INFUSION OR TRANSFUSION SET AND SYSTEM COMPRISING AN INFUSION OR TRANSFUSION SET

Abstract

An infusion or transfusion set for administering a liquid from a container using a pump. The infusion or transfusion set includes a branch that provides a fluid connection between a first supply line, a second supply line and a discharge line. The first supply line includes a liquid-retaining filter membrane having a breakdown pressure. At least the second supply line has a check valve. The check valve is opened for fluid passage in the direction towards the branch if the pressure difference at the check valve is greater than a threshold value that is less than the breakdown pressure of the liquid-retaining filter membrane.

Claims

1. An infusion set or transfusion set for administering a liquid from a container using a pump, wherein the infusion set or transfusion set comprises a branch, wherein a fluid connection is provided via the branch between one end of each of a first supply line, a second supply line, and a discharge line, wherein the first supply line is configured to be connected to the container at its end remote from the branch, wherein at least the first supply line comprises a liquid-retaining filter membrane having a breakdown pressure p.sub.Mem, wherein at least the second supply line comprises a check valve, wherein the check valve is closed to passage of a fluid in the direction from the branch, wherein the check valve is configured to be closed for passage of fluid in the direction towards the branch if the pressure difference Δp=p.sub.A−p.sub.Z between a pressure p.sub.A present in the second supply line on the side of the check valve facing away from the branch and a pressure p.sub.Z present in the second supply line on the side of the check valve facing towards the branch is less than a threshold value p.sub.R, wherein the check valve is configured to be open for fluid passage in the direction towards the branch if the pressure difference Δp=p.sub.A−p.sub.Z between the pressure p.sub.A present in the second supply line on the side of the check valve facing away from the branch and the pressure p.sub.Z present in the second supply line on the side of the check valve facing towards the branch is greater than the threshold value p.sub.R, and wherein p.sub.R is less than the breakdown pressure p.sub.Mem of the liquid-retaining filter membrane.

2. The infusion set or transfusion set according to claim 1, wherein the branch is configured as a Y-port.

3. The infusion set or transfusion set according to claim 1 for sequentially administering first the liquid as a first liquid from the container as a first container and then a further liquid as a second liquid from a further container as a second container using the pump, wherein the first supply line is configured to be connected to the first container at its end remote from the branch, and wherein the second supply line is configured to be connected at its end remote from the branch to the second container.

4. The infusion set or transfusion set according to claim 1, wherein the threshold value p.sub.R is predetermined to be greater than or equal to a predetermined minimum threshold value p.sub.Rmin and/or wherein the threshold value p.sub.R is predetermined to be less than or equal to a predetermined maximum threshold value p.sub.Rmax.

5. The infusion set or transfusion set according to claim 4, wherein the minimum threshold value p.sub.Rmin is determined to be at least 25 mbar, and/or wherein the maximum threshold value p.sub.Rmax is determined to be at most 190 mbar, and/or wherein the maximum threshold value p.sub.Rmax is determined to be less than p.sub.Mem by at least 10 mbar.

6. The infusion set or transfusion set according to claim 1, wherein the first supply line comprises a drip chamber which comprises an inlet through which the liquid from the container or first container may enter in the form of drops, and which comprises an outlet through which the liquid may flow into the remaining first supply line.

7. The infusion set or transfusion set according to claim 3, wherein the second supply line comprises a drip chamber which comprises an inlet through which the second liquid may enter from the second container in the form of drops, and which comprises an outlet through which the second liquid may flow into the remaining second supply line.

8. The infusion set or transfusion set according to claim 1, wherein the liquid-retaining filter membrane of the first supply line is an air-stop membrane.

9. The infusion set or transfusion set according to claim 8, wherein the liquid-retaining filter membrane of the first supply line is a hydrophilic and/or a porous membrane.

10. The infusion set or transfusion set according to claim 1, wherein the first supply line comprises a check valve between the branch and the liquid-retaining membrane, wherein the check valve of the first supply line is closed to passage of a fluid in the direction from the branch.

