Method for reconstructing arterial pressure waveform, display method and monitoring device

Abstract

The present application relates to the technical field of monitoring equipment, in particular to a method for reconstructing an arterial pressure waveform, a method for displaying the arterial pressure waveform and a monitoring equipment, the method comprising: obtaining a photoplethysmogram signal corresponding to a target object; performing a frequency spectrum transformation on the photoplethysmogram signal to obtain first frequency spectrum amplitude response data and first phase response data; performing frequency domain feature reconstruction of the arterial pressure waveform based on the first frequency spectrum amplitude response data and the first phase response data to determine second frequency spectrum amplitude response data and second phase response data of the arterial pressure waveform; and performing an inverse frequency spectrum transformation on the second frequency spectrum amplitude response data and the second phase response data to determine the arterial pressure waveform. The arterial pressure waveform is reconstructed by a non-invasive method. Moreover, since the changes of the photoplethysmogram signal and the arterial pressure signal are both derived from periodic heartbeats, the accuracy of the reconstructed arterial pressure waveform can be ensured.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a method for reconstructing arterial pressure waveforms, a method for displaying such waveforms, and a monitoring device. Background Technology

[0002] Blood pressure is a crucial indicator of cardiovascular function. Both excessively high and low blood pressure can affect blood supply to all organs, increasing the burden on the heart. Clinically, cuff-based non-invasive blood pressure monitoring methods only provide systolic and diastolic blood pressure values, not arterial pressure waveform values. Arterial pressure waveforms contain more information about heart rate, heart rate variability, and arrhythmias, as well as systolic and diastolic blood pressure.

[0003] Arterial pressure waveforms are typically obtained through invasive blood pressure monitoring, which provides continuous blood pressure values ​​and continuous arterial pressure waveforms simultaneously. However, invasive blood pressure measurements during continuous monitoring carry potential risks, such as infection, site bleeding, and vascular injury. Therefore, there is a need for a method to reconstruct arterial pressure waveforms based on non-invasive blood pressure monitoring. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method for reconstructing arterial pressure waveforms, a display method, and a monitoring device to solve the problem of reconstructing arterial pressure waveforms.

[0005] According to a first aspect, embodiments of the present invention provide a method for reconstructing an arterial pressure waveform, comprising:

[0006] Acquire the photoplethysmography signal corresponding to the target object;

[0007] The photoplethysmogram signal is subjected to spectral transformation to obtain first spectral amplitude response data and first phase response data;

[0008] Based on the first spectral amplitude response data and the first phase response data, the frequency domain characteristics of the arterial pressure waveform are reconstructed to determine the second spectral amplitude response data and the second phase response data of the arterial pressure waveform.

[0009] The second spectral amplitude response data and the second phase response data are subjected to inverse spectral transformation to determine the arterial pressure waveform.

[0010] The arterial pressure waveform reconstruction method provided in this invention reconstructs the arterial pressure waveform using photoplethysmography (PPG) signals. Since PPG signals are obtained non-invasively, the arterial pressure waveform is reconstructed non-invasively. Furthermore, because both PPG signals and arterial pressure signals originate from periodic heartbeats, and their time and frequency domains are consistent in signal analysis, utilizing the frequency domain characteristics of PPG signals to reconstruct the arterial pressure signal ensures the accuracy of the reconstructed arterial pressure waveform.

[0011] In some embodiments, the step of reconstructing the frequency domain features of the arterial pressure waveform based on the first spectral amplitude response data and the first phase response data, and determining the second spectral amplitude response data and the second phase response data of the arterial pressure waveform, includes:

[0012] Extract the first amplitude response value and the first phase response value at the preset harmonic from the first spectrum amplitude response data and the first phase response data, respectively;

[0013] Based on the first amplitude response value and the first phase response value at the preset harmonic, the frequency domain characteristics of the arterial pressure waveform are reconstructed to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic, so as to determine the second spectral amplitude response data and the second phase response data.

[0014] The arterial pressure waveform reconstruction method provided in this embodiment of the invention extracts the first amplitude response value and the first phase response value at a preset harmonic from the first spectral amplitude response data and the first phase response data to reconstruct the frequency domain features of the arterial pressure waveform. That is, the second amplitude response value and the second phase response value at the preset harmonic are obtained respectively. The reconstruction of the frequency domain features can improve the accuracy of the obtained arterial pressure waveform while minimizing the introduction of noise.

[0015] In some embodiments, the value of the preset harmonic is less than a preset threshold. The step of reconstructing the frequency domain characteristics of the arterial pressure waveform based on the first amplitude response value and the first phase response value at the preset harmonic to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic, in order to determine the second spectral amplitude response data and the second phase response data, includes:

[0016] By replacing the first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data with the second amplitude response value and the second phase response value at the preset harmonic, the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform are obtained.

[0017] The arterial pressure waveform reconstruction method provided in this embodiment of the invention only reconstructs the frequency domain features of the arterial pressure waveform from the first amplitude response value and the first phase response value at the preset harmonic position to obtain the second amplitude response value and the second phase response value at the preset harmonic position. The amplitude response values ​​and phase response values ​​at other harmonic positions of the arterial pressure waveform are obtained directly from the first spectral amplitude response data and the first phase response data without the need for reconstruction processing. This can reduce the noise of high-order harmonics introduced during reconstruction and further improve the accuracy of the obtained arterial pressure waveform.

