., mean arterial pressure, systolic pressure, diastolic pressure and / or finger artery pressure.

[0048] In another embodiment, the processing unit is configured to control the pressure of the cuff continuously or at intervals during ongoing compressions. In particular, the average cuff pressure may be controlled. However, in case of cNIBP measurement, the processing unit is configured to control the cuff pressure in order to counteract the pressure in the blood vessels and keep the blood volume constant (volume clamp).

[0049] In another embodiment of the system, at least one of the one or more PPG sensors is configured to be arranged on the skin-facing side of the BP cuff, and the processing unit is configured to control the average cuff pressure applied by the cuff to the patient so as to maximize the amplitude of the one or more PPG signals of the at least one PPG sensor and / or the amplitude of the pressure oscillations inside the cuff.

[0050] For example, when performing a PPG measurement distal to the cuff, an algorithm may be selected that causes a cuff pressure sweep to determine at which cuff pressure the spontaneous pulse disappears in the PPG signal. The resulting pressure is a measure of the systolic pressure at that location of the cuff.

[0051] In a preferred embodiment, the system further comprises one or more ECG sensors configured to measure one or more ECG signals, wherein the processing unit is configured to analyze the one or more ECG signals to facilitate obtaining any of the one or more PPG signal attributes. Alternatively or additionally, the system further comprises a chest compression sensor configured to measure a chest compression signal indicative of one or more of the following: transthoracic impedance, chest compression rate, length of inter-compression intervals, chest compression force, chest compression depth, chest compression acceleration, and chest compression velocity, wherein the processing unit is configured to analyze the chest compression signal and identify and process or remove artifacts of the chest compression signal from the one or more PPG signals and / or the ECG signal.

[0052] The chest compression sensor can be an accelerometer, a force sensor, a radar, a communication module for an automated compression device, or defibrillation pads, where the compression rate is inferred from the impedance signal measured between these pads. In fact, the compression sensor can be any sensor that provides a reference about the chest compression rate, depth, speed, or acceleration.

[0053] The one or more ECG sensors may be any of a photoelectric sensor, an ECG electrode, or a piezoelectric sensor. The ECG sensor may be a wearable sensor or may include remote ECG monitoring. The sensor may provide an ECG signal for wired or wireless communication.

[0054] According to another embodiment, the system further comprises a first user interface and / or a second user interface, the first user interface being configured to obtain the user information, the second user interface being configured to provide the ROSC information in a visible manner and / or an audible manner.

[0055] The first user interface and the second user interface may be included in separate units, or may be included in a single unit (i.e., as a single user interface configured to obtain user information and provide ROSC information). The first user interface and the second user interface may include one or more displays, buttons, touch screens, keyboards, or other human-machine interface devices. Thus, for example, user information such as information about the patient's invasive blood pressure data, (central venous) oxygen saturation data, TTI data, and / or NIRS data may be provided via keyboard input or directly from another device. The second user interface may also be used to provide a ROSC probability signal based on the probability of ROSC determined by the processing unit. For example, a bar may be displayed on the display, the lower end of which indicates "cardiac arrest" and the upper end of which indicates "potential ROSC", wherein an arrow aimed at the bar indicates the probability of ROSC, i.e., the state of the indicator of the cardiogenic output. Once the processing unit has detected a cardiogenic output indicating ROSC with a predefined probability, the second user interface may also prompt an audible signal. The information may be provided to the user as real-time feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] These and other aspects of the invention will become apparent with reference to the embodiment(s) described hereinafter. In the following drawings:

[0057] Figure 1 shows a schematic diagram of a first embodiment of a device for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation according to the invention,

[0058] Figure 2 shows a schematic diagram of a second embodiment of the device according to the invention,

[0059] Figure 3 shows a schematic diagram of a third embodiment of the device according to the invention,

[0060] Figure 4 shows a schematic diagram of a first embodiment of a system for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation according to the present invention,

[0061] Figure 5 shows a schematic diagram of a second embodiment of a system for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation according to the present invention,

[0062] Figure 6An exemplary embodiment of a system for supporting detection of restoration of spontaneous circulation in a patient undergoing CPR according to the present invention is shown,

[0063] Figure 7 An embodiment of a display unit of a device according to the invention is shown, and

[0064] Fig. 8A and Figure 8B Different embodiments of a BP sensor and a PPG sensor according to the present invention are shown. DETAILED DESCRIPTION

[0065] Figure 1 A schematic diagram of a first embodiment of a device 10 for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation according to the present invention is shown. The device 10 comprises a PPG input 20, a BP output 30 and a processing unit 40. The PPG input 20 is configured to obtain a PPG signal 21 of a patient and to provide the signal 21 to the processing unit 40. Subsequently, the processing unit 40 analyses the PPG signal 21. In this embodiment, the processing unit 40 is configured to use the signal 21 to detect the pulse rate of the patient.