11. The infusion set or transfusion set according to claim 1, wherein the second supply line comprises a further liquid-retaining filter membrane having a breakdown pressure p.sub.Mem.sup.(2), wherein a third supply line branches off from the branch or a position of the first supply line or second supply line between the branch and the liquid-retaining filter membrane of the respective supply line, wherein the third supply line comprises a further check valve, wherein the check valve of the third supply line is closed for a passage of a fluid in the direction from the branch, wherein the check valve of the third supply line is configured to be closed for passage of fluid in the direction towards the branch if the pressure difference Δp.sup.(3)=p.sub.A.sup.(3)−p.sub.Z.sup.(3) between a pressure p.sub.A.sup.(3) present in the third supply line on the side of the check valve of the third supply line facing away from the branch and a pressure p.sub.Z.sup.(3) present in the third supply line on the side of the check valve of the third supply line facing towards the branch is less than a threshold value p.sub.R.sup.(3), and wherein the check valve of the third supply line is configured to be open for fluid passage in the direction towards the branch if the pressure difference Δp.sup.(3)=p.sub.A.sup.(3)−p.sub.Z.sup.(3) between a pressure p.sub.A.sup.(3) present in the third supply line on the side of the check valve of the third supply line facing away from the branch and a pressure p.sub.Z.sup.(3) present in the third supply line on the side of the check valve of the third supply line facing towards the branch is greater than the threshold value p.sub.R.sup.(3), wherein the threshold value p.sub.R.sup.(3) is predetermined to be greater than the threshold value p.sub.R, and wherein p.sub.R.sup.(3) is less than the breakdown pressure p.sub.Mem of the liquid-retaining filter membrane of the first supply line and less than the breakdown pressure p.sub.Mem.sup.(2) of the liquid-retaining filter membrane of the second supply line.

12. The infusion set or transfusion set according to claim 11, wherein at least one further supply line branches off from the branch- or positions of the supply lines between the branch and the liquid-retaining filter membranes as the n-th supply line in addition to the first, second and third supply lines, wherein n denotes a natural number running from 4 to a predetermined maximum n.sub.max corresponding to the total number of supply lines, wherein the n-th supply line comprises a further check valve associated with the n-th supply line, wherein the check valve associated with the n-th supply line is closed for a passage of a fluid in the direction from the branch, wherein the check valve associated with the n-th supply line is configured to be closed for passage of fluid in the direction towards the branch if the pressure difference Δp.sup.(n)=p.sub.A.sup.(n)−p.sub.Z.sup.(n) between a pressure p.sub.A.sup.(n) present in the n-th supply line on the side of the check valve associated with the n-th supply line facing away from the branch and a pressure p.sub.Z.sup.(n) present in the n-th supply line on the side of the check valve associated with the n-th supply line facing towards the branch is less than a threshold value p.sub.R.sup.(n), and wherein the check valve associated with the n-th supply line is configured to be open for fluid passage in the direction towards the branch if the pressure difference Δp.sup.(n)=p.sub.A.sup.(n)−p.sub.Z.sup.(n) between a pressure p.sub.A.sup.(n) present in the n-th supply line on the side of the check valve associated with the n-th supply line facing away from the branch- and a pressure p.sub.Z.sup.(n) present in the n-th supply line on the side of the check valve associated with the n-th supply line facing towards the branch is greater than the threshold value p.sub.R.sup.(n), and wherein the threshold value p.sub.R.sup.(n) is determined to be greater than the threshold value p.sub.R.sup.(n-1), wherein p.sub.R.sup.(n) is less than the breakdown pressure p.sub.Mem, p.sub.Mem.sup.(2), . . . , p.sub.Mem.sup.(n-1), of the liquid-retaining filter membranes of the first through (n−1)-th supply lines.

13. A system comprising an infusion set or transfusion set according to claim 1 and a pump for conveying liquid through the supply lines and the discharge line.

14. The system according to claim 13, wherein the system further comprises a pressure measuring device for detecting a measured value corresponding to a pump upstream pressure of a conveyed liquids.

15. The infusion set or transfusion set according to claim 6, wherein the liquid-retaining filter membrane is arranged between the inlet and the outlet of the drip chamber.

16. The infusion set or transfusion set according to claim 15, wherein the liquid-retaining filter membrane is arranged in an outlet region of the drip chamber.

17. The infusion set or transfusion set according to claim 7, wherein a further liquid-retaining filter membrane is arranged between an inlet and an outlet of the drip chamber of the second supply line.

18. The infusion set or transfusion set according to claim 17, wherein the further liquid-retaining filter membrane is arranged in an outlet region of the drip chamber of the second supply line.