[0018] In some embodiments, the step of reconstructing the frequency domain characteristics of the arterial pressure waveform based on the first amplitude response value and the first phase response value at the preset harmonic to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic, in order to determine the second spectral amplitude response data and the second phase response data, includes:

[0019] Obtain the cuff pressure pulse signal corresponding to the target object;

[0020] The cuff pressure pulse signal is subjected to spectral transformation to obtain third spectral amplitude response data and third phase response data;

[0021] Extract the third amplitude response value and the third phase response value at the preset harmonic from the third spectral amplitude response data and the third phase response data, respectively;

[0022] Using the third amplitude response value and the third phase response value, the second amplitude response value and the second phase response value are adjusted to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic.

[0023] By replacing the first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data with the second amplitude response value adjusted at the preset harmonic, the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform are obtained.

[0024] The arterial pressure waveform reconstruction method provided in this embodiment of the invention addresses the differences between individual target objects. The second spectral amplitude response data and the second phase response data obtained by the same reconstruction method may be used differently for each individual. Therefore, the systolic and diastolic blood pressure of the target object are used to correct the waveform morphology error caused by individual differences, so as to further improve the accuracy of the obtained arterial pressure waveform.

[0025] In some embodiments, the second amplitude response value and the second phase response value are adjusted using the third amplitude response value and the third phase response value to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic, including:

[0026] Calculate the first ratio data between the first amplitude response value at the preset harmonic and the third amplitude response value at the preset harmonic;

[0027] Calculate the second ratio data between the first phase response value at the preset harmonic and the third phase response value at the preset harmonic;

[0028] The second amplitude response value at the preset harmonic is adjusted using the first ratio data to obtain the adjusted second amplitude response value at the preset harmonic.

[0029] The second phase response value at the preset harmonic is adjusted using the second ratio data to obtain the adjusted second phase response value at the preset harmonic.

[0030] In some embodiments, the step of performing an inverse spectral transform on the second spectral amplitude response data and the second phase response data to determine the arterial pressure waveform includes:

[0031] Perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to obtain the amplitude data of the arterial pressure waveform in the time domain, so as to determine the initial arterial pressure waveform;

[0032] Obtain the systolic and diastolic blood pressure corresponding to the target object;

[0033] The initial arterial pressure waveform is calibrated based on the systolic and diastolic blood pressures to determine the arterial pressure waveform.

[0034] The arterial pressure waveform reconstruction method provided in this embodiment of the invention can directly measure the systolic and diastolic pressures corresponding to the target object in a non-invasive manner. The peak and trough values ​​in the initial arterial pressure waveform are close to the actual systolic and diastolic pressures, but are not the actual systolic and diastolic pressures. Therefore, by using the actual systolic and diastolic pressures to perform amplitude calibration on the initial arterial pressure waveform, the accuracy of the obtained arterial pressure waveform can be further improved.

[0035] In some embodiments, the step of calibrating the initial arterial pressure waveform based on the systolic and diastolic blood pressure to determine the arterial pressure waveform includes:

[0036] The systolic blood pressure and diastolic blood pressure to be calibrated are determined from the initial arterial pressure waveform;

[0037] Based on the relationship between the systolic blood pressure to be calibrated and the diastolic blood pressure to be calibrated and the systolic and diastolic blood pressure, the initial arterial pressure waveform is calibrated to determine the arterial pressure waveform.

[0038] The arterial pressure waveform reconstruction method provided in this invention uses amplitude calibration based on the relationship between the systolic pressure to be calibrated, the diastolic pressure to be calibrated, the systolic pressure, and the diastolic pressure, which simplifies the processing and improves the efficiency of arterial pressure waveform reconstruction.

[0039] Secondly, embodiments of the present invention also provide a non-invasive continuous blood pressure display method, comprising:

[0040] Based on the electrocardiogram and photoplethysmography signals corresponding to the target object, the non-invasive continuous blood pressure value of the target object is determined.

[0041] The arterial pressure waveform is determined based on the reconstruction method of the arterial pressure waveform according to the first aspect or any one of the first aspects;

[0042] Output and display the non-invasive continuous blood pressure value and the arterial pressure waveform.

[0043] The non-invasive continuous blood pressure display method provided in this embodiment of the invention achieves simultaneous display of the non-invasive continuous blood pressure value and the corresponding arterial pressure waveform by determining the non-invasive continuous blood pressure value and the arterial pressure waveform of the target object respectively.

[0044] Thirdly, embodiments of the present invention also provide a monitoring device, comprising:

[0045] The first acquisition module is used to acquire the electrocardiogram signal and photoplethysmography signal corresponding to the target object;

[0046] The second acquisition module is used to acquire the cuff pressure pulse signal corresponding to the target object.

[0047] It should be noted that the corresponding beneficial effects of the monitoring device provided in the embodiments of the present invention can be found in the description of the corresponding beneficial effects of the arterial pressure waveform reconstruction method above, and will not be repeated here. Attached Figure Description

[0048] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1This is a structural block diagram of a monitoring device according to an embodiment of the present invention;

[0050] Figure 2 This is a flowchart of a method for reconstructing arterial pressure waveforms according to an embodiment of the present invention;

[0051] Figure 3 This is a flowchart of a method for reconstructing arterial pressure waveforms according to an embodiment of the present invention;

[0052] Figure 4 This is a flowchart of a non-invasive continuous blood pressure display method according to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Arterial blood pressure (ABP) waveforms contain more information about heart rate, heart rate variability, and arrhythmias, as well as systolic and diastolic blood pressure. Furthermore, the morphological characteristics of the ABP waveform can be used to assess hemodynamic parameters; for example, a rounded ABP waveform with reduced amplitude, slow ascending and descending limbs, a blunt peak, and indistinct dicrotic notch may be related to weakened myocardial contractility or insufficient blood volume; irregular ABP waveform morphology and amplitude may indicate arrhythmias; a tall, sharp ABP waveform with high amplitude, a steep ascending limb, indistinct dicrotic notch, low diastolic pressure, and a wide pulse pressure may indicate hypertension and aortic regurgitation; a flat ABP waveform with slow ascending and descending limbs and low amplitude indicates severe hypotension, which may develop into hypotensive shock or low cardiac output syndrome. Therefore, the reconstruction and visualization of ABP waveforms have significant clinical value.

