WO2023152008A1

WO2023152008A1 - Infusion system for administering a fluid to a patient

Info

Publication number: WO2023152008A1
Application number: PCT/EP2023/052482
Authority: WO
Inventors: Harry Pütter; Tino SCHÜSSLER; Oltjon DIMNI
Original assignee: Fresenius Kabi Deutschland Gmbh
Priority date: 2022-02-08
Filing date: 2023-02-01
Publication date: 2023-08-17

Abstract

An infusion system (S) for administering a fluid (F) to a patient via a fluid path (P), comprises: a pump (1) for conveying the fluid (F) along the fluid path (P), a separation device (2A-2D) in fluid connection with the fluid path (P) to separate gas (G) from the fluid (F) and a pressure- activated valve (3A, 3B) in fluid connection with the fluid path (P) at or downstream the separation device (2A-2D). Therein, it is provided that the separation device (2A-2D) defines a passage (20A-20C) for the fluid (F) and has an opening (21) covered by a gas-permeable, hydrophobic membrane (22) allowing gas (G) to exit from the fluid (F) through the opening (21).

Description

Infusion System for Administering a Fluid to a Patient

Description

The invention relates to an infusion system for administering a fluid to a patient.

In many medical applications fluids have to be provided to a patient for infusion, e.g., for administering medicines or parenteral nutrition. Usually, a bag containing the liquid is connected to a tube for conveying the liquid to the patient.

For various reasons, gas, particularly air, can be introduced into the liquid in the tube. Therefore, infusion systems often comprise a gas detector that detects, e.g., air bubbles in the liquid and causes a stop of the operation of the infusion system in that case. When the operation has been stopped due to the presence of gas, e.g., air, personnel commonly need to remove the gas manually and restart operation of the infusion system. This can be a timeconsuming process and requires the intervention of personnel.

WO 2021/067316 A1 describes an infusion system having a separation device to separate air from a conveyed fluid. The separation device relies on the combination of a hydrophilic filter with a hydrophobic filter. The hydrophobic filter is disposed within a channel and comprises a hydrophobic filter media that prevents the flow of aqueous solutions, such as infusate, therethrough. The hydrophilic filter prevents a migration of air toward an outlet. However, the application of this system is limited. For example, parenteral nutrition would be filtered by the hydrophobic filter and may even block the hydrophobic filter. In addition, this system requires a relatively strong pump to convey the fluid through the separation device. WO 2015/006495 A1 relates to a check valve system coupled to the tubing of an infusion pump system. The check valve causes the fluid entering it to sustain a nominal pressure at any flow rate, which can be used to drive air that may be present such as due to outgassing out of the tubing such as through the permeable material of the tubing. The valve pressure can also be used to prevent air from entering the tubing via the permeable material of the tubing. However, the capability of this system to remove air is not efficient enough for various applications.

It is an object of the instant invention to efficiently remove gas from a fluid to be administered to a patient.

This object is achieved by means of an infusion system comprising the features of claim 1 .

Accordingly, an infusion system for administering a fluid to a patient via a fluid path comprises a pump for conveying the fluid along the fluid path, a separation device in fluid connection with the fluid path to separate gas (e.g., air) from the fluid and a pressure-activated valve in fluid connection with the fluid path at or downstream the separation device. Therein, the separation device defines a passage for the fluid and has an opening covered by a gas-permeable, hydrophobic membrane allowing gas to exit from the fluid through the opening.

This allows to efficiently remove gas from a fluid, particularly a liquid, to be administered to a patient without filtering the fluid. This enables the use of the infusion system for applications such as parenteral feeding. Further, intervention of personnel may not even be necessary. Due to the efficient removal of gas, interruptions of the administration of the fluid are minimized. The pressure-activated valve serves to increase the pressure in the fluid to press the gas through the hydrophobic membrane.

The pressure-activated valve may be arranged within the separation device, e.g., inside the passage. This allows a simple setup and the possibility to have a bypass of the valve by using the open/close mechanism of the pump door. Optionally, the pressure-activated valve is inserted into the separation device through the opening. For example, the pressure-activated valve is arranged downstream the opening or of at least a part of the opening. If inserted into the separation device through the opening, the pressure-activated valve may obstruct a part of the opening.