19. The system according to claim 13, wherein the pump is a peristaltic pump.

20. The system according to claim 19, wherein the peristaltic pump is engaged with or configured to be engaged with a portion of an outer wall of the discharge line.

21. The system according to claim 14, wherein the system is configured to send an alarm signal and/or to stop conveying liquid by the pump when the pump upstream pressure falls below a threshold value p.sub.Alarm.

22. The system according to claim 21, wherein the threshold value p.sub.Alarm is selected such that no value Δp.sup.(n) (n=2, 3, . . . , n.sub.max) exceeds a breakdown pressure p.sub.Mem.sup.(n) (n=1, 3, . . . , n.sub.max) when the pump upstream pressure falls below the threshold value p.sub.Alarm.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0042] Further features, expediencies, and advantages of the invention are described below with reference to exemplary embodiments with reference to the attached FIGURE.

[0043] The FIGURE shows an infusion set or transfusion set 1 according to a first embodiment of the invention as well as a pump 301 and two containers 101, 201.

DETAILED DESCRIPTION

[0044] The infusion set or transfusion set 1 is for administering liquid initially from the container 101 using a pump 301, i.e., the pump 301 delivers the liquid through the infusion set or transfusion set 1 to the patient connection 100. The patient connection 100 provides a connection for a patient access port. The patient access port is not shown in the FIGURE. The patient access port may be, for example, a venous cannula, a venous catheter, etc. The patient access port may optionally also be considered part of the infusion set or transfusion set.

[0045] The infusion set or transfusion set 1 comprises a conduit system through which liquid may be delivered to the patient connection 100.

[0046] The conduit system preferably comprises tubes.

[0047] The conduit system comprises a branch 302, i.e. an element through which a plurality of conduits are interconnected such that a fluid connection exists between all conduits. A fluid connection is therefore provided via the branch 302 between the first supply line 102, the second supply line 202, optionally further supply lines, and the discharge line 303.

[0048] A first supply line 102, a second supply line 202 and a discharge line 303 are connected to the branch 302 via one of their ends 103, 203, 304, respectively. In alternative embodiments not shown in the FIGURE, more than three supply lines are connected to the branch 302, for example, a third supply line in addition to the first supply line 102 and the second supply line 202.

[0049] The terms “supply line” and “discharge line” express that when a liquid is administered to a patient, i.e., when the liquid flows through the infusion set or transfusion set to the patient connection, the liquid flows through a supply line from a container to the branch and through a discharge line from the branch to the patient connection.

[0050] In the embodiment shown in the FIGURE, the branch 302 is a Y-port, i.e., a Y-shaped tubular element, preferably made of plastic, to which the supply lines 102, 202 and the discharge line 303 are connected. The connection may, for example, be made by a push-fit, adhesive, or welded connection. In alternative embodiments with two supply lines and one discharge line, the branch is a T-shaped tubular element. In yet other embodiments, the branch is not formed by a separate element, but is formed, for example, in that the second supply line is branched directly from a line, i.e. the second supply line is connected to or formed integrally with the line at a junction. This line then forms the first supply line upstream of the second supply line (in the direction of flow when administering a liquid to a patient) and the discharge line downstream of the second supply line. The junction then constitutes the branch.

[0051] In embodiments in which more than three lines are connected to the branch, the branch is configured accordingly, for example as a cross-shaped tubular element or as a tubular element with two tubes extending from a tube at an acute angle in the case of three supply lines. Also in embodiments in which more than three supply lines are connected to the branch, it is possible that the branch is not formed by a separate element, but rather, for example, in the case of three supply lines, the second and third supply lines are connected to or formed integrally with one line such that this line forms the first supply line upstream of the second or third supply line and the discharge line downstream of the second or third supply line.

[0052] The first supply line 102 may be connected to a container 101 at its end 105 remote from the branch 302. The container 101 includes a liquid to be administered to the patient.

