Method and system for determining blood coagulation events in arterial line
By providing hemodynamic signals in the arterial line and judging changes in hemodynamic parameters, the problem of difficult coagulation events in the arterial line is solved, and the timely identification and processing of coagulation events is achieved, and the safety of the patient is improved.
Patent Information
- Application Number
- CN202280099261.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-22
- Publication Date
- 2025-04-04
AI Technical Summary
When using the arterial line for measurement, clotting occurs in the arterial line despite the presence of a continuous flushing system designed to prevent clotting, and it is difficult to identify the onset or presence of a clotting event.
Coagulation events in the arterial duct by providing a hemodynamic signal indicating an arterial blood pressure waveform and determining the hemodynamic contraction and relaxation parameters associated with heart contraction and relaxation based on this signal. Specific steps include determining the coagulation event and providing a notification signal when the hemodynamic contraction parameters indicate a decrease in contraction force while the hemodynamic relaxation parameters indicate an increase in contraction force.
Effectively improve the ability to identify coagulation events during the insertion of the arterial line into the patient's body, ensure the safety of the patient, and solve the coagulation problem by automatically or manually flushing the arterial line.
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Figure CN119768111A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a method for notifying a coagulation event in an arterial line of a human body, a corresponding system and a corresponding computer program. Background Art
[0002] An arterial line is a small indwelling catheter that is inserted into a human artery, such as the radial artery. Arterial lines are often used in intensive care. They allow for repeated blood draws without having to prick the patient over and over again, and allow for continuous assessment of blood pressure, e.g., so that the waveform and / or pressure within the artery can be continuously displayed, e.g., on a bedside monitor. In addition, other hemodynamic parameters such as stroke volume, cardiac output, systemic resistance (SVR), maximum pressure gradient (max.dp / dt) and derived parameters such as pulse pressure variation (PPV), stroke volume variation (SVV), or the Hypotension Prediction Index (HPI) developed by Edwards Lifesciences (Irvine, CA) can be used.
[0003] During measurements using an arterial line, clotting can occur in the arterial line, even with a continuous flushing system designed to prevent clotting. The quality of the arterial line can deteriorate, and thus the quality of the measurement. However, it can be difficult to identify the onset or presence of a clotting event. Normally, even if a clotting event occurs, the blood pressure reading (e.g., systolic or diastolic blood pressure reading or mean arterial pressure) remains within the normal physiological range close to the original value.
[0004] Due to the size of the blood pressure waveform signal, the waveform cannot be easily evaluated by the anesthesiologist, for example on a patient monitoring screen. As the pulse pressure decreases gradually, a slow trend, such as the stroke volume (SV), can usually be seen. However, a decrease in SV can also have other physiological reasons, which the anesthesiologist often cannot recognize (in time). In applications such as perioperative fluid management, this slow decay of the measurement signal can even be very misleading and can lead to incorrect diagnoses and unnecessary interventions. Summary of the invention
[0005] It is therefore an object of the present invention to improve patient safety during an intervention for inserting an arterial line into a patient.
[0006] In one aspect, a method for notifying a human of a coagulation event in an arterial line is provided. The method includes the steps of providing a hemodynamic signal indicative of an arterial blood pressure waveform in the arterial line.
[0007] The hemodynamic signal may be a digital or analog representation of the arterial blood pressure waveform itself. In other examples, the hemodynamic signal may be filtered or processed, such as averaged over a much shorter time than the duration of a heartbeat, before being provided.
[0008] In some embodiments, the hemodynamic signal is provided substantially in real time during the intervention, i.e., during the time that the arterial line is inserted into the patient's body. In this case, the hemodynamic signal is preferably provided continuously during the entire intervention period or a portion of the intervention period. In other examples, the hemodynamic signal may be previously recorded and may therefore be indicative of an arterial blood pressure waveform from a previous intervention. In such examples, the hemodynamic signal may be provided by means of wired or wireless data transmission, for example, from a storage device such as a server.
[0009] In the context of the present invention, the hemodynamic signal provided does not imply any spatial relationship between the source of the hemodynamic signal and the destination it reaches. In some instances, the hemodynamic signal can be provided to a processing device in close proximity to the patient. In other instances, the hemodynamic signal can be provided to a processing device remote from the patient, such as a server. Therefore, in the context of the present disclosure, any feasible form of providing the hemodynamic signal is contemplated. The method further includes the step of determining a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal.
[0010] The hemodynamic contraction parameter includes one or a combination of multiple individual hemodynamic parameters. The parameter is related to cardiac contraction when the corresponding characteristics of the parameter are derived from the pulse wave generated by the contraction of the left ventricle. The pulse wave causes a sudden increase in arterial pressure and a sudden increase in forward flow through the artery.
[0011] The method further comprises the step of determining a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal.
[0012] During the relaxation period of the heart, diastolic runoff of arterial blood pressure occurs until the next heartbeat begins. The hemodynamic relaxation parameter includes one or a combination of a plurality of hemodynamic parameters that can be derived from the relaxation of the heart.
[0013] Both the hemodynamic contraction parameter and the hemodynamic relaxation parameter may be predetermined, for example, static during operation of the method. In other examples, the hemodynamic contraction parameter and / or the hemodynamic relaxation parameter may vary over time, as described in detail below.
[0014] Therefore, in some embodiments, steps or mathematical rules for obtaining hemodynamic contraction parameters and / or hemodynamic relaxation parameters may be provided in order to determine the corresponding parameters. All possible forms of implementing the determination of hemodynamic parameters known to the skilled person are contemplated.
[0015] The method further comprises the step of determining a coagulation event in the arterial line when the hemodynamic contraction parameter indicates a decrease in contractility and the hemodynamic relaxation parameter indicates an increase in contractility.
[0016] The inventors of the present disclosure have made an important discovery that an apparent contradiction in the hemodynamic parameters distal to the coagulation artery can indicate that a coagulation event has occurred in the arterial line. Since the hemodynamic contraction parameter indicates a decrease in contractility, while the hemodynamic relaxation parameter indicates an increase in contractility, the two parameters are contradictory. According to the present disclosure, this situation is considered to be a coagulation event.
[0017] The method further comprises the step of providing a signal notifying of a determined coagulation event.
[0018] In the event of a coagulation event being detected, the method provides for a step of notifying the determined coagulation event. The present disclosure contemplates any feasible notification method. In one example, the signal notifying the determined coagulation event is displayed as a message or other visual indication on a patient monitor, which is generally known to show a pulse pressure wave during, for example, a critical care intervention.
[0019] In other instances, the signal is communicated to a server or other entity and used to generate a visual, audible, or other form of overt notification to the medical care provider.