[0055] Plethysmography (PPG) is a signal reflecting the state of the cardiovascular system. Physiologically, both PPG and arterial pressure changes originate from the periodic heartbeat: arterial pressure and volume change periodically in each cardiac cycle, for example, during systole and diastole. These changes propagate along the arterial wall to peripheral vessels in the form of pulse waves. The PPG signal is a pulse wave signal of changes in blood volume in peripheral vessels obtained through optical methods. The delay in the systolic peak of PPG relative to the systolic blood pressure (SBP) of arterial blood pressure (ABP) is mainly due to differences in measurement sites. Therefore, although ABP and PPG are measured at different sites and using different methods, they share the same cardiac excitation source. In addition to being physiologically homologous, ABP and PPG signals are also consistent in the time and frequency domains in signal analysis, indicating a significant causal relationship between ABP and PPG. Based on this, PPG is used to reconstruct the ABP waveform in this embodiment of the invention.

[0056] The arterial pressure waveform reconstruction method provided in this invention can be implemented or run on a monitoring device based on an embedded platform, allowing users to observe synchronized real-time non-invasive continuous blood pressure values ​​and arterial pressure waveforms on the monitoring device, thus providing more hemodynamic information. Alternatively, it can also be applied to other types of monitoring devices; no limitations are placed on its application scenarios here, and it can be set according to actual needs.

[0057] This invention provides a monitoring device including a non-invasive blood pressure monitoring module for outputting non-invasive continuous blood pressure values ​​based on the electrocardiogram (ECG) signal and photoplethysmography (PPG) signal corresponding to a target object. The monitoring device also obtains an arterial pressure waveform based on the arterial pressure waveform reconstruction method described below, and synchronously displays the non-invasive continuous blood pressure values ​​and the arterial pressure waveform.

[0058] It should be noted that the non-invasive blood pressure monitoring module can be a standalone hardware module or a software module. If it is a hardware module, it includes a processor used to calculate the non-invasive continuous blood pressure value based on the target object's corresponding electrocardiogram (ECG) signal and photoplethysmography (PPG) signal. If it is a software module, this function can be implemented within the processor of the monitoring device. Based on this, the processor of the monitoring device is also used to reconstruct the arterial pressure waveform.

[0059] In some alternative implementations, such as Figure 1As shown, the monitoring device includes a first acquisition module 10, a second acquisition module 40, a processor 20, and a display 30. The first acquisition module 10 acquires the photoplethysmography (PPG) signal corresponding to the target object and sends the acquired PPG signal to the processor 20 for ABP waveform reconstruction. Furthermore, the first acquisition module 10 also acquires the target object's electrocardiogram (ECG) signal for subsequent calculation of non-invasive continuous blood pressure values.

[0060] The processor 20 is connected to the first acquisition module 10. The processor 20 is used to perform spectral transformation on the photoplethysmography signal to obtain first spectral amplitude response data and first phase response data. Based on the first spectral amplitude response data and first phase response data, the processor 20 performs frequency domain feature reconstruction of arterial pressure to determine second spectral amplitude response data and second phase response data of the arterial pressure waveform. The processor 20 then performs inverse spectral transformation on the second spectral amplitude response data and second phase response data to determine the arterial pressure waveform.

[0061] Processor 20 reconstructs the ABP waveform by converting the PPG signal to a frequency domain signal and then reconstructing the ABP waveform based on the converted frequency domain signal. As mentioned above, the PPG signal and the ABP signal are identical in both the time and frequency domains; therefore, an accurate ABP waveform can be reconstructed using the frequency domain signal. The specific implementation of waveform reconstruction will be described below.

[0062] The display 30 is connected to the processor 20. The display 30 can be integrated with the processor 20 or set up independently; its structure is not limited here. The display 30 is used to display arterial pressure waveforms; that is, the non-invasive continuous blood pressure value and arterial pressure waveform can be displayed simultaneously on the interface of the display 30.

[0063] The second acquisition module 40 is used to acquire the cuff pressure pulse signal corresponding to the target object and send the cuff pressure pulse signal to the processor 20 to correct the reconstructed initial arterial pressure waveform, thereby obtaining a more accurate arterial pressure waveform. Due to individual differences, the correspondence between ABP waveform and PPG waveform may not be the same between individuals. Therefore, the same ABP waveform reconstruction method may be applicable to different individuals. In order to reduce the waveform morphology error caused by this mismatch, the reconstructed initial dynamic pressure waveform is morphologically corrected using the acquired cuff pressure pulse signal.

[0064] The monitoring device provided in this embodiment reconstructs the arterial pressure waveform using photoplethysmography (PPG) signals. Since the PPG signals are obtained non-invasively, the arterial pressure waveform is reconstructed non-invasively as well. Furthermore, because both the PPG signals and arterial pressure signals originate from the periodic heartbeat, and their time and frequency domains are consistent in signal analysis, using the frequency domain characteristics of the PPG signals to reconstruct the arterial pressure signal ensures the accuracy of the reconstructed arterial pressure waveform.

