JP6787679B2 - Cardiopulmonary function measuring device - Google Patents

Description

The present invention relates to a cardiopulmonary function measuring device, particularly a cardiopulmonary function measuring device that measures heart rate and respiratory rate by using a Doppler sensor using microwaves.

FIG. 8 shows an example of a device for measuring cardiopulmonary function using a conventional microwave Doppler sensor. In FIG. 8, reference numeral 1 is a Doppler sensor, 2 is an LPF (low-pass filter), and 3 is an AD. The (analog / digital) converter, 31 is an LPF having a breathing frequency range as a passing band (for example, a low-pass filter having a frequency characteristic 45 passing through the breathing frequency range Br in FIG. LPF / BPF (low-pass filter or band-pass filter, the low-pass filter has a frequency characteristic 44 for passing the heartbeat frequency range Hr of FIG. 5, for example, and the band-pass filter has a frequency characteristic 44 of FIG. (Has a frequency characteristic 46 that passes only the frequency range Hr of the heartbeat), 34 is a heartbeat measuring unit.

When trying to measure the heartbeat with this cardiopulmonary function measuring device, as shown in FIG. 8, the output of the Doppler sensor 1 is AD-converted, and the signal after the AD conversion is obtained only in the heartbeat frequency range Hr as shown in FIG. The heart rate is measured by passing it through a BPF 33 having a frequency characteristic 46 to be passed, and then performing frequency conversion (Fourier conversion) by the heart rate measuring unit 34 or counting pulses.
When measuring respiration, the output of the AD converter 3 is passed through an LPF 31 having a frequency characteristic 45 that passes only the respiration frequency range Br as shown in FIG. 5, and then the frequency is measured by the respiration measurement unit 32. Respiratory rate is measured by transforming (Fourier transform) or counting pulses.

Conventionally, a Doppler sensor that outputs two signals, I and Q, has also been used. In the case of this Doppler sensor, one of the signals I and Q is selected and processed in the same manner as described above. The measurement is performed by processing both the I and Q signals in the same manner as described above and selecting one of the I and Q results.

Japanese Patent No. 5776817 Japanese Patent No. 5432254 Japanese Patent No. 5333427

However, in the conventional cardiopulmonary function measuring device using the Doppler sensor, the amplitude level of the output signal of the Doppler sensor due to breathing is smaller than the amplitude of the output signal of the Doppler sensor due to minute body movements, and the output signal of the Doppler sensor due to heartbeat Since the amplitude level is even smaller than the amplitude level of the output signal of the Doppler sensor due to breathing, it is difficult to stably measure the heartbeat and breathing.

In addition, relatively low-order harmonics such as the second and third orders of heart rate and respiration often stay within the frequency ranges of heart rate and respiration, which are measured as the fundamental waves of heart rate and respiration rate. It may end up.
For example, as shown in Figure 7, the harmonic a1 signal (fundamental) a ₀ respiration in the frequency range Br breath appears in the frequency range Hr heartbeat, heart beat signal (fundamental) b ₀ and It will be mixed and the heartbeat signal cannot be captured accurately.
In addition, since the amplitude level of the output of the Doppler sensor due to respiration is larger than that of the heartbeat (a ₀ > b ₀ ), even if the harmonics of respiration are attenuated from the fundamental wave, the frequency is in the frequency range of the heartbeat. When it overlapped with, there was a problem that it was difficult to distinguish it from the heartbeat.

Further, when using a Doppler sensor that outputs two signals of I and Q, as described above, one of the signals of I and Q is selected and processed in the same manner as in the case of the one-output Doppler sensor. After processing both the I and Q signals in the same way as in the case of the one-output Doppler sensor, one of the results was selected, but in the former case, the two signals to be processed are I and Q. In the latter case, a method of selecting from the above, and a method of determining the final value from the two results after the processing are required, which causes a problem that the processing becomes complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to use a Doppler sensor that stably and surely measures respiration and heartbeat and outputs two signals, I and Q. It is an object of the present invention to provide a cardiopulmonary function measuring device capable of simplifying the measurement of respiration and heartbeat by processing I and Q signals together in addition to stable and reliable measurement.

