Medical injection device with gas venting

Abstract

An injection device (1) for injecting a medical fluid, comprising: - a piston (6) arranged within an inner space (4) delimiting an upper space (4b) and a lower space (4a), - a venting path, said venting path going through said piston (6) from the lower space (4a) to the upper space (4b) of said inner space, - a selector (24) between a lower portion (17a) and an intermediate portion (17b) of said venting path, said selector being configured to selectively allow a passage of gas and prevent a passage of medical fluid through said selector (24, 50, 60), - a purge valve (22) between the intermediate portion (17b) of said venting path and an upper portion (17c) of said venting path and configured to move between a blocking configuration and a flow-through configuration, said flow-through configuration requiring a presence of an overpressure in said intermediate portion (17b), said overpressure being caused by a travel of said piston (6) towards a lower end of said body (2).

Description

Technical Field

[0001] The present invention relates generally to the injection of medical fluids, and more specifically, to an injection device for injecting medical liquids from a medical liquid container into a medical catheter. Background Technology

[0002] Injection devices are typically used to transfer medical fluids from a medical fluid container into a medical catheter. For example, 70% of CT scan diagnostic cases require the injection of medical fluids such as iodinated contrast agents. In approximately 70% of these cases, this injection is performed using an automated contrast agent injector. An injection catheter is required to connect the automated injector to the patient.

[0003] US patent application 20120209111 discloses a capsule injector for a fluid delivery system, comprising a cylindrical body, a cap-cap assembly, a plunger element disposed within the cylindrical body, and a mounting assembly for securing the cap-cap assembly to the cylindrical body. The cylindrical body has a distal end and a proximal end and defines a through-hole. The cap-cap assembly is adapted to connect to the distal end of the cylindrical body and includes a cap and a capsule. The cap defines an internal cavity and a distal discharge conduit and is adapted to engage the distal end of the cylindrical body. A disc-shaped capsule is disposed within the internal cavity and typically includes a central diaphragm portion. The plunger element is disposed within the through-hole of the cylindrical body and is vented to allow for the venting of the space between the plunger element and the cap-cap assembly within the cylindrical body.

[0004] US patent application 20060249541 discloses a fluid dispensing device comprising a bottle for receiving fluid, a discharge tube, and a pressurizing device connected between the bottle and the discharge tube for pressurizing the fluid and forcing it to flow through the discharge tube without gravity. The pressurizing device includes a container connected between the bottle and the discharge tube, a piston slidably received within the container, and a moving device for moving the piston within the container in a reciprocating motion. For example, a motor is connected to the piston via a crank to move the piston in a reciprocating motion within the container.

[0005] US patent application 20050215850 discloses a syringe pump comprising: a syringe including a plunger sliding in a body having a discharge port; a drive mechanism coupled to the syringe including a cylinder and a biasing device, a piston mounted on a shaft sliding in the cylinder, the biasing device being operable to apply a pushing force to the piston to drive the piston distally in the cylinder; and a safety latch initially preventing the biasing device from moving the piston, the safety latch being removable to allow the biasing device to move the piston.

[0006] Figure 1An example of an infusion system 100 for injecting medical fluid from a medical fluid container 104 into a common conduit 102 is shown. Those skilled in the art will appreciate that the medical fluid container 104 can be any type of container specifically designed to contain medical fluids, such as, but not limited to, vials, bottles, plastic containers, and any type of container manufactured to contain medical fluids. The infusion system includes: a first connector 106 configured to connect to the medical fluid container 104; an injector 108 to which an infusion device 110 with a medical catheter interface 112 is attached; a medical fluid supply line 114 configured to connect the first connector 106 to the medical catheter interface 112 to supply medical fluid to the infusion device 110; and a common conduit 102 configured to connect to the medical catheter interface 112 and a patient conduit 116 to inject medical fluid into the patient conduit 116. More specifically, the first catheter valve 130 connects the fluid supply line 114 to the common line 102 and allows access to the common line 102 only under vacuum pressure. The common line 102 includes a second catheter valve 140 downstream of the first catheter valve 130 and allows access only toward the patient line 102. The infusion device 110 generally includes a body and a piston that defines an internal space. The piston is driven by a plunger rod and configured to travel within the internal space to pump fluid into or expel fluid from the internal space.

[0007] In the depicted example, two different types of medical fluids will be injected into the patient; therefore, the injection system is configured to connect to two medical fluid containers 104 via two different first connectors 106 and two different medical fluid supply lines 114. However, the injection system can also be configured to inject only one type of medical fluid. For simplicity, the following description will refer to the configuration of injecting only one type of medical fluid, as dual injection only involves repeating the described features. Here, "dual injection" is understood to mean two injections.

[0008] For economic and ecological reasons (less use of plastic), multi-patient practices are steadily gaining market share. In a so-called multi-patient practice, the catheter setup for the infusion system consists of two very distinct parts: a day set 120 and a patient set 122. The patient set 122 is replaced for each patient. The patient set 122 is typically used to limit the risk of cross-contamination between consecutive patients, thus protecting the day set. Once installed and ready, the day set 120 remains connected to the power injector for multiple patient cases, as long as the medical fluid to be infused is the same. When it is necessary to change the medical fluid to be infused, the day set 120 is replaced. The day set 120 includes a medical fluid supply line 114 connected to a medical fluid container 104 and a common line 102. The patient set 122 includes a patient line 116, which is supplied with medical fluid through the common line 102 and connected to a cannula or needle for infusing the medical fluid into the patient.

[0009] When the infusion system 100 is configured to infuse medical fluids into a patient, it is important to ensure that there is no gas in the catheter before infusion. Injecting gas, such as air, into a patient's blood vessels can cause gas embolism, i.e., a blockage of a blood vessel caused by one or more air bubbles or other gas bubbles in the circulatory system. When the universal kit 120 or patient kit 116 is in place, the catheter is filled with air. Therefore, it is necessary to purge the gas present in the catheter before infusion. Due to the length of the catheter, a significant amount of gas will be purged from the infusion system 100.

[0010] To purge any present gas from the injection system 100 before injection, the injection device 110 draws or pulls medical fluid from the medical fluid container 104, thereby filling the medical fluid supply line 114. The injection device 110 is now filled with a mixture of medical fluid and gas. The injection device 110 is then positioned so that the medical catheter port 112 is upward, causing gas to accumulate at the medical catheter port 112. It should be noted that the filling of the injection device 110 causes turbulence in the medical fluid, thereby generating microbubbles in the medical fluid. Due to the high viscosity of medical fluids (especially contrast agents), microbubbles may take several minutes to reach the medical catheter port 112. Therefore, it is typically necessary to wait at least 2 or 3 minutes with the medical catheter port 112 upward. Then, by actuating the piston, the gas is vented from the injection device 110 through the still upward-facing medical catheter port 112 into the common line 102. The medical fluid is then injected into the common line 102 to push the gas out of the common line 102, thereby cleaning the injection system 100.

