KR101884377B1

KR101884377B1 - blood flow monitoring system during CPR and thereof method

Info

Publication number: KR101884377B1
Application number: KR1020160011287A
Authority: KR
Inventors: 이경중; 명현석; 강동원; 임은호; 강창훈
Original assignee: 연세대학교 원주산학협력단
Priority date: 2016-01-29
Filing date: 2016-01-29
Publication date: 2018-08-07
Also published as: KR20170090657A

Abstract

The present invention relates to a blood flow monitor for detecting a single blood ejection amount of a heart due to chest compression by using photoplethysmography (PPG), and monitoring blood flow to the brain, And a control method thereof.
A method for driving a blood flow monitoring apparatus for CP resuscitation is characterized in that the operation processing unit is configured to receive a first PPG signal, a second PPG signal, and a signal for receiving a chest impedance signal from the chest impedance detecting unit, the first PPG detecting unit, Receiving step; The arithmetic processing unit may include a motion noise removing step of removing the motion noise of the first PPG signal and the second PPG signal received in the signal receiving step; The arithmetic processing unit sets a sample for calculating a pulse wave propagation time in each of the first PPG signal and the second PPG signal from which motion noise has been removed in the motion noise removal step of the PPG signal; Calculating a pulse wave propagation time calculating step of calculating a difference between a time of a blood flow measurement point of the first PPG signal set at the blood flow measurement point setting in the PPG signal and a time of the blood flow measurement point of the second PPG signal as a pulse wave propagation time; The arithmetic processing unit calculates the blood ejection amount of each cycle once using the pulse wave transmission time PWTT and obtains the average value of the blood ejection amount calculated once for each cycle, And a pressing intensity adjusting notification step of comparing the average value of the blood ejection amount obtained in the output amount calculating step with the one time blood ejection amount threshold value and notifying a notification signal for adjusting the pressing strength through the monitor unit or the speaker unit .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a blood flow monitoring system for CPR,

The present invention relates to a blood flow monitor for detecting a single blood ejection amount of a heart due to chest compression by using photoplethysmography (PPG), and monitoring blood flow to the brain, And a control method thereof. More specifically, the present invention relates to a method for determining the number of CPRs per minute (CPM) performed using the impedance of the chest during CPR, comparing the CPM with the recommended CPR of the CPR guideline, A pulse rate transit time (PWTT) was calculated from the two PPG signals from which the CPR signal was removed, and then the stroke volume was once induced And a CPR quality feedback unit for outputting the CPR quality to the monitor unit and controlling the degree of compression, and a control method thereof.

Cardiopulmonary resuscitation (CPR) is a very important first aid to deliver oxygen-containing blood to the heart and brain artificially when a cardiac arrest (cardiac arrest) occurs. If a heart attack occurs, blood circulation to the whole body is stopped, and if not taken immediately, death or severe brain damage can occur. In particular, the brain begins to irreversibly damage the brain even if the blood supply is interrupted for only 4-5 minutes, and if not done for more than 6 minutes, the brain and all organs of the patient may stop functioning and lose life.

Normal cardiopulmonary resuscitation recovers 20% of normal blood flow, while 100% recovery is possible with an automatic cardiopulmonary resuscitation device or an Automated Extemal Defibrillator (AED), increasing the survival rate of cardiac arrest patients by up to 70% .

As shown in FIG. 1, the chest compressing unit 20 of the automatic CPR device 10 is installed on the chest area of the emergency patient, and CPR is performed.

2, the automatic CPR apparatus includes a CPR sensor 110, a CPR sensing signal preprocessing unit 130, an A / D conversion unit 140, an arithmetic processing unit 150, a motor driving unit 160, a motor 170, a monitor 180, and a transceiver 190.

The CPR sensor 110 is a sensor for checking whether the CPR is properly performed and the number of presses, and may be a chest impedance sensor. The CPR sensing signal detected by the CPR sensor 110 is removed and amplified by the CPR sensing signal preprocessing unit 130 and then converted into a digital signal by the A / D conversion unit 140, ). The operation processing unit 150 analyzes the number of times CPR is performed using the received CPR sensing signal and also outputs a motor control signal for driving the motor 170 of the chest compressing unit 20 to the motor driving unit 150. [ Lt; / RTI >

The American Heart Association (CPR) guidelines emphasize good cardiopulmonary resuscitation (CPR), with adults having more than 100 compression per minute (CPM), CPR It is recommended that a chest compression depth of 5 cm or more be performed (ie, at each compression). The Korean version of the 2011 CPR Guidelines emphasizes good quality CPR and recommends chest compressions of 100 times or more per minute to 120 times per minute for adults. Recently, many studies have been carried out to measure the compression depth of chest using an acceleration sensor.

However, to ensure that a more accurate and effective cardiopulmonary resuscitation is being performed, it is important not to simply measure the pressure depth, but to ensure that the heart and brain are supplying oxygen-enriched blood instead of the actual heart. For this purpose, it is desirable to detect the stroke volume (SV) of the heart at the time of CPR, that is, at the time of each compression, and to control the degree of compression when the CPR is performed according to the stroke volume do.

In the past, methods for detecting the single blood ejection amount (S.V.) of the heart through an electrocardiogram have been proposed. In some cases, however, the patient can not produce a single heart rate of the heart if it is an arrhythmia that can not detect a pulse or blood pressure.

Therefore, the present invention provides a method for determining the compression per minute (CPM) of CPR using the impedance of the chest during CPR, comparing the CPR with CPM of the CPR guideline (Pulse wave transit time) is calculated from two PPG signals from which CPR noise is removed, and then a stroke volume is derived once to output to the monitor, and the degree of compression is controlled (CPR quality) feedback unit for CPR monitoring.

