JP6367016B2 - Evaluation of renal function based on aortic blood flow waveform analysis - Google Patents

Description

  The present invention relates to an apparatus, a program, and a computer recording medium for evaluating renal function based on aortic blood flow waveform analysis.

  The inventor of the present application originally developed an aortic blood flow waveform analysis in a previous study, and found a technique for noninvasively evaluating the degree of arterial stiffness based on the analysis of a subject's aortic blood flow waveform (Non-Patent Document 1). ).

  On the other hand, it is generally known that renal dysfunction is caused by various factors such as aging and aortic stiffness, but the relationship between renal dysfunction and hemodynamics of aortic flow has not been clarified.

Hashimoto J et al. 2013; Sep; 62 (3): 542-549 Published online before print June 24, 2013, doi: 10.1161 / HYPERTENSIONAHA.113.01318

  Non-invasive and simple evaluation of renal function is desired. The objective of this invention is providing the renal function evaluation apparatus, program, and computer recording medium which satisfy | fill this request.

  The present inventor conducted intensive research on the assumption that renal dysfunction is caused by changes in hemodynamics of aortic flow. Surprisingly, the bidirectional blood flow in the aorta is closely related to renal dysfunction. As a result, the present invention has been completed.

That is, the present invention is as follows.
[1] A renal function evaluation apparatus including a renal function index calculating unit that calculates a renal function index indicating renal function based on an aortic blood flow index calculated based on blood flow data of a subject's aorta.
[2] The renal function evaluation apparatus according to [1], further comprising evaluation means for evaluating the presence or absence or degree of renal dysfunction based on the renal function index.
[3] The renal function evaluation apparatus according to Item 1 or 2, wherein the renal function index is a retrograde blood flow / antegrade blood flow ratio (R / F ratio) or characteristic impedance of the descending aorta.
[4] The renal function evaluation apparatus according to Item 2 or 3, wherein the renal dysfunction is chronic kidney disease.
[5] A program for causing a computer to function as the renal function evaluation device according to any one of Items 1 to 4.
[6] A computer-readable recording medium on which the program according to item 5 is recorded.

  According to the present invention, the blood flow waveform of the aorta is recorded by a simple and safe method only by applying the ultrasonic device used in most medical institutions to the body surface of the subject, and based on this, renal dysfunction is recorded. Can be evaluated or predicted non-invasively and simply.

1 is a schematic diagram showing the configuration of a renal function evaluation system. The flowchart which shows operation | movement of a renal function evaluation apparatus. Example of pulse waveform of descending aortic blood flow velocity averaged by ensemble. The graph which shows the aortic reflux / forward flow ratio in the normal group of chronic kidney disease (CKD), and a chronic kidney disease group. P value was evaluated by t test (P <0.001).

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a renal function evaluation system 10 of the present invention. The renal function evaluation system 10 includes a blood flow measurement device 12 that measures the blood flow of the subject, a blood pressure measurement device 14 that measures the blood pressure of the subject's artery, a pulse pressure sensor 16 that measures the blood pressure waveform of the subject's artery, A renal function evaluation device 20 including a blood flow measurement device 12, a blood pressure measurement device 14, and a computer that stores and processes data received from the pulse pressure sensor 16; The renal function evaluation device 20 is a CPU or processor that performs calculations or determinations based on various data received from the blood flow measurement device 12, the blood pressure measurement device 14, and the pulse pressure sensor 16, and data stored or generated internally. The processing device 22 is provided with a storage device 38 such as a hard disk for storing various data, and a display device 40 for displaying the calculation results in the processing device 22.

