JPH0910304A - Continuous blood purifying device - Google Patents

Abstract

PURPOSE: To reduce burden of managing body fluid balance of a patient to an operator, by providing a volume measuring means for measuring intermittently filtrate flow volume on an exhausting side of a filtrate pump, and controlling rotating speed of the filtrate pump so that the obtained measured value of filtrate is matched with a set value. CONSTITUTION: Filtrate is flowed into a measuring container 7 when an opening/ closing valve 9 is opened and a filtrate clamp 8 is closed during rotating a filtrate pump 3. The filtrate clamp 8 is opened while the opening/closing valve 9 is opened thereby the filtrate in the measuring container 7 is flowed out when surface of liquid is beyond a lower filtrate level sensor 10a and reaches an upper level sensor 10b. These operations are repeated at a specified interval, and a time necessary for flowing into the measuring container 7 is measured as the time until the liquid surface is beyond the lower filtrate level sensor 10a and reaches the upper filtrate level sensor 10b, the flow volume of the filtrate pump 3 is calculated from this time and the volume of the measuring container 7. The rotating speed of the filtrate pump 3 is controlled so that this filtrate flow volume is matched with the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention introduces blood removed from a vein or an artery into a blood purifier such as a hemofilter.
The present invention relates to a continuous blood purification device that assists or substitutes for organ functions of a living body by supplementing useful substances to activate and maintain self-protection mechanism after filtering and separating water, metabolites, electrolytes and the like.

[0002]

2. Description of the Related Art Conventionally, as blood purification methods, whole blood exchange, plasma exchange, blood adsorption, hemodialysis, hemofiltration, hemodiafiltration, peritoneal dialysis and the like have been widely applied clinically. Improves the serious condition of patients with renal insufficiency and other conditions that are in a serious condition and therefore show signs of renal insufficiency, or who have become hydrated due to postoperative drug infusion It has been a long time since it was put into practical use to perform hemofiltration in a clinical setting.

Hemofiltration has pores in the membrane, and the solvent itself containing the solute moves from the blood side to the other side through the pores of the membrane due to the pressure difference applied between the membranes. The solute concentration is controlled by the size of the solute and the pore size of the membrane, which, unlike dialysis, allows selective removal by the principle of filtration. In this case, the removed body fluid component is usually replenished as a replenisher (hereinafter referred to as a replenisher).

However, if this therapy is applied in a short time,
A patient's fluid balance changes rapidly and the patient's condition changes suddenly, which adversely affects the patient.Therefore, continuous blood purification therapy is a method for gradually returning the patient to normal over a long period of time, especially for severely ill patients. It is rapidly spreading as an effective treatment method, and it is mainly performed in intensive care units such as ICU and CCU while strictly controlling the body fluid balance. In continuous blood purification therapy, it is necessary to perform blood purification gradually over a long period of time, which requires more strict patient body fluid balance management. Therefore, it has become necessary to develop a highly accurate device that exceeds conventional wisdom.

Conventionally, roller pumps for squeezing liquid by squeezing an elastic soft tube have been widely used as a liquid-sending device (pump) for a blood purification device. However, since the tubes often used for roller pumps are usually made of plastic such as vinyl chloride, the tube cross-sectional area may vary due to variations in the tube diameter or the tube shape being deformed due to changes in the tube internal pressure during liquid transfer. Due to fluctuations, there is a difference between the pump set value and the actual amount, and the error is typically ± 5%
There is about ± 15%. In addition, the degree of error differs depending on the circuit used. Especially, in the case of the filtrate pump, the influence of the pressure change is the largest. That is, the blood purifier gradually adheres to blood clots and proteins in body fluids as the treatment progresses,
Filtration resistance gradually increases. When the filtrate pump is rotated a certain number of times, the pressure on the filtration side of the blood purifier decreases as the filtration resistance increases, which causes deformation of the tube (decrease in cross-sectional area) and decreases the flow rate. This is well known in the field of treatment, and in fact, the filtrate is received in a measuring container such as a graduated cylinder and the volume is successively measured,
The number of rotations of the filtrate pump is adjusted so that the amount of filtrate is kept constant. Not only is it difficult to measure the filtrate with this graduated cylinder, the measurement accuracy with the graduated cylinder is not high, and measurement errors may occur, such as the filtrate overflowing the graduated cylinder because the operator forgets to perform the measurement. There is also.

