JP5302257B2 - Tissue blood flow measuring device and tissue blood flow measuring program - Google Patents

Description

  The present invention relates to a tissue blood flow measuring device and a tissue blood flow measuring program capable of non-invasively measuring tissue blood flow in a living body.

Conventionally, a clearance method is known as a technique for measuring tissue blood flow in a living body. As an indicator used in this method, an inert gas labeled with an isotope, laughing gas (N ₂ O), hydrogen gas, or the like was used (see Non-Patent Document 1). Here, the indicator produced or consumed in the living body cannot be used.

  On the other hand, the inventor of the present application has succeeded in measuring tissue blood flow by the clearance method using oxygen that has been considered to be unusable and giving two different concentrations of oxygen to the living body (see Patent Document 1).

  However, the above-described new clearance method has a problem in that it is essential to supply oxygen to a living body at a required concentration from an oxygen cylinder or the like, which increases the size of the apparatus and increases the cost. In addition, the measurement is performed until the oxygen saturation is constant, and there is a problem that it takes time.

Japanese Patent No. 3530868

Kenichi Yamakoshi and Tatsuo Togawa “Biological Sensors and Measuring Devices” September 25, 2000, Corona Publishing, pages 96-98

  The present invention has been made as a solution to the above-mentioned problems related to tissue blood flow measurement, and its purpose is not to require special equipment such as oxygen cylinders or masks. To provide a tissue blood flow measuring device and a tissue blood flow measuring program capable of measuring a flow rate and reducing the measurement time.

The tissue blood flow measurement device according to the present invention includes a detecting means for non-invasively detecting oxygen saturation information in a subject's tissue over time when holding a breath for a predetermined time; A plotting means for plotting in time series on the coordinates; a means for displaying the plotted points on a display; an indicating means for an operator to specify an approximate interval at the displayed plot points; and Creation means for creating a straight line approximation of the plotted points, time information obtaining means for obtaining half-time information which is a time until a half value of an arbitrary point on the straight line is obtained, Calculating means for calculating tissue blood flow using time, wherein the predetermined time is a time during which a straight line approximating a straight line can be created .

The tissue blood flow measurement program according to the present invention obtains the oxygen saturation information from detection means that non-invasively detects oxygen saturation information in the tissue of the subject when holding for a predetermined time. A computer for performing biological information processing, plotting means for plotting the oxygen saturation information in a time series on a semilogarithmic coordinate, means for displaying the plotted points on a display, and an operator showing approximate intervals at the displayed plotted points Means for receiving when instructed, creation means for creating a straight line approximation of the plotted points in the designated approximation interval, half time which is a time until a half value of an arbitrary point on the straight line is obtained time information obtaining means for obtaining information, a tissue blood flow measurement program to function as a calculating means for calculating the tissue blood flow by using the half-time, the predetermined time Characterized in that is the time that can create a straight line linearly approximated.

  According to the present invention, oxygen saturation information in a subject's tissue is detected non-invasively over time when holding for a predetermined time, and the oxygen saturation information is plotted in time series on semi-logarithmic coordinates. Create a straight line approximating the plotted points, find half-time information based on the straight line, and measure tissue blood flow using this half-time information, so special equipment such as oxygen cylinders and masks are required. However, there is an effect that tissue blood flow measurement can be easily performed at low cost. Moreover, the measurement time can be shortened.

The block diagram which shows the structure of embodiment of the tissue blood flow rate measuring apparatus which concerns on this invention. The flowchart which shows operation | movement of embodiment of the tissue blood flow rate measuring apparatus which concerns on this invention. The figure which shows an example which plotted oxygen saturation information by the time series on the semilogarithmic coordinate by embodiment of the tissue blood flow rate measuring apparatus which concerns on this invention. The figure which shows an example of the approximate line obtained by embodiment of the tissue blood flow rate measuring apparatus which concerns on this invention. The figure which shows the structure of the demonstration experiment apparatus for showing that the result by this invention is appropriate. The figure of the graph explaining the tissue blood flow measurement by a RSPGG measuring method. The figure which shows the correlation with the tissue blood flow measurement result by a RSPGG measuring method, and the tissue blood flow measurement result by this invention.

  Embodiments of a tissue blood flow measurement device and a tissue blood flow measurement program according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a configuration diagram of a tissue blood flow measuring device according to the first embodiment. This tissue blood flow measuring device includes a tissue oximeter sensor 11, a tissue oximeter 12, and a computer system 30 that performs biological information processing.

