DEVICE FOR COLLECTING SAMPLES
The present invention relates to a device (20) for collecting dialysate samples (42). The device (20) comprises an inlet (22) for receiving a flow of dialysate, a plurality of outlets (24) for providing a flow of saturated dialysate and means (26) for sequential selection of one of the outlets (24). The sequential selection means (26) are activated only by the flow of dialysate received from the inlet (22). The present invention further relates to a system for peritoneal dialysis comprising such device (20).
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The invention relates to a device for collecting fluid-samples in circuits, e.g. in circuits for peritoneal dialysis (PD), in particular for automatic peritoneal dialysis (APD).
Peritoneal dialysis is a treatment for purifying the blood of a patient affected by renal insufficiency. Unlike conventional haemodialysis, in peritoneal dialysis the membrane used to filter the blood does not consist of an artificial element provided outside the patient's body, but consists of the peritoneum. The peritoneum is a membrane situated in the abdomen and surrounding the internal organs. Since it is thin and highly vascularized it is possible to apply the physical principle of dialysis directly inside the patient's body.
Peritoneal dialysis requires a catheter which must be introduced permanently inside the abdomen so as to allow connection of the peritoneal cavity to an external circuit. The external circuit generally comprises a bag containing pure dialysate and a drainage outlet.
The treatment of peritoneal dialysis generally comprises a first infusion phase (or fill) during which the pure dialysate is supplied via the catheter to the peritoneal cavity. During the second so-called dwell phase, during which no external operations are required, dialytic exchange between the patient's blood and the dialysate takes place. During the third and final drainage stage (or drain) the saturated dialysate is removed from the peritoneal cavity.
In order to obtain satisfactory purification of the blood, the entire treatment cycle described above must be repeated several times in succession over the course of 24 hours. In the case of APD, the various treatment cycles are performed in succession throughout the night by means of a special machine called an “automatic cycler” which automatically sets and regulates the fill, dwell and drain phases.
In order to monitor the effectiveness and quality of the peritoneal dialysis treatment, it is known to analyse samples of saturated dialysate which is discharged.
For this reason, it has proved to be extremely useful to collect the samples of used dialysate at regular intervals and automatically, i.e. without the need for any intervention either by the patient or by other assisting persons. It is in fact desirable to eliminate any need for intervention, especially during the night, otherwise one of the main advantages of this treatment method is lost.
For these reasons there exists the need to introduce into the circuit a device which autonomously performs periodic sampling of dialysate samples.
A device of this type is described in WO 99/06082. This device, however, is not without drawbacks. It is, in fact, extremely complex since it is also intended to perform other functions, such as that of the cycler itself or also the preparation of the optimum dialysate solution for the individual patient.
The object of the present invention is therefore to overcome the drawbacks identified above in connection with the prior art.
In particular, a task of the present invention is to provide a device for collecting dialysate samples, having an extremely simple and robust structure and mode of operation.
Moreover, a task of the present invention is to provide a device for collecting dialysate samples, which does neither require external supply sources nor input control signals other than the flow rates.
The abovementioned object and tasks are achieved by a device for collecting dialysate samples according to claim 1.
The characteristic features and the further advantages of the invention will emerge from the description, provided hereinbelow, of a number of examples of embodiment, provided purely by way of a non-limiting example, with reference to the accompanying drawings in which:
The present invention relates to a device for collecting dialysate samples 42 denoted overall by 20. The device 20 comprises an inlet 22 for receiving a flow of dialysate, a plurality of outlets 24 for providing a flow of saturated dialysate and means 26 for sequential selection of one of the outlets 24. The sequential selection means 26 are activated only by the flow of dialysate received from the inlet 22.
In the description of the invention, reference will be made to the spatial arrangement of the device 20 which ensures correct operation thereof. During operation of the device 20, in fact, the force of gravity plays a decisive part, especially in the embodiments according to FIGS. 2 to 5. In particular, it will be assumed below that the force of gravity is directed as shown by the vector g in FIGS. 2 to 5 (side views).
With particular reference to the accompanying
In
As can be seen in
As already mentioned above, the sequential selection means 26 are activated only by the flow or by the temperature of saturated dialysate received from the inlet 22. In other words, the sequential selection means 26 do not require the supply of any external power, either for the operation of sensors or transducers which detect the status of the device 20, or for the operation of actuators or motor driven actuators which select the desired outlet 24 for the flow. The physical principles on which operation of the sequential selection means 26 are based represent the main differences between the various embodiments of the device 20 according to the invention.
