JP4393418B2 - Real blood flow measurement system - Google Patents

Description

The present invention relates to Jitsuchi flow measurement systems, in particular, in the extracorporeal blood circulation apparatus, such as a hemodialysis apparatus or a blood purification apparatus, using substantially the existing equipment, determined quickly and accurately the actual flow rate of the blood Matters relating to Jitsuchi flow measurement system that was to be able to.

  BACKGROUND ART An extracorporeal blood circulation device having a blood circuit that circulates blood between a patient's body using a blood pump, in particular, a hemodialysis device and a blood purification device are widely known. For example, in hemodialysis, blood is collected from the arterial side of a patient and purified after being dialyzed by an external hemodialysis apparatus is returned to the vein side. Such hemodialysis apparatuses are widely put into practical use, and typical ones described in Patent Document 1, Patent Document 2, and the like are known.

  In a hemodialysis machine, a hemodialysis element including a dialysis membrane is used as a hemodialysis element for performing hemodialysis. From the blood sent from the patient's artery side, the hemodialysis element is connected to the blood circuit side. Urine components and the like are removed through the dialysis membrane between the dialysis fluid circuit and the dialysate circuit, and excess water is removed, and the blood after dialysis is returned to the venous side of the patient. A blood pump composed of a tube pump provided on the upstream side of the hemodialysis element in the blood circuit is usually used for sending and circulating blood between the patient's body. This tube pump is designed to push the blood in the tube by rotating two rollers like a tube, and extruding the blood in the tube. It can be set.

  When hemodialysis is performed, blood is removed from the shunt by a blood pump. At this time, since the shunt puncture portion becomes resistance, the blood pressure removal on the primary side of the blood pump is usually negative pressure. Due to the characteristics of the tube pump having the above structure, it is known that when the primary side of the pump is a negative pressure, the actual pump discharge amount is reduced compared to the set flow rate.

  The dialysis efficiency of the hemodialysis element and the performance to be exhibited are usually determined based on the total blood flow per hour, so the dialysis efficiency is between the set flow rate of the blood pump and the actual blood flow as described above. If a deviation occurs, it is impossible to accurately set the optimal dialysis time and the optimal setting of the hemodialysis element by judging from the set flow rate. In order to perform the optimum setting, it is desired that the actual blood flow rate can be measured with high accuracy.

  In order to solve such a problem, the applicant of the present application previously described in Patent Document 3 can inject a replacement fluid (for example, physiological saline) into the blood channel and measure the actual blood flow volume from the detected pressure before and after the injection. A proposed system has been proposed. However, in the actual blood flow measurement in this system, it is necessary to inject a physiological saline solution every time measurement is performed, and there remains a problem that the measurement and measurement system become complicated accordingly.

  On the other hand, when blood is removed from the shunt by the blood pump for hemodialysis, the shunt puncture portion becomes resistance as described above, and thus the blood pressure primary blood pressure is normally negative pressure. If the negative pressure value is excessive, the burden on the patient increases, and excessive blood pressure removal may indicate a puncture error. Therefore, it is desired that the blood pressure reduction measurement is performed as quickly and accurately as possible in order to reduce the burden on the patient.

In response to such a request, the present applicant previously disclosed an application that has not yet been disclosed, but in Patent Document 4, the amplitude of fluctuation in the detected pressure by the pressure detecting means in the blood circuit and the set flow rate of the blood pump There has been proposed a blood pressure reduction measurement system that calculates blood pressure reduction based on the above. With this measurement system, the primary pressure of the blood pump can be obtained by using the pressure detection value from the existing pressure detector without substantially changing the existing blood circuit and without adding a pressure detector to the hemodialyzer. Lateral blood pressure can be measured quickly and accurately.
Japanese Patent Publication No.56-82 Japanese Patent Publication No. 61-25382 JP 2004-329746 A Japanese Patent Application No. 2004-172761

  The present inventors pay attention to the fact that there is a close relationship between the blood pressure removal on the primary side of the blood pump and the actual blood flow volume, and it is simpler than the blood pressure removal measurement system in Patent Document 4 proposed above. The present inventors have found that the value of blood pressure obtained by a system capable of measuring blood pressure reduction can also be applied to measurement of actual blood flow, and have completed the present invention.