[0053] In the embodiment shown in the FIGURE, the first supply line 102 comprises a tube having two ends, one end 103 of which is connected to the branch 302 and the other end of which is connected to the outlet 110 of a drip chamber 108. The outlet 110 may allow liquid from the drip chamber 108 to flow into the tube. The drip chamber further comprises an inlet 109 configured as a drop former, which allows the liquid from the container 101 to enter the drip chamber 108 drop by drop. The drip chamber 108 comprises a container connector 105 in the region of its entrance. Through the container connector 105, the first supply line 102 may be connected to the container 101 such that the liquid may flow from the container 101 into the first supply line 102. The container connector 105 may, for example, be a piercing device such as a hollow mandrel that may be used to pierce a septum that closes the container and typically comprises a plurality of channels therein. Such a piercing device is commonly referred to as a “spike”. Other systems are also known for connecting the drip chamber 108 to the container, such as coupling systems that do not allow the drip chamber and container to be separated once they have been connected.

[0054] The drip chamber 108 and the container connector 105 are understood to be part of the first supply line 102. Accordingly, the container connector 105 forms the end of the first supply line 102 remote from the branch 302.

[0055] A liquid-retaining filter membrane 106 is disposed in the region of the outlet 110 of the drip chamber 108. Fluid flowing through the first supply line 102 must flow through the liquid-retaining filter membrane 106.

[0056] Preferably, the liquid-retaining filter membrane 106 is a porous and in particular hydrophilic membrane, and preferably an air-stop membrane.

[0057] The liquid-retaining filter membrane property is achieved, for example, in that the membrane has a porous structure and the liquid flowing through the membrane flows through the pores or through the channels formed by the pores, wherein the abovementioned capillary effect (“capillary stop flow”) occurs.

[0058] In further embodiments, the first supply line 102 comprises a pipe in portions or as a whole instead of a tube.

[0059] In further embodiments, the liquid-retaining filter membrane 106 may alternatively be disposed at a different location of the first supply line 102. In further embodiments, in addition to the liquid-retaining filter membrane 106 in the region of the outlet 110 of the drip chamber, a further liquid-retaining filter membrane 106 may additionally be arranged at a different location of the first supply line 102.

[0060] In alternative embodiments, the drip chamber of the first supply line 102 is not provided. The line of the first supply line 102, which is in particular a tube, is then to be connected directly to the container without the interposition of a drip chamber, for example by a spike or a suitable coupling system. In this case, the liquid-retaining filter membrane 106 is arranged at a suitable location of the first supply line 102. Also in this case, a fluid flowing through the first supply line 102 must flow through the liquid-retaining filter membrane 106.

[0061] A drip chamber provides communication between the conduit and the container, as described. Typically, devices that provide aeration of the system are integrated into the drip chamber. For this purpose, the drip chamber usually comprises a vent device with a manually operated or an automatic vent valve and an aeration channel open to the interior of the drip chamber. A vent device is not shown in the FIGURE. In the prior art, different embodiments of the vent device based on different types of valves and with or without a vent filter are known, for example, manual vent devices that comprise a manually operated flap as a vent valve and automatic vent valves that comprise a check valve as a vent valve. Alternatively, the manual or automatic vent device is not integrated into a drip chamber but is located at another suitable position of the system. The present invention is compatible with manual and automatic vent devices but is not limited to the presence of a vent device.

[0062] In particular, if the container in which the liquid to be administered is provided is collapsible, the use of a drip chamber or vent device may also be omitted because it is then not necessary to allow air to enter the system for pressure equalization.

[0063] The breakdown pressure of the liquid-retaining filter membrane of the first supply line 102 is referred to as p.sub.Mem or synonymously as p.sub.Mem.sup.(n).

[0064] The second supply line 202 optionally comprises a drip chamber 208, wherein reference is made to the above description of the optional drip chamber 108 of the first supply line 102 for details of this optional drip chamber 208.

[0065] The second supply line 202 further comprises an optional container connector 205 for connecting the second supply line 202 to another container 201 (second container 201). With respect to the details of this optional container connector 205, reference is made to the above description of the container connector 105 of the first supply line 102.

[0066] In the embodiment shown in the FIGURE, the second supply line 202 optionally comprises a liquid-retaining filter membrane 206 associated with the second supply line 202. This liquid-retaining filter membrane 206 is arranged, for example, in the region of the outlet 210 of the drip chamber 208 of the second supply line 202, provided that the second supply line 202 comprises a drip chamber 208. Regardless of its arrangement, a fluid flowing through the second supply line 202 flows through the liquid-retaining filter membrane 206 associated with the second supply line 202 if the second supply line comprises a liquid-retaining filter membrane 206. In particular, the second supply line 202 comprises a liquid-retaining filter membrane 206 if there is at least one other supply line in addition to the first supply line 102 and the second supply line 202.