[0066] The detection of the pulse rate provides information about the rate at which the heart is contracting and pumping blood. If this rate is below a predefined threshold (e.g. 0.5 Hz), the processing unit assumes that there is no ROSC yet. Therefore, no other action will be performed than to continue the PPG measurements. Even if the analysis of the PPG signal 21 shows a sufficiently high rate for a potential ROSC, chest compressions should be continued if the heart is not yet pumping blood in a stable manner (i.e. if the variation of the intervals between pulses over time is too high). However, when the heart is pumping blood again at a stable rate above, for example, 0.5 Hz, the presence of a cardiogenic output is checked by predefined subsequent blood pressure measurements.

[0067] Indeed, the presence of a sufficiently high stable pulse rate is a necessary prerequisite for ROSC: without such a rhythm, there will be no ROSC and it will be useless for further assessment of the cardiogenic output and the corresponding ROSC. On the other hand, the presence of a stable sufficiently high pulse rate in the PPG signal does not directly indicate the presence of ROSC, since it does not provide quantitative information about the underlying blood pressure and / or perfusion level. In other words, the restoration of spontaneous circulation is only given after a perfusing rhythm has been reestablished (i.e., when the heart contracts again at a stable rate, thereby obtaining a cardiac output that sustains life). Therefore, the processing unit 40 generates a BP control signal 31 if the pulse rate is above a predefined threshold and the stability condition is met. The BP output 30 then provides a BP control signal, which is used to control the BP sensor to start measuring the patient's blood pressure in order to support the assessment of ROSC.

[0068] Figure 2 A schematic diagram of a second embodiment of a device 10 for supporting detection of recovery of spontaneous circulation during cardiopulmonary resuscitation according to the present invention is shown. In addition to the PPG input 20, the BP output 30 and the processing unit 40, the device 10 also includes a BP input 35, which is configured to obtain a BP measurement 36. By analyzing the patient's blood pressure signal 36, the processing unit 40 can evaluate the probability of recovery of cardiogenic output or recovery of spontaneous circulation. For example, if the systolic blood pressure is above 60mmHg, ROSC may be given. Therefore, the processing unit 40 is configured to check whether the blood pressure is above the threshold or another predefined threshold. If this is the case, the processing unit 40 evaluates the recovery of cardiogenic output. The clinician can then stop delivering chest compressions to the patient in order to prevent re-arrest or other injuries caused by chest compressions and / or evaluate ROSC.

[0069] Figure 3 A schematic diagram of a third embodiment of a device 10 according to the present invention is shown. The device 10 comprises a PPG input 20, a BP output 30, a BP input 35, a chest compression signal input 50, a user input 60 and a processing unit 40.

[0070] The PPG signal 21 obtained by the PPG input 20 is transmitted to the processing unit 40 for analysis. The PPG signal 21 is analyzed for the presence or absence of a spontaneous pulse during compressions. For example, the presence of a spontaneous pulse in the PPG signal 21 during compressions can be identified by increasing the complexity of the shape of the PPG signal 21. Alternatively, the presence of a pulse can be detected via spectral analysis of the PPG signal when two harmonic series can be identified, one of which corresponds to chest compressions and the second to cardiac activity.

[0071] The analysis during ongoing compressions also involves using a chest compression reference 51 to detect the presence of compressions and identify the compression rate. For example, the compression reference 51 can be an impedance signal obtained between defibrillation pads attached to the patient. The chest compression signal input 50 is configured to obtain the chest compression signal 51. The chest compression signal 51 indicates the rate of chest compressions delivered to the patient, the change in the interval between compressions over time, and the compression intensity and / or depth. The processing unit 40 analyzes the properties of the chest compression signal 51. Then, by using the analysis results, the processing unit 40 removes the artifacts of the chest compression signal 51 from the PPG signal 21 by removing all frequency components related to the measured compression rate. In this way, motion artifacts caused by chest compressions are eliminated or attenuated, which can complicate the detection of the heart pulse in the PPG signal 21. Alternatively, the processing unit 40 uses the compression rate derived from the compression reference 51 to identify and ignore all spectral components related to compressions in the PPG signal in order to determine whether the PPG signal contains residual spectral components related to cardiac activity. For example, when the processing unit 40 detects two harmonic series in the PPG signal 21, the compression rate information can be used to identify which of the two harmonic series corresponds to chest compressions and which of the two harmonic series corresponds to spontaneous cardiac activity.