[0020] Therefore, a signal notifying a confirmed coagulation event can help to promptly identify the coagulation event and automatically or manually flush the arterial line to resolve the detected coagulation.
[0021] Although in this embodiment, the step of providing a signal notifying a determined coagulation event is described as being part of the method, in other embodiments, a method without the notifying step may also be beneficial. For example, the determination of a coagulation event may be further processed.
[0022] In a preferred embodiment, the hemodynamic contraction parameter includes at least one hemodynamic parameter derived from the arterial blood pressure waveform from the beginning of the systolic period to the closure of the aortic valve at the end of the systolic period, wherein the hemodynamic contraction parameter particularly includes at least one of the following:
[0023] - Maximum change in blood pressure during systole;
[0024] - end-systolic pressure;
[0025] -The area under the arterial blood pressure waveform curve above the end-diastolic pressure from the beginning of systole to the closure of the aortic valve at the end of systole.
[0026] Therefore, the hemodynamic contraction parameters are related to cardiac contraction because a pulse wave is generated when the left ventricle contracts. This pulse wave causes a sudden increase in arterial pressure and a sudden increase in forward flow through the artery. Therefore, according to this embodiment, any parameter suitable for characterizing the increase in intra-arterial pressure during contraction can become part of the hemodynamic contraction parameters. Further feasible parameters include first-order, second-order, etc. derivatives, maximum derivatives, etc. of the above-listed parameters. It should be noted that the above parameter list is not complete, and those skilled in the art can use other parameters alone or in combination to obtain hemodynamic contraction parameters.
[0027] In a preferred embodiment, the hemodynamic relaxation parameter comprises at least one of end-diastolic pressure, mean arterial pressure and beat-to-beat interval.
[0028] Therefore, the hemodynamic relaxation parameter is a parameter related to the relaxation period of the arterial blood pressure waveform, during which the arterial blood pressure decreases until the next heartbeat starts a new beat. In other words, all parameters that are not related to left ventricular contraction can be regarded as parameters related to the relaxation period, including the beat-to-beat interval. In addition, with respect to the hemodynamic relaxation parameter, it should be emphasized that further additional parameters are well known to those skilled in the art, and in the present embodiment, all of these parameters can be used alone or in combination with further hemodynamic relaxation parameters as hemodynamic relaxation parameters.
[0029] In a preferred embodiment, at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter is determined as an average value over a predetermined time period, in particular as an average value over 20 seconds.
[0030] Determining the hemodynamic contraction parameter and / or the hemodynamic relaxation parameter as an average value over a predetermined time period makes the value of the corresponding parameter more stable. In other words, deviations from extreme values or measurement errors will not inadvertently lead to the determination of a coagulation event. The predetermined time period can be a static amount of time, such as, for example, 20 seconds. In other examples, the time period can be defined as the number of subsequent heartbeats, for example, the average value can always be taken over a certain number of heartbeats, such as 15 or 20 heartbeats. In a preferred embodiment, determining as an average value includes at least one of a filtering process and determining a moving average value.
[0031] The filtering process and the moving average are well known and can be easily implemented to determine the average value. In other examples, other forms of determining the average value can also be considered.
[0032] In a preferred embodiment, a decrease or an increase in a hemodynamic contraction parameter and a hemodynamic relaxation parameter is indicated based on a comparison of two subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively.
[0033] In this embodiment, the subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter are determined separately, and the trends or changes of the respective parameters can be simply compared. The subsequent values can be directly adjacent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively, or can be an intermediate value between two subsequent values, that is, there is a gap between the first and second parameters.
[0034] In particular, it is preferred that the base time interval between subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter be long enough to allow sufficient change in each parameter. Thus, if the change over a longer period of time is large enough, slight trends or changes in the hemodynamic contraction parameter and the hemodynamic relaxation parameter may be detected that do not result in the detection of clotting in the immediately adjacent heartbeats. For example, although the moving average is refreshed with each heartbeat, e.g., approximately once per second, it is preferred to compare moving averages that are more than one heartbeat apart, e.g., two subsequent values whose base time periods are 20 seconds apart.
[0035] In a preferred embodiment, the method further comprises, after determining the coagulation event, taking the following steps:
[0036] - Identify or advise on flushing events for arterial lines, and
[0037] - A coagulation event is verified if the change in at least one predetermined hemodynamic parameter before and after the flushing event, in particular the maximum change in systolic blood pressure or end-systolic blood pressure, exceeds a predetermined flushing threshold.
[0038] The step of identifying or suggesting an arterial line flush event may be performed substantially simultaneously with the step of providing a signal notifying of a determined coagulation event. For example, the suggestion of a flush event may result in additional information or notification to an anesthesiologist on a patient monitor to indicate that the arterial line should be flushed. In other examples, the suggestion of a flush event may include generating a flush signal, which is then used to initiate automatic flushing of the arterial line. Flushing the arterial line will improve the reliability of measurements made by relying on pulse pressure waves measured through the arterial line.
[0039] In a preferred embodiment, a flushing event of the arterial line is determined based on a significant change in at least one of a maximum pressure gradient and a systolic pressure.
[0040] Since the pressure bag provides automatic infusion to prevent clotting, a flushing event may be manifested as a sharp rise in pressure to, for example, 300 mmHg or more. The higher the pressure bag is positioned, the sharper the identifiable pressure peak.
[0041] If, after such a washout event, systolic blood pressure, diastolic blood pressure, and other hemodynamic parameters suddenly return to values similar to those before the event and different from those during the event, coagulation can be identified as a true positive event.
[0042] Based on the off-line analysis of clinical data using the arterial blood pressure waveform, the performance of the method according to the present disclosure can be scored or certified. The determination of a coagulation event and the subsequent provision of a signal notifying the determined coagulation event can be tested and verified when combined with evidence that the arterial line was indeed subsequently flushed. However, if a signal notifying a determined coagulation event is provided, i.e., a coagulation event is determined, but a flushing event is not detected within a reasonable period of time after the coagulation event is determined in the off-line analysis of clinical data, then the trigger is preferentially classified as a false positive determination.
[0043] In this case, a reasonable time period could be, for example, 5 minutes. Thus, the performance of the coagulation detection algorithm can be demonstrated. Since there is a class of coagulation events that has not been recognized as coagulation events by anesthesiologists in practice until now, when scoring the algorithm performance, for example true positive events may be weighted higher than false positive events. Obviously, the number of false positives should not be too high, because of, for example, potential alarm fatigue of anesthesiologists.
[0044] Furthermore, in a preferred embodiment, identifying oscillations in the system following a flushing event can be used to determine damping, wherein the damping is characterized by the frequency instability at which it occurs. The determined damping can then be used to characterize the system.