[0011] During infusion, it is possible that gas may be present in the infusion device 110. For example, the evaporation of medical fluids may generate gas. Additionally, some air bubbles generated during the initial filling of the infusion system 100 may become trapped in the catheter or against the wall of the infusion device 110 and may not be purged during initial cleaning. Therefore, during infusion, the infusion device 110 is positioned with the medical catheter interface 112 facing downwards so that any gas present in the infusion device 100 is trapped away from the medical catheter interface 112 and will not be injected into the common tubing 102.

[0012] This method has several drawbacks. First, the infusion device 110 must move between two opposite positions: up or down the medical catheter interface 112. This requires the infusion unit 108 to be able to rotate. Second, this cleaning process is lengthy, and the infusion system 100 must be monitored by an operator during cleaning. The operator must also assess the quality of the cleaning and whether it is complete. This reliance on the operator, due to the constant interaction, can lead to errors. Third, gas is propelled along the common tubing 102 by the medical fluid that also exits the infusion system. Therefore, this method involves wasting medical fluid, and the wasted medical fluid needs to be collected at the output of the infusion system 100, which can lead to disposal errors.

[0013] Furthermore, gas remaining in the injection device 110 after cleaning may alter the operation of the injection device, even if the gas is trapped within it. The dosage of medical fluid is typically controlled by the movement of the piston in the injection device 110. Since gas is compressible, changes in the volume of the medical fluid within the injection device will be inaccurate. Additionally, the volume of gas trapped in the injection device 110 must be very small; otherwise, it risks being injected into the common conduit 102.

[0014] Therefore, there is a need for an injection system that can quickly purge gas whenever gas is present in the injection device without any operator intervention. Summary of the Invention

[0015] An injection device for injecting medical fluid from a medical fluid container into a medical catheter is proposed, the injection device comprising:

[0016] - A body defining an internal space extending longitudinally between its upper and lower ends, the lower end of the body including a medical catheter interface through which medical fluid can enter the internal space from a medical fluid container and exit the internal space to be injected into the medical catheter.

[0017] - A piston disposed within the internal space and configured to travel longitudinally within the internal space, the piston defining an upper space and a lower space of the internal space, the lower space being configured to receive medical fluid.

[0018] - An evacuation path that runs longitudinally through the piston from the lower space to the upper space of the internal space.

[0019] - A selector disposed within a venting path between a lower portion and a middle portion of the venting path, the lower portion of the venting path connecting to the lower space, wherein the selector is configured to selectively allow gas to pass through the selector and travel along the venting path from the lower portion to the middle portion, and the selector is configured to selectively prevent medical fluid from passing through the selector and traveling along the venting path from the lower space to the upper space of the interior space.

[0020] - A cleaning valve disposed in the venting path between the middle portion and the upper portion of the venting path and configured to move between a blocking configuration and a flow configuration, wherein in the blocking configuration the cleaning valve closes the venting path and in the flow configuration the cleaning valve remains open the venting path, wherein the flow configuration of the cleaning valve requires an overpressure in the middle portion of the venting path caused by the piston moving toward the lower end of the body.

[0021] This invention allows gas to be purged from the injection device each time the piston advances to push medical fluid into the medical catheter. Therefore, purging is automatic, requiring no operator intervention, and ensures that no gas is injected into the medical catheter.

[0022] Other preferred but non-limiting aspects of the invention are as follows, in separate or technically feasible combinations:

[0023] - The cleaning valve is configured to be in a blocking configuration as the piston travels toward the upper end of the body;

[0024] - The lower part of the venting path is configured to receive both medical liquid and gas, and the middle and upper parts of the venting path are configured to receive only gas;

[0025] - The upper space is configured to be maintained at a constant reference pressure, and the overpressure in the middle section of the venting path corresponds to a gas pressure higher than the reference pressure;

[0026] - The piston includes a lower interface that defines a lower space of the interior space, the lower interface including an inlet of the venting path, the inlet opening in the highest portion of the lower interface;

[0027] - The lower interface has a convex surface visible from the lower part of the interior space and the entrance of the drainage path opens in the middle of the lower interface, or the lower interface has a concave surface visible from the lower part of the interior space and the entrance of the drainage path opens at the outer edge of the lower interface.

[0028] - The selector is a float configured to float on a medical liquid and disposed in a cavity, the cavity including at least a passage belonging to the drain path, wherein the float is configured to travel in the cavity along a longitudinal direction between a blocking configuration and an open configuration, in the blocking configuration the float blocks the passage thereby closing the drain path, and in the open configuration the float is spaced apart from the passage thereby opening the drain path;

[0029] - The floating member has a floating portion and at least one blocking portion, the blocking portion being configured to block the passage, wherein the floating portion has an enlarged cross section relative to the widest cross section of the blocking portion;

[0030] - The floating element is configured to block the passage by contacting the base that defines the passage through two different zones;

[0031] - The selector is a diaphragm extending across the venting path, the diaphragm being hydrophobic and configured to allow gas to pass through while preventing medical liquids from passing through;

[0032] - The diaphragm is arranged in the cavity, and a support structure is arranged in the cavity against the upper side of the diaphragm to mechanically support the diaphragm, the support structure allowing gas to pass through the diaphragm and through the support structure.

[0033] The present invention also relates to an injection system, the injection system comprising:

[0034] - An injection device as described in any of the embodiments.

[0035] - A first connector, configured to connect to a medical liquid container.

[0036] - A medical fluid supply line configured to connect the first connector to a medical catheter interface to supply medical fluid to the infusion system.

[0037] - A shared conduit configured to connect to the medical catheter interface and the patient conduit to inject medical fluid into the patient conduit.

[0038] Preferably, the overpressure corresponds to the pressure in the middle portion of the venting path exceeding the reference pressure in the upper space by at least a first pressure threshold, and

[0039] The shared pipeline includes a conduit valve with a second pressure threshold.

[0040] Wherein, the first pressure threshold is lower than the second pressure threshold.

[0041] The present invention also relates to a method for operating an injection device as described in any embodiment, wherein the injection device is held with the upper end of the body upward and the lower end of the body downward, the method comprising:

[0042] - A filling step, wherein the piston travels longitudinally toward the upper end of the body within the internal space, thereby allowing gas and medical fluid from the medical fluid container to enter the internal space through the medical catheter interface, wherein the purge valve is in a blocking configuration.