The separation device may comprise an inlet and an outlet in fluid connection with one another via the passage. The passage may particularly be continuously open from the inlet to the outlet. That is, the passage describes an inner volume that connects the inlet with the outlet. The inner volume extends from the inlet to the outlet. The inner volume is empty (apart from fluid and, optionally, apart from the pressure-activated valve, when arranged within the separation device). At every location along the passage from the inlet to the outlet, the inner volume describes an unobstructed opening. Fluid conveyed through the passage from the inlet to the outlet does not have to pass through a membrane or filter. This allows to avoid filtering of the fluid.

The separation device may define a reservoir. The reservoir may be adjacent the hydrophobic membrane. The reservoir may be arranged so as to collect ascending gas bubbles from the fluid. This allows a particularly simple yet efficient construction.

According to an embodiment, the separation device comprises a check valve. The check valve may be arranged at the opening. The check valve may be adapted to allow gas to exit from the separation device, but to prevent gas to enter the separation device. This allows to avoid the entry of gas in case of a negative pressure.

Optionally, the passage defines a flat channel. For example, the flat channel has a width and/or length (e.g., with respect to the flow direction of the fluid along the passage) that is substantially (e.g., 2 times, 5 times or 10 times) larger than its height. The cross-sectional area of the flat channel may be smaller than the cross-sectional area of adjacent parts of the passage. This allows to separate gas from the fluid irrespective of the orientation of the separation device. Alternatively, or in addition, a housing of the separation device and the hydrophobic membrane may together define the passage. That is, the hydrophobic membrane may form a wall of the passage. This allows a simple and efficient construction that uses little space.

Optionally, the hydrophobic membrane is also oleophobic. This allows to avoid lipids to deposit on the membrane and, thus, to maintain the functionality of the separation device even if fats are present in the fluid, e.g., as in parenteral nutrition. The hydrophobic membrane may be made of polytetrafluoroethylene (PTFE) and/or polyethylene terephthalate (PET).

Alternatively, the hydrophobic membrane is bulged. By this, its surface may be increased. According to an embodiment, the hydrophobic membrane is mounted by means of a weld seam, e.g., on a housing of the separation device. This allows a tight and stable connection that can be made quickly. Optionally, the separation device comprises a cover covering the hydrophobic membrane. The cover may comprise at least one opening or a plurality of openings. The cover can ensure the connection of the hydrophobic membrane with the separation device and allow higher pressures.

The separation device may define two separated passages. Optionally, the opening covered by the hydrophobic membrane is located at one of the separated passages and another opening covered by another gas-permeable, hydrophobic membrane for allowing gas (particularly air) to exit from the fluid through the other opening is located at the other one of the separated passages. This allows to increase the membrane surface. Optionally, the two hydrophobic membranes are located at opposing sides of the separation device. This enables a slim construction and increases the venting performance.

The pressure-activated valve may comprise a (e.g., movable and/or flexible) part. The part may be pretensioned in a closed position preventing a fluid flow along the fluid path, and configurable (e.g., movable) into an opened configuration opening the fluid path by pressure of the fluid. This allows to increase the pressure in the fluid by simple and reliable means.

At least a section of the fluid path may be defined by a silicone tube. Optionally, the pump is a volumetric pump acting on the silicone tube. This may introduce air through the silicone tube into the fluid conveyed along the fluid path. This air can be removed by the infusion system.

Optionally, the infusion system comprises a bypass for the pressure-activated valve. The bypass may be closable. This allows priming of the fluid line. In addition, this allows to switch between pumped infusion and gravitational infusion, e.g., in case of a malfunction of the pump, or when desired. The bypass may be provided at the separation device.

The infusion system may further comprise a casing retaining the pump and/or the separation device.

Therein, the casing may define a receptacle to hold the separation device, e.g., in a predefined orientation with respect to the casing. This allows to make sure that ascending air bubbles are directed to the hydrophobic membrane.

The casing may comprise a door that closes the bypass when the door is in a closed position (e.g., on a main body of the casing) and opens the bypass when the door is in an opened position. This allows to insert the separation device, then to prime the fluid line in a simple manner, and then to close the bypass simply by closing the door.

The idea underlying the invention shall subsequently be described in more detail by referring to the embodiments shown in the figures. Herein:

Fig. 1 shows a schematic view of an infusion system for administering a fluid to a patient via a fluid path, comprising a pump, a separation device and a pressure-activated valve;

Fig. 2 shows a section of a casing of the infusion system and the separation device of the infusion system of Fig. 1.

