JPH0249748B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for aerating dissolved gas in dialysate. Prior art and its problems In dialysis facilities, tap water heated to about 37°C is used as the dialysate for hemodialysis. When water is heated in this way, the solubility of air in water decreases as the water temperature rises, so dissolved air in excess of that which can be dissolved in water at 37°C tends to be expelled and become bubbles. However, in a closed flow path such as a dialysate flow path, the dialysate may not be completely formed into bubbles and may flow into the dialyzer containing dissolved air in excess of its solubility.
When such supersaturated dissolved dialysate flows into the dialyzer, the dissolved air moves into the blood via the dialysis membrane of the dialyzer due to the concentration gradient, forms bubbles in the blood circuit, etc., and enters the body. There may be a risk of introducing air bubbles. In this case, such a risk can be avoided by providing a degassing mechanism in the dialysate supply device. However, many existing dialysate supply devices do not have such a degassing mechanism. In addition, in recent years, dialyzers that use hollow fibers as dialysis membranes have become increasingly compact, and their membranes have become extremely thin. In this case, the risk of bubble introduction as described above increases significantly. In winter, when the water temperature is low, this risk becomes extremely large. Currently, efforts are being made to make dialyzers smaller and more efficient, and for this reason, when using a dialysate supply device that does not have a degassing mechanism, air bubbles are generated in the blood by simple means. There is a need to prevent danger. Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to eliminate the need for a conventional dialysate circuit even when using a dialysate supply device that does not have a degassing mechanism. The object of the present invention is to provide a simple structure that can be connected to the blood to prevent the above-mentioned generation of bubbles in the blood. The present inventor has completed the present invention as a result of conducting various studies for this purpose. That is, the present invention is a device installed in a dialysate circuit that flows into a dialyzer, which has a cylindrical case equipped with a dialysate inlet and a dialysate outlet, and in which a filter medium is placed in the case at a volumetric filling rate. By bringing the dialysate into contact with the filter medium and applying mechanical stimulation, the dissolved gas in the dialysate is bubbled, and the bubbles generated by this bubble formation are mixed with the dialysate. A device for separating dissolved gas in dialysate, characterized in that the gas is caused to flow into the dialyzer. According to the present invention, the supersaturated dissolved gas is made into bubbles in advance using a separation device installed in the dialysate circuit, so that the dissolved gas moves to the blood side through the dialyzer and becomes bubbles in the blood. The aim is to prevent this from happening. The embodiments of the present invention are intended to further enhance such effects, and include the following. ) Filter paper, filter cloth, nonwoven fabric, fiber,
A device for bubbling dissolved gas in dialysate with a case filled with porous or granular material. ) A device for bubbling dissolved gas in a dialysate, in which the filling thickness of the filled filter medium in the direction of flow of the dialysate is 5 to 15 cm. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. Dissolved gas bubble formation device in dialysate of the present invention 1
For example, as shown in FIG.
is provided in the dialysate circuit 51 on the supply side, which flows into the dialysate circuit 51. The foaming device 1 of the present invention has a cylindrical case 11, as shown in FIGS. 2 and 3.
The case 11 is provided at both ends with a dialysate inlet 111 and a dialysate outlet 115 for connection into the supply dialysate circuit 51. Although the case 11 can have various dimensions, the aerating device of the present invention is usually used suspended in the dialysate circuit 51 on the supply side, as shown in FIG. 1, for example. Therefore, it is preferable to make it small and lightweight so that it can be loaded without using a special holder. For this reason, it is generally preferable that the total length is about 10 to 20 cm and the outer diameter is about 3 to 5 cm. Note that the material of the case 11 can also be made of various materials. However, the material must be non-toxic and able to withstand the heat and chemicals used to disinfect the dialysis machine and dialysate circuit.It is also preferable that the material be lightweight and strong. Therefore, polycarbonate, polypropylene, etc. are generally used. In such a case 11, the flow of the inflowing dialysate is changed, and the supersaturated dissolved gas in the dialysate is bubbled. Bubbling of the supersaturated dissolved gas is caused by applying a type of mechanical stimulation to the dialysate flowing into the case 11. In this case, in the present invention, this mechanical stimulation is performed by bringing the inflowing dialysate into contact with the filter medium, which is an obstacle. By configuring it in this way, the entire device can be made smaller, the structure can be simplified, and furthermore,
The efficiency of generating bubbles in the blood is also extremely small, and the pressure loss of the dialysate at that time is also extremely small. In this case, as a mechanical stimulus, for example, the inflow port diameter is narrowed near the dialysate inlet 111 to increase the inflow velocity, and this is caused to collide with the inner wall of the case 11, etc.