[0043] - A cleaning step, wherein the piston travels longitudinally toward the lower end of the body within the internal space, and wherein gas is discharged from the lower space to the upper space of the internal space through a venting path penetrating the piston, while the selector retains medical fluid in the lower space, wherein the cleaning valve is in a flow configuration. Attached Figure Description

[0044] Other aspects, objects, and advantages of the invention will become clearer from the following detailed description of preferred embodiments of the invention, given by way of non-limiting example and made with reference to the accompanying drawings, in which:

[0045] - Figure 1 This is a full view of the injection system connected to two medical liquid containers;

[0046] - Figure 2 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment during the filling step prior to cleaning, wherein the selector is a float;

[0047] - Figure 3 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment during the start of cleaning, wherein the selector is a float;

[0048] - Figure 4It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment at the end of cleaning, wherein the selector is a float;

[0049] - Figure 5 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment during the injection step after cleaning, wherein the selector is a float;

[0050] - Figure 6 This is a cross-sectional view of a floating element used as a selector according to a non-limiting possible embodiment;

[0051] - Figure 7a , Figure 7b , Figure 7c It is a cross-sectional view of the float of the injection device according to a non-limiting possible embodiment during a two-stage blockage in the venting path;

[0052] - Figure 8 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment during the filling step prior to cleaning, wherein the selector is a diaphragm;

[0053] - Figure 9 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment during the cleaning start, wherein the selector is a diaphragm;

[0054] - Figure 10 It is a cross-sectional view of the piston of the injection device according to a non-limiting possible embodiment at the end of cleaning, wherein the selector is a diaphragm;

[0055] - Figure 11 It is a cross-sectional view of the piston of an injection device according to a non-limiting possible embodiment during the injection step after cleaning, wherein the selector is a diaphragm. Detailed Implementation

[0056] The injection device of the present invention can be used as previously described. Figure 1 The injection system 100 is described herein. Apart from the injection device 110, the injection system 100 will not be described further.

[0057] Reference Figures 2 to 5 as well as Figures 8 to 11The injection device 110 includes a body 2 that defines an internal space 4 extending longitudinally between an upper end and a lower end of the body 2. The lower end of the body has a medical catheter interface 112 through which medical fluid can enter the internal space 4 from a medical fluid container 104 and exit the internal space 4 to be injected into a common conduit 102. Unlike previous injection devices, the injection device 110 according to the invention is configured to remain downward, as is the medical catheter interface 112. Spatial terms such as “downward,” “upward,” “lower,” “above,” “higher,” and “highest” must be understood to define generally accepted relative positions with respect to the vertical direction (i.e., the direction of local Earth's gravity). This is because gases and medical fluids are affected by gravity, and the present invention utilizes gravity for proper gas venting. Therefore, in use, the lower end of the body 2 is located below the upper end of the body 2. The body 2 is typically a hollow cylindrical body, for example, made of glass or plastic material, also referred to as a cylinder.

[0058] The injection device 110 also includes a piston 6 disposed within the internal space 4 and configured to travel longitudinally within the internal space 4 (i.e., between the upper and lower ends of the body 2). The piston 6 defines an upper space 4b and a lower space 4a within the internal space. The lower space 4a is configured to receive medical fluids, while the upper space 4b is not intended to receive any fluids. The piston 6 provides an airtight seal between the upper space 4b and the lower space 4a. For this purpose, the piston 6 is provided with at least one outer edge seal 8, 10, for example made of rubber, at different heights along the longitudinal direction, and preferably two outer edge seals 8, 10. Each outer edge seal 8, 10 presses against the wall of the body 2, thereby ensuring a tight seal. As in the depicted example, the outer edge seals 8, 10 may be square rings, but may also be, for example, O-rings.

[0059] Due to the tight seal provided by piston 6, the pressure between the upper space 4b and the lower space 4a of the internal space 4 can differ significantly. The pressure within the upper space 4b remains at a reference pressure that is substantially constant and largely independent of the movement of piston 6. This reference pressure is typically atmospheric pressure, such as the pressure of the system environment. Preferably, the upper end of the body 2 is at least partially open so that the pressure within the upper space 4b corresponds to atmospheric pressure, regardless of the movement of piston 6. Conversely, the pressure within the lower space 4a of the internal space 4 depends on the contents of said lower space 4a and the movement of piston 6. In the following description, overpressure is pressure above the reference pressure, while vacuum pressure is pressure below the reference pressure.

[0060] Piston 6 is connected to piston rod 12, for example, via a protrusion 14 at the top of piston 6, which engages in piston rod 12. Piston rod 12 is driven by injector 108, causing piston 6 to travel longitudinally within internal space 4. Piston 6 can be formed from several components assembled together. In the depicted example, piston 6 has a lower portion 6a, a middle portion 6b, and an upper portion 6c. Connectors such as screws 16 can be used to assemble the piston components.

[0061] Piston 6 has an exhaust path arranged within it. This path runs longitudinally through piston 6 from the lower space 4a to the upper space 4b of the internal space 4. The exhaust path is used to exhaust gas present in the lower space 4a to the upper space 4b. Typically, the exhaust path is not straight and can be closed or opened at different points by the components of piston 6, as described below. More specifically, the exhaust path includes a lower portion 17a, a middle portion 17b, and an upper portion 17c. The lower portion 17a of the exhaust path connects to the lower space 4a, while the upper portion 17c connects to the upper space 4b. The middle portion 17b lies between the lower portion 17a and the upper portion.

[0062] The piston 6 includes a lower interface 18 defining a lower space 4a of the internal space 4, the lower interface 18 having an inlet 20 for a venting path. Preferably, the inlet 20 opens in the highest portion of the lower interface 18 to properly vent all gas present in the lower space against the lower interface 18, without any gas being trapped in the lower space 4a of the internal space. Preferably, the lower interface 18 has a surface with its apex pointing towards the upper end of the body, and the inlet 20 for the venting path opens at said apex. For example, as in the depicted example, the lower interface 18 has a convex surface as seen from the lower space 4a of the internal space, and the inlet 20 for the venting path opens in the middle of the lower interface 18. For example, the surface of the lower interface 18 may correspond to the surface of an upwardly pointing cone, frustum, or pyramid. Alternatively, the lower interface 18 may have a concave surface as seen from the lower space 4a of the internal space, and the inlet 20 for the venting path opens at the outer edge of the lower interface 18. For example, the lower interface 18 may have a groove arranged in the outer edge of the lower interface 18, and the inlet 20 of the drainage path may open in the groove.