[0072] The processing unit 40 of this embodiment is also configured to analyze the chest compression signal 51 to distinguish a pause in compression from ongoing compressions. If the compression signal is determined to indicate a compression rate below a predefined threshold or is determined to contain no characteristics related to compressions, the processing unit 40 evaluates that there is no chest compression delivered to the patient, that is, there is a pause in compression. Identifying a pause in compression based on the compression signal 51 can be used to obtain an alternative detection of whether there is a spontaneous cardiac component in the PPG signal 21. Assuming that there is a pause in compression and the presence of a pulse is detected in the PPG signal 21, the processing unit 40 generates a BP control signal 31 during the pause in compression when the presence of a pulse is detected during the ongoing compression and / or during the pause in compression. The BP output unit 30 obtains the signal to control a BP sensor for measuring the patient's blood pressure. In addition, the processing unit 40 can also be used to extract information about the quality of a CPR component (e.g., compression depth or chest compression score).

[0073] The apparatus 10 for detecting the return of spontaneous circulation further comprises a user input 60 configured to obtain user information 61 from a first user interface 600 and to provide ROSC information 71 to a second user interface 700 (see Figure 5). The processing unit 40 uses the user information 61 to generate the BP control signal 31. The user information 61 may, for example, include a confirmation to start BP measurement. Therefore, if the PPG signal analysis results in a high probability of ROSC, the processing unit 40 can first prompt the user via the user interface 700 that a cardiogenic output has been detected and request whether a BP measurement should be performed. Only after the user confirms via the user interface 600 that it is appropriate to perform a BP measurement is a BP control signal generated to start the BP measurement. This allows the clinician to determine the most appropriate moment to perform a BP measurement. In addition, the user information provided via the user interface 600 can be used to customize thresholds and ranges that are used to evaluate the state of an indicator of a cardiogenic output. These thresholds and ranges can involve the presence of a pulse detected in the PPG signal, PR, duration of the (minimum) PR level, pulse interval, duration of the presence of a pulse, changes in the pulse interval, pulse intensity, BP, duration of a specified BP level, and the number of harmonics caused by the heart.

[0074] Figure 4 A schematic diagram of a first embodiment of a system 100 for supporting detection of restoration of spontaneous circulation during cardiopulmonary resuscitation according to the present invention is shown. The system 100 comprises a second embodiment of an apparatus 10 for supporting detection of restoration of spontaneous circulation, a PPG sensor 201, a BP sensor 300 and an ECG sensor 900.

[0075] In this embodiment, the BP sensor 300 is integrated in a cuff 301. The cuff can be applied to the patient's finger and can measure his or her blood pressure during compression, for example by tracking the mean arterial pressure MAP. After the presence of a pulse is detected in the PPG signal, the tracking of the blood pressure will be performed. The PPG measurement module 201 is integrated in the same cuff 301, in particular, it is integrated below the cuff 301 (i.e., the side facing the skin). PPG and cuff-based pressure measurement can be performed on the middle phalanx or proximal phalanx of the finger (in particular, on the proximal phalanx of the thumb). The PPG sensor 201 continuously measures the patient's PPG signal 21, which is measured at, for example, a green wavelength, a red wavelength and / or an infrared wavelength, respectively. The measured PPG signal 21 is transmitted to the processing unit 40 for subsequent analysis. In particular, the PPG signal 21 is analyzed for the presence or absence of a spontaneous pulse during compression. The analysis is supported by the ECG signal 91 provided by the ECG sensor 900 via the ECG input 90. In particular, before analyzing the PPG signal for the presence of a pulse, the ECG signal should first have an organized appearance. That is, the ECG signal should first contain a QRS complex, which indicates that the electrical activity of the heart has been restored again, which is called rhythm resumption ROR. After the ROR occurs, the mechanical activity of the heart can be checked by searching for a pulse caused by the heart in the PPG signal. The QRS complex in the ECG signal can facilitate the detection of the pulse caused by the heart in the PPG signal, because when the heart is beating, the PPG pulse caused by the heart should follow these QRS complexes. Alternatively, when spectral analysis is applied, the heart rate (HR) derived from the ECG signal can be used to identify the pulse rate (PR) of the spontaneous pulse in the PPG signal.