In order to achieve the above object, the invention according to claim 1 is a cardiopulmonary function measuring device for measuring cardiopulmonary function by a Doppler sensor, in which an output signal of the Doppler sensor is input to obtain a frequency band higher than the frequency range of the heartbeat. A first filter composed of a bandpass filter that is passed through and extracts the harmonics of the heartbeat, a first calculation unit for heartbeat that calculates the absolute value or the square value of the output signal of the first filter, and the first calculation unit for heartbeat. The output signal of the calculation unit is frequency-analyzed and pulse-counted from the frequency of the peak value or the heart rate is measured from the count value .
The invention of claim 2 is a cardiopulmonary function measuring device that measures cardiopulmonary function by a Doppler sensor that outputs two I and Q signals having different phase differences, and inputs the I and Q signals output from the Doppler sensor to perform heartbeat. The first filter consisting of a band path filter that passes through a frequency band higher than the frequency range of the above and extracts the harmonics of the heartbeat, and the squares of the I and Q signals output from this first filter are added. The second calculation unit for heartbeat that calculates the value of the square root and the output signal of this second calculation unit for heartbeat are frequency-analyzed and pulse-counted from the frequency of the peak value or the heart rate is measured from the count value. It is characterized in that a section and a section are provided.
According to the third aspect of the present invention, the output signal of the first calculation unit for heartbeat or the second calculation unit for heartbeat is input to pass the heartbeat frequency range lower than the passband on the lower frequency side of the first filter. A second filter is provided, and the output signal of the second filter is input to the heart rate measuring unit.

The invention of claim 4 is a cardiopulmonary function measuring device for measuring cardiopulmonary function by a Doppler sensor, in which an output signal of the Doppler sensor is input, a frequency higher than the respiration frequency is set as a passing band, and a respiration harmonic is extracted. The frequency of the third filter, the first calculation unit for breathing that calculates the absolute value or the square value of the output signal of the third filter, and the output signal of the first calculation unit for breathing are analyzed and the frequency of the peak value. It is characterized by providing a respiration measurement unit that counts a frequency or a pulse and measures the respiration rate from the count value .
The invention of claim 5 is a cardiopulmonary function measuring device that measures cardiopulmonary function by a Doppler sensor that outputs two I and Q signals having different phase differences, and inputs the I and Q signals output from the Doppler sensor to breathe. The pass band is set to a frequency higher than the frequency of, and the square root value is obtained by adding the squared values of the I and Q signals output from the third filter and the I and Q signals output from this third filter. A second calculation unit for respiration to calculate and a respiration measurement unit for frequency analysis of the output signal of the second calculation unit for respiration and pulse counting from the frequency of the peak value or pulse counting and measuring the respiration rate from the count value are provided. It is characterized by that.
In the invention of claim 6, the output signal of the first calculation unit for breathing or the second calculation unit for breathing is input, and the pass band on the high frequency side is lower than the pass band on the high frequency side of the third filter. A fourth filter is provided to pass the respiration frequency range, and the output signal of the fourth filter is input to the respiration measurement unit.
According to the invention of claim 7, the frequency characteristic on the low frequency side of the first filter for measuring the heart rate is set low when the respiratory rate is measured low and high when the respiratory rate is measured high. It is characterized by.

According to the above structure, the first harmonic of the heart rate is obtained by the filter, the harmonics are absolute values or square values calculated by the first calculation unit for heartbeat becomes Rukoto, first calculating the heartbeat The heart rate is measured by passing the output of the unit through, for example, a second filter and then performing frequency analysis such as FFT (Fast Fourier Transform), or simply counting the pulses. Even when using a Doppler sensor IQ output based on the harmonic obtained in the same manner, by adding I, the square value of the Q signal at a second arithmetic unit for heart rate, by calculating the square root value, heart rate number of Ru is measured.