[0067] The second supply line 202 comprises a check valve 207.

[0068] In operation, fluid is present in the second supply line 202. For example, after priming the infusion set or transfusion set, liquid is present in the second supply line 202.

[0069] The pressure then present in the second supply line 202 on the side 208 of the check valve 207 facing away from the branch 302 is referred to as p.sub.A. The side 208 of the check valve 207 facing away from the branch 302 is the side of the check valve 207 upstream of the check valve 207 as viewed in the direction of a flow of fluid through the second supply line 202 to the patient connection 100. In other words, the side 208 of the check valve 207 facing away from the branch 302 corresponds to the inlet of the check valve 207 for a flow of fluid through the second supply line 202 to the patient connection 100.

[0070] The pressure then present in the second supply line 202 on the side 209 of the check valve 207 facing towards the branch 302 is referred to as p.sub.Z. The side 209 of the check valve 207 facing towards the branch 302 is the side of the check valve 207 downstream of the check valve 207 as viewed in the direction of a fluid flow through the second supply line 202 to the patient connection 100. In other words, the side 209 of the check valve 207 facing towards the branch 302 corresponds to the outlet of the check valve 207 for a fluid flow through the second supply line 202 to the patient connection 100.

[0071] The check valve 207 is closed to a passage of a fluid in the direction from the branch 302. That is, the check valve 207 prevents fluid from flowing back through the second supply line 202. Flowing back is understood to mean flowing in a direction opposite to the direction of flow of the fluid when administered to the patient.

[0072] Further, the check valve 207 is closed to fluid passage in the direction towards the branch 302 if the pressure difference Δp=p.sub.A−p.sub.Z is less than a threshold value p.sub.R.

[0073] Further, the check valve 207 is opened for fluid passage in the direction towards the branch 302 if the pressure difference Δp=p.sub.A−p.sub.Z is greater than a threshold value p.sub.R.

[0074] The threshold value p.sub.R thus corresponds to the valve opening pressure, i.e., the pressure difference between the inlet and outlet sides of the valve required to open the valve.

[0075] For example, the threshold p.sub.R is set to be 50 mbar less than the breakdown pressure p.sub.Mem of the liquid-retaining filter membrane 106 of the first supply line 102. The threshold p.sub.R is set, for example, when the check valve 207 is manufactured. That is, the check valve 207 is manufactured to have the predetermined threshold p.sub.R. It is also possible that the valve opening pressure is variable and has been set by the manufacturer or by the user to an appropriate threshold p.sub.R.

[0076] p.sub.R and p.sub.Mem are matched such that p.sub.R is less than the breakdown pressure p.sub.Mem.

[0077] The check valve 207 is configured to allow fluid to pass through the check valve and thus through the second supply line 202 only under a certain condition (Δp>p.sub.R) in one flow direction and to prevent the passage of fluid otherwise. The passage of fluid is prevented if this condition is not met, and in particular in the direction opposite to said flow direction. The flow direction is the direction from the check valve to the branch 302.

[0078] The first supply line 102 may optionally also comprise a check valve 107. This check valve 107 associated with the first supply line 102 is disposed between the branch 302 and the fluid retaining membrane 106. This check valve 107 is closed to a passage of a fluid in the direction from the branch 302. In particular, this check valve 107 has the advantage that during and after priming of the infusion set or transfusion set 1, an unintentional backflow of the liquid through the first supply line 102 towards the container 101 may be prevented.

[0079] Operation of the infusion set or transfusion set 1 according to the first embodiment or of a system according to the invention comprising the infusion set or transfusion set 1 according to the first embodiment, is described below for a preferred method of use in the context of sequential infusion of two liquids.

[0080] Prior to administering the liquids to the patient, the infusion set or transfusion set 1 is subjected to priming. For this purpose, the ends 105, 205 of the supply lines 102, 202 or the container connectors 105, 205 forming these ends are connected to a first container 101 containing the first liquid to be administered and to a second container 201 containing the second liquid to be administered after the first liquid, respectively. Next, the conduit system is filled with liquid, preferably the first supply line 102 and the discharge line 303 are filled with the first liquid and the second supply line 202 is filled with the second liquid. Before or after priming, the patient access port (not shown in the FIGURE) is connected to the patient connection 100. After priming, the pump 301 begins pumping the liquid entering the first supply line 102 from the first container 101 through the branch 302, the discharge line 303, and the patient connection into the patient access port, through which it enters the patient's body.

