EP0550718A1

EP0550718A1 - Device for continuously collecting a dialysate sample

Info

Publication number: EP0550718A1
Application number: EP92914816A
Authority: EP
Inventors: Gilbert Fellay; Jean-Pierre Gabriel; Pierre Vuilleumier; Gilbert Widmer
Original assignee: Ciposa SA; Ciposa Microtechniques SA
Current assignee: Ciposa SA
Priority date: 1991-07-19
Filing date: 1992-07-17
Publication date: 1993-07-14
Also published as: WO1993002346A1; FR2679334A1; US5404761A; FR2679334B1

Abstract

La présente invention concerne un procédé et un dispositif pour recueillir un échantillon de dialysat en vue de l'analyse qualitative et quantitative du dialysat total recueilli durant le traitement substitutif de l'insuffisance rénale. Selon un mode de réalisation préféré, le dispositif (10) comporte un réservoir tampon (20) constitué par un récipient cylindrique monté sur un séparateur (30). Le séparateur (30) présente une chambre collectrice (36) à la périphérie de laquelle est ménagé un certain nombre de conduits calibrés (39) et (42). Les conduits calibrés (39) débouchent dans une gouttière (38) et le dialysat évacué par ces conduits aboutit dans un conduit d'évacuation (34). Les conduits calibrés (42) aboutissent dans un collecteur (41) qui communique avec un conduit (35). Le dialysat recueilli à la sortie du conduit (34) est destiné à être analysé. Ce dispositif permet d'échantillonner de façon continue le dialysat généré au cours d'un processus de dialyse, la composition de cet échantillon étant représentative de celle de l'ensemble du dialysat produit.The present invention relates to a method and a device for collecting a dialysate sample for the qualitative and quantitative analysis of the total dialysate collected during the replacement therapy for renal failure. According to a preferred embodiment, the device (10) comprises a buffer tank (20) constituted by a cylindrical container mounted on a separator (30). The separator (30) has a collecting chamber (36) at the periphery of which is provided a number of calibrated conduits (39) and (42). The calibrated conduits (39) open into a gutter (38) and the dialysate evacuated by these conduits ends in an evacuation conduit (34). The calibrated conduits (42) terminate in a collector (41) which communicates with a conduit (35). The dialysate collected at the outlet of the conduit (34) is intended to be analyzed. This device makes it possible to continuously sample the dialysate generated during a dialysis process, the composition of this sample being representative of that of the entire dialysate produced.

Description

DEVICE FOR CONTINUOUSLY COLLECTING A SAMPLE FROM A DIALYSATE

The present invention relates to a device for continuously collecting a dialysate sample for analysis, this sample being representative, by its composition and its volume, of the composition and of the volume of all of the dialysate generated during the dialysis process. , this device comprising first means for separating a determined proportion of this dialysate throughout the dialysis process, and second means for directly removing the remainder of this dialysate.

To assess the effectiveness of dialysis and orient the treatment of patients, it is important to determine, with a certain precision, the mass transfer, of blood in the dialysate, of water and of various solutes such as urea, sodium, potassium salts and phosphates. Currently, these determinations are made by the measurement known as "clearances" calculated from the blood flow through the artificial kidney, and the plasma concentrations at the entry and at the exit of this kidney. They imply hypotheses on the kinetics of transfers, unsustainable for many solutes. A much more reliable method, known but not applicable in current practice, involves harvesting the entire dialysate, that is to say 80 to 150 liters per session and per patient and, after a mixture ensuring homogeneity, the measurement of the total volume of the dialysate and the measurement of the solute concentration. This is why methods are commonly used which consist in sampling the dialysate in order to take the volume of material necessary for analyzing it. More or less complex devices are used for this purpose. Such an apparatus is for example described by American patent No. 3,512,418 which is theoretically designed to take a predetermined percentage of a liquid substance circulating through a conduit. Similar devices are described by American patent No. 3,942,388 and French patent No. 1,181,412.

These devices or these devices are unfortunately not very precise and do not make it possible to obtain a sample of material to be analyzed which is the exact reflection of the total material discharged. This constitutes a major drawback, in particular in the case of the analysis of the dialysate removed by a dialysis machine. In fact, for this particular application, it is essential to have a sample which strictly corresponds to the dialysate obtained from the dialysis machine in order to allow the parameters of the dialysis operation to be precisely adjusted.

The present invention proposes to offer a device for the implementation of this process making it possible to collect a sample of dialysate whose composition is perfectly representative of the composition of the entire dialysate and whose volume is a known fraction of the total volume dialysate.