[0006]

As described above, in the conventional techniques, it is difficult to control the flow rate of the filtrate in continuous blood purification therapy, and if the observer is not always clinging to this, it is necessary to treat the patient. There was a great deal of variation, and not only could the features of continuous blood purification therapy that could not be achieved be exerted, but there was also the risk of putting the patient in a serious condition. Therefore, in carrying out reliable flow rate adjustment, that is, the present therapy, the advent of a device that automatically adjusts with high reliability so that the actual flow rate approaches the preset flow rate value has been long awaited.

[0007]

SUMMARY OF THE INVENTION As described above, the present inventors have considered the importance of maintaining a constant and accurate filtrate amount in continuous blood purification therapy, particularly continuous blood filtration therapy. The inventors have earnestly studied the means for automatically and accurately measuring and controlling the amount of the filtrate, and have found the means for improving the accuracy beyond the conventional wisdom, and have accomplished the invention of the present application. That is, according to the first aspect of the present invention, in a continuous blood purification apparatus for guiding blood drawn from a vein or artery of a patient to a blood purifier to perform blood purification and then returning the blood to the vein of the patient, Alternatively, a blood pump is provided in the blood removal circuit that guides blood from the artery to the blood purifier, and a filtrate pump is provided in the filtrate circuit that discharges the filtrate from the blood purifier. A volume measuring means for intermittently measuring the flow rate of the filtrate was provided in the filtrate circuit so that the number of rotations of the filtrate pump could be adjusted so that the obtained actual value of the filtrate and the set value would match.

According to a second aspect of the present invention, in the first aspect of the present invention, a measuring container, which is a plastic molded product, is branched from the filtrate circuit on the discharge pump discharge side, and the measuring container and the filtrate circuit are connected. A volume measuring means for intermittently measuring the flow rate of the filtrate is provided, in which a tube clamp is arranged in a tube flow path connecting the branching portions. Further, in the third invention, the transfer capacities of the blood pump and the filtrate pump of the device are 15 to 250 ml / min and 50 to 2,000, respectively.
In the fourth invention, the accumulated flow rate error of the filtrate pump is within ± 1%, and in the fifth invention, the internal volume of the measuring container is 10 to 10 ml. Thirty
A device for continuous blood purification in the range of ml is provided. Furthermore, in the sixth invention of the present application, an opening / closing means for ventilation control is provided in the upper portion of the weighing container, and after discharging the filtrate, the opening / closing means is closed to stop the inflow of air into the weighing container.

[0009]

The measuring means of this apparatus is to accurately measure the flow rate of the target liquid by measuring the liquid volume at a predetermined time interval using a measuring container having a fixed volume. When this value is lower than the set pump flow value, the pump speed is increased, and when it is higher than the set value, the pump speed is decreased so that the true liquid flow rate approaches the set value. Adjusted to. While the error of a normal roller pump is about ± 5% to ± 15%, by adjusting the flow rate by this method, the flow rate error during 10-hour operation can be stopped to ± 1% or less. Further, by adopting this control mechanism, it is possible to provide a highly accurate device which is beyond the conventional wisdom as a device for performing continuous hemofiltration therapy.

[0010]

Next, the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In FIG. 1, the blood collection amount and the anticoagulant injection amount are set according to the state of the patient, the anticoagulant is injected by the syringe pump 1, and the blood pump 2 in the blood circulation circuits 5a and 5b including the blood purifier 4. Circulate blood to. Further, the amount of filtrate filtered by the blood purifier 4 is determined according to the patient's condition, and the flow rate of the filtrate pump 3 is set. The blood removed from the patient by the blood pump 2 is guided to the blood purifier 4 through the blood removal circuit 5a, and the blood whose wastes have been filtered and purified by the blood purifier 4 passes through the blood return circuit 5b. Blood is returned to the patient. In the blood purifier 4, the rotation of the filtrate pump 3 causes the solute containing waste products to be purified by ultrafiltration together with the solvent due to the pressure difference generated between the membranes. The filtrate filtered by the blood purifier 4 is supplied to the filtrate circuit 6 by the filtrate pump 3.
And is discharged to the waste liquid container 20.