The tissue oximeter sensor 11 has the same configuration as the sensor shown in Patent Document 1, is attached to a desired part of the living body 1, and receives an electrical signal corresponding to the optical signal received by the light receiving unit. To send to. The tissue oximeter 12 samples the signal sent from the tissue oximeter sensor 11 at a sampling rate of 1 sec, for example, detects the venous blood oxygen saturation SvO _2, and is a digital signal oxygen saturation information that can be processed by a computer. To the computer system 30.

  The tissue oximeter sensor 11 and the tissue oximeter 12 constitute detection means that non-invasively detects oxygen saturation information in the tissue of a subject when holding for a predetermined time. Here, the predetermined time is, for example, about 20 seconds to 30 seconds.

  The computer system 30 includes at least a CPU 31, a memory 32, a display unit 33, and an operation unit 34. The memory 32 stores a tissue blood flow measurement program used by the CPU 31, other programs and data, and the CPU 31 is also used as a buffer during data processing. That is, the memory 32 includes a main memory and an external memory.

  The display unit 33 displays processing results and the like, and the operation unit 34 includes a keyboard, a mouse touch panel, and the like, and is used for data input.

  The CPU 31 functions as the plotting means 41, the creating means 42, the time information acquiring means 43, and the calculating means 44 by executing the tissue blood flow measurement program. The plot means 41 plots the oxygen saturation information sent from the tissue oximeter 12 in time series on the semi-logarithmic coordinates. The creating means 42 creates an approximate straight line of oxygen saturation based on the plotted points.

  The time information acquisition means 43 acquires half-time information that is a time until a half value of an arbitrary point on the approximate line is obtained. The calculation means 44 calculates the tissue blood flow volume using the half time acquired by the time information acquisition means 43.

The tissue blood flow calculated by the calculation unit 44 is displayed by the display unit 33. Note that the measurement start timing and measurement end timing including the breath holding period may be input by the operator from the operation unit 34, or a respiratory detection sensor such as a CO ₂ sensor is attached to the subject, and is based on the signal of this sensor. Information on the start time and the end time may be given to the CPU 31.

  Since the tissue blood flow measuring device configured as described above operates as shown in the flowchart of FIG. 2, the operation will be described based on this flowchart. A tissue oximeter sensor 11 is attached to the living body 1 of the subject, the tissue oximeter 12 and the computer system 30 are turned on, and a tissue blood flow measurement program is started.

The CPU 31 takes in the data of the venous blood oxygen saturation SvO ₂ sent from the tissue oximeter 12 in time series (S11), and plots the data of the venous blood oxygen saturation SvO ₂ in time series on the semilogarithmic coordinates ( S12), the approximate section displayed on the display unit 33 and sent from the operator is received (S13). At this time, for example, as shown in FIG. 3, plotting is performed and display on the display unit 33 is performed. That is, venous blood oxygen saturation SvO _{2 is} sampled every 1 sec, and actually about 20 to 30 points are plotted. Of course, the sampling rate may be increased (for example, 5 times per second), and the average value may be plotted by averaging the obtained oxygen saturation information for one second.

When an approximate interval is given (see FIGS. 3 and 4), an approximate straight line of venous oxygen saturation SvO ₂ composed of plot points based on a plurality of venous oxygen saturations SvO ₂ is created (S14). Specifically, an approximate section in which a plurality of plot points are arranged on a straight line is detected, and an approximate straight line is created from the plot points in the measurement section by the least square method. By this processing, for example, an approximate straight line as shown in FIG. 4 is obtained from the plot points shown in FIG.

Next, the CPU 31 acquires half-time information T _(1/2) , which is a time until a half value of an arbitrary point of the approximate line is obtained, based on the approximate line (S15). For example, in the example of FIG. 4, if the point at which oxygen saturation information is 86 on the approximate straight line is an arbitrary point, the time until it becomes 43 which is a value of 1/2 is half-time information T _(1/2) . is there. The approximate straight line in FIG. 4 is obtained as 6.27 scales for 50 sec. When this is converted into seconds, it is calculated as (6.27 × 50) / 60 min (= 5.225). Assuming that the slope of the approximate line is a, the approximate line is alog (y) = x. Therefore, it can also be obtained by calculation using this equation.

Next, the CPU 31 calculates the tissue blood flow rate F from the half-time information T _(1/2) obtained above using the formula F = 69.3λ / T _(1/2) as shown in Patent Document 1. And it outputs to the display part 33 (S15). λ is a constant determined by oxygen, tissue and blood as indicators.