Fig. 3 shows a housing of the separation device of the infusion system of Fig. 1 ;

Fig. 4 shows a cross-sectional view of the separation device of the infusion system of Fig. 1;

Fig. 5 shows a cover of the separation device the infusion system of Fig. 1;

Fig. 6 shows the pressure-activated valve of the infusion system of Fig. 1;

Figs. 7 and 8 show various possible locations for mounting the pressure-activated valve of the infusion system of Fig. 1;

Fig. 9 shows a section of the casing of the infusion system and a separation device with a pressure-activated valve integrated into the separation device;

Figs. 10A-10C show different views of the separation device of Fig. 9;

Fig. 11 shows another separation device for the infusion system of Fig. 1 with a mounting plate;

Figs. 12A-12H show different views of the separation device of Fig. 11 ; and

Figs. 13A-13D show different views of another separation device for the infusion system of

Fig. 1. Subsequently, an infusion system, shall be described in certain embodiments. The embodiments described herein shall not be construed as limiting for the scope of the invention.

Fig. 1 shows an infusion system S for administering a fluid F to a patient via a fluid path P. The infusion system S comprises a pump 1 for conveying the fluid F along the fluid path P. The infusion system S further comprises a separation device 2A that is in fluid connection with the fluid path P and forms a part of the fluid path P, and that is configured to separate gas from the fluid F. The separation device 2A can also be referred to as air remover. Further, the infusion system 1 comprises at least one pressure-activated valve 3A that is in fluid connection with the fluid path P downstream the separation device 2A and that forms a part of the fluid path P. In the example of Fig. 1 , three pressure-activated valves 3A are shown at three different possible locations that will be described further below with reference to Figs. 6-8, but it is noted that one pressure-activated valve 3A (e.g., downstream the separation device 2A) is generally sufficient. The pressure-activated valve 3A increases the pressure between upstream and downstream.

The fluid path P is defined by generally at least one, here several sections of tubes 4. More specifically, in this example the tubes 4 are silicone tubes 4. One tube 4 section is connected to a bag 7 (or other container) containing the fluid F, more specifically: a liquid. This tube 4 is in operative connection with the pump 1. The pump 1 is a volumetric pump that acts (namely: presses) on the tube 4 so as to convey the liquid therein. By this pumping process, air might enter through the material of the tube 4 and into the fluid F.

The bag 7 is hung on a rack 6. A casing 5 is mounted on the rack 6 lower than the bag 7. At the casing 5 the pump 1 is mounted as well as the separation device 2A.

Fig. 2 shows the casing 5 of the infusion system S. The casing 5 has a receptacle 50 in which the separation device 2A is mounted. The receptacle 50 is formed such that the separation device 2A can be (and is) mounted in a predefined orientation with respect to the casing 5. The predefined orientation is such that a cover 25A of the separation device 2A is oriented upwards when the casing 5 is mounted on the rack 6.

Further, Fig. 2 shows a plate 8. The separation device 2A is fixed to the plate 8. The plate 8 serves as a bearing for a closure element. The closure element can be rotated with respect to the plate 8 to clamp and thus close the tube 4. Optionally, a housing 24A of the separation device 2A and the plate 8 are formed in one piece. This allows a particularly simple construction.

The separation device 2A is connected to the tube 4 section that is in operative connection with the pump 1.

Fig. 3 shows the housing 24A of the separation device 2A in more detail. The housing 24A defines an inlet 240 and an outlet 241. The inlet 240 and the outlet 241 are in fluid connection with one another via a passage 20A defined by the separation device 2A. Notably, the passage 20A is continuously open from the inlet 240 to the outlet 241 . At any location from the inlet 240 to the outlet 241 the passage 20A is clear. Apart of the fluid F that may be arranged in the passage 20A, at any location from the inlet 240 to the outlet 241 the passage 20A is empty.

The inlet 240 is connectable (and according to Figs. 1 and 2 connected) to the tube 4 being in engagement with the pump 1. The outlet 241 is connectable (and according to Fig. 1 connected) to a tube 4 towards the patient. Activation of the pump 1 effects that fluid from the bag 7 is conveyed to the inlet 240 of the housing 24A of the separation device 2A and from the inlet 240 of the housing 24A of the separation device 2A to the outlet 241 of the housing 24A of the separation device 2A.