Further, in FIG. 1, 11 is a pillow for detecting poor blood removal, and 12, 13, 14 are pressure chambers for measuring in-circuit pressure, respectively. 15 is a bubble clamp,
Reference numeral 16 denotes a bubble sensor, 17, 18, 19 each denote a pressure sensor, and 21 denotes a replenisher supply unit. As the blood purifier used in the present invention, a hollow fiber membrane module having a hollow fiber ultrafiltration membrane as a filtering material is most suitable.

Next, the operation of volumetric measurement of the flow rate of the filtrate will be described. When the on-off valve 9 is opened and the filtrate clamp 8 is closed while the filtrate pump 3 is rotating, the filtrate flows into the measuring container 7. When the liquid level passes through the lower filtrate level sensor 10a and reaches the upper filtrate level sensor 10b, the on-off valve 9 remains open, the filtrate clamp 8 opens, and the measuring container 7
The filtrate inside flows out of the container due to the height difference. After a predetermined time, when the filtrate clamp 8 is closed, the filtrate again flows into the measuring container 7, and when the liquid level passes through the lower filtrate level sensor 10a and reaches the upper filtrate level sensor 10b, the filtrate clamp 8 Is opened and the filtrate in the measuring container flows out from the container. Such an operation is repeated every predetermined time.
The time T required to flow into the measuring container is such that the liquid surface passes through the lower filtrate level sensor 10a and the upper filtrate level sensor 10a.
It is measured as the time to reach b. Weighing container 7
Since it was manufactured by a plastic molding die and it was confirmed in advance that there was almost no error, it has a constant volume V, and the filtrate flow rate L flowing through the filtrate pump 3 is L = V / T. When the flow rate L is lower than the set value, the rotational speed of the filtrate pump 3 is increased, and when it is high, the rotational speed of the filtrate pump 3 is decreased so that the flow rate is closer to the set value.

Although the predetermined time depends on the liquid flow rate, it is preferably set every 1 to 20 minutes so that the accuracy is sufficiently improved, and is set longer when the flow rate is low and shorter when the flow rate is high. .

The upper tube 22 of the measuring container 7 is
It is connected to the on-off valve 9, and after the filtrate is discharged, the on-off valve 9 is closed immediately after the liquid level passes through the lower filtrate level sensor 10a,
The inflow of air into the container is stopped to prevent an excessive decrease in the liquid level in the drainage tube 23. After the liquid is discharged from the measuring container 7, if the upper tube 22 of the measuring container 7 is in an open state, air is sucked into the drainage tube 23 from the measuring container 7 side by the negative pressure of the head, and bubbles are generated. . After the measurement is started, these bubbles pass through the lower filtrate level sensor 10a, and the detection of the correct liquid level is erroneous, which causes a measurement error.

This point will be described in more detail with reference to FIGS. 2 (a) (b) (c). If the on-off valve 9 is not provided or is left open, after the liquid is discharged, the negative pressure of the head difference (drop) between the branch portion 24 and the filtrate tube discharge end 25 to the waste liquid container 20 causes the negative pressure in FIG. As shown in (), air is sucked in from the measuring container 7 side. When the clamp 8 is closed and weighing is started in this state,
As shown in FIG. 2 (b), bubbles wrap around to the side of the measuring container 7, causing an error in the bubble volume. Therefore, in the device of the present invention, the lower filtrate level sensor 10a constantly monitors the liquid level even after the start of measurement, and cancels the measurement when a non-liquid state is detected even during the measurement, Once the liquid is drained, the measurement will be performed again, but if such a state is repeated, the measurement becomes virtually impossible.