The object of the present invention is to use the pressure detection value from the existing pressure detector without changing the existing blood circuit and without adding a pressure detector to the hemodialysis apparatus in view of the above situation. to, to be able to measure the removal pressure of the blood pump primary is to provide a Jitsuchi flow measurement system which is adapted to Jitsuchi flow from the removal pressure quickly and accurately measured.

In order to solve the above problems, an actual blood flow measurement system according to the present invention has a blood circuit that circulates blood between a patient's body using a blood pump comprising a tube pump having a tube and a roller. A system for measuring an actual blood flow in an extracorporeal circulation apparatus, comprising: a pressure detecting means for detecting a pressure in the blood circuit after the blood pump; a pressure detected by the pressure detecting means; and an amplitude of fluctuation of the detected pressure. A blood pressure removal calculating means for calculating blood pressure removal, which is a primary pressure of the blood pump, based on the blood pressure removal calculated by the blood pressure removal calculating means, and the relationship between the blood pressure obtained in advance and the actual blood flow volume It comprises an actual blood flow rate calculation means for calculating the actual blood flow rate from the characteristic curve to be expressed.

  In the actual blood flow measurement system, the blood pressure removal calculating means includes a means for calculating blood pressure removal based on a characteristic curve representing a relationship between the amplitude and blood pressure obtained in advance for each set flow rate of the blood pump. Can be configured. With reference to the blood pressure thus calculated, the actual blood flow is calculated from the characteristic curve representing the relationship between the blood pressure obtained in advance and the actual blood flow as described above.

Further, the tube pump used as the blood pump is usually provided with two rollers, and the pressure is changed twice by one rotation of the rotor, and the corresponding amplitude is generated.

  The actual blood flow measurement system according to the present invention can be any type of blood extracorporeal circulation device as long as it has a blood circuit that circulates blood between the patient's body using the blood pump as described above. It can also be applied to. Typically, as an extracorporeal blood circulation apparatus, a hemodialysis apparatus that performs hemodialysis between the blood circuit and the dialysate circuit can be cited. The present invention can also be applied to a case where the extracorporeal blood circulation device is composed of a blood purification device that purifies blood in the blood circuit.

As the actual blood flow measuring method that by the present invention, the extracorporeal blood circulating apparatus comprising a blood circuit for circulating blood between a patient's body using a blood pump comprising a tube pump having a tube and rollers, the actual A method for measuring a blood flow, wherein the pressure in the blood circuit after the blood pump is detected, and a blood pressure reduction which is a primary side pressure of the blood pump is detected based on the detected pressure and the amplitude of fluctuation of the detected pressure. There is a method of calculating the actual blood flow from a characteristic curve representing the relationship between the calculated blood removal blood pressure and the actual blood flow with reference to the calculated blood removal blood pressure .

  In this actual blood flow measurement method, a characteristic curve representing the relationship between the amplitude and the blood pressure removal is obtained in advance for the detected pressure, and the blood pressure removal can be calculated based on the characteristic curve.

In addition, since the blood pump includes a tube pump having a tube and a roller , the pressure in the blood circuit after the blood pump is detected by detecting a change in pressure accompanying the rotation of the roller. it can.

Actual blood flow measuring method that by this invention also, the extracorporeal blood circulation apparatus, when a hemodialysis apparatus for performing hemodialysis with the dialysate circuit and a blood circuit and the blood extracorporeal circulation apparatus, the blood circuit The present invention can be applied to any of the blood purification devices that purify the blood therein.