Further, the housing 24A of the separation device 2A defines a reservoir 23. The reservoir 23 is arranged between the inlet 240 and the outlet 241 . The reservoir 23 is in fluid connection with the fluid path P.

The housing 24A of the separation device 2A further has an opening 21. The opening 21 is formed in an external wall of the housing 24A. The reservoir 23 is accessible through the opening 21. That is, the opening 21 is in fluid connection with the passage 20A and, thus, with the fluid path P. The opening 21 spans over a major part of one side of the housing 24A. The reservoir 23 has a larger cross section than the inlet 240 and than the outlet 241. The reservoir 23 extends upwards.

Fig. 4 shows the housing 24A, wherein the opening 21 is covered by a gas-permeable, hydrophobic membrane 22 allowing gas G to exit from the fluid F through the opening 21 . The hydrophobic membrane 22 is arranged adjacent the reservoir 23. In use, the separation device 2A is oriented such that the hydrophobic membrane 22 faces upwards. Thus, gas bubbles B of the gas G (e.g., air) ascend in the reservoir 23 towards (and through) the hydrophobic membrane 22. The hydrophobic membrane 22 allows gas G to exit from the fluid F through the opening 21.

Notably, the hydrophobic membrane 22 is planar. However, it is also conceivable that the separation device 2A instead comprises a bulged (i.e., curved) hydrophobic membrane 22, e.g., as depicted by dashed lines in Fig. 4. Further, the hydrophobic membrane 22 is oleophobic to avoid deposition of lipids.

Fig. 5 shows the cover 25A of the separation device 2A. The cover 25A comprises several (four) openings 250 which are divided from one another by struts 251. The cover 25A secures the hydrophobic membrane 22 to the housing 24A and protects it against damage.

Fig. 6 shows the pressure-activated valve 3A, which comprises a housing 30A defining an inlet 300 and an outlet 301. The inlet 300 is in fluid connection with the outlet 301. The pressure- activated valve 3A further comprises a movable part 31 A arranged in a cavity 32 inside the housing 30A. The movable part 31A is pretensioned in a closed position closing the fluid connection of the inlet 300 with the outlet 301. The movable part 31 A is movable into an opened position opening the fluid connection between the inlet 300 and the outlet 301 by pressure of the fluid F.

The pressure-activated valve 3A may be an anti-siphon valve. For example, the pressure- activated valve 3A is constructed as described in US 6,409,707 B1.

As shown in Fig. 7, the pressure-activated valve 3A may be arranged on the casing 5, e.g., (directly) after the separation device 2A. Optionally, at least a part of the housing 30A of the pressure-activated valve 3A may be formed in one piece with the housing 24A of the separation device 2A. In the present example, the housing 30A of the pressure-activated valve 3A and the housing 24A of the separation device 2A are formed in one piece. The pump 1 , the separation device 2A and the pressure-activated valve 3A are mounted on the casing 5 of the infusion system S.

The pressure-activated valve 3A is in a deactivated, always-open state when it is not mounted on the casing 5. When the pressure-activated valve 3A and the separation device 2A are inserted into the receptacle 50 of the casing 5, optionally under the precondition that the pump door is closed, the pressure-activated valve 3A is transitioned into an activated (openable by pressure) state. Alternatively, the pressure-activated valve 3A can be switched between the deactivated state and the activated state manually by a user. Notably, the pressure-activated valve 3A is always open in the reverse-flow direction.

The infusion system S further comprises a gas detector 9. The gas detector 9 is arranged downstream the separation device 2A and the pressure-activated valve 3A. The gas detector 9 is adapted to trigger an alarm in case that it detects gas in the fluid F in the fluid path P.

Alternatively, or in addition, to the pressure-activated valve 3A being arranged on the casing 5, the (or another) pressure-activated valve 3A can be mounted downstream the infusion system S casing 5, as also shown in Fig. 7. Thus, this pressure-activated valve 3A is mounted between two tube 4 sections.

Further alternatively, or in addition, and as shown in Figs 1 and 8, the (or another) pressure- activated valve 3A can be mounted at an end of the tube 4 at a distal end of the fluid path P.

Fig. 9 shows the casing 5 with another separation device 2B that can be used in the infusion system S instead of the separation device 2A described above. This separation device 2B will be described in more detail below with reference to Figs. 10A-10C. The casing 5 comprises a main body 51. The main body 51 defines the receptacle 50. Further, the casing 5 comprises a door 52. The door 52 can be opened and closed. For this purpose, the door 52 is pivotably connected to the main body 51. The pump 1 is mounted on the main body 51.