[0076] After the presence of a spontaneous pulse is detected in the signal 21 by means of ECG signal analysis, a cuff-based BP measurement is triggered. To this end, the processing unit 40 is configured to scan the cuff pressure to find the mean arterial pressure (MAP). The MAP is approximated by the cuff pressure when the spontaneous pulse component in the PPG signal has maximum pulsatility (i.e., maximum amplitude or maximum average signal level). At maximum pulsatility, vascular compliance is maximum, which means that the vessel wall has been unloaded. Unloading of the vessel wall is achieved when the cuff pressure is equal to the average blood pressure in the vessel. Alternatively, the compression oscillations inside the cuff 301 are measured. Then, the MAP is approximated by the cuff pressure when the compression oscillations in the cuff 301 measured by the BP sensor 300 have maximum amplitude.

[0077] MAP can also be estimated during cardiac arrest.At this time, the pulsatility of the compression-induced component in the PPG signal 21 or the amplitude of the compression-induced component in the cuff pressure is maximized.

[0078] Alternatively, in another embodiment, the PPG measurement and the BP measurement are not integrated in the same cuff. Here, the PPG measurement can be obtained, for example, by using a PPG sensor 201 applied to a finger, forehead, nasal septum, nose wing, earlobe, concha or auricle. The BP measurement can be obtained by using a cuff 301 applied to an arm, wrist or finger. Once the presence of a spontaneous pulse is detected in the PPG signal 21, a cuff-based BP measurement can be triggered. If the cuff 30 is applied to the upper arm and the PPG measurement is applied to the finger on the other arm, a BP measurement can be performed while still using the PPG measurement to track the presence of the pulse. Alternatively, if the PPG measurement is applied to the distal side of the cuff 301 on the same arm, the PPG measurement can be used to determine the BP level. For example, when scanning the pressure in the arm cuff 301, an estimate of the systolic blood pressure (SBP) will be achieved when the spontaneous pulse disappears in the PPG measurement performed distal to the cuff.

[0079] Figure 5 A schematic diagram of a second embodiment of a system for supporting detection of resumption of spontaneous circulation according to the present invention is shown. The system comprises a third embodiment of the device 10, a PPG sensor 201, a BP sensor 300, a chest compression sensor 500, a first user interface 600 and a second user interface 700.

[0080] In this embodiment of the system 100, the PPG sensor 201 is incorporated in a finger cuff 301. At the same time, the cuff contains a BP sensor 300. The BP measurement performed by the cuff is a continuous non-invasive blood pressure measurement (cNIBP). The cNIBP measurement needs to be calibrated to find the mean finger artery pressure, around which the processing unit 40 can track the changes in blood pressure. In this embodiment, the calibration of the cNIBP measurement is performed during ongoing compressions. The mean compression corresponds to the cuff pressure at which the pulsatility of the PPG signal 21 is maximum (pulsatility = amplitude divided by the mean signal level). The compression is determined by the processing unit 40. At maximum pulsatility, the vessel compliance is maximum, which means that the vessel wall is unloaded. Unloading of the vessel wall is achieved when the cuff pressure is equal to the mean blood pressure in the vessel. Tracking the mean blood pressure and thus the operating point of the cNIBP measurement allows faster cNIBP measurements in subsequent pauses in compressions, because the correct mean compression has been estimated and the cNIBP measurement can start immediately. In this embodiment, the operating point of the cNIBP measurement can be tracked continuously over time or at regular time intervals.

[0081] During cardiac arrest or after a spontaneous pulse is detected in the PPG signal 21, the pulsatility of the PPG signal 21 can be maximized. During cardiac arrest, the pulsatility of the signal due to compressions is maximized. After a spontaneous pulse is detected, the pulsatility of the spontaneous pulse component in the PPG signal 21 is maximized. In order to maximize the pulsatility of the spontaneous pulse component, the component is extracted from the PPG signal 21 by removing chest compression artifacts. Removal of the chest compression component involves using the compression reference signal 51 to determine the chest compression rate.

[0082] In this way, when the PPG measurement is performed under the finger cuff, the mean finger artery pressure can be tracked during compressions. Tracking the mean finger artery pressure during compressions has the following advantages: firstly, it ensures that the cNIBP measurement is always at its operating point and can be used, and secondly, it improves the quality of the PPG measurement by maximizing the signal amplitude. In fact, when the PPG measurement is performed under the finger cuff, by maximizing the PPG signal pulsatility, the cuff can continuously apply a low pressure to ensure good signal quality. This improves the signal-to-noise ratio and the quality of the PPG measurement 21. In addition, the cuff pressure ensures good contact between the PPG sensor 201 and the skin, which reduces the movement of the PPG sensor 201 relative to the skin, thereby reducing motion artifacts in the PPG signal 21. In addition, during cardiac arrest, by tracking the mean finger artery pressure, the processing unit 40 is able to evaluate the effectiveness of the chest compressions.