In the above-described apparatus, the tissue oximeter sensor 11 is used, but instead of this, a sensor of a pulse oximeter is used, and the tissue oximeter 12 is configured to correspond to the sensor of this pulse oximeter. Information of ₂ may be used.

It will be described that such measurement of tissue blood flow is appropriate. As shown in FIG. 5, a tissue oximeter sensor 52 is attached to the first node of the second upper left limb of the subject, and preparations are made to record the venous blood oxygen saturation SvO ₂ . Further, a sensor 53 of a rubber range plethysmograph (hereinafter referred to as “RSGPG”), which is one of the conventional methods for obtaining the tissue blood flow of the finger, is mounted around the finger from the second node near the sensor 52. An arm band (manchette or cuff) 54 is wrapped around the upper arm of the left upper limb, and an air balloon 55 and a pressure gauge 56 are attached to enable tissue blood flow measurement by the RSGPG method.

  When 15 minutes have passed since entering the room, measurement with a tissue oximeter is started, and when the recording is stabilized, the subject holds the breath for 30 seconds. After the end of breath-holding, the recording is finished for about 30 seconds.

The result of one subject in this case is as shown in FIG. 4, and the half-time information T _(1/2) is obtained as (6.27 × 50) / 60 [min], where λ is 1. The tissue blood flow was determined to be 13.3 [ml / min · 100 g].

  After the above measurement is completed, when the RSPGG is activated and the recording is stabilized, venous occlusion is performed for about 30 seconds using the air balloon 55 and the pressure gauge 56, and the measurement is completed. Tissue blood flow is determined from the initial maximum slope of the RSPGG waveform. FIG. 6 is an RSGPG curve by RSPGG, and a gradient of 24 mm can be obtained in 20 seconds, and a gradient of 24 × 3 is obtained in 60 seconds. In FIG. 6, this is divided by 5 mm of 1% cal (1% calibration wave) to obtain (24 × 3) / 5 [ml / min · 100 ml]. Using this value, tissue blood flow was obtained by performing a calculation (24 × 3) / (5 × 1.05) by dividing the tissue density by 1.05 [g / ml]. Thereby, the tissue blood flow rate by the subject who obtained the result shown in FIG. 4 was obtained by RSGPG as 13.7 [ml / min · 100 g]. A value extremely close to the tissue blood flow 13.3 [ml / min · 100 g] obtained by the method according to the present invention was obtained.

In the same manner as described above, measurement by venous oxygen saturation SvO ₂ and measurement by RSGPG were performed on 17 boys aged 18 to 24 years. Using this result, taking the measured value by RSGPG on the horizontal axis and taking the value by the method of the present invention on the vertical axis, the regression line is obtained as y = 0.9895x as shown in FIG. It was proved that a high correlation (R ² = 0.89) was obtained at <0.001).

DESCRIPTION OF SYMBOLS 11 Tissue oximeter sensor 12 Tissue oximeter 30 Computer system 32 Memory 33 Display part 34 Operation part 41 Plot means 42 Creation means 43 Time information acquisition means 44 Calculation means

Claims (2)

Detection means for non-invasively detecting oxygen saturation information in the tissue of the subject when holding for a predetermined time;
Plotting means for plotting the oxygen saturation information in a time series on a semilogarithmic coordinate;
Means for displaying the plotted points on a display;
Instruction means for the operator to indicate the approximate interval at the displayed plot points;
Creating means for creating a straight line that approximates the plotted points of the indicated approximation interval;
Time information acquisition means for acquiring half-time information which is a time until a half value of an arbitrary point on the straight line is obtained;
A tissue blood flow measurement device comprising: a calculation means for calculating tissue blood flow using this half-time ;
The tissue blood flow measuring device according to claim 1, wherein the predetermined time is a time during which a straight line approximating a straight line can be created. A computer that performs biological information processing by obtaining the oxygen saturation information from a detection means that non-invasively detects oxygen saturation information in the tissue of the subject when holding a breath for a predetermined time,
A plotting means for plotting the oxygen saturation information in a time series on a semilogarithmic coordinate;
Means for displaying the plotted points on a display,
Means to receive when the operator indicates an approximate interval at the displayed plot point;
Creation means for creating a straight line that approximates the plotted points of the indicated approximation interval;
Time information acquisition means for acquiring half-time information which is a time until a half value of an arbitrary point on the straight line is obtained;
A tissue blood flow measurement program characterized by functioning as a calculation means for calculating tissue blood flow using this half-time ,
The tissue blood flow measurement program characterized in that the predetermined time is a time during which a straight line approximating a straight line can be created .

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