GB2083761A - A combination sorbent, dialyser - Google Patents

Abstract

A combination sorbent dialyser comprises a series connection of one or more haemodialysis units 1 with one or more haemoperfusion units 2. The haemoperfusion units may be arranged on one or both sides of the haemodialysis units. Each haemoperfusion unit may comprise one or more adsorption units with the same or different adsorbent substances or ion exchangers 7. Filters 11 may also be provided. <IMAGE>

Description

SPECIFICATION A combination sorbent dialyser Acute and chronic kidney failure occurs increasingly in clinical practice. In man the functioning of the kidneys can be taken over an extracorporeal system as is known. This "artificial kidney" system involves technical equipment or apparatus and the principle of filtration or exchange. This invention relates to an apparatus for a new mechanism of exchange, a so-called combination sorbent dialyser.

The main known form of treatment for chronic kidney deficiency is still haemodialysis. Therefore this invention is based on the fact that haemodialysis has proved to be very good clinically for 20 years and has good compatibility. The increase in the use of short-term dialysis raises the problem of rapidly and deliberately eliminating those substances which have a uraemic effect. This is a problem which is of very great importance of course particulaly when miniaturising the systems of apparatus and exchange such as arise for example with the portable kidney.

It must be said that haemodialysis involves a relatively high technical cost. Its most significant disadvantage is its limited ability to remove substances selectively. Its effectiveness for removing certain substances is chiefly a question of the molecular weight of those substances which are to be removed. Another method of treatment especially designed for acute kidney deficiency is haemoperfusion. The essential advantage of haemoperfusion is the low technical cost of carrying out the treatment as compared to haemodialysis. In addition there is the principal advantage that absorbent substanaces may be made selective, i.e. they may be changed so that only certain non-physiological substances are adsorbed.If the method of haemoperfusion is used to treat chronic kidney failure or deficiency then there is a very good chance-of removing these substances which are important symptons of uraemia, such as creatinine, uric acid, organic substances such as phenols and guanidine compounds and medium molecular substances, with the aid of active charcoal, but the disadvantages are unmistakable. This is because, based on the adsorbent substances known at the moment, eliminating uric material, water, electrolyte and hydrogen ions is either not possible at all or only possible to an insigificant degree. With haemoperfusion it is particularly difficult to remove water.Even if, when seen in the light of developments, it does seem possible to remove the water with the aid of water-absorbent gen'as, initially it is still necessary to couple a haemoperfusion capsule with an ultrafilter or a dialyser. This coupling of systems by connecting, one'after another, a dialyser and a haemoperfusion capsule as separate exchange or adsorber mechanisms when used in combination in therapy represents the prior art. Until now it has only been known to combine haemoperfusion and dialysis in the form of the so called sorbent dialyser which is equipped with sorbent membranes.

According to East German Application No. 135565 an artificial kidney is known which consists of a cavity, through which blood flows and which is formed by a dialysing membrane, and a dialysate chamber arranged on the other side of the dialysing membrane and the relationship between the volume of the cavity through which the blood has passed to the volume of the dialysate chamber is 1:100. The artificial kidney contains adsorbents outside the cavity through which the blod passes. This is achieved either by arranging at least one layer which contains absorbents in the dialysing membrane or by providing the adsorbents in the dialysate.Furthermore in accordance with West German Patent Specification No. 2 627 858 there is known a dialysing membrane in the form of bi-component hollow threads comprising regenerated cellulose in which the hollow threads are formed from two layers bonded firmly together. One layer consists of regenerated cellulose and if necessary a cellulose derivative. The other layer is formed from regenerated cellulose with 1 to 95% by weight of adsorbent particles evenly distributed and embedded therein, said absorbent particles having a average particle size of up to 40 Rm.

The type of combined haemodialysisihaemoperfu- sion in the form of the sorbent membrane is not very effective. It does not have any particular advantages as compared to the conventional dialyser either during treatment of acute exogenous toxic reactions or chronic kidney failure or liver failure.

It is an object of the present invention to combine the advantages of haemodialysis with those of haemoperfusion when purifying the blood in an extracorporeal circuit in order to achieve an increase in effectiveness when treating chronic and acute kidney deficiencies or failures.

It is another object of the invention to develop a combination sorbent dialyser which makes it possible to couple the techniques of haemodialysis and haemoperfusion in one exchange apparatus.

According to the present invention, there is provided a combination sorbent dialyser characterised by the series connection of at least one haemodialysis unit and at least one haemoperfusion unit.

During treatment of the patient by dialysis, the blood which is to be purified is passed successively through the haemodialysis units and the haemoperfusion units in order to eliminate from the blood on the one hand uric substances, water, electrolytes and hydrogen ions and on the other hand creatinine, uric acid, organic substances such as phenols, guanidine compounds and medium molecular substances.

