JPS649029B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing toxic substances such as urea, uric acid, and creatinine contained in a filtrate in an ultrafiltration artificial kidney device. In recent years, hemodialysis has been widely adopted for chronic uremia, acute kidney disease, or drug poisoning, and artificial kidney devices have become indispensable. the current,
The most widely used artificial kidney device mainly consists of a cellophane dialysis membrane and a dialysate. Blood from the patient's artery and the dialysate flow through the dialysis membrane to remove waste products in the blood, such as urea, Uric acid, creatinine, etc. are transferred into the dialysate by utilizing the difference in concentration between the blood and the dialysate to purify the blood. In the dialysis-type artificial kidney machines to date, once the dialysate has been dialyzed, all the dialysate is discarded, and new dialysate must be constantly supplied, and the cost alone for the dialysate becomes extremely expensive. The reality is that there are. According to the dialysis method, as mentioned above, all the dialysate is discarded, which requires a large amount of water, the equipment is large, and the patient is confined for a long time in a bed in a hospital equipped with water and sewage systems. . There is also a so-called filtration type artificial kidney device that uses an ultrafiltration membrane to separate serum from blood, discard toxic substances contained in the blood along with the serum, and inject replacement fluid into the living body instead. In filtration-type artificial kidney devices, the development of a method that eliminates the need to discard serum containing useful components is awaited. An effective method other than dialysis and filtration is to fill a container with an adsorbent such as activated carbon or alumina that has the property of adsorbing nitrogen-containing compounds such as urea, and allow blood from the artery to pass through the container. There is a method of adsorbing and removing nitrogen-containing compounds. The adsorption method using activated carbon has a much better ability to remove nitrogen-containing compounds than the above-mentioned dialysis method. However, according to this adsorption method, among nitrogen-containing compounds, uric acid and creatinine are adsorbed relatively easily, but the amount of urea adsorbed is relatively small, so a fairly large amount of adsorbent is required. Another major drawback is that when blood comes into direct contact with the adsorbent, the active ingredients in the blood are also adsorbed. The inventors of the present invention have conducted intensive studies to overcome the drawbacks of hemodialysis, filtration, and adsorption methods as described above, and to effectively utilize the advantages of these methods. In addition, nitrogen-containing fibrous activated carbon made from polyacrylonitrile fibers was selected as the activated carbon.
In addition, we have found that it is very effective to adsorb and desorb the adsorbent alternately or in a rotating manner. The present invention provides a method for removing toxic substances such as urea contained in the filtrate obtained by filtering blood from an artery through an ultrafiltration membrane in an artificial kidney device using an ultrafiltration method. 2 or 2 filled with nitrogen fibrous activated carbon adsorbent
One or more adsorbers are used alternately or in rotation, with one or more adsorbers adsorbing toxic substances, while the adsorbed adsorbers not being used for adsorption desorb toxic substances. , a method for removing toxic substances in an artificial kidney device, characterized by returning the regenerated filtrate to the vein. The present invention will be explained in detail below. Blood from the patient's artery is first introduced into an ultrafiltration device, and the filtered filtrate containing urea, uric acid, creatinine, etc. is led to the next polyacrylonitrile-based fibrous activated carbon adsorption device. The patient's unfiltered blood is either returned to the patient's body as is, or mixed with purified serum from which toxic substances have been adsorbed and then returned to the patient's veins. The filtrate containing urea and the like is guided to a fibrous activated carbon adsorber, where toxic substances such as urea, uric acid, and creatinine are adsorbed and removed. Two or more fibrous activated carbon adsorbers are used, and the flow of the filtrate and desorption aqueous solution passing through the adsorbent layer is controlled by an automatic switching device. That is, while one adsorber is adsorbing and removing toxic substances from the filtrate, another adsorber is desorbing them.
In the case of this method, it is preferable to use three adsorbers. A combination configuration in which adsorption is performed in two devices and desorption is performed in one device is most preferable from the viewpoint of efficiency in terms of time and the like. As for the aqueous solution for desorption, an aqueous solution equivalent to a replacement fluid is used to prevent the electrolyte concentration of serum from diluting. However, it is also possible to use water at the beginning of the desorption process. The amount of urea that must be excreted from the human body is very large. However, as mentioned above, activated carbon has the disadvantage that it reaches a saturation point in a short period of time when adsorbing urea. Therefore, a large amount of activated carbon is required to remove urea.
In order to solve this problem, the present inventors adopted a method of adsorbing while regenerating polyacrylonitrile-based fibrous activated carbon, as described above. According to the method of the invention, the contact with the adsorbent can be shortened and removal of the active ingredient can be avoided. In the present invention, by repeating adsorption and desorption using a small amount of fibrous activated carbon in a short period of time, the amount of activated carbon in the adsorber can be reduced to a small amount, so the artificial kidney device can be significantly downsized. Depending on the situation, it can be a portable device. In the present invention, nitrogen-containing fibrous activated carbon made from polyacrylonitrile fibers is used. This device has excellent adsorption and desorption performance of urea, especially in desorption performance, so that the artificial kidney device can be made more compact. The nitrogen-containing fibrous activated carbon made from polyacrylonitrile fibers used in the present invention is obtained by the method described in JP-A-51-137694. According to the present invention, only toxic substances are adsorbed and removed from the filtrate obtained by the ultrafiltration membrane, and then returned to the body. There is no need for fluid replacement upon disposal, making it a very rational system. In the method of the present invention, a system as illustrated in FIG. 1 is used. The present invention will be explained in more detail according to this system diagram. Blood directed from the patient's artery enters the ultrafilter 3 through tube 1 and returns via tube 2 to the patient's vein.
On the other hand, the filtrate filtered through the ultrafiltration membrane 4 of the ultrafilter 3 is led to a pipe 5 and enters the fibrous activated carbon adsorbent 7 by a pump 6. The filtrate leaving the adsorbent 7 passes through a tube 8, merges with the blood in the tube 2, adjusts the electrolyte if necessary, and returns to the patient's vein. For desorption of the fibrous activated carbon adsorber, the aqueous desorption solution entering from the desorption aqueous solution inlet 9 is pumped through the pump 10.
After being led to the fibrous activated carbon adsorber 7 and desorbing the toxic substances, the aqueous desorption solution containing the toxic substances is discarded from the aqueous desorption solution outlet 11. It is clear from the following experimental examples that the present invention is superior to conventional methods. Blood taken from the patient's artery was first passed through an ultrafiltration device, and the resulting filtrate was subjected to adsorption and desorption experiments for the urea contained therein. Table 1 shows the results.

