JP5070103B2 - Shunt stenosis detector - Google Patents

Description

  The present invention relates to a shunt stenosis detection device used in hemodialysis.

  Hemodialysis is one of the common dialysis treatments. Blood is removed from the artery of a patient who has a decreased renal function and introduced into the dialysis machine. The blood is purified by the dialysis machine. Later blood is returned to the patient's vein. In order to ensure a stable blood flow of a certain amount or more in hemodialysis, it is necessary to form a blood vessel joint that bypasses the artery and vein, a so-called shunt, but this shunt may become narrowed due to thrombus formation, etc. There is.

  As an apparatus for detecting shunt stenosis, for example, there is one described in Patent Document 1. In this device, a shunt sound is collected by a microphone mounted in the vicinity of the shunt formation site, and the detection value of the shunt sound is compared with a preset lower limit value, and the detection value falls below the lower limit value and falls outside the allowable range. In case, alert.

It should be noted that the shunt may be “stenotic” or “obstructed”. Since the state of progress of “stenosis” is “occlusion”, “occlusion” and “stenosis” may be clearly distinguished, but in this application “occlusion” is included as part of “stenosis”. It will be defined and explained.
Japanese Patent Laid-Open No. 5-115547

  However, in the above-mentioned conventional apparatus, since it is possible to determine only whether or not the shunt sound is normal, the shunt sound is completely normal, not completely but within an allowable range, or only outside an allowable range. In addition, the degree of shunt stenosis cannot be detected, for example, whether it is particularly urgent.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a shunt stenosis detection device that can accurately detect the degree of shunt stenosis.

  The shunt stenosis detection device of the present invention was measured while changing the degree of stenosis from the shunt sound measuring means for measuring the shunt sound from the shunt formation site of the hemodialysis patient and the pseudo stenosis formation site of the blood vessel in the hemodialysis patient. An acquisition means for acquiring a blood flow sound; and a detection means for detecting an approximate sound that approximates the shunt sound in the blood flow sound by comparing the measured shunt sound with the acquired blood flow sound; And determining means for determining the degree of stenosis of the pseudo stenosis formation site corresponding to the detected approximate sound as the degree of stenosis of the shunt.

  According to the present invention, the degree of shunt stenosis can be accurately detected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a shunt stenosis detection device according to an embodiment of the present invention.

  1 includes a blood pressure measurement unit 11, a turbulent sound measurement unit 12, a shunt sound measurement unit 13, a memory 14, a calculation unit 15, and a display unit 16. A cuff 17 is connected to the blood pressure measurement unit 11, a microphone 18 is connected to the turbulent sound measurement unit 12, and a microphone 19 is connected to the shunt sound measurement unit 13.

  The microphone 19 is attached to the arm of the dialysis patient on which the shunt is formed, collects a shunt sound at the shunt formation site, and generates an electric signal representing the shunt sound (hereinafter referred to as “shunt sound signal”). This is supplied to the shunt sound measurement unit 13.

  The shunt sound measurement unit 13 includes an amplifier, a filter, and an A / D (analog / digital) converter (none of which are shown). Signal processing such as removal and A / D conversion is performed, and the digital data after the signal processing is supplied to the arithmetic unit 15 as shunt sound waveform data.

  The cuff 17 has an inflatable and inflatable air bag (not shown) inside. The cuff 17 is wound around the arm of the dialysis patient on which the shunt is not formed, and the air bag is inflated. Compress the attachment site. As a result, a pseudo-stenosis of the blood vessel is formed at the cuff 17 attachment site (hereinafter referred to as “pseudo-stenosis formation site”).