[0045] In a preferred embodiment, the method further comprises selecting a subset of available hemodynamic parameters from the list of available hemodynamic parameters as single coagulation parameters, wherein the hemodynamic parameters are classified as single coagulation parameters if the change between "before" and "after" the flushing event exceeds a predetermined threshold.
[0046] The selection of generally appropriate hemodynamic parameters as the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively, may be based on the performance score of each parameter according to an off-line analysis of clinical data, as described above.
[0047] However, during, for example, intensive care observation, monitored patients often have multiple coagulation events. For such patients, the various parameters used to determine the coagulation event may be different from the universal parameters determined according to, for example, clinical data off-line analysis. Therefore, it is preferred that after the coagulation event occurs, the suitability of the optional or additional parameters is evaluated to improve the prediction and determination of the future coagulation events of the same patient. Therefore, in the present embodiment, the coagulation event is individually adapted or predicted based on actual data, so that subsequent coagulation events can be determined more reliably or even earlier.
[0048] In a preferred embodiment of the method of determining a subsequent coagulation event, at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter comprises a hemodynamic parameter comprised in the single coagulation parameter.
[0049] In this embodiment, a single coagulation parameter selected from the set of single coagulation parameters can be used in addition, for example, in the form of a parameter combination, or respectively replace a previously considered hemodynamic contraction parameter or a hemodynamic relaxation parameter. In some embodiments, the single coagulation parameters are ranked, wherein the highest ranked parameters show signs of coagulation events as early and reliably as possible. For example, the ranking can be performed using known statistical methods of hemodynamic signals.
[0050] In a preferred embodiment, at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter is modulated using a machine learning prediction algorithm.
[0051] The present disclosure is not limited to a specific machine learning prediction algorithm, and the skilled person can use all available machine learning prediction algorithms. The machine learning prediction algorithm can be used to determine a general hemodynamic contraction parameter and / or a hemodynamic relaxation parameter, which is generally used as an initial parameter for the method according to the present disclosure. In other examples, the machine learning prediction algorithm can also be used to adjust the corresponding parameters during monitoring of the patient.
[0052] In a preferred embodiment, in case the change of the hemodynamic contraction parameter exceeds a decrease threshold, the hemodynamic contraction parameter indicates a decrease in contractility, and in case the change of the hemodynamic relaxation parameter exceeds an increase threshold, the hemodynamic relaxation parameter indicates an increase in contractility. At least one of the increase threshold and the decrease threshold is adjusted based on a previously determined coagulation event, in particular based on a coagulation event verified in the past.
[0053] According to this embodiment, the thresholds for identifying increased and decreased contractility can be adjusted or learned based on the fact that there is flushing and whether flushing causes significant changes in hemodynamic parameters. Therefore, the sensitivity of the method according to the present disclosure can be improved.
[0054] In a preferred embodiment, the method further comprises the step of adjusting at least one of the increase threshold and the decrease threshold before and after flushing the arterial line using the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively.
[0055] In a preferred embodiment, prediction parameters including an increase threshold and a decrease threshold are adjusted using a machine learning prediction algorithm.
[0056] Similar to the use of the machine learning prediction algorithm described above with respect to the definition or combination of hemodynamic contraction parameters and hemodynamic relaxation parameters, the machine learning prediction algorithm can be used to adjust the increase threshold and the decrease threshold.
[0057] In a preferred embodiment, the method further comprises a step of determining the frequency content of the provided hemodynamic signal, wherein in the step of determining a coagulation event, the coagulation event is additionally determined based on the determined frequency content, wherein in particular the coagulation event is determined when the frequency content or a change in the frequency content exceeds a predetermined threshold value.
[0058] It has been recognized that in addition to hemodynamic contraction parameters and hemodynamic relaxation parameters, the spectrum of the hemodynamic signal can also be evaluated to determine the occurrence of coagulation events in the arterial line. Combining the analysis of hemodynamic contraction / relaxation parameters with the spectrum analysis shows particular benefits and improves the reliability of the proposed method.
[0059] The spectral prioritization is based on a hemodynamic signal indicative of a blood pressure waveform, after transformation into the frequency domain, such as using a Fourier or other suitable transform. The spectral prioritization is determined as an integral over a particular frequency range or over the entire frequency range.
[0060] A change in the spectrum is preferably determined based on two subsequent values of the spectrum, wherein the subsequent values preferably include the time interval between them, as described above for subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter. Thus, slow trends or shifts accumulate to significant changes, which can be noticed and not ignored. It is worth noting that all averaging methods known to the skilled person and all further processing methods described above for the hemodynamic contraction parameter and the hemodynamic relaxation parameter are also applicable to the spectrum.
[0061] In a preferred embodiment, the spectrum is determined as the sum of the spectra within a relevant frequency range, which includes the relevant frequencies and in particular the resonant frequencies of the arterial line, such as the natural frequencies, wherein the spectrum is particularly preferably determined as a relative value measured as the sum of the spectra over all frequencies.
[0062] The relevant frequency is preferably determined as the frequency with the largest amplitude. In some embodiments, the relevant frequency may be predetermined and fixed, in other embodiments, the relevant frequency may be variable and may be adjusted according to the current largest amplitude.
[0063] Since the spectrum is first measured relative to the sum of all frequencies, spectra of relevant frequency ranges can be compared over time and, in particular, changes in the spectrum over time can be analyzed more accurately.
[0064] In a preferred embodiment, the relevant frequency range is determined relative to the relevant frequency, and in particular includes frequencies within 50% to 200% of the relevant frequency and / or includes frequencies with amplitudes higher than 50% of the amplitude of the relevant frequency. It should be noted that other methods can also be considered to determine a suitable relevant range.
[0065] In a preferred embodiment, the method further includes the step of performing a flushing test after determining a coagulation event, the flushing test comprising opening a pressurized reservoir and suddenly stopping the flow, causing a sudden change in blood pressure, evaluating the oscillation of the arterial tubing system over a period of time after the sudden stop based on a provided hemodynamic signal indicative of an arterial blood pressure waveform, the oscillation in the hemodynamic signal being caused by the sudden change in blood pressure, and evaluating the damping and natural frequency of the arterial tubing system based on the evaluated oscillations.
[0066] In this embodiment, the evaluation of the washout test can be used to confirm the presence of a coagulation event and, for example, improve the reliability of the proposed method.
[0067] For example, the time period after the sudden stop may include a time period of a few seconds, such as 3 seconds or 10 seconds, or the number of heart beats that follow. Of course, other methods may also be considered to determine the appropriate duration of the time period.