The separation device 2B is shown in a perspective view in Fig. 10A, and in two cross-sectional views in Figs. 10B and 10C.

Here, the pressure-activated valve 3B is arranged at the separation device 2B, more specifically, within the separation device 2B. The pressure-activated valve 3B is arranged inside the passage 20B, between the inlet 240 and the outlet 241 of the housing 24B of the separation device 2B. Gas, e.g., air, in the fluid upstream the pressure-activated valve 3B can exit though the opening 21 B and the membrane 22 covering the opening 21 B upstream the pressure-activated valve 3B.

The pressure-activated valve 3B comprises a housing 30B and a further part 31 B. The part 31 B is arranged between the housing 30B and a surface of the separation device 2B housing 24B. The housing 30B of the pressure-activated valve 3B is retained in a receptacle of the separation device 2B housing 24B. The housing 30B of the pressure-activated valve 3B comprises an opening 302. The opening 302 is adjacent the part 31 B. Fluid flowing from the inlet 240 downstream along the passage 20B may flow through this opening 302 and exert a pressure on the part 31 B. The part 31 B is flexible. Sections of the part 31 B may be elastically deformed by this pressure such that an opening in the part 31 B is formed. In the present example, the part 31 B comprises slits 310 forming a cross for this purpose. When there is no overpressure in fluid upstream the part 31 B, said sections elastically return into a (flat) configuration closing the opening in the part 31 B.

In the reverse direction, i.e. , from the outlet 241 towards the inlet 240, the pressure-activated valve 3B allows a flow around the part 31 B. That is, in the reverse direction, the elastically deformable sections do not have to be deformed, and no corresponding pressure needs to be present to open the pressure-activated valve in the reverse flow direction. A flow in the reverse direction may be present, e.g., when the pump 1 or another part of the infusion system S detects an occlusion (e.g., downstream the pressure-activated valve 3B) and, in response to this detection, pumps in the reverse direction.

To allow such a reverse flow, the part 31 B is movably arranged between the housing 30B and the surface of the separation device 2B housing 24B. the part 31 B comprises a base with the elastically deformable sections, and protrusions 311 and a ring 312 protruding from the base. When fluid flows in the reverse direction, the part 31 B is moved against the housing 30B of the pressure-activated valve 3B. Then, the fluid flows around the outer periphery of the part 31 B and through gaps between the protrusions 311. When the fluid flows in the nominal direction, the part 31 B is moved against the surface of the separation device 2B housing 24B, and the ring 312 seals the part 31 B against the surface of the separation device 2B housing 24B.

During assembly, the pressure-activated valve 3B is moved into its receptacle through the opening 21 of the separation device 2B housing 24B. Then, the opening 21 is covered by the membrane 22 and the cover 25C retaining the pressure-activated valve 3B in its receptacle. Alternatively, the housing of the pressure-activated valve 3B may be formed in one piece with the housing 24B of the separation device 2B.

The separation device 2B further comprises a bypass 26 with a closure mechanism for the bypass 26. The bypass 26 provides a fluid connection between parts of the fluid path P upstream and downstream the pressure-activated valve 3B. In the example of Figs. 10A-10C, the bypass 26 comprises an upstream duct upstream the pressure-activated valve 3B and a downstream duct downstream the pressure-activated valve 3B. The upstream and downstream ducts are formed in the separation device 2B housing 24B. A connecting duct connects the upstream duct with the downstream duct. The connecting duct is formed by the separation device 2B housing 24B and a seal 280. The seal 280 may be pressed against the separation device 2B housing 24B to close the connecting duct. The bypass 26 may thus be selectively opened or closed for a fluid flow. The ducts of the bypass 26 bypass the pressure-activated valve 3B.

By closing the door 52 of the casing 5, the seal 280 is pressed against the separation device 2B housing 24B to close the bypass 26. For this, the seal 280 comprises two pins 281 (or more generally, at least one protrusion) that may be operated by a surface 520 of the door 52 (see Fig. 9). The seal 280 is retained on the separation device 2B housing 24B by means of a cover 282. The cover 282 comprises openings for the pins 281. The pins 281 protrude through these openings. Closing the door 52 presses the surface 520 against the pins 281 , thereby pressing the seal 280 against the ducts of the bypass 26. When the door 52 is opened, the seal clears the bypass 26.

