JP7152268B2 - BIOLOGICAL SIGNAL PROCESSING DEVICE AND CONTROL METHOD THEREOF - Google Patents

Description

TECHNICAL FIELD The present invention relates to a biological signal processing device and its control method, and more particularly to a technique for detecting a heart rate from an electrocardiogram.

2. Description of the Related Art Biological signal processing devices capable of measuring electrocardiograms, such as electrocardiographs and biological information monitoring devices, are known. These biosignal processing apparatuses can detect changes in cardiac potential on the body surface using electrodes attached to the chest and extremities of a subject and record them as an electrocardiogram. 2. Description of the Related Art In recent years, there has been known a biological signal processing apparatus having an electrocardiogram analysis function for processing an electrocardiogram as digital data and acquiring various information from the electrocardiogram.

Basic information acquired by the electrocardiogram analysis function includes heart rate (HR: heart rate [bpm]). A heart rate can be obtained using a period of a specific waveform (for example, an R wave) included in an electrocardiogram (Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2017-131702

Since the waveform of an electrocardiogram differs according to the position of the detected electrode, there is a name according to the detected electrode. For example, electrocardiograms detected by limb electrodes include bipolar limb leads (I lead, II lead, and III lead) and unipolar limb leads (aVF lead, aVR lead, and aVL lead). An electrocardiogram detected by chest electrodes includes chest leads (V1 to V6 leads). An electrocardiogram consisting of these 12 leads measured using limb electrodes and chest electrodes is called a standard 12-lead electrocardiogram. It should be noted that leads other than the standard 12 leads are known.

A conventional biological signal processing device detects a heart rate by analyzing one type of lead set in advance among a plurality of types of measurable leads. However, depending on the subject, the heart rate may not be detected with the set lead. In this case, conventionally, it was necessary to call up a setting screen and change the type of induction used for heart rate detection, which was troublesome.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bio-signal processing apparatus capable of automatically determining a lead to be used for heart rate detection and a control method thereof. and

The above object is a biosignal processing device for acquiring an electrocardiogram consisting of a plurality of leads, comprising detecting means for detecting a heart rate based on one lead, and detecting two types of heart rate based on two or more leads. a selection means for selecting a lead to be used for heart rate detection by the detection means from the above leads , wherein the selection means is a reference value in a predetermined multiple beat rate period for each of the two or more leads and the maximum level within one beat period, and selects the lead with the largest minimum value .

With such a configuration, according to the present invention, it is possible to provide a biological signal processing device capable of automatically determining a lead used for heart rate detection and a control method thereof.

1 is a block diagram showing a functional configuration example of an electrocardiograph as an example of an electrocardiograph according to an embodiment of the present invention; FIG. 4 is a flow chart relating to automatic selection of leads used for heart rate detection in the electrocardiograph according to the embodiment. FIG. 4 is a diagram for explaining a method of determining a representative value for each lead according to the embodiment;

Exemplary embodiments of the invention will now be described in detail with reference to the accompanying drawings. Here, an embodiment in which the present invention is applied to an electrocardiograph as an example of a biological signal processing device will be described. However, the present invention is also applicable to other devices having an electrocardiogram measurement function, such as vital signs monitors. Furthermore, the present invention can also be applied to a biological information processing apparatus such as an electrocardiogram analysis apparatus that does not have an electrocardiogram measurement function and analyzes a measured electrocardiogram. Such a biological information processing apparatus can also be realized by a combination of a general-purpose computer device and an application program that realizes an electrocardiogram analysis function.

(Configuration of electrocardiograph)
FIG. 1 is a block diagram showing a configuration example of an electrocardiograph 100 according to an embodiment of the present invention.
The electrode group 110 consists of a plurality of electrodes, such as four extremity electrodes and six chest electrodes, for acquiring an electrocardiogram consisting of multiple leads. The type and number of electrodes included in the electrode group 110 are determined by the type and number of electrocardiogram signals (leads) measured by the electrocardiograph 100 .