The embodiment of the device 20 shown schematically in FIGS. 2 to 4 is now described in detail. According to this embodiment, the device comprises a main chamber 130 housing a float 132 which occupies most of its volume. In particular, the float 132 is able to perform substantially only one movement: it is able to move vertically from a rest position substantially resting on the bottom 131 of the main chamber 130 into a working position substantially resting on the roof 133 of the main chamber 130. This movement is indicated by the arrow v in
A flexible actuator 134 is mounted on the float 132. The flexible actuator 132 is preferably mounted on the top surface of the float 132, perpendicularly with respect thereto. The flexible actuator 134 is designed to engage selectively with a single tooth of a plurality of teeth 136 integral with a hollow slider 138. The hollow slider 138 has a head 140 designed to slide inside a multiple connector 144 which defines the plurality of outlets 24. The pitch p which separates two successive teeth 136 on the hollow slider 138 is equal to the pitch p which separates two successive outlets 24 in the multiple connector 144. The head 140 comprises a radial opening 146 situated between two seals 141 for ensuring a seal against the inner walls of the multiple connector 144. Moreover, at the opposite end to the head 140, the hollow slider 138 is in fluid communication with the main chamber via an opening 148 formed in a wall of the latter in the vicinity of the bottom. In particular, the opening 148 is formed in a position such that it is covered by the float 132 when the latter is at the bottom end of its travel path and is uncovered when the float 132 is at the top end of its travel path. The volume of the float 132 is designed in order to overcome the friction resistance generated by head 140 during its movement along the multiple connector 144.
Finally, the device 20 comprises a drainage line 28 which extends from the bottom 131 of the main chamber 130. The drainage line 28 may comprise a valve for regulating and/or interrupting the flow or may comprise, preferably, a narrowing for slowing down significantly the flow inside it.
Operation of the device 20 according to the embodiment shown in FIGS. 2 to 4 is now described. When the automatic cycler 14 activates the start of the drain phase, the saturated dialysate leaving the catheter 12 flows along the drainage line 18 and reaches the inlet 22 of the device 20. The flow of the saturated dialysate reaches the main chamber 130. The configuration of the device 20 ensures that the incoming mass of dialysate is positively balanced. The drainage line 28, in fact, is completely closed (in the embodiments comprising a valve) or is greatly narrowed. It is thus ensured that any outgoing flow along the drainage line 28 is significantly less than the incoming flow through the inlet 22. This ensures that the volume of saturated dialysate inside the main chamber 130 increases continuously, generating a floating thrust on the float 132. The floating thrust raises the float from the rest position (see arrow v in
A first effect is that of freeing the opening 148, allowing the dialysate to access it. The other effect is that the floating force is transmitted to the flexible actuator 134 which is formed so as to engage with the first tooth 136.a, adapting its form thereto. The flexible actuator 134 then converts the vertical movement of the float 132 (arrow v) into a horizontal movement of the hollow slider 138 (arrow h). The horizontal movement of the hollow slider 138 produces the forward movement of the head 140 over a distance p inside the multiple connector 144. The head 140 thus isolates the first outlet 24.a between the two seals 141 and substantially aligns the radial opening 146 with it.
According to some embodiments, each bag 52 is able to contain the entire volume of saturated dialysate expelled during the entire drain phase. In such a case a small quantity of dialysate (for example 1%) to be used as a sample will be subsequently removed from the entire volume, probably the next day in the clinic. According to other embodiments, each bag 52 is instead able to contain only a small quantity of dialysate to be used as a sample, while all the remaining volume is drained in a manner known per se.
At the end of the drain phase, the flow of saturated dialysate to the inlet 22 is interrupted. Both in the case where the drainage line 28 comprises a valve and in the case where it is only greatly narrowed, the volume of dialysate inside the main chamber 130 starts to diminish. In the first case, in fact, the valve during this phase is open, allowing the flow along the drainage line 28. In the second case, however, the outlet flow, although minimal, is not balanced by any incoming flow. The volume of saturated dialysate inside the main chamber 130 diminishes, reducing the floating thrust on the float 132 which gradually moves downwards from the working position into the rest position. The downwards movement of the float 132 causes the opening 148 to be covered again and disengages the flexible actuator 134 from the first tooth 136.a. As will be clear to a person skilled in the art, the flexible actuator 134 and the teeth 136 are formed so as not to transmit any movement to the hollow slider 138 during the downward movement of the float 132. The head 140 of the hollow slider 138 therefore maintains the position assumed previously inside the multiple connector 144. The configuration thus assumed by the device 20 is partially shown in the
This operating cycle may be repeated any number of times required until, at the end of the APD treatment, the last outlet 24.n is reached (as shown in
The figures show a multiple connector 144 with five outlets, but it is obvious that, in order to satisfy specific requirements, it is possible to provide a different number of outlets without any substantial modification of the device 20.