[0081] Herein, the pressure difference Δp=p.sub.A−p.sub.Z is less than the predetermined threshold p.sub.R. To ensure this, the second container 202 should not be located significantly higher than the first container 101, otherwise the height difference may provide a disturbing contribution to the pressure difference Δp.

[0082] The check valve 207 is closed to fluid passage in the direction towards the branch 302 because Δp is less than p.sub.R. Therefore, no liquid may flow from the second container 201 through the second supply line 202 and further to the patient connection 100 via the branch 302 and the discharge line 303.

[0083] Thus, as long as liquid flows through the first supply line 102, the following inequalities apply:

Δp<p.sub.R<p.sub.Rmax<p.sub.Mem,

or, written with the appropriate indices, which are not required for the case of two supply lines:

Δp.sup.(2)<p.sub.R.sup.(2)<p.sub.Rmax<p.sub.Mem.sup.(1).

[0084] When the liquid of the first container 101 is used up, the liquid level in the first supply line 102 decreases until the liquid level reaches the liquid-retaining filter membrane 106 associated with the first supply line, which is arranged, for example, at the bottom of a drip chamber 108 of the first supply line 102. As a result of the above-described function and features of the liquid-retaining filter membrane 106, the liquid may not flow further through the first supply line 102, and no gas, i.e., air, may flow through the liquid-retaining filter membrane 106 associated with the first supply line 102. A pressure drop occurs in the fluid system downstream of the liquid-retaining filter membrane 106 associated with the first supply line 102. Therefore, p.sub.Z decreases. As a result, Δp=p.sub.A−p.sub.Z becomes larger. Once Δp exceeds the threshold p.sub.R, the check valve 207 associated with the second supply line 202 opens and liquid from the second container 201 may flow through the second supply line 202, the check valve 207, the branch 302, and the discharge line 303 to the patient connection 100. Further, due to the function and properties of the liquid-retaining filter membrane 106, neither liquid nor gas (i.e. air) may not flow through the first supply line 102. Therefore, the liquid-retaining filter membrane 106 closes off the first supply line 102.

[0085] The following inequalities apply when liquid flows through the second supply line 202:

p.sub.R<Δp<p.sub.Mem,

or, written with the appropriate indices, which are not required for the case of two supply lines

p.sub.R.sup.(2)<Δp.sup.(2)<p.sub.Mem.sup.(1).

[0086] When the liquid in the second container 201 is also used up, the sequential infusion is complete. If the second supply line 202 also has a liquid-retaining filter membrane 206, the liquid level in the second supply line 202 decreases until the liquid level reaches the liquid-retaining filter membrane 206 associated with the second supply line 202, which is arranged, for example, at the bottom of a drip chamber 208. As a result of the above-described function and features of the liquid-retaining filter membrane 206, the liquid may not continue to flow through the second supply line 202, and no gas, i.e., air, may flow through the liquid-retaining filter membrane 206 associated with the second supply line 202. A pressure drop occurs in the fluid system downstream of the liquid-retaining filter membrane 206 associated with the second supply line 202, Δp increases as a result.

[0087] The concept underlying the above described administration of a sequential infusion or transfusion of two liquids from a first container 201 and a second container 201 using the infusion set or transfusion set 1 according to the invention may be summarized as follows: The arrangement comprising the infusion set or transfusion set 1 and the containers 101, 201 comprises two fluid systems, namely a primary system and a secondary system. Both subsystems have the function of a conventional infusion set or transfusion set and each serves to administer a liquid. The primary system includes the first container 101, the first supply line 102, the junction 302, the discharge line 303, and the patient connection 100. The primary system is for administering the liquid from the first container 101. The secondary system includes the second container 201, the second supply line 202, the junction 302, the discharge line 303, and the patient connection 100. The secondary system is for administering the liquid from the second container 201. The primary system is automatically deactivated and the secondary system is automatically activated when the first container 101 has become empty.