The electrode group 110 (electrocardiogram electrodes) is connected to a connector included in the input section 111 of the electrocardiograph 100 . The input unit 111 has, for example, a protection circuit, a lead selector, an amplifier circuit, etc., and outputs a preset type and number of electrocardiogram signals.
The A/D conversion unit 112 digitizes each electrocardiogram signal output from the input unit 111 and outputs the digitized electrocardiogram data. The input section 111 and the A/D conversion section 112 are also called an analog front end (AFE).

The filter processing unit 113 applies a noise removal filter to the electrocardiogram data input through the A/D conversion unit 112 according to settings from the control unit 120 . In the present embodiment, the filter processing unit 113 can selectively apply a myoelectric noise removal filter, an AC noise removal filter, and a drift noise removal filter, as an example. It is not limited to these.
The speaker 114 is used by the controller 120 to output, for example, warning sounds and voice messages.

The control unit 120 includes, for example, a ROM, a RAM, and a programmable processor, and controls the operation of the electrocardiograph 100 as a whole by loading a control program stored in the ROM into the RAM and executing the program by the programmable processor. In addition to the control program, the ROM stores various set values, GUI data, and the like, which are used as appropriate when executing the control program. Also, at least part of the ROM may be rewritable.

Note that, for example, the filter processing unit 113 may be implemented by executing a program by a programmable processor included in the control unit 120, or may be implemented by hardware such as ASIC or ASSP. Filter processing unit 113 may be realized by a combination of hardware and software.

The analysis unit 1201 corresponds to an electrocardiogram data automatic analysis function realized by the control unit 120, and applies automatic analysis processing to measured electrocardiogram data. Automatic analysis processing can be broadly divided into measurement processing and finding classification processing. The measurement process is a process of detecting segment points (P, QRS, T) of an electrocardiogram and obtaining measured values (RR interval, ST level, PQ, QRS width, QT, etc.). Further, the analysis unit 1201 calculates the heart rate [bpm] = 60 [sec]/the cycle [sec] of the feature point from the cycle or interval of the set feature points of one type of lead, for example, the RR interval. Calculate Further, the finding classification process is a process of determining a finding based on the measured value and the determination condition determined in advance. Note that the measured values given here are merely examples, and other measured values may be obtained. The control unit 120 automatically selects the guidance for the analysis unit 1201 to detect the feature points by the process described later.

A memory card can be inserted into and removed from the card slot 116, and the control unit 120 can record electrocardiogram test data on the mounted memory card and read recorded electrocardiogram test data from the mounted memory card. . The electrocardiogram data includes electrocardiogram data and subject information data. When the electrocardiogram data is automatically analyzed, the examination data also includes the data of the automatic analysis result. Electrocardiography data is generated for each examination in a predetermined data format. The electrocardiography data may be composed of a plurality of data files, or may be composed of one data file.

The operation unit 117 is an input device for a user (medical personnel) to input various settings and instructions to the electrocardiograph 100, and buttons, keys, touch panels (software keys) and the like are generally used, but are not limited to these. . Input methods that do not require physical input manipulation, such as voice input, may be supported.

The display unit 118 is a display device such as an LCD, and displays an electrocardiogram being measured or an electrocardiogram and/or an analysis report based on the electrocardiogram test data stored in the memory card loaded in the card slot 116 under the control of the control unit 120. or to display the menu screen, etc. In this embodiment, the display unit 118 is assumed to be a touch display.
The printer 119 is, for example, a thermal printer, and prints out electrocardiogram waveforms and analysis reports in a predetermined format under the control of the control unit 120 .

The power supply unit 121 is, for example, a secondary battery or a commercial power supply (AC adapter), and supplies electric power to each unit of the electrocardiograph 100 .

The external I/F 123 is a general-purpose interface for wired connection with external devices. In this embodiment, the external I/F 123 is assumed to be an interface conforming to the USB 2.0 standard, but may be a general-purpose interface conforming to other standards. Also, the number of external I/Fs 123 may be two or more. Any USB-connectable external device 200 (for example, a USB memory or a personal computer) can be connected to the external I/F 123 .