[0068] For example, for the time period, a damping coefficient or also referred to as a damping ratio can be derived based on the damping of the detectable oscillations. The damping coefficient describes how the oscillations decay over time. The damping coefficient can then be compared, for example, with a predetermined coagulation threshold, and if the damping coefficient exceeds the predetermined coagulation threshold, the presence of a coagulation event can be confirmed. Thus, damping can advantageously be used to confirm coagulation of the arterial line, thereby allowing a more robust system to be built.
[0069] Furthermore, the dominant frequency of at least one induced oscillation can be determined, which is referred to as the natural frequency. The frequency value of the natural frequency can preferably be evaluated to verify the presence of a coagulation event. For example, the natural frequency can be compared with a predetermined frequency, and if the deviation of the natural frequency from the predetermined frequency exceeds a predetermined threshold, the presence of a coagulation event can be verified. The predetermined threshold can be an absolute value or a relative value, such as 10 Hz or 10%, of course without limitation.
[0070] In a preferred embodiment, the flushing test performed in the execution step includes at least one of an automatic quick flush, a manual quick flush, and a manual tapping test. In the automatic quick flush, the opening of the pressurized reservoir and / or the sudden stop of the flow are automatically operated using an automatic flushing device capable of causing the flushing, and the flushing can be the injection of a pressurized liquid, preferably a saline solution, into the arterial line for a short period of time; in the manual quick flush, an instruction is issued to the operator to perform a manual opening of the pressurized reservoir and / or a sudden stop of the flow; in the manual tapping test, the tapping test includes applying an increased pressure through the arterial line, such as by tapping a flexible tube connected to the arterial line, to increase the blood pressure once or several times, preferably simultaneously and suddenly releasing the applied pressure, wherein the manual tapping test includes issuing an instruction to the operator to perform a manual tapping test.
[0071] The rapid flush test allows the natural frequencies and damping coefficients of invasive blood pressure monitoring systems such as arterial line systems to be determined in vivo. For the rapid flush test, a pressurized reservoir, in which the pressure is preferably generated by gravity or mechanical pressure, is connected to the arterial line via an openable and closable connector. The pressurized reservoir is preferably an infusion bag, in which the pressure can be varied by changing the height of the infusion bag. The pressure in the pressurized reservoir is preferably about 200 mmHg or more. In order to increase the blood pressure of the arterial system, the pressurized reservoir can be opened for a short time, preferably within 3 seconds or less, for example only 1 second. By suddenly closing the pressurized reservoir, the blood pressure will drop suddenly and cause oscillations in the hemodynamic signal within a few seconds after the pressurized reservoir is closed.
[0072] Of course, the pressure and time values are only examples, and the technician may also use other values of these parameters, such as dynamically determined parameter values.
[0073] Tapping the arterial line with, for example, a finger can also cause oscillations in the hemodynamic signal, which can be used to assess the damping and natural frequency of the arterial line system. By tapping the arterial line on the flexible connector / hose, the volume of the arterial system decreases, which leads to an increase in blood pressure. By quickly releasing the pressure on the connector / tube, the blood pressure suddenly drops and causes oscillations in the hemodynamic signal. These oscillations begin with the sudden drop in blood pressure and last for a few seconds.
[0074] The instruction to the operator to perform a manual tap test or a manual quick flush test may include any suitable form of visual, auditory or other perceptible signal. In this case, the method preferably includes the step of determining that the operator actually performed the issued test. Some examples include a verbal confirmation provided by the operator or an input to an interface (such as a touch screen) indicating that the test was actually performed. In other examples, the method automatically determines that the test has been performed based on the determined pressure surge.
[0075] In a preferred embodiment, the method further comprises the step of verifying, after determining a coagulation event, that the determined coagulation event is indeed a true coagulation event based on the assessed damping and natural frequency of the arterial system.
[0076] In a preferred embodiment, the method further includes the step of performing automatic flushing when a real coagulation event is verified, wherein the arterial line includes an automatic flushing device capable of causing flushing, and the flushing can be a short-term infusion of a pressurized liquid, preferably a saline solution, into the arterial line to clear the coagulation in the arterial line.
[0077] Flushing the arterial line with saline solution was evaluated to clear the arterial line of clots.
[0078] The automatic flush preferably operates the same pressurized container as that used for the rapid flush. However, other suitable means for flushing the arterial line known in the art may also be employed.
[0079] As an alternative to performing an automatic flush, for example where the arterial line is not attached to an automatic flush device, an instruction may be issued to the operator to perform a manual flush.
[0080] In a preferred embodiment, the steps of the method are performed repeatedly, in particular continuously.
[0081] In a further aspect, a system for notifying a person of a coagulation event in an arterial line is provided. The system comprises:
[0082] - a hemodynamic signal providing unit for providing a hemodynamic signal indicative of an arterial blood pressure waveform in the arterial line;
[0083] a hemodynamic contraction parameter determination unit for determining a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal;
[0084] - a hemodynamic relaxation parameter determination unit for determining a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal;
[0085] a coagulation event determination unit for determining a coagulation event in the arterial line if the hemodynamic contraction parameter indicates a decrease in contractility and the hemodynamic relaxation parameter indicates an increase in contractility, and
[0086] - a notification unit for providing a signal notifying of a determined coagulation event.
[0087] The system according to the present invention can achieve the same advantages and benefits as the above-mentioned method for notifying a coagulation event in an arterial line. Likewise, the system according to the present invention can be combined with any preferred embodiment of the method, thereby also achieving the same advantages.
[0088] The hemodynamic signal providing unit, the hemodynamic contraction parameter determining unit, the hemodynamic relaxation parameter determining unit, the coagulation event determining unit, the spectrum determining unit and the notification unit can be implemented partially or entirely as software and / or hardware. Suitable hardware includes a general processing unit (CPU) or a similar device. The units can be physically installed in the same location or distributed on different devices. For example, one, more or all of the units can be implemented in a server. In other instances, one, more or all of the units can be integrated into a patient monitor, which is known to be used to monitor the arterial blood pressure waveform of an arterial line. In addition, suitable units configured to perform the steps of a preferred embodiment of the method according to the present disclosure can be provided and implemented in part or entirely as software and / or hardware by analogy.
[0089] In a further aspect, a computer program product comprising instructions is proposed. When the instructions are executed by a computer, the computer is caused to perform the steps of the method of the first aspect of the present disclosure or a preferred embodiment thereof.
[0090] In a further aspect, it is proposed to use a computer readable data carrier carrying a computer program product of aspects of the present disclosure. For example, the computer readable data carrier can be implemented as a flash drive, such as a USB flash drive, a solid state drive or a hard drive, cloud storage, etc.