[0088] Optionally, the second supply line 202 comprises an element 402 having a function analogous to the branch 302 if a third supply line 502 having a check valve associated with the third supply line 502 is connected to the element 402 and a liquid-retaining filter membrane 206 associated with the second supply line 202 is provided. The element 402 is disposed between the check valve 207 associated with the second supply line 202 and the liquid-retaining filter membrane 206 associated with the second supply line 202. The second embodiment of the invention, in which the third supply line 502 is connected to the element 402, has an analogous function to the third embodiment, in which a third supply line 502 is connected to the branch 302.

[0089] The second supply line 202 may optionally comprise a further check valve 217 between the element 402 and the fluid retaining membrane 206 associated with the second supply line 202. This further check valve 217 is closed to passage of a fluid in the direction towards the fluid retaining membrane 206 associated with the second supply line 202. In particular, this further check valve 217 has the advantage that during and after priming of the infusion set or transfusion set 1, an unintentional backflow of the liquid through the second supply line 202 towards the container 201 may be prevented.

[0090] Instead of connecting the third supply line 502 by the element 402, the third supply line 502 may also be branched off directly from the second supply line.

[0091] Analogously to the connection of a third supply line 502 to the second supply line 202 by the element 402, a fourth supply line may be connected to the third supply line 502 or a fourth supply line may be branched off directly from the third supply line 502. In an analogous manner, further supply lines may be connected to or directly branched from the supply line having the respective ordinal number lower by one.

[0092] The operation of the infusion set or transfusion set 1 according to the second embodiment with a third supply line 502 connected to or directly branched off from the second supply line 202 and the infusion set or transfusion set 1 according to the third embodiment with three supply lines 102, 202, 502, all of which are connected to the branch 302, and of a system according to the invention with the infusion set or transfusion set 1 according to one of these embodiments with three supply lines 102, 202, 502 is described below for a preferred method of use in the context of the sequential infusion of three liquids.

[0093] This method of use takes place in an analogous manner in the context of the sequential infusion of more than three liquids, in which case an infusion set or transfusion set 1 with a number of supply lines (n.sub.max) corresponding to the number of liquids is used. The case n.sub.max>3 is therefore not described separately.

[0094] Before administering the liquids to the patient, the infusion set or transfusion set 1 is subjected to priming. For this purpose, the ends of the three supply lines or the container connectors forming these ends are connected to a first container 101 containing the first liquid to be administered, to a second container 201 containing the second liquid to be administered after the first liquid, and to a third container (not shown in the FIGURE) containing the third liquid to be administered after the second liquid, respectively. Next, the conduit system is filled with liquid, preferably the first supply line 102 and the discharge line 303 are filled with the first liquid, the second supply line 202 is filled with the second liquid, and the third supply line 502 is filled with the third liquid. Before or after priming, the patient access port (not shown in the FIGURE) is connected to the patient connection 100. After priming, the pump 301 begins pumping the liquid entering the first supply line 102 from the first container 101 through the branch 302, the discharge line 303, and the patient connection into the patient access port, through which it enters the patient's body.

[0095] Herein, the pressure difference Δp.sup.(2)=p.sub.A.sup.(2)−p.sub.Z.sup.(2) (synonymously Δp=p.sub.A−p.sub.Z) is less than the predetermined threshold p.sub.R.sup.(2).

[0096] The check valve 207 associated with the second supply line 202 is closed to fluid passage in the direction towards the branch 302 because Δp.sup.(2) is less than p.sub.R.sup.(2). Therefore, no liquid may flow from the second container 201 through the second supply line 202 and further to the patient connection 100 via the branch 302 and the discharge line 303.

[0097] p.sub.Mem.sup.(1) and p.sub.Mem.sup.(2) may be the same or different from each other. For simplicity, it is assumed that p.sub.Mem.sup.(1) and p.sub.Mem.sup.(2) are the same (p.sub.Mem.sup.(1)=p.sub.Mem.sup.(2)=p.sub.Mem). If p.sub.Mem.sup.(1) and p.sub.Mem.sup.(2) are not equal, the smaller of the two values is to be substituted for p.sub.Mem in subsequent inequalities.

[0098] As long as liquid flows through the first supply line 102, the following inequalities apply:

Δp.sup.(2)<p.sub.R.sup.(2)<p.sub.R.sup.(3)<p.sub.Rmax<p.sub.Mem.