[0065] It should be noted that the monitoring device provided in this embodiment of the invention also includes other functional modules, which are not listed here. The specific modules can be set according to actual needs.

[0066] According to embodiments of the present invention, an arterial pressure waveform reconstruction method and a non-invasive continuous blood pressure display method are provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0067] This embodiment provides a method for reconstructing arterial pressure waveforms, which can be used in the aforementioned monitoring equipment. Figure 2 This is a flowchart of a method for reconstructing arterial pressure waveforms according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps:

[0068] S11, acquire the photoplethysmography signal corresponding to the target object.

[0069] The photoplethysmography (PPG) signal can be obtained by acquiring the target object using the first acquisition module described above. The acquisition site can be any location in the peripheral artery, without any specific limitations.

[0070] The acquired raw PPG signal can be used directly for subsequent spectrum transformation, or it can be preprocessed before subsequent spectrum transformation. Preprocessing methods include, but are not limited to, filtering and normalization.

[0071] In some implementations, baseline drift interference and high-frequency interference are removed from the original PPG signal, and the preprocessing method is not limited. For example, a bandpass filter with a -3dB passband cutoff frequency of 0.1 to 10 Hz is performed; however, to ensure that some important features in the preprocessed PPG signal are not filtered out, the high-pass cutoff frequency should not exceed 0.5 Hz, and the low-pass cutoff frequency should not exceed 11 Hz. The preprocessed PPG signal is then normalized, and the normalization formula is shown below:

[0072]

[0073] Among them, PPG min It can be the minimum PPG within a complete cardiac cycle, or the minimum within a fixed time window.

[0074] After normalization, the PPG signal used for spectral transformation is obtained.

[0075] S12, perform spectral transformation on the photoplethysmography signal to obtain the first spectral amplitude response data and the first phase response data.

[0076] The spectral transformation can be performed using a Fast Fourier Transform, a Linear Frequency Modulation (Z-Transform), or other methods. After performing a spectral transformation on the PPG signal, the first spectral amplitude response data |h(e^(-1 / 2)) is obtained. jw )| and the first phase response data (PhaseData).

[0077] S13, based on the first spectral amplitude response data and the first phase response data, the frequency domain characteristics of the arterial pressure waveform are reconstructed to determine the second spectral amplitude response data and the second phase response data of the arterial pressure waveform.

[0078] Spectral feature reconstruction can be achieved using a reconstruction function or a reconstruction model. If a reconstruction function is used, it can be a linear function, a nonlinear function, and so on. The reconstruction function can be a combination of two functions: a first reconstruction function to obtain second spectral amplitude response data based on first spectral amplitude response data, and a second reconstruction function to obtain second phase response data based on first phase response data; or, the reconstruction function can be a single function used to obtain both second spectral amplitude response data and second phase response data based on first and first phase response data. Taking two reconstructions as an example, corresponding PPG and ABP signals can be collected as sample signals. The spectrum of the sample signals can be transformed to obtain the PPG and ABP signals in the frequency domain. Amplitude and phase features can then be extracted from these signals, and curve fitting can be used to obtain the first and second reconstruction functions, respectively.

[0079] If a reconstruction model is used, it can include two models: a first model to obtain second spectral amplitude response data based on first spectral amplitude response data, and a second model to obtain second phase response data based on first phase response data; or, a single model to obtain both second spectral amplitude response data and second phase response data based on first and first phase response data. The reconstruction model is based on a neural network model, and its specific structure is not limited here; it can be chosen according to actual needs. Taking one reconstruction model as an example, corresponding PPG and ABP signals are collected, and their frequency domain transformation is performed to obtain the frequency domain PPG and ABP signals. The frequency domain features of the PPG signals are extracted to obtain their amplitude and phase features, which are used as sample inputs to the reconstruction model. The sample outputs are the predicted amplitude and phase features of the ABP signal. The differences between the predicted amplitude and phase features of the ABP signal and the sample amplitude and phase features of the ABP signal are then used to update the parameters of the reconstruction model, thereby determining the reconstruction model.

[0080] S14, perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to determine the arterial pressure waveform.

[0081] After obtaining the second spectral amplitude response data and the second phase response data, the time-domain characteristics are obtained by using the inverse spectral transformation method corresponding to S12 above, thereby constructing the arterial pressure waveform.

[0082] Alternatively, after obtaining the second spectral amplitude response data and the second phase response data, an initial arterial pressure waveform can be constructed. Then, by combining the target object's own diastolic and systolic blood pressure, the initial arterial pressure waveform can be corrected, and the final arterial pressure waveform can be determined.

[0083] Alternatively, after obtaining the second spectral amplitude response data and the second phase response data, other parameters can be combined to reconstruct the arterial pressure waveform, and so on. No specific limitations are imposed on this approach.

[0084] The arterial pressure waveform reconstruction method provided in this embodiment reconstructs the arterial pressure waveform using photoplethysmography (PPG) signals. Since PPG signals are obtained non-invasively, the arterial pressure waveform is reconstructed non-invasively. Furthermore, because both PPG signals and arterial pressure signals originate from periodic heartbeats, and their time and frequency domains are consistent in signal analysis, utilizing the frequency domain characteristics of PPG signals to reconstruct the arterial pressure signal ensures the accuracy of the reconstructed arterial pressure waveform.