  The blood pressure measurement unit 11 as the cuff pressure varying means is configured to perform blood pressure measurement using the cuff 17 by the same oscillometric method as in the past. That is, the blood pressure measurement unit 11 includes a pump, an exhaust valve, and a pressure sensor (all not shown). The blood pressure measurement unit 11 inflates the air bag of the cuff 17 by supplying air with a pump into the air bag of the cuff 17 wound around the dialysis patient. When the air pressure of the air bag (hereinafter referred to as “cuff pressure”) reaches a certain value, the blood pressure measurement unit 11 stops air supply and starts exhaust from the air bag by opening the exhaust valve. During exhaust, the blood pressure measurement unit 11 monitors the increase or decrease of the pulse wave amplitude, measures the cuff pressure at a predetermined timing while the pulse wave amplitude is increasing as the maximum blood pressure, and calculates the cuff pressure at the predetermined timing while the pulse wave amplitude is decreasing. Measured as diastolic blood pressure.

  The microphone 18 is attached to a pseudo stenosis formation site, and while blood pressure measurement using the cuff 17 is performed by the blood pressure measurement unit 11, blood flow sound (hereinafter referred to as “turbulent flow sound”) in the pseudo stenosis part or the vicinity thereof. And an electric signal representing the turbulent sound (hereinafter referred to as “turbulent sound signal”) is supplied to the turbulent sound measuring unit 12.

  The turbulent sound measuring unit 12 as the blood flow sound measuring means includes an amplifier, a filter, and an A / D converter (all not shown). For the turbulent sound signal supplied from the microphone 18, Turbulent sound waveform data is generated by performing signal processing such as amplification, high-frequency noise removal, and A / D conversion. The turbulent sound measurement unit 12 stores at least a portion corresponding to a predetermined period in the generated turbulent sound waveform data in the memory 14 (for example, a hard disk). Here, the predetermined period includes a period from the timing at which the cuff pressure monitored by the blood pressure measurement unit 11 exhibits the maximum blood pressure to the timing at which the minimum blood pressure is exhibited.

  Here, the turbulent sound in the above period will be described with reference to FIG. FIG. 2 is a diagram showing waveforms of the turbulent sound 100, the cuff pressure 103, and the electrocardiogram 104 measured during blood pressure measurement.

  In the blood pressure measurement, during the period from when the cuff pressure 103 starts to be reduced by exhaust until the cuff pressure 103 exhibits the maximum blood pressure, the blood vessels are completely narrowed by the compression. Therefore, at the timing when the cuff pressure 103 exhibits the maximum blood pressure, the degree of pseudo stenosis is the maximum. On the other hand, during the period after the timing when the cuff pressure 103 exhibits the minimum blood pressure, the blood vessel is completely released from the compression. Therefore, at the timing when the cuff pressure 103 exhibits the minimum blood pressure, the degree of pseudo stenosis is minimum. That is, the turbulent sound waveform data stored in the memory 14 is turbulent sound waveform data representing at least the turbulent sound 101 to the turbulent sound 102 in FIG. The turbulent sound 101 and the turbulent sound 102 have different waveforms as shown in enlarged views in FIGS. This is because the frequency component of turbulent sound and its intensity change according to the degree of pseudo-stenosis.

  The calculation unit 15 as an acquisition unit and a determination unit includes a calculation processing device and a storage device (both not shown), and executes a shunt stenosis detection program stored in the storage device in advance by the calculation processing device. Thus, the function of determining the degree of shunt stenosis is realized, and the determined degree of shunt stenosis is displayed on the display unit 16 (for example, a liquid crystal display device).

  Note that the method for notifying the degree of shunt stenosis is not limited to screen display, and may be based on audio output.

  The determination function of the shunt stenosis degree is realized by the operation shown in FIG. FIG. 5 is a flowchart showing the shunt stenosis degree determination operation executed in the calculation unit 15.

  First, in step S <b> 1, shunt sound waveform data is received from the shunt sound measurement unit 13. In step S <b> 2, turbulent sound waveform data generated during blood pressure measurement before shunt sound measurement and stored in the memory 14 is read from the memory 14. In step S3, the data is compared by calculating the correlation between the received shunt sound waveform data and the read turbulent sound waveform data. In step S4, in the turbulent sound waveform data compared with the shunt sound waveform data, a portion exhibiting the highest correlation with the shunt sound waveform data is determined. This portion is a portion representing a sound that approximates the measured shunt sound (hereinafter referred to as “approximate sound”), that is, approximate sound waveform data. In this way, the approximate sound is detected in step S4. In step S5, the pseudo stenosis degree corresponding to the turbulent sound waveform data of the portion determined as the approximate sound waveform data is determined as the shunt stenosis degree.