[0091] The computer program product according to the present disclosure and the data carrier signal according to the present disclosure can achieve the same objects as described in the context of the method according to the present disclosure.Even further, the computer program product and the data carrier signal can also be advantageously configured according to any of the described preferred embodiments of the method of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0092] The present disclosure will be explained by means of the non-limiting working examples depicted in the following figures. Specifically:
[0093] Figure 1 An arterial line setup is shown schematically and exemplarily.
[0094] Figure 2 An arterial blood pressure waveform is shown schematically and exemplarily.
[0095] Figure 3 A flow chart of a method according to the present disclosure is schematically and exemplarily shown.
[0096] Figure 4 A flow chart of a further method compatible with the present disclosure is shown schematically and exemplarily.
[0097] Figure 5 A system for notifying of a coagulation event is schematically and exemplarily shown. DETAILED DESCRIPTION
[0098] Figure 1 An interventional procedure is schematically and exemplarily shown, in which an arterial line 1 is inserted into the arm of a patient 2. In this example, the arterial line 1 is inserted into the radial artery, but in other examples a different artery may be used. The arterial line 1 includes a tube 3, which is usually filled with saline and is not compressible. The saline comes from a pressurized reservoir, such as a pressure bag 5, which is usually located above the arterial line 1. A pressure sensor 4 is placed between the pressure bag 5 and the tube 3. The pressure sensor 4 is configured in this example to provide a hemodynamic signal indicative of the arterial blood pressure waveform in the arterial line 1 to a patient monitor 6.
[0099] In some examples, the pressure sensor 4 includes an automatic flushing system for flushing the arterial line with saline in the pressure bag 5. In other examples, the flushing system is manually activated.
[0100] In the present example, the patient monitor 6 comprises a display screen 8 on which a blood pressure waveform 10 is shown.
[0101] Figure 2 An arterial blood pressure waveform 10 of a single heart beat is shown schematically and exemplarily in further detail. Figure 2 The vertical axis shows pressure, and the horizontal axis shows time. It should be considered that other forms of displaying the arterial blood pressure waveform are feasible.
[0102] Figure 2 For illustration only, determining a hemodynamic contraction parameter and a hemodynamic relaxation parameter from a hemodynamic signal according to the present disclosure. At point 12, the aortic valve opens and the systolic period begins. During time period 14, as blood flows into the artery, the pressure increases. At point 16, the systolic pressure reaches a maximum. During time period 18, the heart valve closes and as blood flows out of the artery, the pressure continues to drop. Finally, at point 20, a minimum diastolic pressure is obtained.
[0103] In some examples, the time period from point 12 to point 16 is considered to be systolic, and thus parameters derived from this time period can be attributed to the contraction of the heart and are referred to as hemodynamic contraction parameters. These parameters include, but are not limited to, the maximum change in blood pressure during time period 14, the end-systolic pressure at point 16, or the area under the arterial blood pressure waveform curve above the end-diastolic pressure at point 20 between the start of systole at point 12 and the closure of the aortic valve at the end of systole at point 18. Parameters indicative of relaxation may include, but are not limited to, the end-diastolic pressure at point 20, the mean arterial pressure as an average over the entire heartbeat, and the heartbeat interval.
[0104] Figure 3A flow chart of a method 100 for notifying a coagulation event in an arterial line 1 is shown schematically and exemplarily.
[0105] The method comprises a step 110 of providing a hemodynamic signal indicative of an arterial blood pressure waveform in the arterial line 1 .
[0106] The method further comprises a step 120 of determining a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal and a step 130 of determining a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal provided in step 110 .
[0107] In step 140 , based on the determined hemodynamic contraction parameter and the hemodynamic relaxation parameter, a coagulation event in the arterial line 1 is determined when the hemodynamic contraction parameter indicates a decrease in contraction force and the hemodynamic relaxation parameter indicates an increase in contraction force.
[0108] After a coagulation event is determined in step 140, a test may be performed in step 145 to confirm that the arterial line has coagulated. For example, such a test may include an automatic or requested manual rapid flush test. The test in step 145 preferably determines arterial line characteristics, such as natural frequency and damping, such as by tapping a rapid flush catheter to verify the presence of a coagulation event.
[0109] After a coagulation event is determined in step 140 , and optionally upon testing in step 145 confirming the presence of a coagulation event, a signal is provided in step 150 notifying the determined coagulation event.
[0110] Next, in optional step 160 , a flushing event of the arterial line 1 is performed, for example as a result of automatic flushing, for example identified as a result of manual flushing, or suggested, for example using a signal to an operator.
[0111] Subsequently, in step 170, the occurrence of the coagulation event is verified by using the change of at least one predetermined hemodynamic parameter before and after the flushing event exceeding a predetermined flushing threshold.
[0112] The method further comprises step 180 of selecting a subset of available hemodynamic parameters from the list of available hemodynamic parameters as a single coagulation parameter. The single coagulation parameter can be used to determine a subsequent coagulation event, wherein a machine learning prediction algorithm is preferably employed to adjust the hemodynamic contraction parameter and / or the hemodynamic relaxation parameter based on the single coagulation parameter.
[0113] The method further comprises step 190 of adjusting at least one of an increase threshold and a decrease threshold using the hemodynamic contraction parameter and the hemodynamic relaxation parameter before and after flushing the arterial line 1. In this example, the increase threshold and the decrease threshold are used to describe an increase in contraction force and a decrease in contraction force, respectively.
[0114] Finally, the method preferably returns to step 110 .
[0115] It should be noted that the repetitive or continuous operation of the method is particularly advantageous during monitoring of a patient. In other instances, such as when analyzing offline data, the method need not be repeatedly performed. Offline analysis of data is particularly advantageous in situations where it is desired to define and / or optimize hemodynamic contraction parameters and hemodynamic relaxation parameters.
[0116] Furthermore, it should be noted that steps 110, 120, 130 and 140 are basic steps of the invention, whereas further steps 145, 150, 160, 170, 180 and 190 are optional steps which describe preferred embodiments allowing further advantages to be obtained over the basic method steps 110 to 140.
[0117] In addition, Figure 3 and described below Figure 4 The steps shown in a certain order do not mean that these steps are performed subsequently, that is, they do not mean a limitation on their execution time. For example, steps 120 and 130 can be performed simultaneously, and preferably are performed simultaneously with the hemodynamic signal provided in step 110.
[0118] Figure 4 A further method 200 for notifying a coagulation event in an arterial line is schematically and exemplarily shown. The method 200 may be used in conjunction with Figure 3 The method 100 shown combines, and in particular the steps described with reference to the method 100 may be integrated into the method 200 .
[0119] The method comprises a step 210 of providing a hemodynamic signal indicative of an arterial blood pressure waveform in the arterial line 1 .
[0120] The method further comprises a step 225 of determining a frequency spectrum based on the hemodynamic signal provided in step 110 .