The embodiment of the device 20 shown schematically in
Helical grooves 250 are formed in the float 232 and are designed to engage with corresponding shaped threads 250 formed inside the main chamber 230. A duct is formed inside the float 232 and connects an opening 248 in the bottom of the float to another opening 246 formed at the top.
The roof 233 of the main chamber 230 performs the function of a multiple connector 244 and defines the plurality of outlets 24. The outlets 24 are situated at the same radial distance from the axis of the main chamber 230 and are circumferentially spaced in an equidistant manner. The angle α which separates two successive outlets 24 on the roof 230 is equal to the angle α of extension of the shaped threads 254. It should be noted that
The bottom 231 of the main chamber comprises centring means 258 designed to cooperate with the bottom of the float 232.
Finally, the device 20 comprises a drainage line 28 which extends from the bottom 231 of the main chamber 230. The drainage line 28 may comprise a valve for regulating and/or interrupting the flow or may comprise, preferably, a narrowing for slowing down significantly the flow inside it.
Operation of the device 20 according to the embodiment shown in
At the end of the drain phase, the flow of saturated dialysate to the inlet 22 is interrupted. Both in the case where the drainage line 28 comprises a valve and in the case where it is only greatly narrowed, the volume of dialysate inside the main chamber 230 starts to diminish. In the first case, in fact, the valve during this phase is open, allowing the flow along the drainage line 28. In the second case, however, the outlet flow, although minimal, is not balanced by any incoming flow. The volume of saturated dialysate inside the main chamber 230 diminishes, reducing the floating thrust on the float 232 which gradually moves downwards from the working position into the rest position. As will be clear to a person skilled in the art, the helical grooves 250 and the shaped threads 254 are formed so as not to produce any movement of the float 132 during its downward movement. The opening 246 therefore maintains the angular position assumed previously.
At this point the device 20 is ready for the next operating cycle which, in a manner entirely similar to that described above, will cause rotation of the float 132 through a further angle α so as to bring the opening 246 opposite the second outlet 24.b. A second sample 42.b is thus collected inside the second bag 52.b (see
This operating cycle may be repeated any number of times required until, at the end of the APD treatment, the last outlet 24.n is reached.
The embodiment of the device 20 shown schematically in
The shape memory alloy (SMA) which forms the thruster 366 is able, in a manner known per se, to modify its structure when there is a variation in temperature. In this specific case, the SMA is able to pass from a maitensitic structure, which is stable at temperatures less than 34° C., to an austenitic structure, which is stable at temperatures higher than 34° C. The change in the internal structure of the alloy results in a corresponding change in shape of the thruster 366. In particular,
The annular chamber 330 is in fluid communication with the central chamber 361 via a passage 348. In particular, the passage 348 is formed in a position such that it is covered by the curved slider 364 when the latter is at the anti-clockwise end of its travel path and is uncovered when the curved slider 364 is at the clockwise end of its travel path.
The curved slider 364 is provided with first engaging means 370 designed to engage with corresponding second engaging means 372 provided on the rotor. The engaging means 370 and 372 are formed so as to allow engagement in one sense only, in the example in question in the clockwise direction.
The roof 333 of the main chamber 361 of the stator 360 performs the function of a multiple connector 344 and defines the plurality of outlets 24. Each outlet 24 of the device 20 is connected to a tube 25 in facts. In
The rotor 362 comprises an opening 346 on its top wall 363 (see also
Operation of the device 20 according to the embodiment shown in FIGS. 6 to 7 is now described. When the automatic cycler 14 activates the start of the drain phase, the saturated dialysate leaving the catheter 12 flows along the drainage line 18, reaches the inlet 22 of the device 20 and accesses the annular chamber 330. This results in an increase of the temperature inside the annular chamber 330 from the ambient temperature (typically less than 34° C.) to the body temperature of the patient P (greater than 34° C.). This thus produces the change in the structure of the SMA and therefore the change in shape of the thruster 366. The thrust in the clockwise direction imparted to the curved slider 364 thus overcomes the thrust of the spring 368, therefore moving the curved slider 364 to the clockwise end of its angular travel path. In other words, the change in shape of the thruster 366 moves the curved slider 364 from the position shown in
At this point the device 20 is ready for the next operating cycle which, in a manner entirely similar to that described above, will cause renewed rotation of the curved slider 364 so as to impart a further rotation of the rotor 362 through a further angle β and thus bring the opening 346 opposite the second outlet 24.b. A second sample 42.b is thus collected inside the second bag 52.b (see
This operating cycle may be repeated any number of times required until, at the end of the APD treatment, the last outlet 24.n is reached.