[0085] This embodiment provides a method for reconstructing arterial pressure waveforms, which can be used in the aforementioned monitoring equipment. Figure 3 This is a flowchart of a method for reconstructing arterial pressure waveforms according to an embodiment of the present invention, such as... Figure 3 As shown, the process includes the following steps:

[0086] S21, acquire the photoplethysmography signal corresponding to the target object.

[0087] Please see details Figure 2 S11 of the illustrated embodiment will not be described again here.

[0088] S22, perform spectral transformation on the photoplethysmography signal to obtain the first spectral amplitude response data and the first phase response data.

[0089] Please see details Figure 2 S12 of the illustrated embodiment will not be described again here.

[0090] S23, based on the first spectral amplitude response data and the first phase response data, the frequency domain characteristics of the arterial pressure waveform are reconstructed to determine the second spectral amplitude response data and the second phase response data of the arterial pressure waveform.

[0091] Specifically, S23 above includes:

[0092] S231, extract the first amplitude response value and the first phase response value at the preset harmonic from the first spectrum amplitude response data and the first phase response data, respectively.

[0093] The preset harmonic is not limited to one harmonic; it can be multiple harmonics. For example, the preset harmonics include, but are not limited to, the first harmonic, the second harmonic, the third harmonic, or the fourth harmonic, etc.

[0094] In this embodiment, the preset harmonics include the 1st to kth harmonics, and the specific value of k is not limited. For example, k can be 5, or other values ​​less than 10, etc.

[0095] From the first spectral amplitude response data |h(ejw Extract the first amplitude response value Amp_w1 at the first harmonic, and based on this, determine the second to kth harmonics w2 to w k The first amplitude response values ​​at point Amp_w2 to Amp_w k Therefore, the first amplitude response values ​​Amp_w1 to Amp_w of the preset harmonic are obtained. k Accordingly, harmonics w1 to w2 are extracted from the first phase response data (PhaseData). k The first phase response values ​​at the point are Phase_w1 to Phase_w. k .

[0096] S232, based on the first amplitude response value and the first phase response value at the preset harmonic, the frequency domain characteristics of the arterial pressure waveform are reconstructed to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic, so as to determine the second spectral amplitude response data and the second phase response data.

[0097] The methods for frequency domain feature reconstruction are described above and will not be repeated here. For example, two reconstruction functions can be used; in S232 above, harmonics w1 to w2 are extracted. k The first amplitude response value and the first phase response value are determined. Using harmonics w1~w k After processing the first amplitude response value and the first phase response value using the reconstruction function, the harmonics w1 to w2 are obtained. k The second amplitude response value and the second phase response value will reduce the harmonics w1 to w k The second amplitude response value is used as the second spectral amplitude response data, and the harmonics w1~w k The second phase response value is used as the second phase response data.

[0098] In some implementations, the value of the preset harmonic is less than a preset threshold. That is, for the PPG signal in the frequency domain, only the frequency domain features at the lower harmonics are used to reconstruct the frequency domain features at the lower harmonics of the ABP waveform, while the frequency domain features at the higher harmonics of the ABP waveform are directly taken from the frequency domain features at the higher harmonics of the PPG signal. Based on this, S232 above includes:

[0099] (1) The frequency domain characteristics of the arterial pressure waveform are reconstructed based on the first amplitude response value and the first phase response value at the preset harmonic, so as to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic.

[0100] (2) Replace the first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data with the second amplitude response value and the second phase response value at the preset harmonic to obtain the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform.

[0101] For example, the preset harmonics include harmonics w1 to w2. 10 Accordingly, based on harmonics w1~w 10 The frequency domain characteristics of the arterial pressure waveform are reconstructed using the first amplitude response value and the first phase response value at the point of origin, yielding harmonics w1 to w2. 10 The second amplitude response value and the second phase response value at that location.

[0102] Then utilize harmonics w1~w 10 The second amplitude response value and the second phase response value at that point are used to replace the first spectral amplitude response data |h(e) jw )| and the harmonics w1~w in the first phase response data (PhaseData) 10 The first amplitude response value and the first phase response value at that point. Specifically,

[0103] The first amplitude response value at w1 in the first spectrum amplitude response data is replaced with the second amplitude response value at harmonic w1; the first phase response value at w1 in the first phase response data is replaced with the second phase response value at harmonic w1.

[0104] The first amplitude response value at w2 in the first spectrum amplitude response data is replaced with the second amplitude response value at harmonic w2; the first phase response value at w2 in the first phase response data is replaced with the second phase response value at harmonic w2.

[0105] And so on, utilizing harmonics w 10 The second amplitude response value at that point replaces w in the first spectral amplitude response data. 10 The first amplitude response value at the location; using harmonics w 10 The second phase response value at that point replaces w in the first phase response data. 10 The first phase response value at that point.

[0106] After the above replacement process, the second spectral amplitude response data of the arterial pressure waveform, |ABP_h(e), can be obtained. jw )| and the second phase response data ABP_Phase(e jw ).

[0107] The frequency domain characteristics of the arterial pressure waveform are reconstructed only for the first amplitude response value and the first phase response value at the preset harmonic. The second amplitude response value and the second phase response value at the preset harmonic are obtained. The amplitude response values ​​and phase response values ​​at other harmonics of the arterial pressure waveform can be obtained directly from the first spectral amplitude response data and the first phase response data without reconstruction processing. This reduces the noise of higher harmonics introduced during reconstruction and further improves the accuracy of the obtained arterial pressure waveform.