Generally, the pulse wave of the optic volume is the pulse waveform of the heart by detecting the change of the blood flow caused by repeated contraction and relaxation of the heart, and is used to calculate the oxygen saturation and the heart rate.

In the prior art, Korean Patent No. 10-1456590 not only measures the pulse wave propagation time, but also confirms the pulse pressure change of the pressure pulse, thereby detecting the left / right pulse pressure deviation, the upper / lower pulse pressure deviation, And a blood circulation disorder measurement system using a pulse wave and a pulse wave for detecting a circulatory abnormality by using a new analysis factor of a time difference of transmission time and an up / down pulse pressure transmission.

Korean Patent No. 10-1456590 analyzes blood circulation path characteristics by using the pulse wave transfer time (PWTT) and the intensity of the pulse wave signal of each artery, so that it is not possible to know the one-time blood ejection amount due to chest compression , Which is therefore difficult to use as a blood flow monitor for CPR.

SUMMARY OF THE INVENTION The present invention provides a blood flow monitor for cardiopulmonary resuscitation, which detects one-time blood ejection amount of the heart due to chest compression by using an optical pulse wave when CPR is performed, and monitors whether blood substantially flows into the brain And a control method thereof.

Another object of the present invention is to provide a method and apparatus for performing a resuscitation (CPM) using the impedance of the chest after CPR, (PWTT) was calculated from the two PPG signals with the CPR signal removed, and the stroke volume was measured once to monitor the pulse volume. And a CPR quality feedback unit for controlling the degree of compression of the CPR, and a control method for the blood flow monitor for CPR.

Another problem to be solved by the present invention is to include an algorithm for removing noise by modeling motion noise by CPR using chest impedance to monitor the blood flow to the brain during cardiopulmonary resuscitation The present invention also provides a method for driving a blood flow monitor for a CPR monitoring the blood flow.

According to an aspect of the present invention, there is provided an apparatus for monitoring blood flow for resuscitation of a cardiopulmonary resuscitation, the apparatus comprising: a chest impedance detector having a chest impedance sensor for detecting a chest impedance signal; A first PPG detecting unit for detecting a first PPG signal from a first PPG (optical pulse wave) sensor mounted on a part of a human body; A second PPG detector for detecting a second PPG signal from a second PPG sensor mounted on another part of the human body; The first PPG detecting unit and the second PPG detecting unit remove the motion noise from the first PPG signal and the second PPG signal, respectively, and output the pulse wave propagation time (the first PPG signal and the second PPG signal) An arithmetic processing unit for calculating the blood ejection amount (SV) once after calculating the PWTT, and a monitor unit for displaying the blood ejection amount once received from the operation processing unit.

The arithmetic processing unit detects CPM (the number of CPRs per minute) from the chest impedance signal.

The operation processing unit may generate a motor speed control signal of an automatic CPR device for controlling the chest compression speed by comparing the detected CPM with a predetermined CPM reference value.

The operation processing unit may compare the detected CPM with a predetermined CPM reference value and transmit a notification signal to the monitor unit or the speaker unit to adjust the chest compression speed.

The arithmetic processing unit can generate the motor intensity control signal of the automatic CPR apparatus which compares the detected one-time blood ejection amount with the one-time blood ejection amount threshold to adjust the chest compressive strength.

The operation processing unit may compare the detected blood ejection amount with the once blood ejection amount threshold value and transmit a notification signal to the monitor unit or the speaker unit to adjust the chest pressure intensity.

When the dynamic noise is removed from each of the first PPG signal and the second PPG signal, the arithmetic processing unit obtains the CPR frequency from the first PPG signal and the second PPG signal, and uses the CPR frequency, Phase of the first PPG signal is obtained and a motion noise component in each of the first PPG signal and the second PPG signal is obtained by CPR and a motion artifact in the first PPG signal is removed from the first PPG signal, Detects the first PPG signal from which the dynamic noise is removed, removes the dynamic noise component from the second PPG signal from the second PPG signal, and detects the second PPG signal from which the dynamic noise is removed.

The calculation processing unit may detect the CPM by counting the number of peaks in the chest impedance signal exceeding a predetermined chest impedance threshold in the chest impedance signal received from the chest impedance detecting unit or the calculation processing unit may detect the chest impedance In the signal, a peak is detected in the chest impedance signal above a predetermined threshold impedance, and the CPM

(Where Cr is the number of CPR cycles per minute (CPM), t _i is the time of the i-th maximum compression of the chest, which is the peak of the i th thoracic impedance)

. &Lt; / RTI >

The driving method of a blood flow monitoring apparatus for cardiopulmonary resuscitation according to the present invention is characterized in that the operation processing unit is configured to receive a first PPG signal, a second PPG signal, and a chest impedance signal from a chest impedance detecting unit, a first PPG detecting unit, Receiving a signal; The arithmetic processing unit may include a motion noise removing step of removing the motion noise of the first PPG signal and the second PPG signal received in the signal receiving step; The arithmetic processing unit sets a sample for calculating a pulse wave propagation time in each of the first PPG signal and the second PPG signal from which motion noise has been removed in the motion noise removal step of the PPG signal; Calculating a pulse wave propagation time calculating step of calculating a difference between a time of a blood flow measurement point of the first PPG signal set at the blood flow measurement point setting in the PPG signal and a time of the blood flow measurement point of the second PPG signal as a pulse wave propagation time; The arithmetic processing unit calculates the blood ejection amount of each cycle once using the pulse wave transmission time PWTT and obtains an average value of the blood ejection amount calculated once for each cycle; The calculation processing section compares the average value of the blood ejection amount obtained in the one-time blood ejection amount calculation step with the one-time blood ejection amount threshold value and notifies the notification signal for the adjustment of the compression strength through the monitor section or the speaker section. The method comprising the steps of:

In the blood flow measurement point setting step in the PPG signal, the arithmetic processing unit detects a peak in the first PPG signal during each period, detects a peak of the second PPG signal linked to the peak of the first PPG signal, and outputs a peak of the first PPG signal to the first PPG signal Signal, and the peak of the second PPG signal linked to the peak of the first PPG signal is used as the blood flow measurement point of the second PPG signal.