[0083] The second user interface 700 can display a PPG signal time trace (particularly a PPG signal time trace after removing chest compression artifacts), blood pressure measurements (SBP, MAP, DBP) and cNIBP time traces, as well as derived information such as indicators of cardiogenic output to provide clinical decision support. The interface 700 can also show the spontaneous pulse rate derived from the PPG measurement and the oxygen saturation (SpO2) determined from the spontaneous pulse component of the PPG measurement at, for example, red and infrared wavelengths. In addition, the user interface 700 can provide auditory feedback on the effectiveness of chest compressions and provide suggestions to the user to improve CPR.

[0084] Figure 6 An exemplary embodiment of a system 100 for supporting detection of return of spontaneous circulation in a patient undergoing CPR in accordance with the present invention is shown.

[0085] The system 100 includes the device 10, a PPG sensor 201 disposed in a finger cuff, a BP sensor 300 disposed in an inflatable arm cuff, a chest compression sensor 500 attached to the patient's chest and subjected to compressions, two ECG sensors attached to the patient's chest, a first user interface 600 disposed in the device 10, and a second user interface 700. Chest compressions can be delivered manually by a clinician 8 or using an automatic mechanical device 80.

[0086] In this embodiment of the system 100, a PPG signal 21 can be measured during a pause in compressions, and the PPG signal 21 can be used to arrange BP measurements during the same pause in compressions, wherein the pause in chest compressions can be detected via a compression signal 51, which is delivered to the device 10 from the chest compression sensor 500 via a chest compression cable 55. The PPG signal 21 delivered to the device 10 from the finger cuff 201 via the PPG cable 25 is analyzed for the presence of a spontaneous pulse. To support the analysis, an ECG signal measured by ECG sensors 901 and 902 and provided to the device 10 via an ECG cable 95 is used. The ECG signals 91 and 92 can be analyzed to detect a QRS complex, which indicates a resumption of rhythm ROR. After the ROR is detected, the PPG signal 21 can be analyzed to find the presence of a pulse. Here, the ECG signals 91 and 92 can also help, because the pulse caused by the heart in the PPG signal 21 will follow the QRS complex in the ECG signals 91 and 92. Alternatively, when applying spectral analysis, the heart rate (HR) derived from the ECG signals 91 and 92 can facilitate the determination of the pulse rate (PR) in the PPG signal 21. If a spontaneous pulse is detected in the PPG signal 21 during the pause, a cuff-based BP measurement is scheduled. Then, the BP measurement can be performed automatically directly after the spontaneous pulse is detected.

[0087] Alternatively, the system can prompt the clinician via a display or an audible signal using the second user interface 700 that a spontaneous pulse has been detected and that a cuff-based BP measurement is suggested to be started directly after pressing the button of the first user interface 600. In the latter case, if the clinician is already aware that the pulse is still not life-sustaining, the clinician 8 can choose to postpone the BP measurement. In addition, the system 100 can also measure and analyze the PPG signal 21 for the presence of a pulse during the ongoing compression. In this case, the BP measurement can be performed automatically during the next pause in the compression or after the user confirms via the user interface 600. If the compression is delivered in a cycle of, for example, 2 minutes (a common practice in CPR), a BP measurement with a short pause can be arranged immediately after the two-minute compression cycle. Alternatively, the system can prompt the clinician 8 that a spontaneous pulse has been detected and that a BP measurement is suggested to be started immediately after pressing the button. In the latter case, the clinician 8 can choose not to wait for the next pause in the protocol, but to deviate from the standard protocol to personalize the patient.

[0088] BP measurement can be performed to measure systolic pressure, diastolic pressure and / or mean arterial pressure. User 8 can use user interface 600 to decide the type of blood pressure to be measured. In particular, user interface 600 can be configured to enable the user to change the inflation and / or deflation rate of the BP cuff. The user can also provide user information about the local hospital CPR protocol he / she uses. The measured BP signal 31 is provided to device 10 via BP cable 37. By using BP measurement, device 10 determines whether cardiogenic output (or how high the probability of ROSC) has been achieved. The user can customize the threshold and range used in the assessment of the state of the indicator of cardiogenic output via user interface 600. These thresholds and ranges can be related to the pulse presence detected in the PPG signal, PR, duration of (minimum) PR level, pulse interval, duration of pulse presence, change of pulse interval, pulse intensity, the number of harmonics caused by the heart, BP, and duration of the specified BP level. If the evaluation of the state of the indicator of the cardiogenic output determines that a pulse is present, the processing unit 40 provides corresponding information to the display 700 indicating to the clinician 8 that further evaluation for ROSC is recommended. However, if ROSC may not yet be achieved, a new two-minute CPR block is recommended via the display or directly initiated for execution by the mechanical CPR device 80.