[0108] In some implementations, due to individual differences, the correspondence between ABP waveforms and PPG waveforms may not be the same for individuals. Therefore, the applicability of the same reconstruction method may differ for different individuals. To reduce waveform morphology errors caused by this mismatch, based on the above embodiments, the initial ABP waveform obtained through reconstruction is morphologically corrected by incorporating the individual's cuff pressure pulse signal, thereby obtaining the final ABP waveform. Based on this, S232 includes:

[0109] (1) Obtain the cuff pressure pulse signal corresponding to the target object.

[0110] (2) Perform spectrum transformation on the cuff pressure pulse signal to obtain the third spectrum amplitude response data and the third phase response data.

[0111] (3) Extract the third amplitude response value and the third phase response value at the preset harmonic from the third spectrum amplitude response data and the third phase response data respectively.

[0112] (4) Using the third amplitude response value and the third phase response value, the second amplitude response value and the second phase response value are adjusted to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic.

[0113] (5) Replace the first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data with the second amplitude response value and the second phase response value adjusted at the preset harmonic position to obtain the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform.

[0114] The cuff pressure pulse signal can be the original cuff pressure pulse signal or the signal obtained after preprocessing the original cuff pressure pulse signal. There are no restrictions on it. The specific settings can be made according to actual needs.

[0115] Taking preprocessing as an example, the cuff pressure pulse signal can be acquired through the second acquisition module described above. For instance, when measuring NIBP using the second acquisition module, the cuff pressure pulse signal at a specific cuff pressure step is obtained, where the specific cuff pressure is generally near the mean pressure. The specific cuff pressure setting can be based on a default value, or it can be set by interacting with an interactive interface provided on the monitoring device. Furthermore, the cuff pressure pulse signal can be acquired during the NIBP measurement process or obtained by specifically inflating the cuff.

[0116] The original cuff pressure pulse signal on the cuff pressure step is preprocessed to remove baseline drift interference and high-frequency interference. For example, a bandpass filter with a -3dB passband cutoff frequency of 0.1–10Hz is applied to the original cuff pressure pulse signal. To ensure that some important features in the preprocessed pressure pulse signal are not filtered out, the high-pass cutoff frequency should not exceed 0.5Hz, and the low-pass cutoff frequency should not exceed 11Hz. The preprocessed pressure pulse signal is then normalized as follows:

[0117]

[0118] Among them, CuffPress normal Cuff pressure pulse signal, CuffPress i The original cuff pressure pulse signal, CuffPress min It can be the minimum value of all pressure pulse signals (CuffPress) on the pressure step of the cuff.

[0119] The normalized cuff pressure pulse signal was subjected to spectral transformation to obtain the third spectral amplitude response data |h(e) jw The third phase response data (PhData) is then extracted. The third amplitude response value and the third phase response value at the preset harmonic are then extracted, for example, from the third spectral amplitude response data |h(e jw Harmonics w1 to w1 are extracted from the harmonics w1 to w1. k The third amplitude response value at point CuffPress_Amp_w1~CuffPress_Amp_w k Harmonics w1 to w2 are extracted from the third phase response data. k The third phase response values ​​at point CuffPress_Phase_w1~CuffPress_Phase_w k .

[0120] It should be noted that since the cuff pressure pulse signal is used to correct the initial ABP waveform reconstructed from the PPG signal, the preset harmonics corresponding to the cuff pressure pulse signal are consistent with the preset harmonics corresponding to the PPG signal. For example, if the preset harmonics corresponding to the PPG signal are harmonics w1 to w... 10 Correspondingly, the preset harmonics corresponding to the cuff pressure pulse signal are harmonics w1 to w2. 10 .

[0121] After obtaining the third amplitude response value and the third phase response value, the second amplitude response value and the second phase response value are adjusted using these values ​​to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic. The adjustment method includes, but is not limited to, proportional adjustment, etc., and can be set according to actual needs.

[0122] The processing method after obtaining the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic is similar to the processing method in step (2) of S232 above. In both cases, the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic are used to replace the first amplitude response value and the first phase response value at the preset harmonic. For details, please refer to step (2) of S232 above, which will not be repeated here.

[0123] In some implementations, step 3.4) above includes:

[0124] a) Calculate the first ratio data between the first amplitude response value at the preset harmonic and the third amplitude response value at the preset harmonic.

[0125] b) Calculate the second ratio data between the first phase response value at the preset harmonic and the third phase response value at the preset harmonic.

[0126] c) Adjust the second amplitude response value at the preset harmonic using the first ratio data to obtain the adjusted second amplitude response value at the preset harmonic.

[0127] d) Adjust the second phase response value at the preset harmonic using the second ratio data to obtain the adjusted second phase response value at the preset harmonic.

[0128] Calculate the ratio of amplitude to phase of the PPG signal and the cuff pressure pulse wave signal at each harmonic:

[0129] Amp_w1 / CuffPress_Amp_w1~Amp_w k / CuffPress_Amp_w k The first ratio data is obtained, denoted by R_Amp(k);

[0130] Phase_w1 / CuffPress_Phase_w1~Phase_w k / CuffPress_Phase_w k The second ratio data is obtained and represented by R_Phase(k).

[0131] Then, the second amplitude response value at the preset harmonic is adjusted using the first ratio data R_Amp(k) to obtain the adjusted second amplitude response value at the preset harmonic; the second phase response value at the preset harmonic is adjusted using the second ratio data to obtain the adjusted second phase response value at the preset harmonic.