  The processing device 22 takes an ensemble average of the blood flow data received from the blood flow measurement device 12 for a predetermined period, and generates an average blood flow velocity waveform from the aorta average blood flow velocity waveform generation means 24 and the blood flow measurement device 12. An aortic blood flow index calculating means 26 for calculating an aortic blood flow index that is an index indicating the state of the blood flow of the aorta from the received blood flow data and / or waveform data received from the aorta average blood flow velocity waveform generating means 24; The arterial average pressure waveform generating means 28 for taking an ensemble average of the blood pressure waveform data received from the pulse pressure sensor 16 for a predetermined period and generating an average arterial waveform, and the blood pressure data received from the blood pressure measurement device 14 and the pulse pressure sensor 16 The blood pressure waveform data and / or the blood pressure waveform data received from the arterial mean pressure waveform generating means 28 is an index indicating the state of the arterial blood pressure. A blood pressure index calculating means 30 for calculating an arterial blood pressure index, a renal function index calculating means 32 for calculating a renal function index indicating renal function based on the aortic blood flow index received from the aortic blood flow index calculating means 26, and a kidney Based on the result calculated by the function index calculating means 32, the evaluation means 34 for evaluating the presence or absence or degree of renal dysfunction is correlated with a known index indicating the presence and / or degree of renal function disorder. And a correlation analysis means 36 for analysis. “Calculating a renal function index indicating renal function based on the aortic blood flow index received from the aortic blood flow index calculating means 26” means at least the aortic blood flow index calculating means 26 in calculating the renal function index. Means that the aortic blood flow index received from the aortic blood flow index is calculated based on only the aortic blood flow index received from the aortic blood flow index calculating means 26. This includes a case based on both the arterial blood pressure index received from the calculation means 30 and a case where another index is used in addition to the two.

  The blood flow measuring device 12 may be any device capable of measuring the blood flow of the aorta, and examples thereof include a known ultrasonic device with a transducer (for example, an ultrasonic probe). By using an ultrasonic device with a transducer, it is possible to noninvasively collect blood flow data of the aorta, particularly waveform data of changes in blood flow velocity over time, from the body surface of the subject. The blood flow measuring device 12 records blood flow velocity or blood flow for a certain time (for example, 5 to 30 seconds). This record is stored in the storage device 38, and the user can select a time zone (for example, 10 seconds) in which the user determines that the data is stable from the stored blood flow data displayed on the time series axis on the display device 40. ) May be selected for later processing.

  The aortic average blood flow velocity waveform generating means 24 first averages the instantaneous blood flow velocity obtained by the blood flow measuring device 12 spatially and quantitatively. Next, the average instantaneous speed is interpolated as time series data at equal intervals (for example, 100 Hz). Furthermore, an averaged velocity pulse wave waveform can be obtained by superimposing blood flow velocity waveforms for a plurality of beats starting from the beginning of contraction (when blood flow changes to the maximum) or the like. Normally, taking into account respiratory fluctuations, etc., ensemble averaging is performed for about 5 to 20 cardiac cycles or about 5 to 20 seconds, and an average waveform for one beat is generated (for example, Hashimoto J et al., Hypertension. 2010; 56: 926-933). In this case, the average pulse blood flow waveform can be automatically measured by the arterial average blood flow velocity waveform generation unit 24 and displayed on the display device 40.

The aortic blood flow index calculating means 26 is an aortic blood flow that is an index or parameter indicating the blood flow state of the aorta based on the blood flow data received from the blood flow measuring device 12 or the aortic average blood flow velocity waveform generating means 24. Calculate the index. Such aortic flow index systolic forward flow peak velocity to (V _Fwd), diastolic backflow peak velocity (V _Rev), end-diastolic velocity (V _ED), average speed time-averaged (V _M), the forward flow peak time (T _Fwd ), regurgitation peak time (T _Rev ), retrograde aortic retrograde blood flow / forward blood flow ratio (R / F ratio; hereinafter simply referred to as “reverse flow / forward flow ratio”), and combinations thereof Is included. These aortic blood flow indexes are known, and are described, for example, in Hashimoto J et al., Hypertension. 2010; 56: 926-933.
R / F ratio indicates the degree of retrograde aortic blood flow,

It is represented by

  The blood pressure measurement device 14 may be any device capable of measuring arterial blood pressure, such as a known cuff oscillometer. Arterial blood pressure measured with a cuff oscillometer includes systolic blood pressure, diastolic blood pressure, mean blood pressure and / or heart rate of arteries such as brachial artery, radial artery and / or lower limb artery. Such a blood pressure measurement method is a well-known technique and can be carried out by those skilled in the art with ordinary skills. A record of blood pressure measured by the blood pressure measurement device 14 is stored in the storage device 38. A user (hereinafter referred to as a user) of the renal function evaluation system 10 who is usually a medical worker such as a doctor or a nurse determines that the user is stable from the stored blood pressure data displayed on the display device 40. The selected data can be selected and / or averaged and used for later processing.