When measuring and recording an electrocardiogram signal using the electrocardiograph 100 having such a configuration, the connector provided at the other end of the electrode group 110 is connected to the input unit 111, and the electrocardiograph 100 is powered on. In the ON state, the chest electrodes provided at one end of the electrode group 110 are attached to predetermined positions on the body surface of the subject's chest, and the limb electrodes are attached to the limbs of the subject.

When the electrode group 110 is connected to the input unit 111, the detected electrocardiogram signal is input to the input unit 111, processed by the A/D conversion unit 112, the filter processing unit 113, etc., and input to the control unit 120 as electrocardiogram data. be done. The control unit 120 uses part of the internal RAM as a buffer to temporarily store electrocardiogram data for the most recent predetermined number of seconds. Also, the control unit 120 starts displaying an electrocardiogram on the display unit 118 using the electrocardiogram data in the buffer. In the present embodiment, the control unit 120 controls the electrocardiogram signal (lead) used by the analysis unit 1201 to detect the heart rate from the time when the electrocardiogram signal starts to be input until the recording (measurement) start instruction is input. Select automatically. Details of the selection process will be described later.

It is assumed that the electrocardiograph 100 of this embodiment has the following measurement modes.
(1) 12-lead automatic measurement mode Automatic analysis of 12-lead electrocardiogram signals measured in a predetermined period (for example, 10 seconds) from the time of inputting a recording start instruction (for example, pressing a start button of the operation unit 117). The electrocardiogram data including the results are recorded and output to the display unit 118 and the printer 119 .
(2) 12-lead manual measurement mode From the time of inputting the recording start instruction until the time of inputting the recording stop instruction (for example, pressing the start button of the operation unit 117 again), the electrocardiogram of a part of the specified leads out of the 12 leads. The waveform is output from the printer 119 in real time.
(3) Arrhythmia measurement mode For three specified leads out of the 12 leads, the waveforms of the leads measured in a predetermined period (for example, several minutes) after the recording start instruction is input are displayed in real time by the printer 119. Output from
(4) Rhythm measurement mode For one of the 12 leads, the waveform of the lead measured in a predetermined period (for example, several minutes) after the recording start instruction is input is printed in real time by the printer 119. Output from
Note that these measurement modes and operations are merely examples, and it is not necessary to have all of these measurement modes, and other measurement modes may be provided.

When a recording start instruction is input from the operation unit 117, the control unit 120 executes a recording operation according to the set measurement mode, and when the set recording time elapses or the recording end instruction is received from the operation unit 117. When the input is detected, the recording operation is terminated.

During recording, the control unit 120 (analysis unit 1201) automatically analyzes the electrocardiogram data accumulated in the buffer for the recording period. As one of the automatic analysis processes, the analysis unit 1201 detects predetermined feature points for each one-beat period of the selected lead, and calculates the heart rate for each beat based on the period or interval. The control unit 120 can display the calculated heart rate on the display unit 118 at any time. In addition, the control unit 120 generates examination data including electrocardiogram data, data of the automatic analysis result thereof, and data of subject information, and stores the data in the memory card attached to the card slot 116 or connected to the external I/F 123 . Record in the external device 200 .

The format of the inspection data is not limited, and may be composed of a plurality of data files or a single data file. For example, when a data file containing subject information and electrocardiogram data and data of automatic analysis results are generated as separate data files, a plurality of data files relating to the same examination are recorded so as to be distinguishable. For example, each data file can be recorded in the same folder, or can be recorded with the same file name but different extensions. In addition, when examination data is composed of one data file, a data file containing electrocardiogram data, its automatic analysis result data, and subject information data is generated. These are merely examples, and inspection data may be generated in other ways.

In the case of the 12-lead automatic measurement mode, when the automatic analysis process is finished, the control unit 120 outputs the electrocardiogram waveform accumulated in the buffer and the automatic analysis result in a predetermined format to the display unit 118 and/or the printer 119. .