The bypass 26 allows priming of the fluid path P, i.e., filling it with a fluid, e.g., a liquid, and removing another fluid, e.g., air. In addition, this allows to switch to gravitational infusion, e.g., in case of a malfunction of the pump 1 , or when desired.

The separation device 2B further comprises a check valve 27. The check valve 27 comprises a cover 271 and a valve element 270 movably arranged between the separation device 2B cover 25C and the check valve 27 cover 271 . Specifically, the valve element 270 is arranged in a recess 252 of the check valve 27 cover 271. The valve element 270 is planar. Between opposing outer lateral edges of the valve element 270 and the check valve 27 cover 271 there are clearances. The check valve allows gas, e.g., air, to exit the separation device 2B and prevents gas, e.g., air, to enter the separation device 2B. Optionally, grooves are formed at an inner side of the check valve 27 cover 271 and/or at an outer side of the valve element 270

In a mounted condition in the receptacle 50 of the casing 5, the opening 21 B with the hydrophobic membrane 22 is arranged above the passage 20B. Thus, gas of ascending bubbles in the fluid may exit the fluid path through the hydrophobic membrane 22.

Figs. 11 and 12A-12H show another separation device 2C that can be used in the infusion system S instead of the separation devices 2A, 2B described above. This separation device 2C is constructed similar to the separation device 2A described above with reference to Figs. 2-5. Fig. 11 shows the separation device 10C mounted on the plate 8; Figs. 12A-12H show the separation device 10C without the plate 8.

Here, the housing 24C of the separation device 2C defines a flat channel 200, as particularly visible in Figs. 12B and 12F. From the inlet 240, the fluid F is guided by a wall 242 to the side and to the flat channel 200. From the flat channel 200, the fluid F is further guided along another wall 243 to the outlet 241 . The wall 242 and the other wall 243 are parallel to one another.

The flat channel 200 is defined by an even surface 244 of the housing 24C and the (even) hydrophobic membrane 22. The even surface 244 of the housing 24C and the hydrophobic membrane 22 extend in parallel to one another. Thus, the housing 24C of the separation device 2C and the hydrophobic membrane 22 together define the passage 20C.

The cover 25B covers the hydrophobic membrane 22 and retains it in place with several struts 251. The cover 25B comprises several (here: 6) openings 250.

The hydrophobic membrane 22 is fixed to the housing 24C and to the cover 25B by means of a weld seam W (see Fig. 12B). The weld seam W is made by ultrasonic welding.

Notably, an outer wall 245 of the housing 24C extends parallel to the even surface 244 (see, e.g., Figs. 12B, 12D and 12E).

The tube 4 is secured to the separation device 2C housing 24C by means of a retaining ring 40.

Figs. 13A-13D show another separation device 2D that can be used in the infusion system S instead of the separation devices 2A-2C described above. This separation device 2D is constructed similar to the separation device 2C described above with reference to Figs. 11- 12H. However, in contrast thereto the separation device 2D of Figs. 13A-13D comprises two separated passages 20C, wherein the opening 21 covered by the hydrophobic membrane 22 is located at one of the separated passages 20C and another opening 21 covered by another gas-permeable, hydrophobic membrane 22 for allowing gas G to exit from the fluid F through the other opening 21 is located at the other one of the separated passages 20C.

Therein, the two hydrophobic membranes 22 are located at opposing sides of the separation device 2D. The two hydrophobic membranes 22 are arranged in parallel to one another. Both may be covered by a respective cover. The separation device 2D thus comprises two (parallel) flat channels 200. Therefore, the separation device 2D defines two passages 20C for the fluid F.

Tests with the infusion system S have revealed that air can be removed very efficiently, even if a user, e.g., connects a second infusion tube and without stopping the pump 1. No air was conveyed to the patient. It is further worth noting that the described infusion system allows a simplified priming of the fluid path P.

The idea of the invention is not limited to the embodiments described above but may be implemented in a different fashion.