  The pulse pressure sensor 16 is a sensor capable of measuring a blood pressure waveform from an artery such as the radial artery, the carotid artery, the brachial artery, the femoral artery and / or the dorsal artery by the tonometry method. The pulse pressure sensor 16 records a blood pressure waveform for a predetermined time (for example, 5 to 30 seconds), and this record is stored in the storage device 38, and the user displays the stored blood pressure waveform displayed on the time series axis on the display device 40. From the data, the time zone (eg, 10 seconds) that the user has determined that the data is stable may be selected for later computation.

  The arterial average pressure waveform generating means 28 is a program including a transfer function. For example, the pulsatile pressure signal of the radial artery recorded by the pulse pressure sensor 16 is ensemble averaged for a predetermined period (usually 5 to 20 cycles) to obtain an aortic pressure waveform. Convert. In this case, the average pulse pressure waveform for a predetermined period can be automatically measured by the arterial average pressure waveform generating means 28 and displayed on the display device 40.

  Based on the blood pressure data received from the blood pressure measurement device 14, the blood pressure waveform data received from the pulse pressure sensor 16, and / or the blood pressure waveform data received from the arterial mean pressure waveform generation means 28, the blood pressure index calculation means 30 An arterial blood pressure index which is an index or parameter indicating the state is calculated. The “blood pressure data” in the case of “arterial blood pressure index calculated based on blood pressure data” includes blood pressure data received from the blood pressure measurement device 14, blood pressure waveform data received from the pulse pressure sensor 16, and / or Blood pressure waveform data received from the arterial mean pressure waveform generating means 28 is included.

  For example, the blood pressure index calculating unit 30 calculates the absolute value (estimated value) of the aortic blood pressure by calibrating the aortic pressure waveform generated by the arterial average pressure waveform generating unit 28 with the absolute value of the brachial blood pressure. The calculation result can be displayed on the display device 40.

Arterial blood pressure indicators include aortic systolic blood pressure, aortic pulse pressure (difference between systolic and diastolic blood pressure), aortic augmentation pressure, aortic augmentation factor that may optionally be adjusted to a given heart rate, aortic projection pressure Wave height, pulse pressure amplification between the aorta and radial artery, pulse pressure amplification between the aorta and femoral artery, pulse wave velocity between the aorta and femoral artery (PWV _CF ), pulse wave velocity between the aorta and radial artery (PWV _CR) ), PWV _CF to PWV _CR ratio (PWV _CF / PWV _CR ), a gradient ratio of aortic-peripheral renal dysfunction, standardized PWV _CF , and combinations thereof. These arterial blood pressure indices are known, for example, the above arterial blood pressure indices other than the standardized PWV _CF are, for example, Hashimoto J et al., Hypertension. 2010; 56: 926-933; Weber T et al., J Hypertens. 2009 27: 1624-1630 .; Hashimoto J et al., Hypertension. 2011; 58: 839-846. Standardized PWV _CF can be calculated by known methods (Eur Heart J. 2010; 31: 2338-2350; Van Bortel LM et al., J Hypertens. 2012; 30: 445-448.).

  Based on the aortic blood flow index received from the aortic blood flow index calculating means 26, the renal function index calculating means 32 calculates a renal function index that is an index or parameter indicating the renal function. The renal function index may be the aortic blood flow index itself received from the aortic blood flow index calculating means 26, or the renal function index calculating means 32 as a function of the aortic blood flow index received from the aortic blood flow index calculating means 26. May be an index generated in the above, or a renal function index calculating means as a function of both the aortic blood flow index received from the aortic blood flow index calculating means 26 and the arterial blood pressure index received from the blood pressure index calculating means 30 The index generated at 32 may be used.