[Table] Looking at the column next to "Desorption" at the bottom of Table 1, the initial concentration at the time of desorption is 0, but after 3 minutes (min) it reaches 32.3 mg%, and this is essentially maintained for 30 minutes. This means that the concentration during desorption reached equilibrium in just 3 minutes, and desorption was carried out effectively.According to this, when nitrogen-containing fibrous activated carbon was used,
It can be seen that urea was easily and effectively desorbed in an extremely short period of time. In the present invention, nitrogen-containing fibrous activated carbon (PAN-based ACF) made from polyacrylonitrile fibers is used. It has excellent adsorption and desorption effects for harmful substances such as creatinine. In both AC and ACF, urea is generally difficult to adsorb and easily becomes saturated, but as mentioned above,
In the case of PAN-based ACF, it is easy to desorb urea, and the desorbed and regenerated ACF can be used repeatedly. Moreover, PAN-based ACF can be recycled in a short time, so only a small amount of it can be used.
Since adsorption and desorption can be carried out in a short time, the device to which the method of the present invention is applied can be made smaller and simpler. On the other hand, in the case of AC, PAN-based
It is the same as ACF, but its drawback is that it has a slow desorption speed, making it unsuitable for recycling. Used ACs are normally disposed of, but if you try to recycle them, you will need a fairly large piece of equipment. Comparative experimental results regarding urea desorption using AC are shown in Table 2.

[Table] According to the results in Table 2, when AC was used, the time required to reach a concentration of 32.3 mg% during desorption was 30 minutes.
Compared to the 3 minutes required to reach the same 32.3 mg% using ACF, the time required using AC is actually 10 times longer. The effects of the present invention can be summarized as follows. As is clear from the results in Table 1, the present invention can reduce the amount of urea in the blood to approximately 3/4 of the initial amount (in other words, the amount of urea adsorbed and removed is reduced to approximately 3/4 of the initial amount). (The amount of urea remaining without being adsorbed is approximately 3/4 of the original amount.) If the amount of urea is reduced to this extent, no problem will occur even if the filtrate is returned to the human blood. According to the present invention, by combining an ultrafiltration method and a fibrous activated carbon adsorbent, urea, uric acid,
It can effectively remove toxic substances such as creatinine, significantly shorten treatment time, and allow long-term use. According to the present invention, the device can be made small and portable, and in addition, it is considerably inexpensive since it does not require the use of dialysate or fluid replacement. The method of the present invention solves the problem of not being able to maintain a mass balance, which was the biggest drawback of conventional filtering artificial kidneys, and from this point alone, the present invention is revolutionary. It can be said to be a thing.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the method of the present invention. 3: ultrafilter, 4: ultrafiltration membrane, 7: fibrous activated carbon adsorber, 9: inlet of aqueous solution for desorption, 11: outlet of aqueous solution for desorption.

Claims (1)

[Claims] 1 In removing toxic substances such as urea contained in the filtrate obtained by filtering blood from the artery through an ultrafiltration membrane in an ultrafiltration artificial kidney device, a nitrogen-containing fibrous material made from polyacrylonitrile fiber is used. Two or more adsorbers filled with activated carbon adsorbent are used alternately or in rotation, with one or more adsorbers adsorbing the toxic substance, while the adsorbed material not being used for adsorption is removed. A method for removing toxic substances in an artificial kidney device, characterized by desorbing toxic substances in an adsorption device and returning the regenerated filtrate to the vein.