The peak of the second PPG signal interlocked with the peak of the first PPG signal is a peak of the second PPG signal before and after the peak of the first PPG signal and a peak of the second PPG signal before and after the peak of the first PPG signal The peak of the second PPG signal close to the peak of the first PPG signal is detected as the peak of the second PPG signal interlocked with the peak of the first PPG signal.

In the one-shot blood volume calculation step, the calculation processing unit calculates the blood volume (S.V.)

(However, PWTT is the pulse wave propagation time, and α is -0.30, β is 131.9 ± 16.5, Im K is 0. 96 ± 0. 31)

.

The average value of the blood ejection amount per one time in the one time blood ejection operation step is the average value of the one time blood ejection amount for 5 seconds.

When the average value of the blood ejection amount once is not larger than the one-time blood ejection amount threshold value, the arithmetic processing unit generates the motor strength control signal of the automatic CPR apparatus for increasing the compression strength of the CPR And transmits it to the motor driver.

Between the signal reception step and the motion noise removal step of the PPG signal, the calculation processing unit receives the first PPG signal, the second PPG signal, and the chest impedance signal from the chest impedance detection unit, the first PPG detection unit, and the second PPG detection unit Receiving a signal; The calculation processing unit calculates CPM (the number of CPRs per minute) from the received thoracic impedance signal in the signal reception step; Determining whether the CPM is greater than 100, determining whether the CPM is greater than 100, if the CPM is not greater than 100, and informing the CPM by the monitor or the speaker; If the CPM is greater than 100, the calculation processing unit determines whether the CPM is smaller than 120. If the CPM is not smaller than 120, the operation processing unit sends a notification signal for decreasing the CPM to the monitor unit or the speaker unit And determining whether the CPM is less than 120,

In the step of determining whether the CPM is greater than 100, the operation processing unit generates a motor speed control signal of the automatic CP resuscitation apparatus for CPM increase if the CPM is not greater than 100, a step of determining whether the CPM is smaller than 120, If the CPM is not less than 120, a motor speed control signal of the automatic CPR device for CPM reduction is generated.

In the dynamic noise removing step of the PPG signal, the arithmetic processing unit obtains a peak in each of the first PPG signal and the second PPG signal, and calculates a CPR signal of the first PPG signal and the CPR signal using the period of the obtained peak A CPR frequency calculation step of calculating a CPR using the obtained CPR frequency; The operation processing unit may include a dynamic noise component estimation step by a CPR method for obtaining a dynamic noise component in each of the first PPG signal and the second PPG signal by CPR using the phase obtained in the CPR frequency calculation step; In the first PPG signal, the dynamic noise component in the first PPG signal obtained in the step of estimating the dynamic noise component by CPR is removed to detect the first PPG signal from which the dynamic noise is removed. In the second PPG signal, A PPG signal estimation step of measuring a flow of blood flow by removing a dynamic noise component in a second PPG signal obtained in the step of estimating a dynamic noise component by a resuscitation to detect a second PPG signal from which motion noise is removed; .

In the step of estimating the dynamic noise component by CPR, the arithmetic processing unit calculates the dynamic noise component

)of

(However, the first gajilttae the N harmonics from by having the N-th harmonic harmonic, c _k (n) denotes the amplitude of the n-th sample in the k-th harmonic, θ _k (n) is the n-th sample in the k-th harmonic a represents the phase, Φ (n) is n denotes the phase of the second sample, a _k (n) is the variation of the amplitude of in-phase (in-phase) component, b _k (n) is the quadrature phase (quadrature) component and the variation of the amplitude, and S _I (n) is a statue reference signal, and the quadrature reference signals, a (n) is a filter coefficient of the LMS adaptive filter, n is the statue coefficients in the second sample, b (n) is LMS Filter coefficient of the adaptive filter, which is the quadrature phase coefficient in the nth sample)

.

A method of driving a blood flow monitor apparatus for CPR includes an LMS adaptive filter coefficient updating step of calculating a filter coefficient of an LMS adaptive filter in a next sample after a PPG signal estimation step of measuring a blood flow .

In the LMS adaptive filter coefficient updating step, the filter coefficients a (n + 1) and b (n + 1) of the LMS adaptive filter to be updated are

(Note that all harmonics are arranged in different step sizes mu _k , grouped in a diagonal matrix M)

.

The blood-flow monitoring apparatus for CPR of the present invention detects the one-time blood ejection amount of the heart due to chest compression by using an optical pulse wave when CPR is performed, monitors whether the blood flows substantially into the brain, It is possible to confirm whether effective CPR is properly implemented. In other words, in the case of estimating the existing compression depth, it is not immediately known what effect the cardiopulmonary resuscitation has on the cardiopulmonary patients, but in the present invention, since the blood flow is monitored, more accurate and effective cardiopulmonary resuscitation Able to know. It is also possible to control the degree of compression during CPR, based on the amount of blood that is delivered once.

In addition, the CPM monitoring apparatus for CPR of the present invention is a CPM monitoring apparatus that, when CPR is performed, obtains CPM (number of CPRs) per minute by using the impedance of the chest and then sets a predetermined CPM reference value (PWTT) was calculated from two PPG signals with CPR removed, and then the stroke volume was calculated once. And CPR quality feedback unit which outputs the output to the monitor unit and controls the degree of compression. Thus, it is possible to drive the CPR device to enable accurate and effective CPR.