The embodiment of the device 20 shown schematically in
Operation of the device 20 according to the embodiment shown in
When the flow of saturated dialysate is interrupted, the remaining dialysate flows completely from the device 20 into the sample bag 52.a. The temperature inside the annular chamber 330 decreases producing a new change in the shape of the thruster 366 which 366 moves back the curved slider 364. The anti-clockwise rotation of the curved slider 364 does not cause the movement of the rotor 362 and the outlets 24 maintain the angular position assumed previously.
The device 20 is ready for the next operating cycle. A new rotation of the curved slider 364 will impart a further rotation of the rotor 362 through a further angle β bringing the second outlet 24.b in line with the opening 346.
This operating cycle may be repeated any number of times required until, at the end of the APD treatment, the last outlet 24.n is reached.
The difference between the two above described embodiments, the one shown in
FIGS. 6 to 9 show multiple connectors 344 with six outlets, but it is obvious that, in order to satisfy specific requirements, it is possible to provide a different number of outlets without any substantial modification of the device 20.
With reference to the embodiments of the device for collecting dialysate samples described above, the person skilled in the art may, in order to satisfy specific requirements, make modifications to and/or replace elements described with equivalent elements, without thereby departing from the scope of the accompanying claims.
Claims
1. Device (20) for collecting dialysate samples (42), comprising:
- an inlet (22) for receiving a flow of dialysate;
- a plurality of outlets (24) for providing a flow of saturated dialysate;
- means (26) for sequentially selecting one of said outlets (24);
- wherein the sequential selection means (26) are activated only by the flow of dialysate received from the inlet (22).
2. Device (20) according to claim 1 wherein said plurality of outlets (24) is defined by a multiple connector (144, 244, 344).
3. Device (20) according to claim 1 or 2 wherein said sequential selection means (26) comprise a float (132, 232) suitable to generate a floating thrust when reached by said flow of dialysate.
4. Device (20) according to claim 3 wherein said float (132) is able to move vertically from a rest position to a working position, so as to act on a hollow slider (138) designed to slide inside said multiple connector (144).
5. Device (20) according to the preceding claim wherein said hollow slider (138) comprises a radial opening (146) adapted to be selectively aligned with any of said outlets (24).
6. Device (20) according to claim 2 wherein said float (232) is able to move vertically from a rest position to a working position and to rotate about its vertical axis, with respect to said multiple connector (244).
7. Device (20) according to the preceding claim wherein said float (232) comprises a duct connecting an opening (248) in the bottom of the float to another opening (246) formed at the top of the float, the opening (246) being adapted to be selectively aligned with any of said outlets (24).
8. Device (20) according to claim 1 or 2 wherein said sequential selection means (26) comprise a thruster (366) made of a shape memory material and suitable to change its shape when reached by said flow of dialysate.
9. Device (20) according to the preceding claim wherein said thruster (366) is suitable to act on a rotor (362) comprising an opening (346), the opening (346) being adapted to be selectively aligned with any of said outlets (24).
10. Device (20) according to any of the preceding claims, further comprising a drainage line (28).
11. A system for peritoneal dialysis comprising a device (20) according to any of the preceding claims, having a tubeset comprising:
- a supply line (18) for connection or being connected to the inlet (22) of the device (20) and
- at least one repository (52) for connection or being connected to one of the outlets (24) of the device (20).
12. A system according to claim 11 comprising a drainage line (28) connected to the device (20).
Type: Application
Filed: May 27, 2010
Publication Date: Oct 4, 2012
Applicant: FRESENIUS MEDICAL CARE DEUTSCHLAND GMBH (BAD HOMBURG)
Inventors: ALAIN VENERONI (SPINO D'ADDA), MIHAI DIGA (FRIEDRICHSDORF), DANIEL DAETWYLER (PIETERLEN), DOMINIK UEHLINGER (KERZERS)
Application Number: 13/322,993
International Classification: A61M 1/28 (20060101); G01N 1/12 (20060101);