[0132] Due to the differences between individual target subjects, the second spectral amplitude response data and the second phase response data obtained by the same reconstruction method may be used differently for each individual. Therefore, the systolic and diastolic blood pressure of the target subject are used to correct the waveform morphology error caused by individual differences, so as to further improve the accuracy of the obtained arterial pressure waveform.

[0133] S24, perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to determine the arterial pressure waveform.

[0134] Specifically, S24 above includes:

[0135] S241, perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to obtain the amplitude data of the arterial pressure waveform in the time domain, so as to determine the initial arterial pressure waveform.

[0136] The method of inverse spectrum transformation corresponds to the method of spectrum transformation in S22 above, and will not be repeated here. After inverse spectrum transformation, the amplitude data of the arterial pressure waveform in the time domain is obtained, and waveform fitting is performed on it to obtain the initial arterial pressure waveform.

[0137] Since the fitted initial arterial pressure waveform obtained in S241 is morphologically similar to the actual ABP waveform, the absolute values ​​of the peak and trough of the ABP waveform may not necessarily correspond to the actual systolic and diastolic blood pressures. Therefore, it is necessary to perform amplitude calibration on the initial ABP waveform using the systolic and diastolic blood pressures of the target object.

[0138] S242, obtain the systolic and diastolic blood pressure corresponding to the target object.

[0139] The systolic and diastolic blood pressure of the target individual can be obtained through pulse transit time (PTT) or PPG waveform characteristics. Of course, it is not limited to PTT or PPG; other methods can also be used to obtain systolic and diastolic blood pressure. Systolic and diastolic blood pressure also change over time; they are dynamic values.

[0140] For example, while acquiring the PPG signal of the target object, the corresponding systolic and diastolic blood pressure of the target object can also be collected.

[0141] S243, based on systolic and diastolic blood pressure, performs amplitude calibration on the initial arterial pressure waveform to determine the arterial pressure waveform.

[0142] During amplitude calibration, the time axes of systolic and diastolic blood pressure must first be aligned with the time axis of the initial arterial pressure waveform. Amplitude calibration is then performed based on this alignment. This calibration is not limited to calibrating only the peaks and troughs of the initial arterial pressure waveform; to ensure waveform continuity, it also includes calibrating the amplitude of adjacent points between peaks and troughs, and so on. After amplitude calibration, the arterial pressure waveform is obtained.

[0143] In some embodiments, S243 includes:

[0144] (1) Determine the systolic blood pressure and diastolic blood pressure to be calibrated from the initial arterial pressure waveform.

[0145] (2) Based on the relationship between the systolic pressure to be calibrated and the diastolic pressure to be calibrated and the systolic and diastolic pressure, the initial arterial pressure waveform is calibrated to determine the arterial pressure waveform.

[0146] The initial arterial pressure waveform is analyzed to determine the peaks and troughs, thereby obtaining the systolic and diastolic pressures to be calibrated from the initial arterial pressure waveform. Then, the systolic and diastolic pressures to be calibrated are compared separately, and the amplitude is calibrated using the comparison results.

[0147] For example, the ratio of the systolic blood pressure to the diastolic blood pressure is calculated, and the systolic blood pressure to be calibrated and its adjacent points are scaled proportionally based on this ratio. Similarly, the ratio of the diastolic blood pressure to the diastolic blood pressure is calculated, and the diastolic blood pressure to be calibrated and its adjacent points are scaled proportionally based on this ratio. Since the obtained systolic and diastolic blood pressures represent the actual systolic and diastolic blood pressures, amplitude calibration is performed based on the obtained systolic and diastolic blood pressures.

[0148] Amplitude calibration is performed by comparing the magnitudes of the systolic and diastolic blood pressure to be calibrated with those of the systolic and diastolic blood pressures, simplifying the processing and improving the efficiency of arterial pressure waveform reconstruction.

[0149] The arterial pressure waveform reconstruction method provided in this embodiment extracts the first amplitude response value and the first phase response value at a preset harmonic from the first spectral amplitude response data and the first phase response data to reconstruct the frequency domain features of the arterial pressure waveform. That is, it obtains the second amplitude response value and the second phase response value at the preset harmonic. By reconstructing the frequency domain features while minimizing the introduction of noise, the accuracy of the obtained arterial pressure waveform can be improved. Since the systolic and diastolic blood pressure corresponding to the target object can be directly measured non-invasively, and the peak and trough values ​​in the initial arterial pressure waveform are close to the actual systolic and diastolic blood pressure, but are not the actual systolic and diastolic blood pressure, amplitude calibration of the initial arterial pressure waveform using the actual systolic and diastolic blood pressure can further improve the accuracy of the obtained arterial pressure waveform.

[0150] This embodiment provides a method for reconstructing arterial pressure waveforms, which can be used in the aforementioned monitoring equipment. Figure 4 This is a flowchart of a method for reconstructing arterial pressure waveforms according to an embodiment of the present invention, such as... Figure 4 As shown, the process includes the following steps:

[0151] S31, Based on the electrocardiogram signal and photoplethysmography signal corresponding to the target object, determine the non-invasive continuous blood pressure value of the target object.

[0152] The system simultaneously acquires electrocardiogram (ECG) and photoplethysmography (PPG) signals from the target subject, and calculates the subject's non-invasive continuous blood pressure using these two signals. The specific calculation method is not limited here; it can be set according to actual needs.

[0153] S32, Determine the arterial pressure waveform based on the above-described method for reconstructing the arterial pressure waveform. For details regarding the specific processing steps of the arterial pressure waveform reconstruction method, please refer to the above description; they will not be repeated here.