  In one embodiment, the renal function indicator is the retrograde blood flow / antegrade blood flow ratio (R / F ratio) of the descending aorta. The retrograde blood flow / antegrade blood flow ratio (R / F ratio) is advantageous in that it can be obtained only from the blood flow data of the patient, and the retrograde blood flow / antegrade blood flow ratio (R / F ratio). It is an unexpected finding that renal dysfunction can be predicted by itself.

In another embodiment, the renal function indicator is characteristic impedance (Z ₀ ). The characteristic impedance (Z ₀ ) is

Or

And is calculated in the time domain from the aortic forward flow velocity (V _Fwd ), the aortic projection pressure wave height (P _1h ), and the aortic radius (R). Equation (2) is the impedance defined by the blood flow rate, and Equation (3) is the impedance defined by the blood flow velocity, and either may be used.

  The evaluation unit 34 evaluates the renal function, that is, the presence / absence and / or degree of renal dysfunction based on the result calculated by the renal function index calculation unit 32. Renal dysfunction includes chronic kidney disease and chronic renal failure. In one embodiment, the renal dysfunction is chronic kidney disease. Chronic kidney disease includes, but is not limited to, nephrosclerosis, chronic glomerulonephritis, diabetic nephropathy, and nephritis. The degree of renal dysfunction includes a stage that is the degree of progression of the stage.

  For example, based on the measured value of the above-mentioned renal function index of a healthy person or a patient having renal dysfunction, a reference value for determining the presence and / or degree of renal dysfunction is set as a threshold value and stored in the storage device 38.

  The evaluation unit 34 further includes a comparison unit that compares a renal function index of a subject with the reference value, and a determination unit that determines the presence and / or degree of renal dysfunction in the subject based on the comparison result. The evaluation means 34 determines the presence or absence of renal dysfunction and / or by determining whether the value of a renal function index of a subject is greater than or less than the reference value, or less than or greater than the threshold value. Degree can be determined.

  For example, the value of a renal function index of a subject is compared with a reference value that is a measured value of renal dysfunction obtained from a healthy subject, and the value of the renal function index of the subject is statistically more significant than the reference value ( When P <0.05, it can be determined that the subject is likely to suffer from renal dysfunction. In addition, the value of a renal function index of a subject is compared with a reference value that is a measurement value of a patient at a stage of a stage, and the value of the renal function index of the subject is statistically more significant than the reference value ( When P <0.05, it can be determined that the subject is likely to be in the stage of the stage.

  The correlation analysis means 36 analyzes the correlation between the renal function index and a known index that indicates the presence and / or extent of renal dysfunction. Known indicators indicating the presence and / or extent of renal dysfunction include, for example, estimated glomerular filtration rate (eGFR), glomerular filtration rate (GFR), urea nitrogen (BUN), creatinine (Crea), uric acid (UA), Cystatin C and the like can be mentioned. For example, by plotting a known index indicating the presence and / or degree of renal dysfunction on the horizontal axis and the renal function index in the present application on the vertical axis and visualizing it as a graph on the display device 40, the medical staff etc. It is possible to examine and confirm the correlation between the two parameters and the accuracy of the renal function index as an index for evaluating the renal function.

  FIG. 2 is a flowchart showing main operations of the processing device 22 of the renal function evaluation device 10. In step S <b> 1, the aortic average blood flow velocity waveform generating unit 24 generates an aortic average blood flow velocity waveform from the blood flow data received from the blood flow measuring device 12. In step S <b> 2, the aortic blood flow index calculating unit 26 calculates an aortic blood flow index from the blood flow data received from the blood flow measuring device 12 and / or the waveform data received from the aortic average blood flow velocity waveform generating unit 24. In step S3, based on the arterial blood flow index received from the aortic blood flow index calculating unit 26, the renal function index calculating unit 32 calculates an index related to renal dysfunction as a function of the arterial blood flow index. Calculate. In step S <b> 4, the evaluation unit 34 determines the presence and / or extent of renal dysfunction based on the renal function index calculated by the renal function index calculation unit 32.