[0121] In step 240 , a coagulation event in the arterial line 1 is determined based on the determined frequency spectrum of the hemodynamic signal, wherein in particular a coagulation event is determined if the frequency spectrum or a change in the frequency spectrum exceeds a predetermined threshold value.
[0122] After a coagulation event is determined in step 240, a test to confirm arterial line coagulation may be performed in step 245. Similar to step 145, such a test may include, for example, an automated or requested manual rapid flush test. The test in step 245 preferably determines arterial line characteristics, such as natural frequency and damping, by tapping the rapidly flushed catheter to verify the presence of a coagulation event.
[0123] After a coagulation event is determined in step 240 , and optionally upon testing in step 245 confirming the presence of a coagulation event, a signal is provided in step 250 notifying of the determined coagulation event.
[0124] Finally, the method preferably returns to step 210 .
[0125] Figure 5 A system 300 for notifying a coagulation event in an arterial line is shown schematically and exemplarily. Figure 1 An arterial line 1 of a human body 2 is shown in FIG.
[0126] The system 300 comprises a hemodynamic signal providing unit 310 for providing a hemodynamic signal indicative of an arterial blood pressure waveform 10 in the arterial line 1 .
[0127] The system 300 may further include a hemodynamic contraction parameter determination unit 320 for determining a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal provided by the hemodynamic signal providing unit 310 .
[0128] The system 300 may further include a hemodynamic relaxation parameter determination unit 330 for determining a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal provided by the hemodynamic signal providing unit 310 .
[0129] The system 300 may further include a frequency spectrum determining unit 325 for determining the frequency spectrum of the hemodynamic signal provided by the hemodynamic signal providing unit 310 .
[0130] The system 300 further comprises a coagulation event determination unit 340 for determining a coagulation event in the arterial line 1. The coagulation event determination unit 340 may be configured to determine a coagulation event when the hemodynamic contraction parameter indicates a decrease in contractility and the hemodynamic relaxation parameter indicates an increase in contractility. Alternatively or additionally, the coagulation event determination unit may be configured to determine a coagulation event in the arterial line 1 based on a spectrum of the hemodynamic signal, wherein in particular a coagulation event is determined when the spectrum or a change in the spectrum exceeds a predetermined threshold.
[0131] The system 300 may further include a coagulation event verification unit 345. After the coagulation event detection unit 340 determines the coagulation event, a test to confirm arterial line coagulation may be performed according to step 145 of method 100 or step 245 of method 200.
[0132] The system 300 further includes a notification unit 350 for providing a signal notifying a determined coagulation event. The notification unit 345 is operably connected to the display screen 8 of the patient monitor 6 so as to display the notification thereon. In other examples, other forms of acoustic, optical or data signal notifications may be implemented.
[0133] The system 300 may further include a flush suggestion / execution unit 360 configured to perform step 160 of the method 100. The system 300 may further include a flush detection unit 370 configured to perform step 170 of the method 100. The system 300 may further include an adaptive parameter selection unit 380 configured to perform step 180 of the method 100. Finally, the system 300 may further include an adaptive threshold determination unit 390 configured to perform step 190 of the method 100.
[0134] By simultaneously comparing waveforms obtained using noninvasive continuous blood pressure technology (such as the ClearSight system from Edwards Lifesciences, Irvine, Calif.) with radial artery pressure waveforms, characteristic patterns of coagulation development in the arterial line can be identified from the signal from the radial artery catheter.
[0135] It can be confirmed that the clotting period detected by the method 100 of the present disclosure is eventually detected by the anesthesiologist (experimenter), but not always, because the catheter pressure gauge system is usually flushed after this occurs. Usually, after flushing the catheter system, the invasive arterial blood pressure measurement results will improve significantly. Therefore, before and after flushing the arterial system to resolve the clotting problem, the jump in the hemodynamic parameters can be used to confirm that the event is indeed caused by clotting.
[0136] The present invention arises from a simultaneous (offline) comparison of ClearSight and radial blood pressure waveforms in existing clinical data. From this observation, the present inventors were able to develop patterns that could be identified when only the arterial line was monitored with no other blood pressure for comparison.
[0137] By using the method described in this article, a typical coagulation event on an arterial line can be identified. This event can be used, for example, to alert the anesthesiologist that the radial artery data is unreliable due to coagulation. The catheter system must be flushed to resolve the problem.
[0138] The various illustrative logic blocks and units associated with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a special purpose processor, a circuit, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device designed to perform the functions described herein, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The processor may be a microprocessor or any conventional processor, controller, microcontroller, circuit, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration.
[0139] The steps of the methods or algorithms described in connection with the embodiments disclosed herein and the units of the system may be embodied directly in hardware, or in software modules / firmware executed by a processor, or any combination thereof. The software module may be present in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, non-temporary computer readable medium, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. In an alternative, the storage medium may be integrated into the processor.
[0140] Furthermore, embodiments of the present invention include:
[0141] Embodiment 1. A method (100) for notifying a coagulation event in an arterial line (1) of a human body (2), the method (100) comprising:
[0142] - providing (110) a hemodynamic signal indicative of an arterial blood pressure waveform (10) in the arterial line (1);
[0143] - determining (120) a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal;
[0144] - determining (130) a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal;
[0145] - determining (140) a coagulation event in the arterial line (1) when the hemodynamic contraction parameter indicates a decreased contractility and the hemodynamic relaxation parameter indicates an increased contractility, and
[0146] - providing (150) a signal informing of a determined coagulation event.
[0147] Embodiment 2. The method (100) according to embodiment 1, wherein:
[0148] The hemodynamic contraction parameter comprises at least one hemodynamic parameter derivable from the arterial blood pressure waveform between the start of systole and the closure of the aortic valve at the end of systole, wherein:
[0149] The hemodynamic contraction parameters include in particular at least one of the following:
[0150] - Maximum change in systolic blood pressure;
[0151] - end-systolic pressure;
[0152] -The area under the arterial blood pressure waveform curve above the end-diastolic pressure from the beginning of systole to the closure of the aortic valve at the end of systole.
[0153] Embodiment 3. The method (100) according to any one of the preceding embodiments, wherein:
[0154] Hemodynamic relaxation parameters include at least one of the following:
[0155] - end-diastolic pressure;
[0156] - mean arterial pressure;
[0157] -Interbeat interval.
[0158] Embodiment 4. The method (100) according to any of the preceding embodiments, wherein at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter is determined as an average value over a predetermined time period, in particular an average value over 20 seconds.
[0159] Embodiment 5. The method (100) according to embodiment 4, wherein determining as an average value comprises at least one of a filtering process and determining a moving average value.