List of Reference Numerals

1 Pump

2A-2D Separation device

20A-20C Passage

200 Flat channel

21 Opening

22 Membrane

23 Reservoir

24A-24D Housing

240 Inlet

241 Outlet

242 Wall

243 Wall

244 Even surface

245 Outer wall

25A-25C Cover

250 Opening

251 Strut

252 Recess

26 Bypass

27 Check valve

270 Valve element

271 Cover

28 Closure device

280 Seal

281 Pin

282 Cover

3A, 3B Pressure-activated valve

30A, 30B Housing

300 Inlet

301 Outlet

302 Opening

31A, 31B Part

310 Slit

311 Protrusion

312 Ring

32 Cavity 4 Tube

40 Retaining ring

5 Casing

50 Receptacle 51 Main body

52 Door

520 Surface

6 Rack

7 Bag 8 Plate

9 Gas detector

B Gas bubble

F Fluid

G Gas P Fluid path

S Infusion system

W Weld seam

Claims

1. An infusion system (S) for administering a fluid (F) to a patient via a fluid path (P), comprising: a pump (1) for conveying the fluid (F) along the fluid path (P), a separation device (2A-2D) in fluid connection with the fluid path (P) to separate gas (G) from the fluid (F) and a pressure-activated valve (3A, 3B) in fluid connection with the fluid path (P) at or downstream the separation device (2A-2D), wherein the separation device (2A-2D) defines a passage (20A-20C) for the fluid (F) and has an opening (21) covered by a gas-permeable, hydrophobic membrane (22) allowing gas (G) to exit from the fluid (F) through the opening (21).

2. The infusion system (S) according to claim 1 , characterized in that the pressure-activated valve (3B) is arranged within the separation device (2B).

3. The infusion system (S) according to claim 1 , characterized in that the separation device (2A-2D) comprises an inlet (240) and an outlet (241) in fluid connection with one another via the passage (20A-20C), the passage (20A-20C) being continuously open from the inlet (240) to the outlet (241).

4. The infusion system (S) according to any of the preceding claims, characterized in that the separation device (2A, 2B) defines a reservoir (23) adjacent the hydrophobic membrane (22) to collect ascending gas bubbles (B).

5. The infusion system (S) according to any of the preceding claims, characterized in that the separation device (2B) comprises a check valve (27) at the opening (21).

6. The infusion system (S) according to any of the preceding claims, characterized in that the passage (20A-20C) is defined by a housing (24A, 24C, 24D) of the separation device (2A, 2C, 2D) and the hydrophobic membrane (22) and/or defines a flat channel (200).

7. The infusion system (S) according to any of the preceding claims, characterized in that the hydrophobic membrane (22) is oleophobic.

8. The infusion system (S) according to any of the preceding claims, characterized in that the hydrophobic membrane (22) is bulged and/or mounted by means of a weld seam (W).

9. The infusion system (S) according to any of the preceding claims, characterized in that the separation device (2A, 2C, 2D) comprises a cover (25A-25C) covering the hydrophobic membrane (22), wherein the cover (25A-25C) comprises a plurality of openings (250).

10. The infusion system (S) according to any of the preceding claims, characterized in that the separation device (2D) defines two separated passages (20C), wherein the opening (21) covered by the hydrophobic membrane (22) is located at one of the separated passages (20C) and another opening (21) covered by another gas-permeable, hydrophobic membrane (22) for allowing gas (G) to exit from the fluid (F) through the other opening (21) is located at the other one of the separated passages (20C), wherein the two hydrophobic membranes (22) are located at opposing sides of the separation device (2D).

11. The infusion system (S) according to any of the preceding claims, characterized in that the pressure-activated valve (3A, 3B) comprises a part (31 A, 31 B) being pretensioned in a closed position closing the fluid path (P), and that can be brought in an opened configuration opening the fluid path (P) by pressure of the fluid (F).

12. The infusion system (S) according to any of the preceding claims, characterized in that at least a section of the fluid path (P) is defined by a silicone tube (4), wherein the pump (1) is a volumetric pump acting on the silicone tube (4).

13. The infusion system (S) according to any of the preceding claims, characterized by a closable bypass (26) for the pressure-activated valve (3B).

14. The infusion system (S) according to any of the preceding claims, characterized by a casing (5) retaining the pump (1) and the separation device (2A-2D).

15. The infusion system (S) according to claim 13, characterized in that the casing (5) defines a receptacle (50) to hold the separation device (2A-2D) in a predefined orientation with respect to the casing (5).

16. The infusion system (S) according to claim 13 and according to claim 14 or 15, characterized in that the casing (5) comprises a door (52) that closes the bypass (26) when the door (52) is in a closed position and opens the bypass (26) when the door is in an opened position.