Further, when air bubbles are mixed in, there is a case where the drainage becomes defective. That is, when the filtrate tube discharge end 25 is deeply dipped below the liquid surface in the waste liquid container 20, the head is balanced with the bubble rising force and the bubbles are not extruded and the bubbles are blocked. The surface may rise and reach the weighing container 7, and in fact, it may be impossible to weigh (in order to weigh, the liquid level must be below the lower filtrate level sensor 10a at the start). In the present embodiment, when the liquid level passes through the lower filtrate level sensor 10a after the liquid has been discharged from the measuring container 7 after the measurement, the opening / closing valve 9 is closed with a slight time lag, so that FIG. )
As described above, the occurrence of the above-mentioned bubble inclusion state is prevented. The on-off valve 9 provided on the upper tube 22 of the measuring container 7 is preferably an electromagnetic valve from the viewpoint of convenience of operation and no omission in management. Since the filtrate is a waste product of body fluid and is colored, as a filtrate level sensor,
An ultrasonic sensor that is not affected by liquid coloring is preferable.

Incidentally, the blood purifier is
Although the filtration resistance gradually increases due to the gradual increase in blood clots and proteins in body fluids, the filtrate flow rate decreases as described above when the filtrate pump is at a constant rotation speed. Since the increase in filtration resistance is gradual, it is not usually a large error even if the time interval of measurement is lengthened and the flow rate during non-measurement does not change. But,
Do not set the measurement time interval to a fixed predetermined time and start the next measurement as soon as the drainage is completed after the measurement is completed, except for the short time required for discharging the filtrate in the weighing container. Since it is measured, even if there is an unexpected change in the flow rate, it is more preferable to achieve high flow rate accuracy. The measurement time interval can be easily set by using a known means such as a timer. By setting the measurement time interval to be extremely short, almost continuous measurement can be performed and higher flow rate accuracy can be realized.

(Example) In the system of the present invention, the flow rate of the filtrate pump was set to 500 ml / hour and the predetermined time was set to every 3 minutes, and the liquid (clean water) contained in the closed container was sucked and discharged by the filtrate pump. When the integrated flow rate of the liquid (clean water) discharged in 3 hours and 30 minutes was measured by an electronic balance, it was 1756 grams,
The error was 0.34%. The pressure in the closed container is -32 after 3 hours and 30 minutes from the atmospheric pressure before the start of suction.
It had dropped to 2 mmHg.

Further, in order to compare with the effect of the system of the present invention, the flow rate of the filtrate pump 3 is eliminated by not using the measuring container 7 and thus not controlling the rotational speed of the filtrate pump 3 based on the measurement result. Is set to 500 ml / hour,
The liquid (for example, clean water) contained in the closed container was sucked and discharged by the filtrate pump 3. At this time, the integrated flow rate of the liquid (clean water) discharged in 3 hours and 30 minutes was measured by an electronic scale to find that it was 143
It was 3 grams and the error was -18.1%. In addition,
The pressure inside the closed container was reduced to -71 mmHg after 3 hours and 30 minutes from the atmospheric pressure before the start of suction.

Table 1 shows the results of measuring the flow rate of the filtrate pump using another pump tube in the system of the present invention.

[0021]

[Table 1]

In the system of the present invention, when a pump tube of specified material and size (tube inner diameter and outer diameter) is used, the relationship between the pump rotational speed and the flow rate is preset in the computer of the system so that the set flow rate can be achieved. Remembered Table 1 shows that although the specified material is used, the size of the electronic balance is adjusted by using a pump tube with a slightly larger size, while suctioning and discharging it with a filtrate pump from an air-released container containing tap water placed on the electronic balance. The fluctuation of the flow rate obtained from the change of the measured value is measured. That is, the effect on the influence of the tube size was investigated without any change in filtration resistance.

FIG. 3 is a diagram based on Table 1. That is, the first ● sets the flow rate setting value of the filtrate pump 3 to 500 ml / hour, does not use the measuring container 7,
Therefore, it indicates the pump flow rate when the rotation speed control of the filtrate pump 3 based on the measurement result is not performed,
The subsequent ◯ indicates the pump flow rate when the measurement was started after 120 minutes had elapsed and the rotation speed control of the filtrate pump 3 was performed based on the result. The flow rate on the vertical axis in FIG. 3 is obtained from the change in the measured value of the electronic balance. In the latter case, the next measurement was started immediately after the completion of measurement and discharge of the liquid from the measurement container, and a measurement container having a volume of 20 ml was used.