Therefore it is advisable to arrange the haemoperfusion units on one or both sides of the haemodialysis unit and also to form the blood inlet and/or the blood outlet of the haemodialysis unit as a haemoperfusion unit. It is advisable if one or more adsorption units having the same or different adsorbents or ion exchangers is/are arranged in a haemoperfusion unit. When treating acute toxic reaction it is therefore possible to connect several suitable adsorption units one after another in order to dissolve the substances which are to be eliminated out of the blood, more particularly with a mixture of toxic reactions. Furthermore, it is advisable to form parts of the blood-conducting system as haemoperfusion units.

It is advisable for adsorbents to be contained in the cavity of the haemodialysis unit through which the blood flows but outside the hollow silk-type membrane or the dialysing surface membrane. It is advantageous if the haemoperfusion unit or the absorption unit is provided on both sides with filter systems. The filter systems ensure that the adsorbents or ion exchangers are fixed in one unit during blood flow.

Preferred embodiments of the present invention will now be described, by way of example only with reference to the accompanying drawings of which Figure 1 shows a combination sorbent dialyser with haemoperfusion units connected before and after the haemodialysis units; and Figure 2 shows a combination sorbent dialyser with a haemoperfusion unit connected after the haemodialysis unit.

In Figure 1 a series connection of a haemodialysis unit 1 with haemoperfusion units 2 arranged on both sides thereof is shown. The dialysis unit 1 comprises hollow fibres 3 embedded in a suitable material. The fibres form a hollow silk-type dialysis membrane.

The blood which is to be purified flows through the cavities 4 of these hollow fibres 3 and also comprises a rinsing solution member 5 which allows the flow of the necessary rinsing solution. Each haemoperfusion unit 2 is formed by a casing 6 which is filled with an absorbent substance 7 or with a mixture of adsorbents. On both sides i.e. at the coupling points with other units or directly at the blood inlet 8 and blood outlets 9 of the blood-conducting system 10 this casing or envelope 6 is limited by a filter-system 11.

The combination sorbentdialysershown in Figure 2 comprises a haemodialysis unit 1 to which a haemoperfusion unit 2 is coupled on one side. The haemoperfusion unit 2 comprises two adsorption units 12 into which different adsorbent substances 7 or adsorbent substances mixtures or ion exchangers are introduced. The adsorption units 12 are limited on both sides by filter systems 11.

This embodiment makes it possible to arrange two or more adsorption units 12 in rows with different adsorbent substances 7 in a single haemoperfusion unit 2 in order to remove quite different poisons from the blood as and when necessary.

The dialysis units 1 and haemoperfusion units 2 can be manufactured in unsterile conditions in accordance with medical requirements in order to be made available to the user, after sterilisation, as a sterile combination sorbent dialyser. The combination sorbent dialyser may alternatively be completed under clinical conditions in accordance with medical requirements, the sterile dialysis 1 and haemoperfusion units 2 or adsorption units being connected together while maintaining sterile conditions.

The medical advantages which are provided by the combination sorbent dialyser in accordance with the invention consist in that the advantages of the haemodialysis unit, such as the additional filtering possibilities, control of the temperature of the blood and the possibility of removing desorbent substances for example are added to those of the fundamental process of haemoperfusion. In relation to specific applications some special advantages can also be stated: When required, substances may be eliminated which are only insufficiently eliminated with the aid of haemodialysis, such substances are inorganic phosphate during short-term dialysis or medium, molecular substances. Thus haemoperfusion may be regarded as an addition to dialysis therapy when treating chronic kidney deficiency.

The dialysis time is reduced by increasing the efficiency when treating chronic kidney deficiency.

An increase in efficiency when treating acute intoxications or toxic reactions more particularly by expanding the spectrum of substances to be eliminated in the case of mixed toxic reactions including an unknown noxious substance.

In the case of treating liver failure, low and medium molecular substances are eliminated efficiently.

Claims (9)

1. A combination sorbent dialyser characterised by the series connection of at least one haemodialysis unit and at least one haemoperfusion unit.

2. A combination sorbent dialyser according to claim 1, wherein haemoperfusion units are arranged on one side only of a haemodialysis unit.

3. A combination sorbent dialyser according to claim 1 wherein haemoperfusion units are arranged on both sides of a haemodialysis unit.

4. A combination sorbent dialyser according to any preceding claim, wherein the blood inlet and/or the blood outlet of the haemodialysis unit is/are formed as a haemoperfusion unit.

5. A combination solvent dialyser according to any of claims 1 to 3 wherein parts of the system for conducting blood are formed as a haemoperfusion unit.

6. A combination sorbent dialyser according to any preceding claim wherein one or more adsorption units having the same or different adsorbent substances or ion exchangers are arranged in the haemoperfusion unit.

7. A combination sorbent dialyser according to any preceding claim wherein the haemodialysis unit has a cavity through which blood flows with a fibrous dialysis membrane and/or a dialysis surface membrane, one or more adsorbent substances being arranged in said cavity but outside the membrane or membranes.

8. A combination sorbent dialyser according to any preceding claim, wherein filter systems are provided on both sides of the haemoperfusion unit.

9. A combination sorbent dialyser substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.