[0160] Embodiment 6. The method (100) according to any of the preceding embodiments, wherein a decrease or an increase of the hemodynamic contraction parameter and the hemodynamic relaxation parameter is indicated based on a comparison of two subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively.
[0161] Embodiment 7. The method (100) according to any one of the preceding embodiments, further comprising the following steps after determining the coagulation event:
[0162] - identifying (160) or suggesting a flushing event for the arterial line, and
[0163] - If the change of at least one predetermined hemodynamic parameter before and after the flushing event, in particular the maximum change of the systolic blood pressure or the end-systolic pressure, exceeds a predetermined flushing threshold, then verifying (170) a coagulation event.
[0164] Embodiment 8. The method (100) according to embodiment 7, wherein:
[0165] A flushing event of the arterial line is determined based on a significant change in at least one of a maximum pressure gradient and a systolic pressure.
[0166] Embodiment 9. The method (100) according to embodiment 7 or 8 further comprises:
[0167] A subset of available hemodynamic parameters is selected (180) from the list of available hemodynamic parameters as individual coagulation parameters, wherein the hemodynamic parameter is classified as an individual coagulation parameter if a change before and after the flushing event exceeds a predetermined threshold.
[0168] Embodiment 10. The method (100) according to embodiment 9, wherein, for determining a subsequent coagulation event, at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter comprises a hemodynamic parameter contained in a single coagulation parameter.
[0169] Embodiment 11. The method according to any one of embodiments 8 to 10, wherein at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter is adjusted using a machine learning prediction algorithm.
[0170] Embodiment 12. The method (100) according to any one of the preceding embodiments, wherein:
[0171] When the change in the hemodynamic contraction parameter exceeds a reduction threshold, the hemodynamic contraction parameter indicates a reduction in contractility, and wherein
[0172] When the change in the hemodynamic relaxation parameter exceeds an increase threshold, the hemodynamic relaxation parameter indicates an increase in contractility, wherein
[0173] At least one of the increase threshold and the decrease threshold is adjusted based on previously determined coagulation events, in particular based on coagulation events verified in the past.
[0174] Embodiment 13. The method (100) according to embodiment 12 further comprises the following steps:
[0175] - before and after flushing the arterial line, adjusting (190) at least one of the increase threshold and the decrease threshold using the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively.
[0176] Embodiment 14. The method (100) according to any one of embodiments 12 or 14, wherein the prediction parameters including the increase threshold and the decrease threshold are adjusted using a machine learning prediction algorithm.
[0177] Embodiment 15. The method (100) according to any one of the preceding embodiments, further comprising the following steps:
[0178] - determining the frequency spectrum of the provided hemodynamic signal,
[0179] Therein, in the step of determining (130) a coagulation event, a coagulation event is additionally determined based on the determined frequency spectrum, wherein in particular a coagulation event is determined if the frequency spectrum or a change in the frequency spectrum exceeds a predetermined threshold value.
[0180] Embodiment 16. The method (100, 200) of embodiment 15, wherein:
[0181] - determining the spectrum as the sum of the spectra in a relevant frequency range, which includes relevant frequencies, in particular resonant frequencies of the arterial line (1), such as natural frequencies, wherein the spectrum is particularly preferably determined as a relative value measured as the sum of the spectra at all frequencies.
[0182] Embodiment 17. The method (100, 200) according to embodiment 16, wherein:
[0183] The relevant frequency range is determined relative to the relevant frequency and in particular comprises frequencies within 50% to 200% of the relevant frequency and / or comprises frequencies having an amplitude higher than 50% of the amplitude of the relevant frequency.
[0184] Embodiment 18. The method (100, 200) according to any of the preceding embodiments, wherein the steps of the method (100, 200) are repeatedly performed, in particular continuously performed.
[0185] Embodiment 19. The method (100, 200) according to any one of the preceding embodiments, further comprising the following steps after determining the coagulation event:
[0186] -Perform a flush test, which involves opening a pressurized reservoir and abruptly stopping the flow, resulting in a sudden change in blood pressure;
[0187] - assessing oscillations in the arterial line system over a period of time following a sudden cessation based on a provided hemodynamic signal indicative of an arterial blood pressure waveform, the oscillations in the hemodynamic signal being caused by a sudden change in blood pressure, and
[0188] -Evaluation of the damping and natural frequency of the arterial line system based on the assessed oscillations.
[0189] Embodiment 20. The method (100, 200) of embodiment 19, wherein the flushing test performed in the performing step comprises at least one of the following:
[0190] - Automatic rapid flush, in which the opening of a pressurized reservoir and / or the sudden cessation of flow is automatically operated using an automatic flushing device capable of inducing a flush, which may be a short injection of a pressurized liquid, preferably a saline solution
[0191] Arterial line;
[0192] - a manual fast flush, in which instructions are given to the operator to perform a manual opening of the pressurized reservoir and / or a sudden stop of flow, and
[0193] - A manual tap test, wherein the tap test comprises increasing the blood pressure once or several times by applying an increased pressure through the arterial line, for example by tapping a flexible tube connected to the arterial line, preferably while suddenly releasing the applied pressure, wherein the manual tap test comprises issuing an instruction to an operator to perform the manual tap test.
[0194] Embodiment 21. The method (100, 200) according to embodiment 19 or 20, further comprising the following steps after determining the coagulation event:
[0195] - Verify that the identified coagulation events are indeed real coagulation events based on the assessed damping and natural frequencies of the arterial system.
[0196] Embodiment 22. The method (100, 200) according to embodiment 21 further comprises the following steps in the case of verifying that it is a true coagulation event:
[0197] - performing an automatic flush, wherein the arterial line comprises an automatic flush device capable of inducing a flush, which may be a short-term injection of a pressurized liquid, preferably a saline solution, into the arterial line in order to release clots from the arterial line.
[0198] Embodiment 23. A computer program product comprising instructions, which, when executed by a computer, causes the computer to perform the steps of the method of any one of embodiments 1 to 22.
[0199] Embodiment 24. A computer-readable data carrier carrying the computer program product of embodiment 23.
[0200] The foregoing description of the disclosed embodiments is intended to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A system for notifying a coagulation event in an arterial line (1) of a human body (2), the system comprising: - a hemodynamic signal providing unit (310) for providing (110) a hemodynamic signal indicative of an arterial blood pressure waveform (10) in the arterial line (1); - a hemodynamic contraction parameter determination unit (320) for determining (120) a hemodynamic contraction parameter related to cardiac contraction based on the hemodynamic signal; - a hemodynamic relaxation parameter determination unit (330) for determining (130) a hemodynamic relaxation parameter related to cardiac relaxation based on the hemodynamic signal; - a coagulation event determination unit (340) for determining (140) a coagulation event in the arterial line if the hemodynamic contraction parameter indicates a decrease in contractility and the hemodynamic relaxation parameter indicates an increase in contractility, and; A notification unit (345) for providing (150) a signal notifying of the determined coagulation event.