[0099] When the liquid of the first container 101 is used up, the liquid level in the first supply line 102 decreases until the liquid level reaches the liquid-retaining filter membrane 106 associated with the first supply line 102, which is arranged, for example, at the bottom of a drip chamber 108 of the first supply line 102. As a result of the above-described function and features of the liquid-retaining filter membrane 106 associated with the first supply line 102, the liquid may not flow further through the first supply line 102, and no gas, i.e., air, may flow through the liquid-retaining filter membrane 106 associated with the first supply line 102. A pressure drop occurs in the fluid system downstream of the liquid-retaining filter membrane 106 associated with the first supply line 102. Therefore, p.sub.Z.sup.(2) decreases. As a result, Δp.sup.(2)=p.sub.A.sup.(2)−p.sub.Z.sup.(2) becomes larger. Once Δp.sup.(2) exceeds the threshold p.sub.R.sup.(2), the check valve 207 associated with the second supply line 202 opens and liquid from the second container 201 may flow through the second supply line 202, the check valve 207, the branch 302, and the discharge line 303 to the patient connection 100. Further, due to the function and features of the liquid-retaining filter membrane 106, neither liquid nor gas, i.e. air, may not flow through the first supply line 102. Therefore, the liquid-retaining filter membrane 106 closes off the first supply line 102.

[0100] The following inequalities apply when liquid flows through the second supply line 202:

p.sub.R.sup.(2)<Δp.sup.(2)<p.sub.R.sup.(3)<p.sub.Rmax<p.sub.Mem.

[0101] When the liquid of the second container 201 is used up, the liquid level in the second supply line 202 decreases until the liquid level reaches the liquid-retaining filter membrane 106 associated with the second supply line 202, which is arranged, for example, at the bottom of a drip chamber 208 of the second supply line 202. As a result of the above-described function and features of the liquid-retaining filter membrane 206 associated with the second supply line 202, the liquid may not flow further through the second supply line 202, and no gas, i.e., air, may flow through the liquid-retaining filter membrane 206 associated with the second supply line 202. A pressure drop occurs in the fluid system downstream of the liquid-retaining filter membrane 206 associated with the second supply line 202. Therefore, p.sub.Z.sup.(3) decreases. As a result, Δp.sup.(3)=p.sub.A.sup.(3)−p.sub.Z.sup.(3) becomes larger. Once Δp.sup.(3) exceeds the threshold p.sub.R.sup.(3), the check valve associated with the third supply line 502 (not shown in the FIGURE) opens and liquid from the third container (not shown in the FIGURE) may flow through the third supply line 502, the check valve associated with the third supply line, the branch 302, and the discharge line 303 to the patient connection 100. Further, due to the function and features of the liquid-retaining filter membranes 106, 206 associated with the first supply line 102 and the second supply line 202, neither liquid nor gas, i.e., air, may flow through the first supply line 102 and the second supply line 202. Therefore, the liquid-retaining filter membranes 106, 206 close off the first supply line 102 and the second supply line, respectively.

[0102] The following inequalities apply when liquid flows through the third supply line 502:

p.sub.R.sup.(2)<p.sub.R.sup.(3)<Δp.sup.(3)<p.sub.Mem.

[0103] When the liquid in the third container is also used up, the sequential infusion is completed. If the third supply line 502 also has a liquid-retaining filter membrane, the liquid level in the third supply line 502 decreases until the liquid level reaches the liquid-retaining filter membrane associated with the third supply line 502, which is arranged, for example, at the bottom of a drip chamber (not shown in the FIGURE) of the third supply line 502. As a result of the above-described function and features of the liquid-retaining filter membrane associated with the third supply line 502, the liquid may not flow further through the third supply line 502, and no gas, i.e., air, may flow through the liquid-retaining filter membrane associated with the third supply line 502. There is a pressure drop in the fluid system downstream of the liquid-retaining filter membrane associated with the third supply line 502, Δp.sup.(3) increases as a result.

[0104] The infusion set or transfusion set 1 may optionally include other components, such as one or more flow controllers 600, 700 for shutting off the discharge line and/or supply lines and/or controlling the flow rate of the liquid. Two optional flow regulators 600, 700 are shown as exemplary roller clamps in the FIGURE.