[0063] The piston 6 includes a purge valve 22 disposed in the venting path between the intermediate portion 17b and the upper portion 17c of the venting path. The purge valve 22 is configured to move between a blocking configuration in which the purge valve 22 closes the venting path and a flow configuration in which the purge valve 22 keeps the venting path open. The flow configuration of the purge valve 22 requires an overpressure in the intermediate portion 17b of the venting path relative to a reference pressure in the upper space 4b, caused by the piston 6 moving toward the lower end of the body 2. Since the upper space 4b is at a reference pressure (e.g., atmospheric pressure), the overpressure means a pressure higher than the reference pressure. More specifically, the overpressure required by the flow configuration of the purge valve 22 corresponds to a pressure in the intermediate portion 17b exceeding the reference pressure in the upper space 4b and the upper portion 17c of the venting path by at least a first pressure threshold. Because there is no overpressure in the middle part 17b relative to the reference pressure in the upper space 4b, but rather a vacuum pressure, i.e. a pressure lower than the reference pressure, the cleaning valve 22 is configured to be in a blocking configuration when the piston 6 moves toward the upper end of the body 2.

[0064] The piston 6 also includes selectors 24 and 60 arranged in the venting path between the lower portion 17a and the middle portion 17b of the venting path. Selectors 24 and 60 are configured to selectively allow gas to pass through them and travel along the venting path from the lower portion 17a to the middle portion 17b. Selectors 24 and 60 are also configured to selectively prevent medical fluid from passing through them and traveling along the venting path from the lower portion 17a to the middle portion 17b, and thus from the lower space 4a to the upper space 4b of the internal space. Therefore, the lower portion 17a of the venting path is configured to receive a mixture of both medical fluid and gas, while the middle portion 17b and the upper portion 17c are gas portions configured to receive only gas.

[0065] The purge valve 22 is arranged above the selectors 24 and 60 in the longitudinal direction from the lower space 4a to the upper space 4b of the internal space. Therefore, the purge valve 22 is arranged in the gas section of the venting path and does not come into contact with any liquid.

[0066] In the blocking configuration, the purge valve 22 seals the vent 26 between the middle portion 17b and the upper portion 17c of the drain path. In the flow configuration, the purge valve 22 leaves the vent 26 open. In the depicted example, two vents 26 appear between the middle portion 17b and the upper portion 17c of the drain path. More or fewer vents 26 can be provided, as long as they can be sealed by the purge valve 22.

[0067] Preferably, as depicted in the illustrated embodiment, the cleaning valve 22 is an umbrella valve having a diaphragm-shaped sealing disc 22a and a stem 22b. The stem 22b engages in a hole 28 disposed in the fixed portion of the piston 6 and presents an enlarged lower portion with a cross-section larger than that of the hole 28, thereby securing the cleaning valve 22. The diaphragm-shaped sealing disc 22a is disposed above at least one vent hole 26, which is part of the venting path and defines an intermediate portion 17b from the upper portion 17c of the venting path. The umbrella valve may be deformable and / or slidably movable along the hole 28 disposed in the fixed portion of the piston 6 to change its configuration (e.g., due to deformation of the stem). In the flow configuration, the sealing disc 22a is moved away from the vent hole 26 due to the higher gas pressure within the intermediate portion 17b, thereby allowing gas to pass through the vent hole 26. In the blocking configuration, the sealing disc 22a presses against the vent 26 due to the higher gas pressure within the upper portion 17c of the vent path, thereby sealing the vent 26 and closing the vent path. For example, the umbrella valve can be made of a rubber-type elastomer or silicone.

[0068] Selectors 24 and 60 can be, for example, a float 24 configured to float on medical liquids or a hydrophobic diaphragm 60. Reference will now be made to... Figure 2 Figure 7 illustrates a method for operating an injection device having a float 24 as a selector, and will be referred to later. Figures 8 to 11 A method for operating an injection device having a diaphragm 60 as a selector will be described later. The features of the injection device 110 and the method described below, apart from the selectors 24 and 60, can be adapted to any implementation.

[0069] The selector is a floating component.

[0070] exist Figure 2 In this diagram, the injection device 110 is shown prior to cleaning, for example during a filling step (in which the injection device 110 is filled with medical fluid and unwanted gas). During this filling step, the piston rod 12 is driven upward, for example by an injector 108 acting on the piston rod 12, thereby causing the piston 6 to travel longitudinally toward the upper end (i.e., upward) of the body 2 within the internal space 4. The lower space 4a expands, causing the gas pressure within the lower space 4a to drop below a reference gas pressure, such as atmospheric pressure, in the upper space 4b.

[0071] Because selector 24 allows gas to travel from the lower portion 17a of the vent path to the middle portion 17b, the reduced pressure in the lower space 4a is also present in both the lower portion 17a and the middle portion 17b of the vent path. However, because purge valve 22 requires overpressure in the middle portion 17b of the vent path to be in the flow configuration, purge valve 22 remains in the blocking configuration. More precisely, purge valve 22 is pressed downwards, sealing the vent orifice 26, thereby closing the vent path in the blocking configuration.

[0072] The expansion of the lower space 4a, combined with the closure of the venting path by the purge valve 22, effectively creates a vacuum pressure in the lower space 4a, i.e., a pressure below the reference pressure. The pressure in the lower space 4a decreases until it reaches the opening pressure of the first conduit valve 130, which is, for example, between 0.2 bar and 0.5 bar below the reference pressure. The opening of the first conduit valve 130 causes the aspiration of medical fluid to compensate for this vacuum pressure in the lower space 4a. The medical fluid travels through the filling line 114 connected to the medical fluid container 104 to fill the lower space 4a. Gas present in the conduit is also aspirated into the lower space 4a.

[0073] Gradually, as the lower space 4a becomes filled with medical liquid and gas, the pressure within the lower space 4a increases and becomes closer to atmospheric pressure. When the pressure within the lower space 4a reaches the closing pressure of the first conduit valve 130 (essentially similar to the opening pressure), the first conduit valve 130 closes and filling stops. At the end of the filling step, the lower space 4a is filled with a certain volume of gas 32, which is above a certain volume of medical liquid 34. The gas pressure within the lower space 4a remains lower than the gas pressure within the upper space 4b because the closure of the first conduit valve 130 stops the pressure increase before the vacuum pressure is fully compensated. Therefore, the purge valve 22 remains in a blocking configuration.

[0074] As explained above, after the injection device 110 is filled, the gas in the lower space 4a must be vented during the purging process. This purging is performed by driving the piston 6 downwards, as... Figure 3 As shown. The piston 6 moves longitudinally toward the lower end of the body 2 within the internal space 4. The lower space 4a contracts, and the gas pressure in the lower space 4a increases until the pressure difference between the gas pressure in the middle portion 17b, which is still connected to the lower space 4a, and the reference gas pressure in the upper space 4b becomes higher than the opening pressure threshold of the purge valve 22, that is, until the pressure difference reaches the first pressure threshold.