Forcible collision or stirring may be considered. However, when excessive stimulation is forcibly applied in this manner, irrespective of the effectiveness of preventing bubble generation in the blood, the pressure loss caused by narrowing the inflow port is large, making it impractical. Therefore, a so-called filter material is used as the obstacle brought into contact with the inflowing dialysate. As a result, the structure becomes simple, and the occurrence of bubbles in the blood due to supersaturated dissolved gas in the dialysate is extremely reduced. Various filter media are possible. just,
As with the case material mentioned above, it is necessary to use a material that is non-toxic and has excellent heat resistance and chemical resistance. Therefore, a non-toxic, heat-resistant, and chemical-resistant material may be selected from filter media such as filter paper, filter cloth, nonwoven fabric, fiber, porous material, and granular material. These filter media 15 are then filled into the case 11, as shown in FIG. In this case, when filling the filter medium 15, if necessary, a mesh may be provided near the dialysate inlet 111 and outlet 115 to prevent the filter medium 15 from flowing out. When filling the filter medium 15 in this manner, the volume filling rate is preferably 5 to 20%. If the volume filling rate is too small, the effect of preventing air bubbles in the blood will be reduced, and if it is too large, the pressure loss of the dialysate will increase. This is because the effect of preventing bubble generation is extremely high, and the pressure loss is extremely low. Here, the volume filling rate refers to the volume ratio occupied by the filter medium 15 to the internal volume of the case 11.
In this case, the volume occupied by the filter medium 15 refers to the substantial volume excluding pores and the like inside the filter medium. On the other hand, the filling thickness of the filter medium 15 filled in the case 11 in the dialysate flow direction is preferably 5 to 15 cm. In this case, too, if the filling thickness is too small, there will not be enough contact area and it will not be possible to sufficiently prevent the supersaturated dissolved gas from forming bubbles in the blood, and if the filling thickness is too large, the pressure loss will increase. but,
This is because within such a range, both the foaming efficiency and pressure loss characteristics are extremely good. By setting the volume filling rate and filling thickness to values within a preferable range in this way, the pressure loss can be reduced to 15 mm at a dialysate flow rate of 500 ml/min, for example.
Hg or less, and very favorable results can be obtained. In addition, when filling the case 11 with the filter medium 15 as described above, there may be a cavity inside the case in which the filter medium 15 is not filled, and the volume of this cavity can be set arbitrarily depending on the required size of the apparatus. Specific Effects of the Invention As shown in FIG. 1, for example, the aerating device 1 of the present invention includes, for example, a dialyzer supply device 9, dialysate circuits 51, 55 on the supply side and discharge side, and a dialyzer 6. When performing a dialysis procedure by connecting the dialyzer 6 and blood circuit 7 to a patient, the dialyzer 6 is used by being connected to the supply-side dialysate circuit 51 that flows into the dialyzer 6. In this case, the dialysate is heated by the dialysate supply device 9, etc.
When a dialysate in which a gas such as air is supersaturated flows into the aerating device of the present invention, the dialysate comes into contact with obstacles. In this case, since the filter medium is used as an obstacle in the present invention, the dialysate passes through the pores and the like of the filter medium filled portion while coming into contact with the filter medium. During this period, the dialysate is subjected to relatively gentle mechanical stimulation, and the supersaturated dissolved gas bubbles as it attempts to shift from an unstable state in which air is dissolved in excess of its solubility to a stable state. The air bubbles formed in this way usually flow into the dialyzer 6 along with the flow of the dialysate, and some of them are trapped inside the housing of the dialyzer 6, but most of them remain as microbubbles and undergo dialysis. It is discharged according to the flow of liquid. As a result of the dialysate being no longer supersaturated in this way, there is almost no concentration gradient of dissolved air between the dialysate and the blood, which are in contact across the dialysis membrane, and the amount of dissolved air that migrates into the blood is extremely small. The amount of bubbles generated inside is extremely small. In addition, when preparing the dialysate, tap water may be used, and the flow rate is usually 300~
The rate may be about 500 ml/min, and at that time, the bubble generation rate and pressure loss in the blood will be sufficiently small values. Further, the bubble forming device 1 of the present invention has a dialysate circuit 5.