(Automatic selection processing of leads used for heart rate calculation)
Next, automatic selection processing of leads used for heart rate calculation in the electrocardiograph 100 of the present embodiment will be described with reference to the flowchart of FIG. The automatic selection process shown in the flowchart of FIG. 2 can be realized by the control unit 120 executing a program. Further, the automatic selection process is performed automatically when the control unit 120 detects inputs of multiple leads (electrocardiogram signals), or detects inputs of all leads to be measured in the set measurement mode, for example. can start. However, it may be started based on other conditions such as execution in response to operation of the operation unit 117 .

For example, when detecting that a plurality of types of guidance are input from the electrode group 110 via the filter processing unit 113, the control unit 120 executes automatic selection processing. Whether or not a lead is input can be determined for each lead based on the value of the electrocardiogram data input from the filter processing unit 113 and stored in the buffer.

In S103, the control unit 120 reads electrocardiogram data for one beat for each lead, and detects the maximum level within the one-beat interval. Note that the control unit 120 can read one beat of electrocardiogram data from continuous electrocardiogram data by a known method. For example, it is possible to detect an R wave for one lead, define a predetermined period of time before and after the peak of the R wave as a one-beat interval, and read electrocardiogram data for the same time interval for other leads. Alternatively, the segment points detected by the analysis unit 1201 may be used. Filtering for removing the T-wave component may be applied before detecting the maximum level.

In S105, for each lead, the control unit 120 determines whether the maximum level (maximum value) of the electrocardiogram data for one beat extracted in S103 is equal to or greater than a predetermined threshold. This threshold is a threshold for determining whether or not the electrocardiogram data for one beat has a normal level, and can be experimentally determined in advance, for example. The control unit 120 skips the processing of S107 and S109 for electrocardiogram data whose maximum level is less than the threshold.

In S107, the control unit 120 calculates a reference value from the electrocardiogram data for which the maximum level was determined to be equal to or greater than the threshold in S105 for each lead. The reference value may be, for example, the average level (average value) of electrocardiogram data for one beat or a value based on the average level (eg, n times the average level). This treatment is not required, but is introduced to allow comparison of maximal levels to account for the inherent difference in maximal levels due to induction.

In S109, the control unit 120 obtains the difference between the maximum level of electrocardiogram data for one beat and the reference value calculated in S107 for each lead, associates it with the lead type, and stores it in the RAM, for example.

In S111, the control unit 120 determines whether or not a predetermined number of beats has passed, that is, the electrocardiogram data of the predetermined number of beats in S105 (if the maximum level is equal to or higher than the threshold, further S107 and S109). ) is executed. If the control unit 120 determines that the predetermined number of beats has elapsed, the process proceeds to S113, and if not determined, the process proceeds to S105 to process the electrocardiogram data for the next one beat. If the predetermined number of heartbeats is too large, the time lag until the lead is first selected will be large, and if it is too small, the selection will be more susceptible to fluctuations in values between heartbeats. The predetermined number of beats may be, for example, about 3 to 6 beats.

In S113, the control unit 120 detects the minimum value of the stored difference for each lead as a representative value, and compares the representative values between the leads.

In S115, the control unit 120 selects the lead with the largest representative value as the lead used for calculating the pulse rate. The analysis unit 1201 then starts detecting (calculating) the heart rate using the selected lead.

FIG. 3 is a diagram schematically showing a method of determining representative values for certain leads. Here, the predetermined number of beats is set to 4. Also, here, it is assumed that a filtering process for removing the T wave is applied. Also, the reference value (reference level) is calculated as a predetermined multiple of the average value (average level). In the example shown in FIG. 3, it is assumed that the differences between the maximum level and the reference level are 0.8 mV, 0.5 mV, 0.4 mV, and 0.3 mV at beats 1 to 4, respectively. A typical value for this induction would then be 0.3 mV. Although the values of the electrocardiogram data are shown in units of mV here, the actual data may be in other units. Control unit 120 determines a representative value for each lead in a similar manner.