[0075] As described above, the purge valve 22 is configured to move into a flow configuration in response to an overpressure in the lower space 4a exceeding a reference pressure in the upper space 4b by at least a threshold pressure of the purge valve 22 (e.g., a pressure difference between the overpressure and the reference pressure between 20 mbar and 100 mbar). Therefore, the purge valve 22 moves into the flow configuration, thereby opening the vent path. In the depicted example, the sealing disc 22a moves away from the vent 26, thereby opening the vent 26.

[0076] Gas is discharged from the lower space 4a to the upper space 4b of the internal space 4 through the venting path that runs through the piston 6. More specifically, the gas enters the venting path through inlet 20, then travels along the lower portion 17a of the venting path, then along the middle portion 17b of the venting path, then through the vent 26, and finally reaches the upper space along the upper portion 17c. This... Figure 3 The dashed arrow is shown in the middle.

[0077] As piston 6 moves downwards while gas is vented through the venting path, the piston reaches the volume of medical liquid in the lower space 4a. More specifically, the lower interface 18 contacts the medical liquid, and because inlet 20 opens in the highest portion of the lower interface 18, the gas is pushed back towards inlet 20 of the venting path. Thus, gas is vented from the lower space 4a before the medical liquid reaches inlet 20 of the venting path. When all the gas has been vented, the medical liquid passes through inlet 20 in the lower interface 18 of piston 6 and fills the lower portion 17a of the venting path.

[0078] As shown, the lower portion 17a of the drain path may include a cavity 36 in which a selector 24 is disposed, and medical fluid begins to fill the cavity 36. The selector is a float 24 configured to float on the medical fluid, and the cavity 36 is configured to allow the float 24 to move up and down within the cavity 36 in a longitudinal direction. The cavity 36 includes at least a passage 38 that forms the boundary between the lower portion 17a and the middle portion 17b of the drain path. The passage 38 is disposed at the top of the cavity 36. The float 24 is configured to travel in a longitudinal direction within the cavity 36 between a blocking configuration and an open configuration. In the blocking configuration, the float 24 blocks the passage 38, thereby closing the drain path. In the open configuration, the float 24 is spaced apart from the passage 36, thereby keeping the drain path open and unobstructed.

[0079] More precisely, when cavity 36 is filled with gas 32, the float 24 remains at the bottom of cavity 36, keeping passage 38 open and thus keeping the drainage path unobstructed. When medical fluid arrives at cavity 36, float 24 begins to float on the medical fluid and is thus carried upward by the medical fluid 34 according to the upward buoyancy exerted on the float by the medical fluid (Archimedes' principle). Under the action of this force, float 24 travels upward until it reaches the top of cavity 36 and blocks passage 38.

[0080] The passage 38 is defined by the outer edge of the base 40 forming the float 24, facing the float 24. The float blocks the passage 38 by pressing against the base. The base 40 is made of, for example, metal or plastic such as thermoplastic polyurethane, polyoxymethylene, polycarbonate, polyvinyl chloride, etc. Advantageously, the base 40 is made of a material with an elastic modulus higher than 2500 MPa. Preferably, the base 40 has a reduced cross-section in the direction of the middle portion 17b of the drainage path, and for example, the shape of the base 40 is at least partially a hollow truncated cone. A reinforcing element 42, such as a washer, may be disposed above the base 40 to reinforce the base, especially when the base is made of a highly deformable material.

[0081] As in Figure 6 In the depicted example, the float 24 has at least a blocking portion 24a configured to block the passage 38. Typically, the passage 38 has a circular cross-section, and the blocking portion 24a of the float 24 also has a circular cross-section. For example, the blocking portion 24a of the float 10 may be at least partially elliptical, spherical, or pine-tree-like conical. For example, the float 24 may simply be a sphere. Preferably, the blocking portion 24a of the float is coated with a deformable material to better seal the passage 38 when the float 24 presses against the base 40.

[0082] Preferably, the floater 24a has a floater portion 24b with an enlarged cross-section relative to the widest portion of the blocking portion 24a, the floater portion 24b supporting the blocking portion 24a. The floater can be as follows: Figure 6 The float can be divided into two parts or be a single piece comprising a blocking part 24a and a floating part 24b. The blocking part 24a of the float 24 is, for example, a ball. The diameter of the floating part 24b of the float 24 is larger than the widest diameter of the blocking part 24a (i.e., the ball part). The larger diameter (perpendicular to the longitudinal direction) of the floating part 24b makes the float 24 more sensitive to smaller forces exerted on it by the medical fluid 34. This enhanced response allows the float 24 to be pushed upwards once the medical fluid reaches it, and thus ensures that no medical fluid can reach the passage 38 before it is blocked by the float 24.

[0083] When the medical fluid 34 comes into contact with the float 24 (e.g., the float portion 24b of the float 24), the float 24 begins to float and thus moves upward until it reaches the base 40. The shape of the float 24 is adapted to the shape of the base 40 so that the float 24 creates a continuous seal when it presses against the base 40. At this point, the passage 38 is blocked, and neither gas nor medical fluid can pass through the blocked passage 38. A small volume of gas may be trapped in the cavity 36, i.e., in the lower part of the venting path, between the blocked passage 38 and the surface of the medical fluid 34. This small volume allows the base to remain dry and prevents any material from depositing on the base 40. This small volume may, for example, be less than 10 ml at atmospheric pressure. This small volume of air may be sufficient to dry the float 24. The density of the float 24 and the complementary shape of the blockage portion 24a and the base 40 are chosen to minimize the volume of trapped air while keeping the surface of the medical fluid away from the base 40. For example, the cross-section of the base can be reduced in the direction of the middle portion 17b of the drainage path.

[0084] Once passage 38 is blocked, no gas escapes from the overpressure in the lower portion 17a of the venting path and reaches the intermediate portion 17b. Therefore, the pressure above the blocked passage 38 in the intermediate portion 17b drops until the pressure difference between the intermediate portion 17b and the reference pressure reaches the closing pressure threshold of the purge valve 22, which is slightly higher than the reference pressure because the upper space 4b is at the reference pressure. For example, the closing pressure threshold of the purge valve 22 may correspond to a positive pressure difference of 20 mbar to 100 mbar between the pressure in the intermediate portion 17b and the reference pressure. Preferably, the closing pressure threshold and the opening closing threshold are substantially the same, but they can also be different. Therefore, the purge valve 22 is now closed in the blocked configuration ( Figure 5 In this example, the sealing disc 22a covers the vent 26. The purge process is complete. A small volume of gas 32, under residual overpressure (i.e., slightly above the reference pressure), remains in the intermediate section 17b. The residual overpressure is not high enough to cause the purge valve 22 to open the vent 26. This residual overpressure ensures that air at atmospheric pressure from the upper space 4b cannot enter the intermediate section 17b of the venting path, thus preventing unsterilized air from entering the sterilization zone of the medical fluid circulation.