  Alternatively, when the renal function index is calculated by the renal function index calculation unit 32, when the arterial blood pressure index is also used, in step S5, the arterial average pressure waveform generation unit 28 determines the blood pressure of the subject in step S2. An average arterial pressure waveform is generated from the pulse waveform data. Next, in step S6, the arterial blood pressure index calculating means 30 receives the blood pressure data received from the blood pressure measurement device 14, the blood pressure waveform data received from the pulse pressure sensor 16, and / or Alternatively, the arterial blood pressure index is calculated from the waveform data received from the arterial average pressure waveform generating means 28. In step S3, the renal function index calculating means 32 is based on the arterial blood flow index received from the aortic blood flow index calculating means 26 and the arterial blood pressure index received from the blood pressure index calculating means 30, specifically arterial blood. An index associated with renal dysfunction is calculated as a function of the flow index and the arterial blood pressure index. In step S <b> 4, the evaluation unit 34 determines the presence and / or extent of renal dysfunction based on the renal function index calculated by the renal function index calculation unit 32.

  The present invention also includes a program for causing a computer to function as the renal function evaluation apparatus 20 and a computer-readable recording medium on which the program is recorded.

  As described above, according to the present invention, blood flow analysis data can be used as a marker for prevention or improvement of renal dysfunction, and renal function can be non-invasively and simply performed by applying an ultrasonic device to the body surface. Can be evaluated.

  In addition, the aortic blood flow index may be combined with a blood pressure index obtained by a non-invasive method in order to evaluate renal function, but in this case also, the physical and economic burden on the subject is extremely small. As described above, the blood flow waveform measurement and the renal function evaluation can be performed easily and safely simply by incorporating low-cost software using an existing medical device. The present invention can also be used as a support tool for improving the diagnostic accuracy of existing renal diseases. Further, according to the present invention, early detection or treatment of renal disorder can be performed, which can contribute to improvement of the patient's life prognosis.

In addition, said embodiment can be changed as follows.
The renal function index may be calculated based only on the aortic blood flow index received from the aortic blood flow index calculating unit 26, and the blood pressure measurement device 14, the pulse pressure sensor 16, the arterial average pressure waveform generating unit 28, and the blood pressure The index calculation means 30 may be omitted.
○ When calculating the renal function index by the renal function index calculating means 32, an index other than the aortic blood flow index calculated by the aortic blood flow index calculating means 26 and the arterial blood pressure index calculated by the blood pressure index calculating means 30 is used. May be.
○ When measuring blood pressure data (including blood pressure waveform data) and / or blood flow data (including blood flow waveform data), the measurement time may be determined manually by the user's operation. All the processes may be automatically measured by the processing device 22 so that the measurement is automatically started and ended in that time zone using (for example, 5 to 30 seconds) as a preset. Moreover, the structure which a user can switch between manual and automatic may be sufficient.
In the above embodiment, blood flow data and blood pressure data are measured by time series (time domain) analysis, but may be measured by frequency analysis (frequency domain).
○ Instead of measuring blood flow and blood pressure separately, blood flow from the subject and blood pressure can be measured at the same time, and both data can be synchronized in time and taken into a personal computer for automatic processing. Good. In this case, more accurate measurement is possible.
In the above embodiment, the aortic average blood flow velocity waveform generating means 24 and the arterial average pressure waveform generating means 28 are present in the same processing device 22 as the aortic blood flow index calculating means 26 and the blood pressure index calculating means 30, and The function index calculating means 32 is also present in the same processing device 22 as the aortic blood flow index calculating means 26 and the blood pressure index calculating means 30, but the members 24 and 28 are physically separate from the members 26 and 30. The members 26 and 30 and the kidney function index calculating means 32 may also be present in a physically separated processing apparatus. That is, the present invention includes not only the case where each member in the processing apparatus 22 is in the same processing apparatus but also the case where they exist in different processing apparatuses.