[0089] The PPG measurement can be performed on the same arm as the arm on which the BP measurement is performed at the distal end of the cuff 301, and can also be performed on another arm that is not used for the BP measurement. After the presence of a pulse is detected in the PPG signal 21, the BP measurement will be performed. In the first case (PPG measurement performed at the distal end of the cuff 301), the PPG measurement can no longer be used for pulse presence detection during the BP measurement. However, in this case, the PPG measurement can be used to determine the BP level. For example, when scanning the pressure in the arm cuff 301, when the spontaneous pulse disappears in the PPG measurement performed at the distal end of the cuff 301, an estimated value of the systolic blood pressure (SBP) will be reached. Alternatively, when the PPG measurement is performed on a finger on another arm different from the arm on which the BP measurement is performed, a BP measurement can be performed while the PPG measurement will still be used to track the presence of a pulse.

[0090] Figure 7 An exemplary embodiment of a second user interface 700 of the system 100 according to the present invention is shown.

[0091] In this embodiment, the second user interface 700 is a display unit showing the tracking of the diastolic pressure signal 32, the oscillations 33 of said signal and the chest compression signal 51 over time. The diastolic pressure 32 and the oscillations 33 are depicted on a compression scale of 0-50 mmHg. It can be seen that the oscillations 33 are directly related to the chest compression signal 51.

[0092] The processing unit 40 processes the measured PPG data 21 and BP data 31 to determine the state of an indicator of a cardiogenic output having a continuous scale from "cardiac arrest" to "potential ROSC". The scale is also displayed as a ROSC probability bar 45 on the display unit 700. The indicator 46 indicates in real time the probability of ROSC as assessed by the processing unit. Thus, once a potentially life-sustaining pulse is detected, the user is immediately notified and can therefore decide to stop CPR actions on the restarted heart and further assess for potential ROSC.

[0093] Fig. 8A and Figure 8B Different embodiments of a BP sensor and a PPG sensor according to the present invention are shown.

[0094] Fig. 8AA finger cuff 301 wrapped around a finger 9 is shown, which includes both a PPG sensor 201 and a BP sensor 300. In this embodiment, continuous non-invasive blood pressure measurement is achieved via a volume clamp cuff. The PPG sensor 201 integrated in the cuff includes a red LED and an infrared LED as a light source and a photodiode for detecting light emitted by the light source and reflected by / transmitted through the patient's skin. Here, PPG measurement is used continuously to detect the presence of a pulse. Once a pulse is detected, a blood pressure measurement is triggered. Since BP measurement is based on a volume clamp method, PPG measurement can no longer be used during BP measurement. After the presence of a pulse is detected via PPG, a volume clamp-based method can be used continuously or intermittently. In the case of intermittent BP measurement, PPG measurement can be used alternately with BP measurement to keep track of the presence of a pulse.

[0095] For determining certain vital signs, certain light-colored ranges of the PPG signal 21 have shown the best results. Furthermore, while it is possible to determine the pulse rate of a patient using a single wavelength (corresponding to, for example, red, infrared or green), only analysis using at least two different wavelengths gives clear information about the blood oxygenation level (SpO2), thus providing further indications for ROSC. For example, it has been shown that the relative amplitude ratio of the wavelength interval from around 650 nm (red) to 840 nm or 900 nm (infrared) provides reliable results for SpO2.

[0096] exist Figure 8B In the embodiment of the BP sensor and the PPG sensor shown, three PPG sensors 201, 202 and 203 are used in conjunction with a finger cuff 301 for BP measurement, i.e., include a BP sensor wrapped around a patient's finger 9. While the first PPG sensor 201 is arranged on the finger skin on the distal side of the cuff 301, the second PPG sensor 202 is arranged on the skin-facing side of the inside of the cuff 301, and the third PPG sensor 203 is located on the patient's skin on the proximal side of the cuff 301.