[0085] The method may include a supplementary filling step that occurs after the cleaning step and before the injection step. The supplementary filling step allows the lower space 4a to be filled with a precisely defined volume 34 of medical fluid, which is not possible in the first filling step because the gas volume 32 results in incorrect volume measurements (typically based on the piston 36 process).

[0086] The method may include an injection step in which a piston travels longitudinally toward the lower end of the body within an internal space, and where medical fluid exits the lower space of the internal space to be injected into a medical catheter. Because the venting path is closed, the pressure within the lower space 4a increases when the piston 6 is pushed downwards. When the pressure within the lower space 4a reaches the opening pressure of the second catheter valve 140, the second catheter valve 140 opens, and medical fluid 34 can exit the lower space 4a and flow through the common conduit 102 to the patient conduit 116. Thus, medical fluid can be injected without any gas. During injection, the float 24 contacts the medical fluid.

[0087] It should be noted that the opening pressure threshold (i.e., the first pressure threshold) of the purge valve 22 is lower than the opening pressure threshold (second pressure threshold) of the second conduit valve 140, so that when air is to be vented, the purge valve 22 opens before the second conduit valve 140 opens. However, during this injection step, the passage 38 is blocked by the selector (float 24), meaning that the pressure increases in the lower space 4a but not in the isolated middle section 17b of the venting path. The purge valve 22 thus remains in the blocked configuration.

[0088] As a variant, such as Figure 7a , Figure 7b and Figure 7c As shown, the selector can be a float 50 that provides two-stage blocking of the drainage path. The float 50 is configured to block the passage 38 by contacting the base 40, which defines the passage 38, through two distinct contact areas. To this end, the float 50 includes a first blocking portion 50a and a second blocking portion 50b, which are arranged such that when the float 50 moves upward to block the passage 38, the first blocking portion 50a first cooperates with the base 40 to form a first seal, and then the second blocking portion 50b cooperates with the base 40 to form a second seal.

[0089] Preferably, the first blocking portion 50a faces the passage 38, while the second blocking portion 50b has a sealing portion 52 configured to cooperate with the base 40 to surround the first blocking portion 50a (in projection on a plane perpendicular to the longitudinal direction). Thus, as the float 50 moves upward, the second seal surrounds the first seal. In the depicted example, the first blocking portion 50a of the float 50 can be a blocking portion as described above and can be a sphere as shown. The second blocking portion 50b of the float 50 can correspond to the float portion 24b of the previously described float. The second blocking portion 50b can still be enlarged relative to the first blocking portion 50a, but now also has at least one sealing portion 52 projecting upward around the upper portion. Preferably, the highest point of the sealing portion 52 is lower than the highest point of the first blocking portion 50a, so that the first seal occurs before the second seal. It should be noted that, as previously stated, although a two-piece float is illustrated, the float 50 can be a one-piece float.

[0090] The base 40 can be adapted to accommodate this type of float 50. The base 40 can define two wall portions of the passage 38, corresponding to a first base 40a and a second base 40b. The second base 40b surrounds the first base 40a (in its projection onto a plane perpendicular to the longitudinal direction). Preferably, the first base 40a is deformable (e.g., with a stiffness of 20-30 ShA to allow the float 50 to remain in an upward position so that the float 50 can contact the second base 40b after the first base 40a has deformed).

[0091] exist Figure 7a In this configuration, the floating element 50 is positioned away from the bases 40a and 40b and does not obstruct the passage 38. Gas can pass through the passage 38 and be discharged into the upper space 4b. Figure 7b In the process, the float 50 begins to float on the medical liquid and thus moves upward toward the bases 40a and 40b. The first blocking portion 50a of the float contacts the first base 40a and causes a first seal, as described above. The passage 38 is blocked by the first blockage. As the piston 6 continues to move downward, the pressure in the cavity 36 of the lower portion 17a of the drain path increases, and the medical liquid fills the cavity 36. The float 50 remains pressed against the first base 40a, which deforms due to the force applied by the float 50. Therefore, the float 50 can move upward, and the sealing portion 52 of the second blocking portion 50b contacts the second base 40b. A second blockage occurs, as... Figure 7c As shown.

[0092] In this variant, a larger volume of gas is trapped below the blocked passage, and the second seal ensures that no medical fluid will come into contact with the first blockage 50a, which remains dry and free of contaminants. The first blockage 50a remains clean and ensures the first seal occurs.

[0093] The selector is a diaphragm.

[0094] Reference Figures 8 to 11 A method for operating an injection device 110 with a diaphragm 60 as a selector is now described. The diaphragm 60 extends across a drain path, thereby defining a lower portion 17a and a middle portion 17b of the drain path. The diaphragm 60 is hydrophobic and configured to allow gas to pass through while preventing the passage of medical fluids. In this example, the diaphragm 60 is arranged in a cavity having a larger cross-section (perpendicular to the longitudinal direction) than the inlet 20 of the drain path. This is not necessary, and the inlet 20 may have a larger cross-section than the cavity 36. However, the larger cavity increases the surface area of ​​the diaphragm 60 that allows gas to pass through, thus accelerating cleanup.

[0095] exist Figure 8 In the diagram, the injection device 110 is shown prior to cleaning, for example during a filling step, wherein the injection device 110 is filled with medical fluid and unwanted gas. During this filling step, the piston rod 12 is driven upward, for example by an injector 108 acting on the piston rod 12, thereby causing the piston 6 to travel longitudinally toward the upper end (i.e., upward) of the body 2 within the internal space 4. The lower space 4a expands, causing the gas pressure within the lower space 4a to drop below the gas pressure within the upper space 4b, for example, to atmospheric pressure.

[0096] Because the diaphragm 60 allows gas to travel from the lower portion 17a of the vent path to the middle portion 17b, the reduced pressure in the lower space 4a also exists in both the lower portion 17a and the middle portion 17b of the vent path. However, because the purge valve 22 requires overpressure in the middle portion 17b of the vent path to be in the flow configuration, the purge valve 22 remains in the blocking configuration. More precisely, the purge valve 22 is pressed downwards, sealing the vent 26, thereby closing the vent path.