Further, a respiration harmonic is obtained by the third filter , and the absolute value and the square value of this harmonic are calculated by the respiration first calculation unit, and the output of the respiration first calculation unit is, for example, the fourth. After passing through a filter, the respiratory rate is measured by frequency analysis such as FFT or pulse counting. When using the IQ output Doppler sensor, the square root value of the I and Q signals is added by the second calculation unit for respiration based on the harmonics obtained in the same manner, and the respiration is performed. number of Ru is measured.

Furthermore, in heart rate measurement, when the respiratory rate is detected in a place where the respiratory frequency range is low, the characteristics on the low frequency side of the first filter that extracts the harmonics of the heartbeat are set to a low position. When the respiratory rate is detected in a high frequency range of the breath, the harmonics of the breath are set in the frequency range of the first filter by variably setting the characteristics of the low frequency side of the first filter to a high position. It is possible to avoid appearing in.

According to the configuration of the present invention, when the low-order harmonics of heartbeat and respiration are in the respective frequency ranges in the output signal of the Doppler sensor having a weak amplitude level due to heartbeat and respiration, the harmonics of respiration are the heartbeat. Even when it overlaps with the frequency range, it is possible to stably and surely measure the heartbeat or respiration.
Further, when using a Doppler sensor that outputs two signals of I and Q, in addition to the above advantages, it is not necessary to select the I and Q signals or the measurement result of the I and Q signals, and the processing is performed. Has the effect of being simplified.
Further, the present invention can be used as a device for measuring heart rate and respiratory rate without contact.

It is a circuit block diagram which shows the structure of the cardiopulmonary function measuring apparatus of 1st Example which concerns on this invention. It is a circuit block diagram which shows the structure of the cardiopulmonary function measuring apparatus of 2nd Example. It is a circuit block diagram which shows the structure of the cardiopulmonary function measuring apparatus of 3rd Example. It is a figure which shows the relationship between the frequency characteristic of the filter used in an Example, and the frequency range of respiration and heartbeat. It is a figure which shows the relationship between the frequency characteristic of an example and a filter used conventionally, and the frequency range of respiration and heartbeat. It is a figure which shows the relationship between the frequency characteristic of the bandpass filter used in an Example and a prior art, and the frequency range of a heartbeat. It is a figure which shows the relationship between the fundamental wave and harmonics of a respiration signal and a heartbeat signal, and the frequency range of respiration and a heartbeat. It is a circuit block diagram which shows the structure of the conventional cardiopulmonary function measuring apparatus.

FIG. 1 shows the configuration of the cardiopulmonary function measuring device (when measuring the heartbeat) of the first embodiment, and FIGS. 4 to 6 show the characteristics of the filter used in each embodiment. In the first embodiment of FIG. 1, reference numeral 1 is a Doppler sensor, 2 is an anti-aliasing filter LPF (low-pass filter), 3 is an AD (analog / digital) converter, and 4 is a frequency range higher than the heartbeat frequency range. This is a first filter composed of a BPF (bandpass filter) having a pass band. The first filter 4 has the frequency characteristic (solid line) 43 of FIG. 4, and extracts the harmonics of the heartbeat by passing frequencies in a range higher than the frequency range Hr of the heartbeat.

5 is from the first calculation unit for heartbeat that calculates the absolute value or the square value of the output signal of the first filter 4 , and 6 is from LPF / BPF (low-pass filter or bandpass filter) whose pass band is the frequency range of the heartbeat. The second filter 6 comprises an LPF having the frequency characteristic 44 of FIG. 5 or a BPF having the frequency characteristic 42 of FIG. 4, and passes a heartbeat signal. Reference numeral 7 denotes a heart rate measuring unit, and the heart rate measuring unit 7 counts the heart rate by performing frequency conversion such as fast Fourier transform (FFT) or simply counting pulses (waveforms).