[0097] In this embodiment, the spontaneous pulse component in the signal of the first PPG sensor 201 is used to determine the systolic blood pressure (SBP). After the spontaneous pulse is detected in the first PPG signal 21, the cuff-based BP measurement is triggered. The cuff pressure is scanned to determine the SBP. This can be done during compressions or during pauses in compressions. If done during compressions, the SBP can be obtained in various ways. The cuff 301 is inflated until the spontaneous pulse component in the first PPG signal 21 disappears, wherein the spontaneous pulse component is extracted from the first PPG signal 21. The cuff pressure at which this occurs is an estimate of the SBP. Alternatively, when the spontaneous pulse component is not explicitly extracted from the PPG signal 21, the SBP is approximated by the cuff pressure at which the PPG signal amplitude / variation is minimized, because some compression artifacts in the PPG signal may not be due to the propagation of pressure waves through the blood vessels caused by the compression, but rather due to sensor-tissue movement caused by the compression. Next, by using the cuff 301 and the second PPG sensor 202 together with the volume clamp method to measure cNIBP during pauses in compressions, a blood pressure waveform can be obtained. The pulse pressure measured by cNIBP is a good estimate, but the absolute level of the cNIBP waveform needs to be calibrated. This calibration will be performed here using the SBP measurement obtained using the first PPG sensor 201. The systolic pressure in the cNIBP waveform is set equal to the SBP estimate obtained using the first PPG sensor 201. This also allows the diastolic pressure (DBP) to be measured. During the use of the volume clamp method during the compression pause, the first PPG sensor 201 may provide unreliable results because the pulse signal will be affected upstream by the cuff. Therefore, during the cNIBP measurement, the third PPG sensor 203 can be used for PR measurement and SpO2 measurement.

[0098] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered illustrative or exemplary rather than restrictive; the present invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure, and the claims.

[0099] In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. Although certain measures are recited in mutually different dependent claims, this does not indicate that a combination of these measures cannot be used to advantage.

[0100] The computer program may be stored / distributed on suitable non-transitory media, such as optical storage media or solid-state media supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0101] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A device (10) for supporting detection of return of spontaneous circulation during cardiopulmonary resuscitation, the device comprising: A PPG input (20) configured to obtain one or more photoplethysmographic (PPG) signals (21) of a patient; A BP output unit (30) configured to provide a BP control signal (31), wherein the BP control signal is used to control the BP sensor to start measuring the blood pressure BP of the patient; a BP input (35) configured to obtain one or more BP measurements (36); as well as a processing unit (40) configured to analyze one or more predefined PPG signal attributes of the one or more PPG signals (21, 22, 23) and generate the BP control signal (31) if one or more of the PPG signal attributes satisfies a predefined condition, wherein the one or more PPG signal attributes correspond to at least a pulse rate, a pulse strength, and a duration of presence of a pulse of the patient, and wherein the predefined condition comprises respective threshold values ​​for the pulse rate, the pulse strength, and the duration of presence of a pulse, and wherein the predefined condition is used to detect resumption of a spontaneous pulse, Therein, the processing unit (40) is configured to evaluate a state of an indicator of a cardiogenic output indicative of restoration of spontaneous circulation based on a combination of the one or more PPG signals (21, 22, 23) and the BP measurement.

2. The device (10) according to claim 1, in, The one or more PPG signal attributes correspond to one or more of: duration at a predefined pulse rate level, variation of inter-pulse intervals over time, number of cardiac-induced harmonics, and a PPG waveform.

3. The device (10) according to any one of claims 1 to 2, in, The predefined conditions include one or more of: a threshold, a range, an entry in a lookup table, a position in a graph, and a comparison with a stored PPG waveform.

4. The device (10) according to any one of claims 1 to 2, Also included is an ECG input unit (90) configured to obtain one or more electrocardiogram (ECG) signals (91), in, The processing unit (40) is configured to analyze the one or more predefined PPG signal properties using the one or more ECG signals (91).

5. The device (10) according to claim 4, Also included is a chest compression signal input unit (50), which is configured to obtain a chest compression signal (51) indicating one or more of the following: transthoracic impedance, chest compression rate, length of inter-compression interval, chest compression force, chest compression depth, chest compression acceleration, and chest compression speed, wherein: The processing unit (40) is configured to analyze the chest compression signal (51) and identify and process or remove artifacts of the chest compression signal (51) from the one or more PPG signals (21, 22, 23) and / or the ECG signal (91).

6. The device (10) according to claim 5, wherein: The processing unit (40) is configured to analyze the chest compression signal (51) to distinguish pauses in compressions from ongoing compressions, and to generate the BP control signal (31) during pauses in compressions or during ongoing compressions.