[0097] The expansion of the lower space 4a, combined with the closure of the venting path by the purge valve 22, effectively creates a vacuum pressure in the lower space 4a, i.e., a pressure below the reference pressure. This pressure decreases until it reaches the opening pressure of the first conduit valve 130, which is, for example, between 0.2 bar and 0.5 bar below the reference pressure. The opening of the first conduit valve 130 causes the aspiration of medical fluid to compensate for this vacuum pressure in the lower space 4a. The medical fluid travels through the filling line 114 connected to the medical fluid container 104 to fill the lower space 4a. Gas present in the conduit is also aspirated into the lower space 4a.

[0098] Gradually, as the lower space 4a becomes filled with a certain volume of medical liquid 34 and a certain volume of gas 32, the pressure within the lower space 4a increases and becomes closer to atmospheric pressure. When the pressure within the lower space 4a reaches the closing pressure of the first conduit valve 130 (essentially similar to the opening pressure), the first conduit valve 130 closes and filling stops. At the end of the filling step, the lower space 4a is filled with a certain volume of gas 32, which is above the certain volume of medical liquid 34. The gas pressure within the lower space 4a remains lower than the gas pressure within the upper space 4b because the closing of the first conduit valve 130 stops the pressure increase before the vacuum pressure is fully compensated. Therefore, the purge valve 22 remains in a blocking configuration.

[0099] As explained above, after the injection device 110 is filled, the gas in the lower space 4a must be vented during the purging process. This purging is performed by driving the piston 6 downwards, as... Figure 9 As shown. The piston 6 moves longitudinally toward the lower end of the body 2 within the internal space 4. The lower space 4a contracts, and the gas pressure in the lower space 4a increases until the pressure difference between the gas pressure in the middle portion 17b, which is still connected to the lower space 4a, and the gas pressure in the upper space 4b becomes higher than the opening pressure threshold of the purge valve 22, that is, until the pressure difference reaches the first pressure threshold.

[0100] As described above, the purge valve 22 is configured to move into a flow configuration in response to an overpressure in the lower space 4a exceeding a reference pressure in the upper space 4b by at least a threshold pressure of the purge valve 22 (e.g., a pressure difference between the overpressure and the reference pressure between 20 mbar and 100 mbar). Therefore, the purge valve 22 moves into the flow configuration, thereby opening the vent path. In the depicted example, the sealing disc 22a moves away from the vent 26, thereby opening the vent 26.

[0101] Gas is discharged from the lower space 4a to the upper space 4b of the internal space 4 through the venting path that runs through the piston 6. More specifically, the gas enters the venting path through inlet 20, then travels along the lower portion 17a of the venting path, passes through the diaphragm 60, then travels along the middle portion 17b of the venting path, then through the vent 26, and finally reaches the upper space 4b along the upper portion 17c. This... Figure 9 The dashed arrow is shown in the middle.

[0102] As piston 6 moves downwards while gas is vented through the venting path, the piston reaches the volume of medical liquid in the lower space 4a. More specifically, the lower interface 18 contacts the medical liquid, and because inlet 20 opens in the highest portion of the lower interface 18, the gas is pushed back towards inlet 20 of the venting path. Thus, gas is vented from the lower space 4a before the medical liquid reaches inlet 20 of the venting path. When all the gas has been vented, the medical liquid passes through inlet 20 in the lower interface 18 of piston 6 and fills the lower portion 17a of the venting path.

[0103] As shown in the figure, a diaphragm 60 can be disposed within a cavity 36, and medical fluid begins to fill the cavity 36, while gas escapes from the lower part of the cavity 36 (which belongs to the lower portion 17a of the drainage path) and reaches the upper part of the cavity 36 (which belongs to the middle portion 17b of the drainage path). The diaphragm 60 is configured to allow gas to pass through while preventing the medical fluid from passing through. The diaphragm 60 is a hydrophobic material and can be made of, for example, PET (polyethylene terephthalate), ABS (acrylonitrile-butadiene-styrene), PA (polyamide), or other plastic materials or medical-grade stainless steel. The diaphragm 60 can be coated with, for example, PTFE (polytetrafluoroethylene), ePTFE (expanded polytetrafluoroethylene), or other hydrophobic raw materials.

[0104] The diaphragm 60 can be characterized by its air permeability and its pore size. In particular, the diaphragm 60 allows for very low air permeability, for example, 5 l / m at 120 Pa.s or lower. 2 / sec. Low permeability allows for small pore sizes in the diaphragm. For example, the pore size of diaphragm 60 can range from approximately 0.01 micrometers to 0.25 micrometers. Optionally, diaphragm 60 can have small pores measured at 0.07 micrometers or less. For example, the tissue thickness of diaphragm 60 can be approximately 200 micrometers.

[0105] When the medical fluid comes into contact with the diaphragm 60, the diaphragm 60 prevents the medical fluid from passing through, and the medical fluid is blocked in the lower part of the cavity 36, which belongs to the lower portion 17a of the venting path. Since gas can still escape from the middle portion 17b of the venting path to reach the upper space 4b, while gas no longer reaches the middle portion 17b from the lower portion 17a, the pressure in the middle portion 17b of the venting path decreases until the pressure difference between the middle portion 17b and the reference pressure reaches the closing pressure threshold of the purge valve 22, which is slightly higher than the reference pressure because the upper space 4b is at the reference pressure. For example, the closing pressure threshold of the purge valve 22 may correspond to a positive pressure difference of 20 mbar to 100 mbar between the pressure in the middle portion 17b and the reference pressure. Preferably, the closing pressure threshold and the opening closing threshold are substantially the same, but they can also be different. Therefore, the purge valve 22 is now closed ( Figure 11 The sealing disc 22a covers the vent 26. Cleaning is now complete.

[0106] The method may include a supplementary filling step that occurs after the cleaning step and before the injection step. The supplementary filling step allows the lower space 4a to be filled with a precisely defined volume 34 of medical fluid, which is not possible in the first filling step because the gas volume 32 results in incorrect volume measurements (typically based on the piston 36 process).

[0107] The method may include an injection step in which a piston travels longitudinally toward the lower end of the body within an internal space, and in which medical fluid exits the lower space of the internal space to be injected into a medical catheter. Because the venting path is closed, the pressure within the lower space 4a increases when the piston 6 is pushed downwards. When the pressure within the lower space 4a reaches the opening pressure of the second catheter valve 140, the second catheter valve 140 opens, and medical fluid 34 can exit the lower space 4a and flow through the common line 102 to the patient line 116. Thus, medical fluid can be injected without any gas. It should be noted that the opening pressure threshold of the purge valve 22 (i.e., the first pressure threshold) is lower than the opening pressure threshold of the second catheter valve 140 (the second pressure threshold) so that the purge valve 22 opens before the second catheter valve 140 opens when air is to be vented. The purge valve 22 therefore remains in a blocking configuration during the injection step.