  Therefore, when the turbulent sound waveform data at the timing when the cuff pressure exhibits the highest blood pressure is determined as the approximate sound waveform data, the degree of pseudo stenosis is the maximum, so the degree of shunt stenosis is the maximum while the cuff pressure is the lowest. When the turbulent sound waveform data at the timing of presenting blood pressure is determined as approximate sound waveform data, the degree of pseudo-stenosis is minimum, so the degree of shunt stenosis is also minimum. The shunt stenosis degree may be obtained by ranking the magnitude of the stenosis degree (for example, A rank, B rank, etc.) or numerically (for example, 0%, 30%, etc.).

  In this way, the function of determining the degree of shunt stenosis is realized.

  As described above, according to the present embodiment, a pseudo stenosis is formed at a site different from the shunt formation site of a dialysis patient, and the turbulent sound measured while changing the degree of stenosis from the pseudo stenosis formation site is collected. In addition, by comparing the measured shunt sound with the turbulent sound, the sound that approximates the shunt sound is detected in the turbulent sound, and the degree of pseudo-stenosis corresponding to the approximated sound is determined as the degree of shunt stenosis. The degree of shunt stenosis of the patient can be accurately determined.

  Further, in the present embodiment, blood pressure pseudo-stenosis is caused in a dialysis patient by compressing with a cuff, and turbulent sound is measured while the degree of stenosis is variable. Since it is adapted to a general blood pressure measurement method, when measuring the blood pressure of a dialysis patient, the degree of shunt stenosis can be determined simultaneously with the blood pressure measurement. Furthermore, since blood pressure is generally measured in advance when hemodialysis is performed, the degree of shunt stenosis can always be determined before hemodialysis.

  The embodiment of the present invention has been described above. The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. That is, the description of the configuration of the above apparatus is an example, and it is obvious that various modifications and additions to these examples are possible within the scope of the present invention. For example, in the present embodiment, the blood pressure measurement unit is provided in the shunt stenosis detection device, but the blood pressure measurement unit may be separate from the shunt stenosis detection device. In the present embodiment, the shunt stenosis detection apparatus adopts a configuration that measures blood pressure by the oscillometric method, but may adopt a configuration that measures blood pressure by the Korotkoff sound method.

The block diagram which shows the structure of the shunt stenosis detection apparatus which concerns on one embodiment of this invention The figure which shows each waveform of the turbulent flow sound, cuff pressure, and electrocardiogram which concerns on one embodiment of this invention Enlarged view of the waveform of turbulent sound during systolic blood pressure in FIG. Enlarged view of the waveform of turbulent sound at the time of diastolic pressure in FIG. The flowchart for demonstrating the shunt stenosis degree determination operation | movement which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shunt stenosis detection apparatus 11 Blood pressure measurement part 12 Turbulent sound measurement part 13 Shunt sound measurement part 15 Calculation part

Claims (2)

A shunt sound measuring means for measuring a shunt sound from a shunt forming site of a hemodialysis patient;
An acquisition means for acquiring a blood flow sound measured while changing the degree of stenosis from a pseudo-stenosis formation site of a blood vessel in the hemodialysis patient;
By comparing the measured shunt sound with the acquired blood flow sound, an approximate sound that approximates the shunt sound is detected in the blood flow sound, and the stenosis of the pseudo-stenosis formation site corresponding to the approximate sound is detected. Determining means for determining the degree as the degree of stenosis of the shunt;
A shunt stenosis detection device comprising: Cuff pressure varying means for varying the degree of stenosis of the pseudo stenosis formation site by varying the cuff pressure of the cuff wound around the pseudo stenosis formation site;
A blood flow sound measuring means for measuring a blood flow sound from the pseudo stenosis formation site during the variable degree of stenosis of the pseudo stenosis formation site;
The shunt stenosis detection device according to claim 1, further comprising:

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