2. The system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 1, wherein: The hemodynamic contraction parameter comprises at least one hemodynamic parameter derivable from the arterial blood pressure waveform from the beginning of systole to the closure of the aortic valve at the end of systole, wherein: The hemodynamic contraction parameters include in particular at least one of the following: - Maximum change in systolic blood pressure; - end-systolic pressure; - The area under the curve of the arterial blood pressure waveform above the end-diastolic pressure from the beginning of systole to the closure of the aortic valve at the end of systole.
3. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein: The hemodynamic relaxation parameter includes at least one of the following: - end-diastolic pressure; - mean arterial pressure; -Interbeat interval.
4. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein: At least one of the hemodynamic contraction parameter determination unit (320) and the hemodynamic relaxation parameter determination unit (330) is further configured to determine the respective hemodynamic contraction parameter or hemodynamic relaxation parameter as an average value within a predetermined time period, in particular an average value of 20 seconds.
5. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 4, wherein at least one of the hemodynamic contraction parameter determination unit (320) and the hemodynamic relaxation parameter determination unit (330) is further configured such that determining the average value includes at least one of a filtering process and determining a moving average value.
6. System for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein: The system further comprises an indicating unit configured to indicate a decrease or an increase of the hemodynamic contraction parameter and the hemodynamic relaxation parameter, respectively, based on a comparison of two subsequent values of the hemodynamic contraction parameter and the hemodynamic relaxation parameter.
7. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein: The system further comprises a flushing suggestion / execution unit (360) and / or a flushing detection unit (370), wherein the flushing suggestion / execution unit (360) is configured to suggest a flushing event in the arterial line, and the flushing detection unit (370) is configured to identify a flushing event in the arterial line and a change in at least one predetermined hemodynamic parameter before and after the flushing event, in particular a maximum change in systolic blood pressure or end-systolic pressure exceeding a predetermined flushing threshold, and verify (170) a coagulation event, wherein: The flushing detection unit (370) is particularly further configured to determine the flushing event of the arterial line based on a significant change in at least one of a maximum pressure gradient and a systolic pressure.
8. The system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 7, wherein: The system further comprises an adaptive parameter selection unit (380) configured to select (180) a subset of the available hemodynamic parameters from a list of available hemodynamic parameters as a single coagulation parameter, wherein the hemodynamic parameter is classified as a single coagulation parameter if the change before and after the flushing event exceeds a predetermined threshold.
9. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 8, wherein, in order to determine a subsequent coagulation event, at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter includes a hemodynamic parameter contained in the single coagulation parameter.
10. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of claims 7 to 9, wherein the system is configured to adjust at least one of the hemodynamic contraction parameter and the hemodynamic relaxation parameter using a machine learning prediction algorithm.
11. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, configured to indicate a decrease in contractility based on a hemodynamic contraction parameter when a change in the hemodynamic contraction parameter exceeds a decrease threshold; and wherein the system is further configured to indicate an increase in contractility based on the hemodynamic relaxation parameter when a change in the hemodynamic relaxation parameter exceeds an increase threshold; wherein the system is further configured to adjust at least one of the increase threshold and the decrease threshold based on a previously determined coagulation event, in particular based on a coagulation event verified in the past.
12. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 11, wherein the system further comprises an adaptive threshold determination unit (390) configured to adjust (190) at least one of the increase threshold and the decrease threshold using the hemodynamic contraction parameter and the hemodynamic relaxation parameter before and after flushing the arterial line, respectively.
13. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of claims 11 or 12, configured to adjust prediction parameters including the increase threshold and the decrease threshold using a machine learning prediction algorithm.
14. The system for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein the system further comprises: a spectrum determination unit (325) configured to determine a spectrum of the provided hemodynamic signal; The coagulation event determination unit (340) is further configured to determine the coagulation event based on the determined frequency spectrum, wherein the coagulation event is particularly determined when the frequency spectrum or a change in the frequency spectrum exceeds a predetermined threshold.
15. The system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 14, wherein: The spectrum determination unit (325) is further configured to determine the spectrum as the sum of the spectra within a relevant frequency range, the relevant frequency range comprising relevant frequencies, in particular a resonant frequency of the arterial line (1), such as a natural frequency, wherein the spectrum is particularly preferably determined as a relative value measured as the sum of the spectra at all frequencies.
16. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 15, further configured to determine the relevant frequency range relative to the relevant frequency, and in particular including frequencies within 50% to 200% of the relevant frequency and / or including frequencies with amplitudes higher than 50% of the amplitude of the relevant frequency.
17. System for notifying a coagulation event in an arterial line (1) of a human body (2) according to any one of the preceding claims, wherein the system is further configured to perform a flush test after determining a coagulation event, the flush test comprising opening a pressurized reservoir and a sudden stop of flow, resulting in a sudden change in blood pressure, and wherein the system is further configured to evaluate oscillations of the arterial tubing system over a period of time after the sudden stop based on a provided hemodynamic signal indicative of the arterial blood pressure waveform, the oscillations in the hemodynamic signal being induced by the sudden change in blood pressure, and wherein The system is further configured to assess damping and natural frequency of the arterial tubing system based on the assessed oscillations.
18. The system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 18, wherein the flushing test comprises at least one of the following: - automatic rapid flush, wherein the opening of the pressurized reservoir and / or the sudden stop of flow is automatically operated using an automatic flushing device capable of causing a flush, which may be a short-term injection of a pressurized liquid, preferably a saline solution, into the arterial line, - a manual fast flush, wherein instructions are given to the operator to perform a manual opening of the pressurized reservoir and / or a sudden stop of the flow, and - a manual tap test, wherein the tap test comprises increasing the blood pressure once or several times by applying an increased pressure to the arterial line, for example by tapping a flexible tube connected to the arterial line, preferably while suddenly releasing the applied pressure, wherein the manual tap test comprises issuing an instruction to an operator to perform the manual tap test.
19. A system for notifying a coagulation event in an arterial line (1) of a human body (2) according to claim 18 or 19, wherein the system is further configured to verify, after determining the coagulation event, that the determined coagulation event is indeed a real coagulation event based on the assessed damping and the natural frequency of the arterial system, in particular, wherein the system is further configured to perform automatic flushing when verified as a real coagulation event, wherein the arterial line includes an automatic flushing device that is capable of causing flushing, and the flushing can be a short-term injection of a pressurized liquid, preferably a saline solution, into the arterial line to release clots from the arterial line.