In order to monitor the blood flow to the brain during cardiopulmonary resuscitation, the present invention models blood flow by cardiopulmonary resuscitation using chest impedance, and monitors blood flow including an algorithm for removing noise The present invention provides a method for driving a CPR assist device. Therefore, when CPR is performed, it is possible to detect a PWTT signal with higher purity by excluding the mixed motion noise signal, and to detect a more accurate blood flow amount once.

Electrocardiograms show electrical activity, especially pulseledss electrical activity (PEA), but in the case of arrhythmia that can not detect pulse or blood pressure, one can not produce blood volume. However, even in such a case, since the blood flow can be sensed by using the present invention, it is also effective in determining the pulsating electrical activity. In addition, the present invention can be used as an indicator for determining the presence or absence of a return of spontaneous circulation (ROSC) after cardiopulmonary resuscitation and electrical defibrillation in a cardiac arrest state.

1 is a state of use of a conventional automatic cardiopulmonary resuscitation apparatus.
FIG. 2 is an explanatory view schematically illustrating the configuration of the automatic CPR device of FIG. 1. FIG.
FIG. 3A is a block diagram schematically illustrating a configuration of a blood flow monitor for CPR according to an embodiment of the present invention.
FIG. 3B is a block diagram schematically illustrating a configuration of a blood flow monitor for CPR according to another embodiment of the present invention. Referring to FIG.
4 shows a position candidate group in which the first PPG sensor and the second PPG sensor can be mounted in the present invention.
5 is a flow chart of the arithmetic processing unit of the blood flow monitoring apparatus for cardiopulmonary resuscitation of the present invention.
FIG. 6 is an explanatory diagram illustrating a method for detecting the CPM count from the chest impedance. FIG.
7 is a schematic diagram for explaining a motion noise removing process according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

FIG. 3A is a block diagram for schematically illustrating the configuration of a blood flow monitor for CPR according to an embodiment of the present invention, a chest impedance sensor 111, a first PPG sensor 121, a second PPG sensor 122, A first PPG preprocessor 132, a second PPG preprocessor 133, an A / D converter 140, an arithmetic processing unit 150, a motor driver 160, a motor 170, A monitor 180, and a transceiver 190.

The A / D converter 140, the operation processor 150, the motor driver 160, the motor 170, the monitor 180, and the transceiver 190 are connected to the automatic CPR device 10 of FIG. Can be used. The transmitting / receiving unit 190 may be omitted in some cases.

The chest impedance sensor 111 is a sensor used as the CPR sensor 110 and is generally a sensor mounted on an automatic CPR device 10. The chest impedance sensor 111 is provided at the chest contact portion in the automatic CPR device 10 to measure the chest impedance signal from the patient's chest.

The chest impedance signal preprocessing unit 131 removes noise from the chest impedance signal measured from the chest impedance sensor 111, amplifies the amplified chest impedance signal, and transmits the amplified noise to the A / D conversion unit 140.

Here, the chest impedance sensor 111, the chest impedance signal preprocessing unit 131, and the A / D conversion unit 140 are referred to as a chest impedance detecting unit.

Each of the two PPG sensors, that is, the first PPG sensor 121 and the second PPG sensor 122, is mounted on any one of the face, head, neck, and ear, and is provided with a photoplethysmography (PPG) 1 PPG signal and the second PPG signal.

The PPG sensor is composed of a light emitting diode (light emitting portion) and a photodiode (light receiving portion). That is, light having a wavelength in the infrared band can be irradiated to a portion near the artery of a human body using a light emitting diode, and the PPG signal can be obtained by detecting reflected or transmitted light at a measurement site using the photodiode.

The first PPG preprocessing unit 132 and the second PPG preprocessing unit 133 generate a PPG signal that is detected by the first PPG sensor 121 and the second PPG sensor 122, that is, a first PPG signal, Removes noise from the PPG signal, amplifies the amplified signal, and transmits the amplified signal to the A / D converter 140.

Here, the first PPG sensor 121, the first PPG preprocessor 132, and the A / D converter 140 are referred to as a first PPG detector 122. The second PPG sensor 122, the second PPG preprocessor 133, / D conversion unit 140 is referred to as a second PPG detection unit.

The A / D conversion unit 140 converts the received first PPG signal, the second PPG signal, and the thoracic impedance signal into a digital signal, and transmits the digital signal to the arithmetic processing unit 150.

The computation processor 150 obtains the CPM per minute (CPM) of CPR performed by the patient using the chest impedance signal, and compares the obtained CPM with the predetermined CPM reference value to calculate the chest compression rate And transmits the generated motor speed control signal to the motor driving unit 160. [ Here, the CPM reference value is the recommended CPR CPM of the CPR Guidelines, and may be stored in a memory unit (not shown) at the time of shipment from the factory.

In addition, the arithmetic processing unit 150 removes motion noise from the two PPG signals, that is, the first PPG signal and the second PPG signal, and transmits the pulse wave using the first PPG signal and the second PPG signal, After calculating the pulse wave transit time (PWTT), the stroke volume is calculated and output to the monitor to monitor the CPR quality (CPR quality), and the motor intensity And transmits the generated control signal to the motor driving unit 160. Here, the motor strength control signal and the motor speed control signal may be referred to as motor control signals. In addition, the pulse wave transmission time refers to the time taken for the pulse wave to move between the two artery pulses.

The operation processing unit 150 may be any one of a computer, a microprocessor, and a controller.

In the present invention, two PPG sensors, that is, the first PPG sensor 121 and the second PPG sensor 122 are used to obtain the pulse wave transmission time between two PPG signals.

Generally, the PPG signal detected during CPR contains a lot of motion noise, especially the CP noise due to CPR. Accordingly, the arithmetic processing unit 150 includes an algorithm for modeling dynamic noise caused by CPR using chest impedance, and then removing noise.