For this purpose, the device according to the invention is characterized in that it comprises a buffer tank through which the entire dialysate passes, this tank being associated with a separator equipped with said first means and said second means.

According to a preferred embodiment the separator is mounted at the base of the buffer tank and said first and second means are arranged so that the free level of liquid contained in the buffer tank is constantly above the upper level of the separator.

Said first means advantageously comprise at least one calibrated conduit and said second means comprise a series of calibrated conduits, these calibrated conduits being all identical, and situated at the same height relative to the free surface of liquid in the buffer tank.

The calibrated conduits are preferably arranged radially and are regularly spaced on a circular sector centered on the axis of the buffer tank. In a particularly advantageous manner, the calibrated conduits are arranged to ensure communication between a receiving chamber formed at the base of the buffer tank and in communication with it and a gutter.

According to this embodiment, the gutter is arranged to communicate with a flow by means of a funnel and the level of liquid in the gutter is arranged below the calibrated conduits.

The calibrated conduit is preferably arranged to ensure communication between a receiving chamber formed at the base of the buffer tank and a collector.

The collector is preferably provided with a drain and the level of liquid in the collector is lower than the level of the calibrated conduit.

According to an advantageous construction in that it is compact, the separator comprises a central cone, the apex of which is located on the axis of the buffer tank and the base of which is located near the calibrated conduits and partially delimits said receiving chamber.

The buffer tank preferably comprises a nozzle for supplying the liquid, the section of which is substantially equal to the sum of the sections of the flows, so that the flow rate of entry into the buffer tank is substantially equal to the total flow rate of exit from the device. and that the level in the tank remains substantially constant.

The inlet nozzle preferably opens into the buffer tank via a bundle of channels distributed substantially radial with respect to said nozzle.

The present invention will be better understood with reference to the description of an embodiment and the accompanying drawing in which: fig. 1 represents a schematic view illustrating the principle which inspired the method according to the invention,

fig. 2 represents a view in longitudinal section of a preferred embodiment of the device according to the invention, and

fig. 3 shows a plan view of the device according to the invention.

With reference to fig. 1, the device 10 for collecting a sample of a dialysate for analysis is connected to the output of a dialysis equipment 11 which receives a basic solution conveyed by

'a conduit 12 and rejects a dialysate which is directed by a conduit 13 to the device 10. It is important that the doctor knows the flow rate and the composition of the initial dialysate but also the flow rate and the composition of the output dialysate. Since the volumes involved are too large for us to be able, in current practice, to systematically collect all of the dialysate in the clinic, the purpose of the device 10 is to separate the dialysate into two streams, respectively 14 and 15 , which have exactly the same composition. The volume 15 is intended to be collected in an appropriate container 16 for analysis while the stream 14 is directly discharged to the sewer. The composition of the two flows being identical, and the ratio of the flow rates known, the precise analysis of the liquid collected in the container 16 makes it possible to provide the information required so that the doctor knows the parameters of the dialysate necessary for the conduct of the treatment.

The device 10 includes a buffer tank 17 which makes it possible to collect the dialysate at the outlet of the dialysis equipment 21 before releasing this dialysate towards the separator proper which separates the two flows 14 and 15. It is essential that the buffer tank 17 is constantly supplied and that the height of the liquid it contains is sufficient for the separator to function properly. In order for this condition to be fulfilled, it is advantageously possible to provide a level control element 18 which maintains the level of the liquid on a mark A or in an area between two marks A and B. In practice, we determine the conduits which define the flows 14 and 15 in such a way that the volume of dialysate collected by the buffer tank corresponds substantially to the volume of dialysate discharged, so that the level remains automatically constant. When the level rises in the tank, the pressure in the evacuation zone increases and the flow increases, which has the effect of readjusting the level. In practice, there is self-regulation of the level.

Fig. 2 illustrates a preferred embodiment of the device 10. In this embodiment, the buffer tank 20 is substantially cylindrical and comprises at its upper end a closure plug 23 provided with a nozzle 24 in which the conduit 13 (defined in Fig. 1). This endpiece 24 communicates with the interior of the buffer tank 20 by at least one channel 25 _" and preferably a bundle of channels 25 regularly distributed around the endpiece 24.