Normally, the maximum level of electrocardiogram data for one beat corresponds to the peak of the R wave. Therefore, the representative value for each lead is the least detectable value (worst value) when detecting the R-wave by comparing the value of the electrocardiogram data to a predetermined threshold. The maximum representative value means that the worst value is the largest, so it can be said that the R wave is an induction that is easy to detect.

In this manner, the control unit 120 can automatically select a lead that is determined to be suitable for R-wave detection from electrocardiogram data consisting of multiple leads. Therefore, the heart rate can be detected based on the optimum guidance for the subject and the state at the time of measurement, without requiring the user to set or change the settings.

Returning to FIG. 2, in S117, the control unit 120 determines whether or not a measurement start instruction has been input from the operation unit 117. If it is determined that an instruction has been input, the process ends, and if not, the process proceeds to S119. proceed.

In S119, the control unit 120 determines whether or not it is necessary to reselect the lead, and if it is determined to be necessary, returns the process to S103, and selects the lead again based on the electrocardiogram data of the predetermined beat rate. . On the other hand, if it is not determined that reselection is necessary, control unit 120 returns the process to S117.
The control unit 120 can determine that reselection is necessary when, for example, R-wave detection or heart rate calculation fails, but the present invention is not limited to these. In this way, by repeatedly executing the automatic selection of leads as necessary, the optimal lead can always be selected.

As described above, according to the present embodiment, in a biological signal processing device that detects a heart rate based on one type of lead in an electrocardiogram consisting of a plurality of types of leads, can automatically select the lead it believes to be the best for heart rate detection. Therefore, even if the subject, the observation environment, or the like changes, it is possible to obtain an accurate heart rate without the need for the user to change the settings.

The biological signal processing device according to the present invention is a program (application software) that causes a general-purpose information processing device such as a personal computer, a tablet terminal, or a smartphone to execute the operation of the control unit 120 (including the analysis unit 1201) described above. It can also be realized as The present invention can also be implemented as a program that is stored in a ROM of a biological signal processing device such as an electrocardiograph or a biological information monitor and causes a processor of the device to implement the above-described operation of the control unit 120 . Therefore, such programs and recording media storing the programs (optical recording media such as CD-ROMs and DVD-ROMs, magnetic recording media such as magnetic discs, semiconductor memory cards, etc.) also constitute the present invention. .

DESCRIPTION OF SYMBOLS 100... Electrocardiograph, 118... Display part, 120... Control part, 123... External I/F, 1201... Analysis part

Claims (5)

A biological signal processing device for acquiring an electrocardiogram consisting of multiple leads,
detection means for detecting heart rate based on one lead;
a selection means for selecting a lead to be used for heart rate detection by the detection means from the two or more leads based on two or more leads;
The selecting means obtains a minimum value of a difference between a reference value in a period of predetermined multiple beats and a maximum level in a period of one beat for each of the two or more types of leads, and the minimum value is the maximum. A biological signal processing device characterized by selecting a lead. 2. The biological signal processing apparatus according to claim 1 , wherein said selection means generates said reference value based on the average level of said electrocardiogram during said one beat period. 3. The biomedical signal processing apparatus according to claim 1, wherein said selection means executes said selection again when a predetermined condition is satisfied. A control method for a biological signal processing device that acquires an electrocardiogram consisting of multiple leads,
a detecting step for detecting heart rate based on one lead;
a selecting step of selecting a lead to be used for heart rate detection in the detecting step from the two or more leads based on the two or more leads;
In the selecting step, for each of the two or more leads, a minimum difference between a reference value in a predetermined multiple beat period and a maximum level in one beat period is obtained, and the minimum value is the maximum. A control method for a biological signal processing device, characterized by selecting a lead. A program for causing a computer to function as each means of the biological signal processing apparatus according to any one of claims 1 to 3 .

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