The motor driving unit 160 drives the motor 170 according to the motor speed control signal and the motor strength control signal received from the arithmetic processing unit 150 to perform simpathic resuscitation.

In the present invention, the chest impedance sensor 111, the chest impedance signal preprocessing unit 131, the A / D conversion unit 140, and the arithmetic processing unit 150 may be referred to as a speed feedback unit. The second PPG sensor 122, the first PPG preprocessor 132, the second PPG preprocessor 133, the A / D converter 140, and the calculation processor 150 to the CPR quality feedback section can do.

FIG. 3A shows the case of using an automatic CPR device, but it is not intended to limit the present invention.

FIG. 3B is a block diagram schematically illustrating a configuration of a blood flow monitor for CPR according to another embodiment of the present invention. Referring to FIG.

FIG. 3B shows a case in which a cardiopulmonary resuscitation practitioner (rescuer) performs cardiopulmonary resuscitation without using an automatic cardiopulmonary resuscitation device, and uses a blood flow monitor device for CPR as an assist device for CPR.

In FIG. 3B, the motor driving unit 160 and the motor 170 shown in FIG. 3A are not provided.

In FIG. 3B, the calculation processing unit 150 calculates a CPM (Per Minute CPM) number per minute to the patient using the chest impedance signal, compares the calculated CPM with the predetermined CPM reference value , And outputs a notification signal for controlling the chest compression speed to the monitor 180 or the speaker 185 or an alarm (not shown). In addition, the arithmetic processing unit 150 removes motion noise from the two PPG signals, that is, the first PPG signal and the second PPG signal, and transmits the pulse wave using the first PPG signal and the second PPG signal, After calculating the pulse wave transit time (PWTT), the stroke volume is calculated once and output to the monitor section to monitor the CPR quality (CPR quality), and a notification signal for controlling the chest compressive strength To the monitor 180 or the speaker 185 or an alarm (not shown).

4 shows a position candidate group in which the first PPG sensor and the second PPG sensor can be mounted in the present invention.

The PPG (pulse width pulse) sensor is attached to the lower part of the heart located in the upper part of the heart, where the movement of the patient during CPR is less. As a candidate position of the attachment position considering this, there are a beneath the eyes, a nose, a mouth, a neck, an ear, a head, and a jaw as shown in FIG.

5 is a flow chart of the arithmetic processing unit of the blood flow monitoring apparatus for cardiopulmonary resuscitation of the present invention.

When the arithmetic processing unit 150 receives the start key value as a start key (not shown) is pressed from a key input unit (not shown), the arithmetic processing unit 150 transmits a motor control signal to the motor driver 160 To perform CPR (S110).

The signal processing unit 150 receives the first PPG signal, the second PPG signal, and the chest impedance signal through the A / D conversion unit 140 (S120). Then, the operation processing unit 150 extracts, from the chest impedance signal, (CPM), and outputs it to the monitor 180 (S130).

As shown in FIG. 6, the calculation processing unit 150 detects a peak in a chest impedance signal exceeding a predetermined threshold impedance value in a chest impedance signal, and the peak is a maximum chest tightness when performing a single chest compression Time. That is, the number of CPRs (CPM) can be detected by counting the number of peaks.

In the case of CPM, the difference between successive chest compressions can be used to calculate Eq. (1).

Here, Cr is the number of CPR cycles per minute, and t _i is the time of the i th peak of the chest compressions, which is the peak of the i th thoracic impedance. Also, (cpm) represents the number of CPR per minute as a unit.

In step S 140, it is determined whether CPM is greater than 100. If the CPM is greater than 100, the operation processing unit 150 determines whether CPM is greater than 100, ) Is not greater than 100, the use of an automatic CPR device produces a motor speed control signal to increase the number of CPR cycles per minute (CPM), or without an automatic CPR device (i.e., (S150), the CPR rescue practitioner (rescuer) is requested to perform a quicker CPR through the monitor unit or the speaker unit (or alarm) (not shown).

If the number of CPRs per minute (CPM) per minute is greater than 100 in the step of determining whether or not the number of CPRs per minute (CPM) is less than 120 and whether or not the number of CPRs per minute CPM is greater than 100, (CPM) is less than 120, and if CPM is not less than 120, then CPR 150 is used for CPR if per minute CPR is less than 120, (CPR), or to perform a slower cardiopulmonary resuscitation if the CPR is to be used without an automatic CPR device (i.e., without a motor and motor drive) Through a monitor unit or a speaker unit (or an alarm) (not shown) (S170).

That is, in the case of the 2011 Korean type CPR Guideline, since the chest compression of 100 times or more and less than 120 times per minute is recommended for adult CPR, the CPM (number of CPRs per minute) A motor speed control signal is generated or requested from the CPR rescuer (rescuer) so as to perform a faster CPR if the CPM value is less than 100 cpm, and if the CPM value is greater than 120 cpm, Speed control signals, or an alarm and display function that requests CPR rescuers (rescuers, paramedics).

In operation S210, the operation processor removes motion noise from the two PPG signals received in the signal reception and CPM operation steps, i.e., the first PPG signal and the second PPG signal, from the PPG signal. In other words, during the CPR, the CPR sensor moves according to the movement of the living body during the CPR, while the CPR sensor performs the movement during the compression of the CPR. So that only the movement of the blood flow toward the actual brain can be observed. The process of removing the detailed motion noise will be described later.

In step S220, a sample is set for calculating a pulse wave transmission time in two PPG signals from which motion noise is removed in the motion noise removal step in the PPG signal. That is, a peak is obtained in the first PPG signal for one period, a peak of the second PPG signal linked to the peak of the first PPG signal is found, a peak of the first PPG signal is set as a blood flow measurement point of the first PPG signal, The peak of the second PPG signal to be interlocked is set as the blood flow measurement point of the second PPG signal.