[0154] S33 outputs and displays non-invasive continuous blood pressure values ​​and arterial pressure waveforms.

[0155] The monitoring device's interface displays non-invasive continuous blood pressure values ​​and arterial pressure waveforms. Since both are time-dependent, they can be correlated over time for intuitive monitoring. Of course, no specific restrictions are placed on the display method of the non-invasive continuous blood pressure values ​​and arterial pressure waveforms.

[0156] The non-invasive continuous blood pressure display method provided in this embodiment achieves simultaneous display of the non-invasive continuous blood pressure value and the corresponding arterial pressure waveform by determining the non-invasive continuous blood pressure value and the arterial pressure waveform of the target object respectively.

[0157] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for reconstructing arterial pressure waveforms, characterized in that, include: Acquire the photoplethysmography signal corresponding to the target object; The photoplethysmogram signal is subjected to spectral transformation to obtain first spectral amplitude response data and first phase response data; Based on the first spectral amplitude response data and the first phase response data, the frequency domain characteristics of the arterial pressure waveform are reconstructed to determine the second spectral amplitude response data and the second phase response data of the arterial pressure waveform. Perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to determine the arterial pressure waveform; The step of reconstructing the frequency domain features of the arterial pressure waveform based on the first spectral amplitude response data and the first phase response data, and determining the second spectral amplitude response data and the second phase response data of the arterial pressure waveform, includes: Extract the first amplitude response value and the first phase response value at the preset harmonic from the first spectrum amplitude response data and the first phase response data, respectively; The first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data are replaced by the second amplitude response value and the second phase response value at the preset harmonic to obtain the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform. The value of the preset harmonic is less than the preset threshold.

2. The method according to claim 1, characterized in that, The process of reconstructing the frequency domain characteristics of the arterial pressure waveform based on the first amplitude response value and the first phase response value at the preset harmonic to obtain the second amplitude response value and the second phase response value of the arterial pressure waveform at the preset harmonic, thereby determining the second spectral amplitude response data and the second phase response data, includes: Obtain the cuff pressure pulse signal corresponding to the target object; The cuff pressure pulse signal is subjected to spectral transformation to obtain third spectral amplitude response data and third phase response data; Extract the third amplitude response value and the third phase response value at the preset harmonic from the third spectral amplitude response data and the third phase response data, respectively; Using the third amplitude response value and the third phase response value, the second amplitude response value and the second phase response value are adjusted to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic. By replacing the first amplitude response value and the first phase response value in the first spectrum amplitude response data and the first phase response data with the second amplitude response value adjusted at the preset harmonic, the second spectrum amplitude response data and the second phase response data of the arterial pressure waveform are obtained.

3. The method according to claim 2, characterized in that, The step of adjusting the second amplitude response value and the second phase response value using the third amplitude response value and the third phase response value to obtain the adjusted second amplitude response value and the adjusted second phase response value at the preset harmonic includes: Calculate the first ratio data between the first amplitude response value at the preset harmonic and the third amplitude response value at the preset harmonic; Calculate the second ratio data between the first phase response value at the preset harmonic and the third phase response value at the preset harmonic; The second amplitude response value at the preset harmonic is adjusted using the first ratio data to obtain the adjusted second amplitude response value at the preset harmonic. The second phase response value at the preset harmonic is adjusted using the second ratio data to obtain the adjusted second phase response value at the preset harmonic.

4. The method according to claim 1, characterized in that, The step of performing an inverse spectral transformation on the second spectral amplitude response data and the second phase response data to determine the arterial pressure waveform includes: Perform inverse spectral transformation on the second spectral amplitude response data and the second phase response data to obtain the amplitude data of the arterial pressure waveform in the time domain, so as to determine the initial arterial pressure waveform; Obtain the systolic and diastolic blood pressure corresponding to the target object; The initial arterial pressure waveform is calibrated based on the systolic and diastolic blood pressures to determine the arterial pressure waveform.

5. The method according to claim 4, characterized in that, The step of calibrating the initial arterial pressure waveform based on the systolic and diastolic blood pressure to determine the arterial pressure waveform includes: The systolic blood pressure and diastolic blood pressure to be calibrated are determined from the initial arterial pressure waveform; Based on the relationship between the systolic blood pressure to be calibrated and the diastolic blood pressure to be calibrated and the systolic and diastolic blood pressure, the initial arterial pressure waveform is calibrated to determine the arterial pressure waveform.

6. A method for displaying non-invasive continuous blood pressure, characterized in that, include: Based on the electrocardiogram signal and photoplethysmography signal corresponding to the target object, the non-invasive continuous blood pressure value of the target object is determined. The arterial pressure waveform is determined based on the method described in any one of claims 1-5; Output and display the non-invasive continuous blood pressure value and the arterial pressure waveform.

7. A monitoring device, comprising a non-invasive blood pressure monitoring module, wherein the non-invasive blood pressure monitoring module outputs non-invasive continuous blood pressure values ​​based on an electrocardiogram signal and a photoplethysmography signal corresponding to a target object, characterized in that, The monitoring device is used to determine the arterial pressure waveform based on the arterial pressure waveform reconstruction method as described in any one of claims 1-5, and to display the non-invasive continuous blood pressure value and the arterial pressure waveform.

8. The monitoring device according to claim 7, characterized in that, The monitoring device also includes: The first acquisition module is used to acquire the electrocardiogram signal and photoplethysmography signal corresponding to the target object; The second acquisition module is used to acquire the cuff pressure pulse signal corresponding to the target object.

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