The first embodiment has the above configuration, and the signal output from the Doppler sensor 1 is AD-converted by the AD (analog-digital) converter 3 after passing through the LPF (anti-aliasing filter) 2, and this AD conversion is performed. As shown in FIG. 4, the signal is input to the first filter 4 (BPF of characteristic 43) having a pass band higher than the frequency range Hr of the heartbeat, and the harmonics of the heartbeat are extracted. In the next first calculation unit 5 for heartbeat, the absolute value or the square value of the signal passed through the first filter 4 is calculated, and the output of the second filter (characteristic 44) having the frequency range Hr of the heartbeat as the pass band. Is input to the LPF of the above or the BPF) 6 of the characteristic 42 .

Next, the signal that has passed through the second filter 6 is input to the heart rate measuring unit 7, and the heart rate measuring unit 7 performs frequency analysis or counts the pulses. In the case of the above frequency analysis, the heart rate is obtained from the frequency of the peak value of the power (amplitude) calculated from the result. Here, if it is considered that the peak appears even at a frequency higher than the heartbeat, the second filter 6 can be omitted. On the other hand, when the heart rate measuring unit 7 counts the pulses, the heart rate is obtained from the counted value.

FIG. 2 shows the configuration of the cardiopulmonary function measuring device of the second embodiment. In this second embodiment, not only the heartbeat but also the respiration is measured, and the measurement result of the respiration is used for measuring the heartbeat. This is reflected in the frequency characteristics of the filter 4 of 1.
In FIG. 2, the Doppler sensor 1 to the heart rate measuring unit 7 are the same as those in FIG. 1, and circuit units of reference numerals 9 to 12 are provided as a configuration for respiration. Reference numeral 9 denotes a third filter, and the third filter 9 is an LPF having a pass band up to a frequency range higher than the respiration frequency range Br as shown in the characteristic 41 of FIG. 4, or a characteristic 42 such as the characteristic 42. It is a BPF having a pass band up to a frequency in a range higher than the frequency range Br of respiration, and serves to extract harmonics of respiration. Next 10 in the first arithmetic unit for breathing, compute the absolute value or the square value of the output of the third filter 9. Reference numeral 11 denotes a fourth filter, which is an LPF that passes through the respiration frequency range Br, as in the characteristic 45 of FIG. Reference numeral 12 denotes a respiratory measurement unit, which measures the respiratory rate by performing frequency conversion such as fast Fourier transform (FFT) or simply counting pulses (waveforms).

Further, in the first filter 4 for heart rate measurement of the second embodiment, based on the respiratory rate obtained by the respiratory measurement unit 12, when the respiratory rate is low, as shown in the characteristic 47 of FIG. The characteristic on the low frequency side of the pass band is set to be lower than the characteristic 43, and when the respiratory rate is high, the characteristic on the low frequency side of the pass band is higher than the characteristic 43 as shown in the characteristic 48 of FIG. To set.

The second embodiment has the above configuration, and first, the measurement of respiration will be described.
The signal from the AD converter 3 of FIG. 2 is input to a third filter (LPF / BPF) 9 having a frequency higher than the respiration frequency range in the pass band, and the respiration harmonics are extracted. In the next first calculation unit 10 for respiration, an absolute value or a square value is calculated, and the output of the first calculation unit 10 for respiration is a fourth filter (LPF) 11 having a respiration frequency range Br as a pass band. Is entered in. In the next respiratory measurement unit 12, the respiratory rate is measured by frequency-analyzing the signal passing through the fourth filter 11 or counting the pulses. In the case of frequency analysis, the respiratory rate is obtained from the frequency of the peak value of power calculated from the result. At this time, if it is considered that the peak appears even at a frequency higher than that of respiration, the fourth filter 11 can be omitted. When counting pulses, the respiratory rate can be obtained from the count value.