Here, the peak of the second PPG signal interlocked with the peak of the first PPG signal is a peak of the second PPG signal before and after the peak of the first PPG signal, and a peak of the second PPG signal before and after the peak of the first PPG signal. In the peaks, the peak of the second PPG signal close to the peak of the first PPG signal is made the peak of the second PPG signal interlocked with the peak of the first PPG signal.

The difference between the time of the blood flow measuring point of the first PPG signal set at the step of setting the blood flow measuring point in the two PPG signals and the time of the blood flow measuring point of the second PPG signal is obtained as the pulse wave transmitting time PWTT S230).

Pulse wave delivery time (PWTT) is the most important parameter for deriving the one time blood flow (SV). It can be obtained by differentiating the attachment position of two PPG sensors which measure the flow of blood flow, It is.

The blood ejection amount (S.V.) is calculated by the formula (2) using the pulse wave transfer time (PWTT) in step of calculating the blood volume once (S240).

Here, α, β, and K are experimental constants, which can be determined at the time of shipment from the factory or set at the beginning of use. Alternatively, alpha may be -0.30, beta may be 131.9 +/- 16.5, and K may be 0 . 96 ± 0 . 31.

(SV) calculated by repeating the step of setting the blood flow measurement point in the two PPG signals and the one step of blood ejection amount calculation step for 5 seconds, (Average SV) (S250).

In step S260, it is determined whether the average value (average SV) of the one-time blood ejection amount (SV) calculated for 5 seconds is greater than the one-time blood ejection amount (SV) threshold value (TH) (SV) threshold value (TH), a notification signal indicating that the CPR is properly performed is notified through the monitor unit 180 or the speaker unit 185 (S280).

(SV) threshold value (TH) of the one-time blood ejection amount (SV) calculated for 5 seconds in the CPR evaluation stage, If the CPR is not properly performed, a notification signal indicating that the CPR should be increased is notified through the monitor unit 180 or the speaker unit 185 (S270). If the CPR apparatus is used, The arithmetic processing unit 150 generates a motor strength control signal and transmits it to the motor driving unit 160. [

7 is a schematic diagram for explaining a motion noise removing process according to the present invention.

The algorithm for removing CPR noise from each of the two PPG signals is based on a least mean square (LMS) adaptive LMS filter.

When CPR is performed, the PPG signal measured from the PPG sensor contains the PPG component measuring the flow of blood flow and the CPG component by CPR. This can be expressed by the following equation (3).

Here, PPG _IN represents the PPG signal measured from the PPG sensor, PPG _flow represents the PPG component measuring the _flow of the blood flow, and e represents the dynamic noise component by CPR.

However, the original motion artifact (e) due to CPR in the PPG signal (PPG _IN ) measured from the PPG sensor can not be known. To do this, we use a minimum mean square algorithm to estimate and remove motion artifacts by CPR using a chest impedance (TTI) with a correlation with the dynamic noise component (e) by CPR . At this time, the motion artifact due to the estimated cardiopulmonary resuscitation

Respectively.

The process of estimating and removing CPR noise using the least mean square algorithm is as follows.

First, in the step of calculating the CPR frequency, the operation processing unit 150 obtains a CPR frequency f _i , and obtains a phase Φ (n) between pressures of the CP using the CPR frequency.

The CPR frequency can be found from equation (4) as the reciprocal of the difference in successive chest compression time.

Where f _i is the CPR frequency, more specifically the CPR frequency at the i-th chest compression. t _i represents the time of the i th maximum compression of the chest, and t _i ₊ ₁ represents the time of the i + 1 th maximum compression of the chest.

Here, it is assumed that the frequency between two consecutive chest compressions is constant. Also, the frequency of CPR varies with time, but since CPR compression cycles are almost constant, the CPR frequency is also almost constant. The phase (phi (n)) between consecutive chest compression times can be calculated using Equation 5 using the CPR frequency.

Here, Φ (n) denotes the phase of the n-th sample, f _s represents the sampling frequency.

Secondly, the step of estimating the dynamic noise component by CPR is to calculate the dynamic noise component by CPR

).

During cardiopulmonary resuscitation, the CPR noise model can be modeled as a pseudo periodic signal with the CPR frequency as the fundamental frequency. In this case, the quasi-periodic signal can have a CPR frequency as a fundamental frequency as shown in Equation (6), a harmonic of the fundamental frequency as a frequency, and a sum of sinusoidal signals whose phases and amplitudes vary with time.

Here, the first, gajilttae the N harmonics by having the N-th harmonic from the harmonic c _k (n) is the k-th denotes the time variation (time-varying) amplitude of the harmonic, θ _k (n) is the phase of the k-th harmonic . That is, c _k (n) represents the amplitude of the nth sample at the kth harmonic, and θ _k (n) represents the phase of the nth sample at the kth harmonic. a _k (n) is the variation of the amplitude of the in-phase component and b _k (n) is the variation of the amplitude of the quadrature component.

S _I (n) is an in-phase reference signal, expressed as:

S _Q (n) is a quadrature reference signal, expressed as:

A (n) is an in-phase coefficient at time n (i.e., the nth sample), and b (n) is a filter coefficient of a least mean square (LMS) adaptive filter at time n (n) is a quadrature coefficient at time n (or nth sample), and is expressed as follows.

Third, the PPG signal estimation step in which the flow of blood flow is measured. In the PPG signal (PPG _IN ) measured in the CPR procedure as shown in Equation (7), the motion noise component

) Is removed, and the PPG signal (PPG _filtered ) obtained by measuring the flow of blood flow is obtained.

Fourth, in the minimum mean square (LMS) adaptive filter coefficient update step, the filter coefficients a (n + 1), b (n) of the LMS adaptive filter at time n + 1 +1)) is obtained by the following equation (8).