  The disclosures of all patent applications and documents cited herein are hereby incorporated by reference in their entirety.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

The present inventor uses a non-invasive and quantitative method (Hashimoto J et al., Hypertension. 2010; 56: 926-933; Hashimoto J et al., Hypertension. 2011; 58: 839-846.) The blood flow waveform of the descending aorta in hypertensive patients was evaluated. The inventor's goal is to investigate the relationship between aortic hemodynamics and chronic kidney disease.
(Method)
1. We examined adult hypertensive patients (222 men and women, average age 53 ± 13 years) examined at Tohoku University Hospital. Exclusion criteria are heart failure, heart valve disease including aortic regurgitation (ultrasonic grade> I °, Omoto R et al., Jpn Heart J. 1984; 25: 325-340), aortitis syndrome, aortic aneurysm, atrial detail Motion, carotid stenosis, history of symptomatic stroke, and poor ultrasound signal quality.
2. Measurement of aortic blood flow Blood flow velocity was measured using a duplex ultrasonic device (Vivid i, GE Health care, Tokyo, Japan) equipped with a 3.5-MHz sector probe. Two-dimensional real-time B-mode and bidirectional pulse Doppler signals were acquired from the proximal descending aorta using the suprasternal fossa approach. Specifically, the probe was placed in the suprasternal fossa and oriented across the descending aorta as viewed from the long axis direction so that the angle of ultrasonic incidence to the blood flow was 0 °. The Doppler shift signal was sampled at the center of the aortic lumen since the flow velocity distribution hardly changed across the vessel lumen. The lowest possible wall filter was selected to include the slowest possible blood flow. The instantaneous velocity was calculated as a spatial average of Doppler signals weighted by intensity within a 5.5 mm sample width. The spatially averaged instantaneous average speed was recorded continuously for 16 seconds and stored as time series data for further analysis. The inner diameter of the descending aorta was also measured by B mode at the same site as the Doppler recording.

16-second blood flow velocity data was interpolated off-line at 100 Hz (Mathematica version 4.0, Wolfram Research, Champaign, Illinois, USA). Next, the velocity pulse waveform was ensemble averaged over 10 consecutive cardiac cycles, using the rising point at which the blood flow velocity over time changes from the bottom to the top of the systole as a reference point (Hashimoto J et al., Hypertension 2010; 56: 926-933). Plotting the velocity toward the probe above the reference line and the velocity moving away from the probe below the reference line with respect to the time axis, the average flow velocity waveform was plotted, and the following parameters were measured (Fig. 3) :
Systolic forward flow peak velocity (V _Fwd );
Diastolic backflow peak velocity (V _Rev );
End-diastolic blood flow velocity (V _ED );
Time-averaged mean blood flow velocity (V _M );
Forward flow peak time (T _Fwd );
Back flow peak time (T _Rev ).

The reverse flow / forward flow ratio (R / F ratio) based on the descending aortic blood flow velocity was calculated from the above formula (1) as a percentage.
3. Aortic blood pressure measurement and arterial function measurement A series of blood pressure measurement was performed by a known method under a quiet temperature control environment (Hashimoto J et al., Hypertension. 2010; 56: 926-933; Hashimoto J et al., Hypertension. 2011; 58: 839-846.). Briefly, after placing the patient in the supine position for 20 minutes, the blood pressure of the upper arm was measured with a cuff oscillometric pressure measuring device (HEM-907, Omron Healthcare, Kyoto, Japan). Thereafter, pulsatile pressure signals were recorded from the radial artery, carotid artery and femoral artery non-invasively using a pen-type pressure sensor probe (SPT-301, Millar Instruments, Houston, Texas, USA) by the applanation method (tonometry method). The recorded radial artery pulsation pressure waveform was ensemble averaged for 11 seconds and converted to the corresponding aortic pressure waveform using a generalized transfer function (SphygmoCor version 8.2, AtCor Medical, Sydney, Australia). Calibrate the averaged radial artery with brachial systolic and diastolic pressures, determine the mean arterial pressure from the area under the curve, thereby approximating the aortic systolic and diastolic pressures, and the difference between them to determine the aortic pulse pressure Was calculated. Also, the aortic wave height (P _1h ) is calculated using the calibrated aortic waveform (Hashimoto J et al., Hypertension. 2010; 56: 926-933; Weber T et al, J Hypertens. 2009; 27: 1624 Hashimoto J et al., Hypertension. 2011; 58: 839-846.) And the characteristic impedance (Z ₀ ) (Dujardin JP et al., Med Biol Eng Comput. 1981; 19: 565-568; Lucas CL et al .; Nichols WW et al., McDonald's Blood Flow in Arteries: Theorertical, Experimental and Clinical Principles. London: Hodder Arnold; 2011).