On the other hand, the measurement of the heart rate is basically performed in the same manner as in the case of FIG. 1, but in the first filter 4, as described above, the characteristic on the low frequency side is the characteristic 47 in FIG. 4 when the respiratory rate is low. When it is low and high, it is set high as shown in the characteristic 48 of FIG. According to this, when the setting is low (characteristic 47), the harmonics of the heartbeat can be satisfactorily extracted in a wide range, and when the setting is high (characteristic 47), the harmonics of respiration are the first. By suppressing the entry into the filter 4, there is an advantage that the harmonics of the heartbeat can be reliably extracted.

FIG. 3 shows the configuration of the cardiopulmonary function measuring device of the third embodiment, and this third embodiment uses a Doppler sensor that outputs two signals of I and Q.
As shown in FIG. 3, in this example, LPF2a, 2b and AD converters 3a, 3b composed of anti-aliasing filters are provided corresponding to the two signals I and Q, and the measurement of respiration is described in the above-mentioned first. Similar to the second embodiment, the third filters 9a and 9b made of LPF or BPF are arranged, and the second calculation unit for breathing made of the square calculation circuit 13a and 13b, the addition circuit 14a and the square root calculation circuit 15a is provided. Be done.

Regarding the measurement of heartbeat, the first filters 4a and 4b composed of BPF are arranged corresponding to the two signals I and Q, and the square calculation circuits 13c and 13d, the addition circuit 14b and the square root calculation circuit are arranged. A second calculation unit for heartbeat including 15b is provided.

According to this third embodiment, the two signals I and Q output from the Doppler sensor 1 pass through the LPF2a and 2b, respectively, and after being AD-converted, they are divided into two systems, respiratory measurement and heart rate measurement. The I and Q signals for the breath measurement are input to the third filters (LPF or BPF) 9a and 9b having a frequency higher than the breath frequency range Br in the pass band, and the breath harmonics are extracted.
Then, the square values of the I and Q signals output from the third filters 9a and 9b are calculated by the square calculation circuits 13a and 13b of the second calculation unit for breathing, and the square values are calculated by the addition circuit 14a. After the addition, the square root is calculated by the square root calculation circuit 15a. After that, as in the case of FIG. 2, it is input to the respiration measurement unit 12 through the fourth filter (LPF) 11, and the respiration rate is measured by performing frequency analysis or pulse counting here.

On the other hand, the I and Q signals of the heartbeat measurement output from the AD converters 3a and 3b do not include the frequency range of the heartbeat and have a higher frequency in the pass band, and have the same characteristics as those of the first embodiment. It is input to the filters (BPF) 4a and 4b of No. 1 and the harmonics are taken out.
Then, the squared values of the I and Q signals output from the first filters 4a and 4b are calculated by the squared calculation circuits 13c and 13d of the second calculation unit for heartbeat, and the squared values are transferred to the addition circuit 14b. After the addition, the square root is calculated by the square root calculation circuit 15b. After that, as in the case of FIGS. 1 and 2, the heart rate is input to the heart rate measuring unit 7 through the second filter (LPF or BPF) 6, and the heart rate is measured by performing frequency analysis or pulse counting here. To.

Further, the measurement result of respiration is fed back to the first filters (BPF) 4a and 4b of the heart rate measurement, and as described above, the frequency characteristics on the low frequency side of the BPF (4a, 4b) according to the magnitude of the respiratory rate ( By shifting 47 and 48), the influence of respiratory harmonics can be avoided, and the heartbeat harmonics can be stably extracted. If the output of the second calculation unit for respiration is considered to have a peak even at a frequency higher than that of respiration, omit the fourth filter 11 and use the second calculation unit for heartbeat. It is also possible to omit the second filter 6 when considering that the peak appears at a frequency higher than the heartbeat in the output.