That is, in the case of the phase and amplitude of the harmonics that change with time, it is updated as shown in Equation (8) using a method of updating the filter coefficient of the LMS adaptive filter.

All harmonics are assigned to different step sizes μ _k , grouped in a diagonal matrix M. That is, M = diag (μ ₁ , .... μ _N ). here,

Represents a diagonal matrix of S _I (n) as a transposed matrix,

(N + 1), b (n + 1)) of the LMS adaptive filter using the diagonal matrix of S _Q (n)
The step size of each harmonic component, mu _k ,

Where μ ₀ is the basic step size set by the user or may be a factory set value.

If the process from the first CPR frequency calculation step to the fourth least mean square (LMS) adaptive filter coefficient update step is repeatedly performed, the minimum mean square algorithm is used to estimate and remove the CPR noise, Can be measured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, it is intended that the scope of the invention be defined by the claims appended hereto, and that all equivalent or equivalent variations thereof fall within the scope of the present invention.

10: Automatic CPR device 110: CPR sensor
111: Chest Impedance Sensor 121: First PPG sensor
122: second PPH sensor 131: chest impedance signal preprocessing section
132: FirstPPG preprocessing unit 133: SecondPPG preprocessing unit
140: A / D converter 150:
160: motor driving unit 170: motor
180: Monitor section 185: Speaker section
190: Transmitting /

Claims

A chest impedance detector having a chest impedance sensor for detecting a chest impedance signal;
A first PPG detecting unit for detecting a first PPG signal from a first PPG (optical pulse wave) sensor mounted on a part of a human body;
A second PPG detector for detecting a second PPG signal from a second PPG sensor mounted on another part of the human body;
The first PPG detecting unit and the second PPG detecting unit remove the motion noise from the first PPG signal and the second PPG signal, respectively, and output the pulse wave propagation time (the first PPG signal and the second PPG signal) An arithmetic processing unit for calculating a blood ejection amount (SV) once after calculating PWTT;
A monitor unit for displaying the blood ejection amount once received from the operation processing unit;
And,
The arithmetic processing unit calculates the blood ejection amount (SV)

(However, PWTT is the pulse wave propagation time, and α is -0.30, β is 131.9 ± 16.5, Im K is 0. 96 ± 0. 31)
Wherein the blood flow monitoring device comprises:

The method according to claim 1,
Wherein the calculation processing unit detects CPM (the number of CPRs per minute) from the chest impedance signal.

3. The method of claim 2,
Wherein the operation processing unit compares the detected CPM with a predetermined CPM reference value to generate a motor speed control signal of an automatic CPR device that adjusts a chest compressing speed.

3. The method of claim 2,
Wherein the operation processing unit compares the detected CPM with a preset CPM reference value and transmits a notification signal for controlling the chest compression speed to the monitor unit or the speaker unit.

The method according to claim 1,
Wherein the operation processing unit generates a motor intensity control signal of an automatic CPR device for comparing the detected one-time blood ejection amount with the one-time blood ejection amount threshold value and controlling the chest compressive strength. Device.

The method according to claim 1,
Wherein the calculation processing unit compares the detected one-time blood ejection amount with the one-time blood ejection amount threshold value, and transmits a notification signal for controlling the chest pressure intensity to the monitor unit or the speaker unit.

The method according to claim 1,
When the dynamic noise is removed from each of the first PPG signal and the second PPG signal,
The first PPG signal and the second PPG signal are used to obtain the CPR frequency, the CPR frequency is used to obtain the phase between the compression times, and the first PPG signal by the CPR signal and the second PPG signal using the obtained phase are obtained. The motion noise component in each of the PPG signals is obtained,
Noise component in the first PPG signal is removed from the first PPG signal to detect the first PPG signal from which the motion noise is removed and the dynamic noise component in the second PPG signal is removed from the second PPG signal, And detects the second PPG signal from which noise has been removed.

3. The method of claim 2,
Wherein the calculation processing unit detects the CPM by counting the number of peaks in the chest impedance signal exceeding the predetermined threshold impedance in the chest impedance signal received from the chest impedance detecting unit.

3. The method of claim 2,
The computation processor detects a peak in a chest impedance signal that exceeds a predetermined threshold impedance in a chest impedance signal received from the chest impedance detector,

(Where Cr is the number of CPR cycles per minute (CPM), t _i is the time of the i-th maximum compression of the chest, which is the peak of the i th thoracic impedance)
Wherein the blood flow monitoring device comprises:

The operation processing unit includes: a signal receiving step of receiving a first PPG signal, a second PPG signal, and a thoracic impedance signal from the chest impedance detecting unit, the first PPG detecting unit, and the second PPG detecting unit;
The arithmetic processing unit may include a motion noise removing step of removing the motion noise of the first PPG signal and the second PPG signal received in the signal receiving step;
The arithmetic processing unit sets a sample for calculating a pulse wave propagation time in each of the first PPG signal and the second PPG signal from which motion noise has been removed in the motion noise removal step of the PPG signal;
Calculating a pulse wave propagation time calculating step of calculating a difference between a time of a blood flow measurement point of the first PPG signal set at the blood flow measurement point setting in the PPG signal and a time of the blood flow measurement point of the second PPG signal as a pulse wave propagation time;
The arithmetic processing unit calculates the blood ejection amount of each cycle once using the pulse wave transmission time PWTT and obtains an average value of the blood ejection amount calculated once for each cycle;
The calculation processing section compares the average value of the blood ejection amount obtained in the one-time blood ejection amount calculation step with the one-time blood ejection amount threshold value and notifies the notification signal for the adjustment of the compression strength through the monitor section or the speaker section. step;
/ RTI >
In the blood flow measurement point setting step in the PPG signal, the arithmetic processing unit detects a peak in the first PPG signal during each period, detects a peak of the second PPG signal linked to the peak of the first PPG signal, and outputs a peak of the first PPG signal to the first PPG signal Wherein the peak of the second PPG signal linked to the peak of the first PPG signal is used as the blood flow measurement point of the second PPG signal.