The pulse wave velocity between the aorta and radial artery (PWV _CF ) and the pulse wave velocity between the aorta and femoral artery (PWV _CR ) were measured (Hashimoto J et al., Hypertension. 2010; 56: 926-933). Weber T et al., J Hypertens. 2009; 27: 1624-1630 .; Hashimoto J et al., Hypertension. 2011; 58: 839-846).
4). Measurement of the first estimated glomerular filtration rate (eGFR). Estimated glomerular filtration rate (ml / min / 1.73m ² ) of 222 patients was calculated from serum creatinine, age and sex, and CKD Medical Guide 2012 (Japan Nephrology Society, Journal of the Japan Kidney Society 2012; 54 (8): 1031 according to the classification -1189), who patients normal group (CKD stages of G1～G2, eGFR is 60ml / min / 1.73m ² or more, n = 0.99) and chronic kidney disease group (CKD stage persons G3~G5 The eGFR was classified as less than 60 ml / min / 1.73 m ² and n = 72).
5. Statistical analysis values are shown as mean ± standard deviation or percentage unless otherwise specified. Where appropriate, univariate analysis was performed using t-test or Pearson correlation coefficient. Multivariate linear regression analysis was used to assess independent associations. P <0.05 was considered statistically significant.
(result)
The flow velocity waveform of the descending aorta was measured, and all 222 subjects (100%) showed the normal flow (downward blood flow toward the abdominal aorta) and the early regurgitation (aortic arch) shown in FIG. A bidirectional waveform with positive and negative peaks (upward blood flow in the direction) was shown (FIG. 3).

The average eGFR of all subjects is 66 ± 27 ml / min / 1.73 m ² , and eGFR is the reverse flow / forward flow ratio (| V _Rev | / | V _Fwd |) (r = −0.25), PWV _CF (r = −0.40). ), Characteristic impedance Z _{0 F} (r = −0.25), and aortic pulse pressure (r = −0.30) are significantly correlated, but PWV _CR (r = −0.06) and mean arterial pressure (r = −0.10) ), And further adjustment of the reflux / forward ratio and aortic pulse pressure revealed that the reflux / forward ratio was the strongest determinant of eGFR.

  In addition, the reflux / forward ratios in the normal group (CKD stages G1 to G2, n = 150) and the chronic kidney disease group (CKD stages G3 to G5, n = 72) are 33 ± 10% and 38 ± 11%, respectively. The chronic kidney disease group (CKD stages G3 to G5, n = 72) was significantly higher than the normal group (P <0.001, FIG. 4).

  From the above results, it has been clarified that an increase in reflux in the aorta leads to a decrease in renal function, and renal dysfunction can be evaluated by measuring a reflux / forward flow ratio.

10 ... renal function evaluation device, 32 ... renal function index calculating means 34 ... evaluation unit, Z ₀ ... characteristic impedance, reflux / down flow ratio R / F ... descending aorta.

Claims (5)

Based on the aortic blood flow index calculated based on the blood flow data of the subject's aorta, it comprises a renal function index calculating means for calculating a renal function index indicating renal function ,
A renal function evaluation apparatus , wherein the renal function index is a retrograde blood flow / antegrade blood flow ratio (R / F ratio) or characteristic impedance (Z _o ) of the descending aorta .   The renal function evaluation apparatus according to claim 1, further comprising an evaluation unit that evaluates the presence or absence or degree of renal dysfunction based on the renal function index. The renal function evaluation apparatus according to claim 2 , wherein the renal dysfunction is chronic kidney disease. The program for functioning a computer as a renal function evaluation apparatus as described in any one of Claims 1-3 . The computer-readable recording medium which recorded the program of Claim 4 .