Actual blood flow measurement system according to the present invention has been completed based on following technical idea. That is, in an extracorporeal blood circulation apparatus having a blood pump and having a pressure detection unit on the artery side and / or vein side (for example, before and after the hemodialysis element (dialyzer) in the hemodialysis apparatus) The pressure detected by the detector generates an amplitude of two pressure fluctuations in one rotation in a two-rotor (two-roller) blood pump. Corresponding amplitudes are also generated on the venous side. The magnitude of the amplitude varies depending on the detection pressure and the pressure on the primary side of the blood pump (that is, blood pressure removal). The amplitude increases as the detection pressure increases. The lower the blood pump primary pressure that is negative pressure, the lower the pressure detected by the arterial pressure detector, and the greater the amplitude. As an absolute value of the amplitude, the higher the detected pressure, the larger the amplitude the lower the pressure on the primary side of the blood pump. As described above, the detection pressure in the arterial side pressure detection unit in particular depends on the blood pump primary side pressure (that is, blood pressure removal), and the amplitude that is the difference between the maximum value and the minimum value is also the above-described detection pressure and blood pressure reduction. It will change depending on. Accordingly, if the magnitude of the fluctuation of the detected pressure at a certain detected pressure can be grasped, the pressure (blood pressure removal) on the primary side of the blood pump at that time can be measured. The present invention has been completed using such a technical idea, and as is clear from the verification results described later, it is possible to measure blood pressure removal quickly and accurately by actually calculating based on this technical idea. Has been confirmed. By referring to the measured blood pressure removal, the actual blood flow rate can be calculated quickly and accurately from the characteristic curve of the blood pressure removal and the actual blood flow obtained in advance.

According to the actual blood flow measurement system according to the present invention, though it is extremely simple circuit structure, particularly, only by using the existing mechanical structure for measuring the magnitude of the amplitude of the arterial pressure, the removal pressure It can be measured easily, quickly, and with sufficient accuracy for practical use. By referring to the measured blood pressure removal, it can be quickly and accurately obtained from the characteristic curve of blood pressure removal and actual blood flow obtained in advance. The actual blood flow at that time can be measured.

  As a result of accurately grasping the actual blood flow rate, it is possible to accurately set the optimal dialysis time and the optimal setting of hemodialysis factors, and to perform hemodialysis and blood purification under more desirable conditions. become able to.

  Hereinafter, preferred embodiments of the present invention will be described with respect to hemodialysis apparatuses with reference to the drawings. As described above, the present invention can be applied to an extracorporeal blood circulation apparatus such as a blood purification apparatus in addition to a hemodialysis apparatus.

  FIG. 1 shows an actual blood flow measurement system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a hemodialysis apparatus as a blood extracorporeal circulation apparatus, and has a blood circuit 4 that circulates blood between a patient 3 and a body using a blood pump 2. Blood is collected from the shunt artery side 5 and returned to the patient 3 through the shunt vein side 6. The blood is sent to the blood circuit 4 by a blood pump 2 comprising a tube pump having a tube and a roller (for example, 2 rollers), but the primary side of the blood pump 2 is generally at a negative pressure due to the resistance of the shunt artery side 5. Become. In the present invention, the pressure on the primary side of the blood pump 2 is referred to as blood removal pressure.

  The blood discharged from the blood pump 2 is sent to the blood flow path 9 side of the hemodialysis element (dialyzer) 8 through the sealed drip device 7. The hemodialysis element 8 is defined by the dialysis membrane 10 on the blood channel 9 side and the dialysate channel 11 side. A dialysate liquid supply path 13 and a dialysate drainage path 14 of the dialysate circuit 12 are connected to the dialysate flow path 11 side of the hemodialysis element 8, and blood circulated through the dialysis membrane 10. Dialysis is performed on the blood to purify blood and remove water as needed. The dialyzed blood is returned from the blood flow path 9 of the hemodialysis element 8 to the venous side of the patient 3 via the sealed drip device 15.