7. The device (10) according to any one of claims 1 to 2, It also includes a user input unit (60), which is configured to obtain user information (61) from a first user interface, wherein: The processing unit (40) is configured to generate the BP control signal (31) and / or adjust the predefined condition based on the user information (61); and / or further comprises a user output unit (70) configured to provide ROSC information (71) to a second user interface.

8. A system (100) for supporting detection of return of spontaneous circulation during cardiopulmonary resuscitation, the system (100) comprising: one or more PPG sensors (201, 202, 203) configured to measure one or more PPG signals (21, 22, 23); The device (10) according to claim 1, configured to generate a BP control signal (31) by using the one or more PPG signals (21, 22, 23); as well as a BP sensor (300) configured to perform BP measurement (36) based on the BP control signal (31); Therein, the device (10) is configured to evaluate a state of an indicator of a cardiogenic output indicative of restoration of spontaneous circulation based on a combination of the one or more PPG signals (21, 22, 23) and the BP measurement.

9. The system (100) according to claim 8, in, The BP sensor (300) includes a BP cuff (301), which can be any one of the following: a finger cuff, a wrist cuff, and an arm cuff, and Wherein, the one or more PPG sensors (201, 202, 203) are configured to be arranged in one of the cuff, one or more other finger cuffs, wrist cuffs or arm cuffs, or to be arranged on the patient's fingers, earlobes, concha or auricle, forehead, nose wings or nasal septum, or to be arranged inside the mouth, for example, inside the cheek or tongue.

10. The system (100) according to claim 9, in, The processing unit (40) is configured to control the pressure of the cuff continuously or intermittently during ongoing compressions or during pauses in compressions.

11. The system (100) according to claim 9 or 10, in, At least one of the one or more PPG sensors (201, 202, 203) is configured to be arranged on a skin-facing side of the BP cuff (301), and The processing unit (40) is configured to control the average cuff pressure applied by the cuff (301) to the patient so as to maximize the amplitude of the one or more PPG signals (21, 22, 23) of the at least one PPG sensor (201, 202, 203) and / or the amplitude of the pressure oscillations inside the cuff (301).

12. The system (100) according to any one of claims 8 to 10, Also included is one or more ECG sensors (900, 901, 902), wherein the one or more ECG sensors are configured to measure one or more ECG signals (91), wherein: The processing unit (40) is configured to analyze the one or more ECG signals (91) to cause any of the one or more PPG signal properties to be obtained, and / or Also included is a chest compression sensor (500) configured to measure a chest compression signal (51) indicative of one or more of: transthoracic impedance, chest compression rate, length of an inter-compression interval, chest compression force, chest compression depth, chest compression acceleration, and chest compression velocity, The processing unit (40) is configured to analyze the chest compression signal (51), and identify and process or remove artifacts of the chest compression signal (51) from the one or more PPG signals (21, 22, 23) and / or the ECG signal (91).

13. The system (100) according to any one of claims 8 to 10, The invention also comprises a first user interface (600) and / or a second user interface (700), wherein the first user interface is configured to obtain user information (61), and the second user interface is used to provide ROSC information (71) in a visible manner and / or an audible manner.

14. A computer program product which, when executed by a processor, causes the processor to perform a method for supporting detection of return of spontaneous circulation during cardiopulmonary resuscitation, the method comprising: obtaining one or more photoplethysmographic (PPG) signals of a patient (21, 22, 23); Providing a BP control signal (31), wherein the BP control signal is used to control a BP sensor (300) to start measuring the patient's blood pressure (BP); obtaining one or more BP measurements (36); analyzing one or more predefined PPG signal attributes of the one or more PPG signals (21, 22, 23) and generating the BP control signal (31) if one or more of the PPG signal attributes satisfies a predefined condition, wherein the one or more PPG signal attributes correspond to at least a pulse rate, a pulse strength, and a duration of presence of a pulse of the patient, and wherein the predefined conditions include respective thresholds for the pulse rate, the pulse strength, and the duration of presence of a pulse, and wherein the predefined conditions are used to detect resumption of a spontaneous pulse, and A state of an indicator of a cardiogenic output indicative of restoration of spontaneous circulation is assessed based on a combination of the one or more PPG signals (21, 22, 23) and the BP measurement.

15. The computer program product according to claim 14, in, The one or more PPG signal attributes correspond to one or more of: duration at a predefined pulse rate level, variation of inter-pulse intervals over time, number of cardiac-induced harmonics, and a PPG waveform.

16. A computer readable medium comprising a computer program product according to any of claims 14-15.

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