1 ... Doppler sensor, 2 ... LPF (anti-aliasing filter),
3 ... AD converter, 4, 4a, 4b ... First filter (BPF),
5 ... 1st calculation unit for heartbeat, 6 ... 2nd filter (LPF or BPF),
7,34 ... Heart rate measuring unit, 9,9a, 9b ... Third filter (LPF or BPF),
10 ... 1st calculation unit for breathing, 11 ... 4th filter (LPF),
12, 32 ... Respiration measurement unit, 13a to 13d ... Square calculation circuit,
14a, 14b ... Addition circuit, 15a, 15b ... Square root calculation circuit,
13a, 13b, 14a, 15a ... Second calculation unit for respiration,
13c, 13d, 14b, 15b ... Second calculation unit for heartbeat.

Claims (7)

In a cardiopulmonary function measuring device that measures cardiopulmonary function with a Doppler sensor
A first filter consisting of a bandpass filter that inputs the output signal of the Doppler sensor, passes through a frequency band higher than the frequency range of the heartbeat, and extracts harmonics of the heartbeat, and
A first calculation unit for heartbeat that calculates the absolute value or square value of the output signal of this first filter, and
A cardiopulmonary function measuring device comprising: a heart rate measuring unit that analyzes the output signal of the first calculation unit for heart rate and measures the heart rate from the frequency of the peak value or the pulse count and the count value . In a cardiopulmonary function measuring device that measures cardiopulmonary function by a Doppler sensor that outputs two I and Q signals with different phase differences.
A first filter consisting of a bandpass filter that inputs the I and Q signals output from the Doppler sensor, passes through a frequency band higher than the heartbeat frequency range, and extracts the heartbeat harmonics.
The second calculation unit for heartbeat, which adds the square values of the I and Q signals output from the first filter and calculates the value of the square root,
A cardiopulmonary function measuring device comprising: a heart rate measuring unit that analyzes the output signal of the second calculation unit for heart rate and measures the heart rate from the frequency of the peak value or the pulse count and the count value . A second filter is provided which inputs the output signal of the first calculation unit for heartbeat or the second calculation unit for heartbeat and passes the frequency range of the heartbeat lower than the pass band on the lower frequency side of the first filter. The cardiopulmonary function measuring device according to claim 1 or 2, wherein the output signal of the second filter is input to the heart rate measuring unit. In a cardiopulmonary function measuring device that measures cardiopulmonary function with a Doppler sensor
A third filter that inputs the output signal of the Doppler sensor, sets the passband up to a frequency higher than the respiration frequency, and extracts the respiration harmonics.
The first calculation unit for respiration that calculates the absolute value or square value of the output signal of this third filter, and
A cardiopulmonary function measuring device comprising: a respiration measuring unit that frequency-analyzes the output signal of the first respirating calculation unit, counts pulses from the frequency of the peak value, and measures the respiratory rate from the count value . In a cardiopulmonary function measuring device that measures cardiopulmonary function by a Doppler sensor that outputs two I and Q signals with different phase differences.
The I output from the Doppler sensor, enter the Q signal, and pass band up to a frequency higher than the frequency of breathing, and a third filter to eject the harmonics of breathing,
A second calculation unit for respiration that adds the square values of the I and Q signals output from this third filter and calculates the value of the square root.
A cardiopulmonary function measuring device comprising: a respiration measuring unit that frequency-analyzes the output signal of the second respiration unit, counts pulses from the frequency of the peak value, and measures the respiratory rate from the count value . The output signal of the first calculation unit for breathing or the second calculation unit for breathing is input, the pass band on the high frequency side is made lower than the pass band on the high frequency side of the third filter, and the frequency range of breathing is set. The cardiopulmonary function measuring apparatus according to claim 4 or 5, wherein a fourth filter to be passed is provided, and an output signal of the fourth filter is input to the respiratory measuring unit. Claim 1 is characterized in that the frequency characteristic on the low frequency side of the first filter for measuring the heart rate is set low when the respiratory rate is measured low and high when the respiratory rate is measured high. The cardiopulmonary function measuring device according to any one of 3 to 3.

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