  As means for detecting the pressure in the blood circuit 4 after the blood pump 2, in this embodiment, a pressure sensor 16 is provided in the drip device 7 portion, and the pressure on the inlet side of the hemodialysis element 8 is detected. It is like that. In the present invention, this pressure is called arterial pressure. Then, the amplitude of fluctuation of the detected pressure by the pressure sensor 16 is calculated by a blood pressure removal calculating means 18 incorporated in the control / arithmetic unit 17. The calculated amplitude of fluctuation of the arterial pressure is used to calculate blood pressure reduction described later. Then, referring to the calculated blood pressure removal, a characteristic curve representing the relationship between the blood pressure removal and the actual blood flow obtained in advance by the actual blood flow calculation means 19 incorporated in the control / arithmetic unit 17, as described later. The actual blood flow is calculated. In this embodiment, the fluctuation of the arterial pressure is generated twice by one rotation by the rotation of the blood pump 2, more precisely by the rotation of the two rollers, and each has an amplitude. Since the fluctuation corresponding to the fluctuation of the arterial pressure can be detected even on the vein side after passing through the hemodialysis element 8, the amplitude of the detected value by the pressure sensor 20 on the vein side provided in the drip device 15 is used to be described later. It is also possible to calculate blood pressure removal.

  Based on the signal from the control device 17, the speed of the blood pump 2 is set and the flow rate of the blood pump 2 is set. Based on the detected pressure detected by the pressure sensor 16 accompanying the rotation of the blood pump 2 and the amplitude of fluctuation of the detected pressure, the blood pressure removal pressure, which is the primary pressure of the blood pump 2, is reduced by the blood pressure removal calculating means 18. Calculated.

  As described above, in this embodiment, the blood pressure removal is calculated by the blood pressure removal calculating means 18 from the detected pressure by the pressure sensor 16 and the amplitude of the fluctuation of the detected pressure. This calculation is basically performed by the pressure sensor. 16 for each detected pressure. Therefore, if a characteristic curve representing the relationship between the amplitude and the blood pressure reduction is obtained in advance for each detected pressure by the pressure sensor 16, the blood pressure removal at that time can be calculated quickly and easily by the blood pressure removal calculating means 18. Will be. Further, when the pressure detected by the pressure sensor 16 is in an intermediate region between the pressures detected by the pressure sensor 16 in a test performed in advance, the pressure sensor 16 is based on both characteristic curves in the pressure detected by the pressure sensor 16 actually tested on both sides. (For example, by adding a correction coefficient), it is possible to easily calculate a characteristic curve at the pressure detected by the pressure sensor 16 in the intermediate region, and based on the characteristic curve, change in the detected pressure The blood pressure removal pressure can be calculated by the blood pressure reduction calculating means 18 from the amplitude of the blood pressure.

  In order to obtain a characteristic curve representing the relationship between the amplitude of the fluctuation in the detected pressure and the blood pressure removal, the following test was performed. The apparatus used for the test is shown in FIG.

  In FIG. 2, 21 indicates a hemodialysis apparatus (TR-7000S, manufactured by Toray Medical Co., Ltd.). The hemodialysis apparatus 21 includes a blood pump 22 including a tube pump (flow rate control range in the test: 50). -400 mL / min) and a pressure sensor and a display unit (arterial pressure sensor and display unit 24) before and after dialyzer 23 (BS-1.6UL, manufactured by Toray Medical Co., Ltd.) in the blood flow path A venous pressure sensor and display unit 25) is provided.