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11. The method of claim 10,
The peak of the second PPG signal interlocked with the peak of the first PPG signal is a peak of the second PPG signal before and after the peak of the first PPG signal and a peak of the second PPG signal before and after the peak of the first PPG signal Characterized in that the peak of the second PPG signal close to the peak of the first PPG signal is detected as the peak of the second PPG signal interlocked with the peak of the first PPG signal at the peaks of the first PPG signal Driving method.

11. The method of claim 10,
In the one-shot blood volume calculation step, the arithmetic processing unit calculates the blood volume output (SV)

(However, PWTT is the pulse wave propagation time, and α is -0.30, β is 131.9 ± 16.5, Im K is 0. 96 ± 0. 31)
Wherein the blood flow monitoring device further comprises:

11. The method of claim 10,
Wherein the average value of the one blood discharge amount in the one blood discharge amount calculation step is an average value of the one blood discharge amount in five seconds.

11. The method of claim 10,
When the average value of the blood ejection amount once is not larger than the one-time blood ejection amount threshold value, the arithmetic processing unit generates the motor strength control signal of the automatic CPR apparatus for increasing the compression strength of the CPR To the motor driving unit. The method for driving the blood flow monitor for CPR according to claim 1,

11. The method of claim 10,
Between the signal reception step and the dynamic noise cancellation step of the PPG signal,
The operation processing unit includes: a signal receiving step of receiving a first PPG signal, a second PPG signal, and a thoracic impedance signal from the chest impedance detecting unit, the first PPG detecting unit, and the second PPG detecting unit;
The calculation processing unit calculates CPM (the number of CPRs per minute) from the received thoracic impedance signal in the signal reception step;
Determining whether the CPM is greater than 100, determining whether the CPM is greater than 100, if the CPM is not greater than 100, and informing the CPM by the monitor or the speaker;
If the CPM is greater than 100, the calculation processing unit determines whether the CPM is smaller than 120. If the CPM is not smaller than 120, the operation processing unit sends a notification signal for decreasing the CPM to the monitor unit or the speaker unit Determining whether the CPM is less than 120;
Further comprising the steps of: monitoring the blood flow rate of the at least one blood flow monitor device;

17. The method of claim 16,
In the CPM calculation step, the calculation processing unit detects a peak in a thoracic impedance signal exceeding a predetermined threshold impedance value in the thoracic impedance signal received from the thoracic impedance detection unit,
CPM

However, Cr is the number of CPR cycles per minute (CPM), t _i is the time of the i th maximum compression of the chest, which is the peak of the i th thoracic impedance.
Wherein the blood flow monitor apparatus further comprises:

17. The method of claim 16,
Wherein the step of determining whether the CPM is greater than 100 is characterized in that, if the CPM is not greater than 100, the operation processor generates a motor speed control signal of the automatic CP resuscitation device for CPM increase Way.

17. The method of claim 16,
Determining whether the CPM is less than 120, and if the CPM is not less than 120, generating a motor speed control signal of an automatic CPR resuscitation device for CPM reduction, Way.

11. The method of claim 10, wherein removing the dynamic noise of the PPG signal comprises:
The operation processing unit obtains a peak at each of the first PPG signal and the second PPG signal, obtains the CPR signal and the CPG signal CPR frequency using the obtained period of the peak, and uses the obtained CPR frequency A CPR frequency calculation step of calculating a CPR phase;
The operation processing unit may include a dynamic noise component estimation step by a CPR method for obtaining a dynamic noise component in each of the first PPG signal and the second PPG signal by CPR using the phase obtained in the CPR frequency calculation step;
In the first PPG signal, the dynamic noise component in the first PPG signal obtained in the step of estimating the dynamic noise component by CPR is removed to detect the first PPG signal from which the dynamic noise is removed. In the second PPG signal, A PPG signal estimation step of measuring a flow of blood flow by removing a dynamic noise component in a second PPG signal obtained in the step of estimating a dynamic noise component by a resuscitation to detect a second PPG signal from which motion noise is removed;
And a controller for controlling the blood flow monitor device.

21. The method of claim 20,
In the step of estimating the dynamic noise component by CPR, the arithmetic processing unit calculates the dynamic noise component

)of

(However, the first gajilttae the N harmonics from by having the N-th harmonic harmonic, c _k (n) denotes the amplitude of the n-th sample in the k-th harmonic, θ _k (n) is the n-th sample in the k-th harmonic a represents the phase, Φ (n) is n denotes the phase of the second sample, a _k (n) is the variation of the amplitude of in-phase (in-phase) component, b _k (n) is the quadrature phase (quadrature) component and the variation of the amplitude, and S _I (n) is a statue reference signal, and the quadrature reference signals, a (n) is a filter coefficient of the LMS adaptive filter, n is the statue coefficients in the second sample, b (n) is LMS Filter coefficient of the adaptive filter, which is the quadrature phase coefficient in the nth sample)
Wherein the blood flow monitor apparatus further comprises:

22. The method of claim 21,
After the PPG signal estimation step in which the blood flow is measured, the arithmetic processing unit includes: an LMS adaptive filter coefficient updating step of obtaining a filter coefficient of the LMS adaptive filter in the next sample;
Further comprising the steps of: (a) monitoring the blood flow rate of the patient;

23. The method of claim 22,
In the LMS adaptive filter coefficient updating step, the filter coefficients a (n + 1) and b (n + 1) of the LMS adaptive filter to be updated are

(Note that all harmonics are arranged in different step sizes mu _k , grouped in a diagonal matrix M)
Wherein the blood flow monitoring device further comprises:

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