The separator 30 consists of a block mounted at the lower end of the buffer tank and comprising two flows 34 and 35 respectively corresponding to the respective flows 14 and 15. For this purpose, the separator comprises a receiving chamber 36 formed in its upper part and having an annular shape coaxially surrounding a distributor cone 37. This receiving chamber communicates with a gutter 38, at least partially annular, via a number of calibrated conduits 39. The dialysate which flows in this gutter 38 is collected by a funnel 40 and ends in conduit 34 for its evacuation. Furthermore, the receiving chamber 36 communicates with a collector 41 by means of at least one calibrated conduit 42. The dialysate collected in the collector 41 is conveyed by the conduit 35 to the analysis container 16.

As shown in the plan view of FIG. 3, the calibrated conduits 39 and 42 are all identical. In the embodiment shown, the conduits 39 which communicate with the gutter 38 are nineteen and the conduit 42 which communicates with the manifold 41 is unique. However, this proportion could be different and the number of conduits 39 and 42 could be modified on other constructions. In this realization 1/20 th of the volume of dialysate is collected for its analysis. The dialysate sampling is carried out continuously so that at all times the composition of the dialysate collected and corresponding to flow 15 is identical to that of the dialysate removed and corresponding to flow 14.

It is particularly important that the entry into the device is free and that the upper level of the liquid in the buffer tank is free. Furthermore, it is essential that all the conduits 39 and 42 are identical and that they open into discharge chambers constituted by the funnel 40 on the one hand and the collector 41 on the other hand, where the liquid also has a free surface respectively C & D. Therefore no constraint disturbs the free flow of the flows 14 and 15. The pressure upstream of the conduits 39 and 42 is absolutely identical because it is given by the column of liquid contained in the buffer tank. The level variations generate pressure variations which are the same for all the conduits.

Since the duct outlets are free, the divider does not generate any back pressure on the part of the switchgear located upstream.

Finally, the construction of this device is simple and precise. The calibration is particularly easy because all the conduits are identical. The star arrangement allows a compact construction and an efficient separation of the jets at the outlet of the conduits.

The present invention is not limited to the embodiments described but can undergo different modifications and present various variants obvious to a person skilled in the art. In particular, according to another variant, the first separation means could comprise at least one metering pump, for example a peristaltic pump, which would be activated intermittently, for example every ten seconds.

Claims

1. Device for continuously collecting a dialysate sample for analysis, this sample being representative, by its composition and its volume, of the composition and of the volume of the entire dialysate generated during a dialysis process , this device comprising first means for separating a determined proportion of this dialysate throughout the dialysis process, and second means for directly removing the remainder of this dialysate, characterized in that it comprises a buffer tank (20) crossed by the entire dialysate, this reservoir being associated with a separator (30) equipped with said first means and said second means.

2. Device according to claim 1, characterized in that the separator (30) is mounted at the base of the buffer tank and in that said first and second means are arranged so that the free level of liquid contained in the buffer tank is located constantly above the upper level of the separator.

3. Device according to claim 2, characterized in that said first means comprise at least one calibrated conduit (42) and said second means comprise a series of calibrated conduits (39) and in that these calibrated conduits are all identical, and are located at the same height from the free surface of liquid in the buffer tank.

4. Device according to claim 3, characterized in that the calibrated conduits (39) are arranged radially and are regularly spaced on a circular sector centered on the axis of the buffer tank.

5. Device according to claim 3, characterized in that the calibrated conduits (39) are arranged to ensure communication between a receiving chamber (36) formed at the base of the buffer tank and in communication with it and a peripheral gutter (38) .

6. Device according to claim 5, characterized in that the gutter (38) is arranged to communicate with a flow (34) via a funnel (40) and in that the level (C) of liquid in the gutter is arranged below the calibrated conduits (39 ⁾ .

7. Device according to claim 3, characterized in that the calibrated conduit (42) is arranged to ensure communication between a receiving chamber (36) formed at the base of the buffer tank and a collector (41).

8. Device according to claim 7 _» characterized in that the coEector (41) is provided with a flow (35) and in that the level (D) of liquid in the collector (41) is lower than the level of the calibrated conduit (42).

9. Device according to claim 2, characterized in that the separator comprises a central cone whose apex is located on the axis of the buffer tank and whose base is located near the calibrated conduits (39, 42) and partially delimits said receiving chamber (36).

10. Device according to claim 1, characterized in that the buffer tank (20) comprises a nozzle (24) for supplying the liquid, the section of which is substantially equal to the sum of the sections of the flows (34, 35), in such a way that the input flow rate into the buffer tank is substantially equal to the total output flow rate of the device and that the level (A) in this tank remains substantially constant.

11. Device according to claim 10, characterized in that the end piece (24) for inlet opens into the buffer tank via a bundle of channels (25) arranged substantially radially with respect to said end piece.