[0108] During injection, the diaphragm 60 comes into contact with the medical fluid and bears the full injection pressure due to this contact. For an injection rate of 10 cc / s, the injection pressure can reach values ​​such as 24 bar. The diaphragm 60 is chosen to withstand such high pressure. To help the diaphragm 60 withstand the mechanical forces exerted by the medical fluid, a support structure can be arranged in the upper part of the cavity 36, i.e., in the middle portion 17b of the drain path.

[0109] The support structure remains against the upper side of the diaphragm 60 to mechanically support the diaphragm 60. The support structure is permeable to gases (e.g., air) and, of course, allows gas to pass through the diaphragm 60 and through the support structure. The support can be made of semi-rigid or rigid foam. Alternatively, the support can be a porous plastic plate or a microporous metal sheet. For example, the support structure can be foam, mesh, or grid, preferably made of metal. However, the support structure can be of any type, as long as it provides mechanical support to the diaphragm without preventing gas from passing through the middle portion 17b of the venting path.

[0110] While the invention has been described with respect to certain preferred embodiments, it is apparent that the invention is by no means limited thereto, and that the invention includes all technical equivalents of the described apparatus and combinations thereof. In particular, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. An injection device (110) for injecting medical fluid from a medical fluid container into a medical catheter, the injection device comprising: - Body (2), which defines an internal space (4) extending longitudinally between the upper end and the lower end of the body (2), the lower end of the body including a medical catheter interface (112), through which medical fluid can enter the internal space (4) from a medical fluid container and exit the internal space (4) to be injected into the medical catheter. - A piston (6) disposed within the internal space (4) and configured to travel longitudinally within the internal space (4), the piston (6) defining an upper space (4b) and a lower space (4a) of the internal space, the lower space (4a) being configured to receive medical fluid. - An evacuation path that runs through the piston (6) along a longitudinal direction from the lower space (4a) to the upper space (4b) of the internal space. - A selector disposed within the venting path between the lower portion (17a) and the middle portion (17b) of the venting path, the lower portion (17a) of the venting path connecting to the lower space (4a), wherein the selector is configured to selectively allow gas to pass through the selector and travel along the venting path from the lower portion (17a) to the middle portion (17b), and the selector is configured to selectively prevent medical fluid from passing through the selector and traveling along the venting path from the lower space (4a) to the upper space (4b) of the interior space. - A cleaning valve (22) is disposed in the venting path between the middle portion (17b) and the upper portion (17c) of the venting path and is configured to move between a blocking configuration and a flow configuration, in which the cleaning valve (22) closes the venting path and in the flow configuration, the cleaning valve (22) remains open in the venting path, wherein the flow configuration of the cleaning valve (22) requires an overpressure in the middle portion (17b) of the venting path caused by the piston (6) moving toward the lower end of the body (2).

2. The injection device (110) according to claim 1, wherein, The cleaning valve (22) is configured to be in the blocking configuration when the piston (6) travels toward the upper end of the body (2).

3. The injection device (110) according to claim 1, wherein, The lower portion (17a) of the venting path is configured to receive both medical liquid and gas, and the middle portion (17b) and upper portion (17c) of the venting path are configured to receive only gas.

4. The injection device (110) according to claim 1, wherein, The upper space (4b) is configured to be maintained at a constant reference pressure, and the overpressure in the middle portion of the venting path corresponds to a pressure higher than the reference pressure.

5. The injection device (110) according to claim 1, wherein, The piston includes a lower interface (18) that defines a lower space (4a) of the internal space (4), the lower interface (18) including an inlet (20) of the venting path, the inlet opening in the highest part of the lower interface.

6. The injection device (110) according to claim 5, wherein, The lower interface (18) has a convex surface visible from the lower space (4a) of the interior space and the entrance (20) of the drainage path is open in the middle of the lower interface (18), or the lower interface (18) has a concave surface visible from the lower space (4a) of the interior space and the entrance (20) of the drainage path is open at the outer edge of the lower interface (18).

7. The injection device (110) according to claim 1, wherein, The selector is a float configured to float on a medical liquid and disposed in a cavity (36) including at least a passage (38) belonging to the drain path, wherein the float is configured to travel in the cavity (36) longitudinally between a blocking configuration and an open configuration, in which the float blocks the passage (38) to close the drain path, and in the open configuration, the float is spaced apart from the passage (38) to open the drain path.

8. The injection device (110) according to claim 7, wherein, The floating member has a floating portion (24b) and at least one blocking portion (24a) configured to block the passage (38), wherein the floating portion (24b) has an enlarged cross section relative to the widest cross section of the blocking portion (24a).

9. The injection device (110) according to claim 7, wherein, The floating element is configured to block the passage (38) by contacting the base (40) that defines the passage (38) through two different zones.

10. The injection device (110) according to claim 1, wherein, The selector is a diaphragm extending across the venting path, the diaphragm being hydrophobic and configured to allow gas to pass through while preventing medical liquids from passing through.

11. The injection device (110) according to claim 10, wherein, The diaphragm is arranged in the cavity (36), and a support structure is arranged in the cavity (36) against the upper side of the diaphragm to mechanically support the diaphragm, the support structure allowing gas to pass through the diaphragm and through the support structure.

12. An injection system (100), comprising: - The injection device (110) according to claim 1. - A first connector (106) configured to connect to a medical liquid container (104). - A medical fluid supply line (114) configured to connect the first connector (106) to the medical catheter interface (112) to supply medical fluid to the infusion system. - A common conduit (102) configured to connect to the medical catheter interface (112) and the patient conduit (116) to inject medical fluid into the patient conduit.

13. The injection system (100) according to claim 12, wherein, The overpressure corresponds to the pressure in the middle section (17b) of the venting path exceeding the reference pressure in the upper space (4b) by at least a first pressure threshold, and The common pipeline (102) includes a conduit valve (140) having a second pressure threshold. Wherein, the first pressure threshold is lower than the second pressure threshold.

14. A method for operating the injection device according to claim 1, wherein, The injection device (110) is held such that the upper end of the body (2) is upward and the lower end of the body (2) is downward, the method comprising: - Filling step, wherein the piston (6) moves longitudinally toward the upper end of the body (2) within the internal space (4), thereby allowing gas and medical liquid from the medical liquid container (104) to enter the internal space (4) through the medical catheter interface (112), wherein the cleaning valve (22) is in a blocking configuration. - Cleaning step, wherein the piston (6) travels longitudinally toward the lower end of the body (2) within the internal space (4), and wherein gas is discharged from the lower space (4a) of the internal space (4) to the upper space (4b) through an venting path through the piston (6), while the selector holds the medical fluid in the lower space (4a), wherein the cleaning valve (22) is in a flow configuration.

Images