1 in relatively close proximity to the dialyzer 6, with the dialysate flow preferably directed upwards to avoid the accumulation of separated air bubbles within the device 1. As shown in FIG. 4, the pump (pump P ₁ ) for feeding the dialysate is preferably provided at least on the upstream side of the foaming device 1, and a roller pump is preferably used. As the dialyzer 6, any known dialyzer can be used. However, as described above, the foaming device 1 of the present invention uses a thin membrane dialysis membrane such as a hollow fiber dialyzer that uses hollow fibers as the dialysis membrane, which has an extremely high risk of generating bubbles in the blood. Extremely effective when using a dialysis machine. Specific Effects of the Invention According to the present invention, the phenomenon in which gas such as air supersaturatedly dissolved by heating the dialysate moves into the blood according to the concentration gradient and becomes bubbles is significantly reduced. Therefore, even without using a dialysate supply device equipped with a degassing mechanism, the above-mentioned risks can be avoided by using the extremely simple configuration of inserting the bubble forming device of the present invention into the dialysate circuit that flows into the dialyzer. is resolved. In addition, the pressure loss of the dialysate caused by the aerating device of the present invention is extremely small. Additionally, the device itself can be made smaller and lighter.
It has a simple structure and is easy to manufacture. As mentioned above, by forcibly colliding the dialysate inside the device or forcibly stirring it,
Applying excessive mechanical stimulation to the dialysate is effective in preventing the formation of bubbles in the blood as described above, but in such cases, the structure of the device itself becomes complicated and the pressure loss of the dialysate increases. It's too big to be practical. In addition, since the foaming ability is high, there is no need to heat the inside of the foaming device to a temperature higher than the operating temperature using a heater, which also makes the device smaller and simpler. In addition, the device of the present invention can also prevent foreign matter mixed into the dialysate, and therefore has the effect of preventing foreign matter from entering the dialyzer. It should be noted that this effect of removing foreign matter cannot be achieved by conventional methods, nor can it be achieved by methods that use forced collision or stirring as described above. Furthermore, the effect of preventing bubble generation according to the present invention is as follows:
It has been confirmed that it is maintained well over a long period of time. Furthermore, the bubbles generated by the bubble generation device of the present invention flow into the dialyzer, and some of them remain as bubbles in the housing of the dialyzer.
Despite the presence of such air bubbles, it has been determined that the dialyzer clearance is not affected in any way. That is, after the dissolved gas is bubbled, there is no need to discharge the bubbles out of the system using a pump, and from this point as well, the apparatus of the present invention is small, lightweight, and simple in structure. In order to confirm the effects of the present invention, the present inventors
Various experiments were conducted. An example is shown below. Experimental Example 1 A foaming device 1 of the present invention as shown in FIGS. 2 and 3 was manufactured. In this case, the case 11 is made of polycarbonate, and the inner dimensions of the cylindrical part of the case are 30 mmφ x 70 mm, and the total length is 135 mm.
mm, and the inner diameters of the dialysate inlet 111 and outlet 115 were 7 mmφ. . On the other hand, inside the cylindrical part of this case 1, a polyolefin nonwoven fabric (manufactured by Nippon Vilene Co., Ltd.) is used.
PM4100) was filled at a volume filling rate of 10% and a filling thickness of 70 mm. Using such a bubble forming device of the present invention, the generation of bubbles in blood was evaluated by simulating the actual dialysis conditions. Figure 4 shows the circuit used in the experiment. In Figure 4, tap water is in a constant temperature bath _V1 ,
It is kept at 10 degrees Celsius and air bubbles are blown into it, making it saturated. Check whether it is saturated by measuring the O ₂ concentration. This tap water enters the heat exchanger E by the roller pump _P1 , is heated, and then enters the dialyzer 6 through the aerating device 1 of the present invention. The temperature of the tap water discharged from the dialyzer 6 is measured by a thermometer T, and the temperature is controlled by a heat exchanger E to be 37±1°C. Then, the tap water is returned to the constant temperature bath _V1 to form a dialysate circuit. On the other hand, for the blood circuit, tap water is kept in a constant temperature bath V _2.
This is kept at 37±1°C and brought to a saturated state by bubbling air in the same manner as above, and then pumped by pump _P2 to the arterial side chamber _C1 , dialyzer 6, and static side chamber. Circulate through _C2 . In this case, the dialyzer is made of copper with a film thickness of 11 μm.
A dialysis membrane (membrane area: 1.0 m ² ) made of hollow fibers made of ammonia cellulose was used. In addition, two polyester multifilament meshes M and M were used for the vein side chamber. Circulation was carried out in such a circuit by setting the flow rate of tap water in the blood circuit to 200 ml/min and the flow rate of tap water in the dialysate circuit to 500 ml/min. After 20 minutes of circulation, the amount of air bubbles accumulated in the venous chamber _C2 in the blood circuit and the blood port of the dialyzer 6 was measured. Similar measurements were made in the case where the aerating device 1 was not provided, and the defoaming efficiency was measured. The results are shown in Table 1.