  A test liquid (xanthan gum (XG) solution (equivalent to hematocrit value [Ht] 20%, 30%, 40%)) having a viscosity equivalent to that of blood is stored in the test liquid storage tank 26 in each test, and blood pump The pressure on the primary side of the blood pump 22, that is, the blood pressure drop, was measured with the pressure gauge 28 for each set flow rate of the blood pump 22 while changing the flow path resistance with the flow rate adjustment valve 27. At the same time, the pressure detected by the arterial pressure sensor 24 is recorded by the recorder 29 so that the detected pressure at that time and the amplitude of the fluctuation of the detected pressure can be calculated. The dialysate was supplied to the dialysate circuit 31 side of the dialyzer 23 relative to the blood circuit 30 side (dialyte temperature: 36 ° C., dialysate flow rate: 500 mL / min). The return blood pressure from the dialyzer 23 was measured by a pressure gauge 32, and the return side (venous side) test solution was collected in the test solution storage tank 26 via the relief valve 33. The arterial pressure was changed to -100, 0, 100, 200, 300, and 400 mmHg in the flow configured as described above. The relationship between blood pressure removal and arterial pressure amplitude at that time was obtained. As for the arterial pressure amplitude, the scale of the maximum value and minimum value of the arterial pressure voltage fluctuation shown in the recorder 29 is read and replaced with the arterial pressure, and the difference between the maximum value and the minimum value of the arterial pressure at that time is determined. (Amplitude) was calculated. The results are shown in FIG.

In FIG. 3, for each Ht value (20%, 30%, 40%), the data obtained above is approximated by a polynomial in the form of y = ax ² + bx + c to obtain a characteristic line, and the correlation at that time The number is represented by R ² (this polynomial of the form y = ax ² + bx + c and the correlation coefficient R ² are shown in Table 1).

  As is clear from FIG. 3, it was confirmed that the relationship between the arterial pressure amplitude and the blood pressure reduction can be expressed by a specific characteristic curve with a sufficiently high correlation at each arterial pressure. Therefore, the blood pressure removal can be calculated based on the arterial pressure and the arterial pressure amplitude at that time. In FIG. 3, since there is no influence due to the difference in the Ht value and the blood pump set flow rate, the characteristic curve of the Ht value and the blood pump set flow rate is representatively represented as a characteristic curve for each arterial pressure.

  Also, when the arterial pressure at that time is between the arterial pressures obtained from the characteristic curve in the above test (for example, the arterial pressure at that time is 120 mmHg, and the arterial pressure obtained from the test is 100 mmHg and 150 mmHg) In some cases, it is possible to calculate the characteristic curve at the current arterial pressure using the correction coefficient, etc., based on both characteristic curves obtained in the test, and based on the calculated characteristic curve, Blood pressure can be calculated from the arterial pressure amplitude.

  Thus, according to the present invention, it is possible to calculate blood pressure removal quickly, accurately and easily based on the detected pressure in the blood circuit after the blood pump and the amplitude of fluctuation of the detected pressure. The present invention can be easily applied to an existing apparatus without adding a new meter.

  In the above embodiment and the test apparatus, the blood pressure is calculated from the arterial pressure amplitude before the dialyzer, but even the venous pressure after the dialyzer causes pressure fluctuation due to the blood pump rotation, and the amplitude can be calculated. By calculating the relationship between the amplitude and blood pressure removal for each arterial pressure, blood pressure removal calculation similar to the above can be performed.

  With reference to the blood pressure removal calculated as described above, the actual blood flow rate calculation means 19 calculates the actual blood flow rate from the characteristic curve representing the relationship between the blood pressure reduction and the actual blood flow rate obtained in advance. FIG. 4 is a characteristic curve representing the relationship between the blood pressure reduction obtained in advance and the flow rate ratio with respect to the blood pump set flow rate for calculating the actual blood flow as a characteristic curve representing the relationship between the blood pressure removal and the actual blood flow. Is shown for each Ht value (20%, 30%, 40%).

The blood pressure reduction data obtained as described above is approximated by a polynomial in the form of y = ax ² + bx + c, and the characteristic curve of the flow rate ratio is obtained for each Ht value (20%, 30%, 40%). The correlation coefficient at that time is represented by R ² (the polynomial in the form of y = ax ² + bx + c and the correlation coefficient R ² are shown in Table 2).