As is clear from FIG. 3, in the case of ●, the actual average flow rate obtained from the electronic balance was obtained although the flow rate setting value was 500 ml / hour because the size of the pump tube was slightly larger than the specified value. Is 553.1 ml / hour, which is about 11% higher. On the other hand, the average flow rate of ◯, which was switched to measurement / control from the middle, was 499.4 ml / hour.

FIG. 4 shows the accumulated flow rate error based on the result of FIG. As is clear from FIG. 4, the error of ● is about 10.6%, while the integrated flow error of 320 minutes after the start of measurement and control is −0.10%.

[0026]

In the continuous blood purification apparatus of the present invention, the filtrate flow rate is intermittently measured by the volume measuring means, and the measured value is reflected in the pump rotation speed control, whereby the filtrate is automatically set with high accuracy. As the flow rate is achieved as it is, it is necessary for the practitioner to constantly monitor blood flow in a continuous blood purification device for critically ill patients who require strict fluid balance management. Can be reduced, and the accuracy is high, so there is no risk of causing serious problems in treatment.

[Brief description of the drawings]

FIG. 1 is a representative flow chart of the present invention.

FIG. 2 is a schematic diagram illustrating the operation of a ventilation control opening / closing valve in the upper tube of the weighing container.

FIG. 3 is a diagram created based on the results of Table 1, in which the horizontal axis represents time and the vertical axis represents the filtrate pump flow rate, ● represents the case where no measuring container was used, and ○ represents the measuring container after 120 minutes. Shows the case of using.

FIG. 4 is a graph showing time on the horizontal axis and cumulative flow rate error on the vertical axis based on the results of FIG. 3.

[Explanation of symbols]

 1 Syringe Pump 2 Blood Pump 3 Filtration Pump 4 Blood Purifier 5a Blood Removal Circuit 5b Blood Return Circuit 6 Filtration Circuit 7 Measuring Container 8 Filtration Clamp 9 Open / Close Valve 10a Lower Filtration Level Sensor 10b Upper Filtration Level Sensor 11 Pillow 12, 13, 14 Pressure chamber 15 Bubble clamp 16 Bubble sensor 17, 18, 19 Pressure sensor 20 Waste liquid container 21 Replenisher supply part 22 Upper tube 23 Discharge tube 24 Branch part 25 Filtrate tube discharge end

Claims (6)

[Claims] 1. A continuous blood purification apparatus for guiding blood drawn from a patient's vein or artery to a blood purifier to perform blood purification, and then returning the blood to the patient's vein.
A blood pump is provided in the blood removal circuit that guides blood from the vein or artery to the blood purifier, and a filtrate pump is provided in the filtrate circuit that discharges the filtrate from the blood purifier. The filtrate circuit is equipped with a volume measuring means for intermittently measuring the flow rate of the filtrate, and the number of rotations of the filtrate pump is adjusted so that the obtained actual measured value of the filtrate matches the set value. A device for continuous blood purification. 2. A tube clamp which is branched from a filtrate circuit on the discharge side of the filtrate pump and is connected to a measuring container which is a plastic molded product, and which is provided in a tube flow path connecting the measuring container and a branch portion of the filtrate circuit. 2. The continuous blood purification apparatus according to claim 1, further comprising a volume measuring means for intermittently measuring the flow rate of the filtrate, which is provided with. 3. A blood pump and a filtrate pump having transfer capacities,
15-250ml / min, 50-2,000ml respectively
The device for continuous blood purification according to claim 1, wherein the device is / hour. 4. The continuous blood purification apparatus according to claim 1, wherein the accumulated flow rate error of the filtrate pump is within ± 1%. 5. The continuous blood purification apparatus according to claim 2, wherein the measuring container has an inner volume of 10 to 30 ml. 6. An opening / closing means for ventilation control is provided at an upper part of the weighing container, and the opening / closing means is closed after the filtrate is discharged to stop the inflow of air into the weighing container. Continuous blood purification device.