[Table] From the results shown in Table 1, the effects of the present invention are clear. On the other hand, when such an experiment was continued for 6 hours, the foaming performance remained almost the same. During the continuation of such dialysis, the bubbles generated by the bubble generator 1 are discharged along with the flow of the dialysate, and also accumulate little by little on the dialysate side in the housing of the dialyzer 6. For this reason, 20 ml of air, which is much larger than the amount of bubbles generated per minute by the bubble generator, was intentionally mixed into the dialysate side of the housing of the dialyzer, and the clearance was measured. The results are shown in Table 2.

[Table] As shown in Table 2, the clearance of the dialyzer hardly decreases even if a much larger amount of air bubbles are mixed in than the amount of air bubbles generated per minute by the air bubble generator. Therefore, it can be seen that even if some of the bubbles generated by the bubble generation device of the present invention exist within the housing of the dialyzer, the clearance is not affected at all. Furthermore, tap water was sampled in the dialysate circuit immediately before the dialysate inlet port indicated by X in FIG. 4, and the O ₂ partial pressure was measured. The results are shown in Table 3. In addition, in the saturated state
_O2 partial pressure is 150mmHg. Table 3 also lists the foaming efficiency calculated from the O ₂ partial pressure.

[Table] From the results shown in Table 3, it can be seen that the present invention eliminates the supersaturation state of the dialysate, and thereby exhibits the excellent defoaming effect shown in Table 1. Note that Table 3 also lists the pressure loss of the dialysate due to the aerating device of the present invention. The results shown in Table 3 show that the pressure loss is extremely low. Experimental Example 2 As shown in Table 4 below, similar aerating apparatuses were prepared in which the dimensions of the case, the type of filter medium, the filling rate, and the filling thickness were variously changed in the aerating apparatus of Experimental Example 1. conducted a similar experiment. In Table 4, F1 is the polyolefin nonwoven fabric in Experimental Example 1, F2 is the polyolefin nonwoven fabric (STB5 manufactured by Nippon Vilene Co., Ltd.), and F3 is the polyester mesh. The defoaming efficiency and pressure loss of these various aerating devices were measured in the same manner as in Experimental Example 1. The results are shown in Table 4.

[Table] As shown in Table 4, the volume filling rate of the filter medium is 5
It can be seen that very favorable characteristics can be obtained in the present invention where the filling thickness is in the range of 5 to 15 cm, particularly in the range of 5 to 15 cm. Furthermore, it can be seen that the same effects can be achieved even if various filter media are used. On the other hand, in Comparative Example 1, although the bubble removal efficiency is excellent, the pressure loss is large. Comparative example 2 In Figure 1, the length of the cylindrical part of case 1 is 5 cm.
A comparative device was prepared in which a nozzle (opening diameter 1.0 mmφ) was inserted inside the dialysate inlet 111 so that the dialysate collided with the inner wall of the cylindrical part, and no filter material was filled, and similar measurements were performed. The results showed that the bubble removal efficiency was 80%, but the pressure loss was extremely large at 150 mmHg, making it unsuitable for practical use.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of use of the foaming device of the present invention. FIG. 2 is a longitudinal cross-sectional view showing an example of the configuration of the foaming device of the present invention. FIG. 3 is a side view of FIG. 2. FIG. 4 is a circuit diagram used in an experiment to confirm the effects of the present invention. Explanation of symbols, 1... Aeration device, 11... Case, 111... Dialysate inlet, 115... Dialysate outlet, 15... Filter material, 51... Supply side dialysate circuit,
55... Discharge side dialysate circuit, 6... Dialyzer, 7...
... Blood circuit, 9... Dialysate supply device.

Claims (1)

[Scope of Claims] 1. A device installed in a dialysate circuit that flows into a dialyzer, which has a cylindrical case equipped with a dialysate inlet and a dialysate outlet, and has a filter medium in the case at a volumetric filling rate. By bringing the dialysate into contact with the filter medium and applying mechanical stimulation, the dissolved gas in the dialysate is bubbled, and the bubbles generated by this bubble formation are transferred to the dialysate. A device for bubbling dissolved gas in a dialysate, characterized in that the gas dissolved in the dialysate is caused to flow into the dialyzer. 2. The device for aerating gas dissolved in a dialysate according to claim 1, wherein the case is filled with filter paper, filter cloth, nonwoven fabric, fiber, porous material, or granular material as the filter medium. 3 The filling thickness of the filled filter media in the dialysate flow direction is 5
15 cm. The apparatus for aerating gas dissolved in a dialysate according to claim 1 or 2, which has a diameter of 15 cm.