The actual blood flow is calculated as follows.
(1) A flow rate ratio is obtained from the calculated blood pressure removal (substituting the calculated blood pressure removal into the above approximate expression). (2) The actual blood flow is calculated by the following equation.
Actual blood flow = Blood pump speed setting value (ml / min) (Set flow rate) x Flow rate ratio

  For example, when the blood pump speed set value is 200 ml / min and the blood pressure removal measurement result is −200 mmHg, each actual blood flow rate calculation value is as follows.

As a result of confirming the actually measured value under the conditions at this time, it was as follows.
Ht20%: 191.7 ml / min
Ht30%: 194.1 ml / min
Ht40%: 190.7 ml / min
Therefore, it was confirmed that the actual blood flow rate was calculated from the measurement result of blood pressure removal with an accuracy with no practical problem.

  3 and 4, characteristic curves are obtained for each Ht value. Depending on the blood pump set flow rate, these characteristic curves can be represented by a single characteristic curve. In this case, even if represented by one characteristic curve, sufficient accuracy can be obtained regardless of changes in the Ht value.

Actual blood flow measurement system according to the present invention, in addition to the hemodialysis apparatus, can simply be applied to extracorporeal blood circulation apparatus of the blood purification device and the like just for purifying blood.

It is a schematic block diagram of the actual blood flow measuring system which concerns on one embodiment of this invention. It is a schematic block diagram of the test apparatus for calculating | requiring the characteristic curve of an arterial pressure amplitude and a blood pressure reduction. It is a characteristic view which shows the test result in the test apparatus of FIG. It is a relationship diagram of blood pressure reduction and flow rate ratio showing a characteristic curve for obtaining actual blood flow volume from calculated blood pressure removal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hemodialysis apparatus as an extracorporeal blood circulation apparatus 2 Blood pump 3 Patient 4 Blood circuit 5 Shunt artery side 6 Shunt vein side 7, 15 Sealed drip apparatus 8 Hemodialysis element (dialyzer)
DESCRIPTION OF SYMBOLS 9 Blood flow path of hemodialysis element 10 Dialysis membrane 11 Dialysate flow path 12 Dialysate circuit 13 Dialysate liquid supply path 14 Dialysate drainage path 16 Arterial side pressure sensor 17 Control / arithmetic unit 18 Depressor blood pressure calculation means 19 Actual Blood flow rate calculation means 20 Venous pressure sensor 21 Hemodialysis apparatus 22 Blood pump 23 Dialyzer 24 Arterial pressure sensor and display unit 25 Venous pressure sensor and display unit 26 Test fluid storage tank 27 Flow rate adjustment valve 28 Pressure gauge for blood pressure reduction 29 Recording Total 30 Blood circuit 31 Dialysate circuit 32 Pressure gauge for return blood pressure 33 Relief valve

Claims (4)

  An actual blood flow measurement system in an extracorporeal blood circulation device having a blood circuit for circulating blood between a patient's body using a blood pump comprising a tube pump having a tube and a roller, the blood flow measuring system being A blood pressure calculation means for calculating a blood pressure removal pressure as a primary pressure of the blood pump based on a pressure detection means for detecting a pressure in the blood circuit, and a detected pressure by the pressure detection means and an amplitude of fluctuation of the detected pressure; Means and an actual blood flow rate calculating means for calculating the actual blood flow rate from a characteristic curve representing the relationship between the blood pressure removed in advance and the actual blood flow rate with reference to the blood pressure removed by the blood pressure removal calculating unit. Real blood flow measurement system.   2. The actual blood flow measurement system according to claim 1, wherein the blood pressure removal calculating means includes means for calculating blood pressure removal based on a characteristic curve representing a relationship between amplitude and blood pressure obtained in advance for the detected pressure.   The actual blood flow measurement system according to claim 1 or 2, wherein the extracorporeal blood circulation device comprises a hemodialysis device that performs hemodialysis between the blood circuit and a dialysate circuit.   The actual blood flow measurement system according to claim 1 or 2, wherein the extracorporeal blood circulation device comprises a blood purification device that purifies blood in the blood circuit.

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