Gas exhaust medical injection device

Abstract

1. An injection device (1) for injecting a medical liquid, comprising: a piston (6) arranged inside an internal space (4) defining an upper space (4b) and a lower space (4a); a discharge path traversing the piston (6) from the lower space (4a) to the upper space (4b) of the internal space; a selector (24) between a lower part (17a) and a middle part (17b) of the discharge path, configured to selectively allow gas to pass and to prevent medical liquid from passing through the selector (24, 50); and a purge valve (22) between the middle part (17b) of the discharge path and an upper part (17c) of the discharge path, configured to move between a blocking configuration and a passing configuration requiring overpressurization of the middle part (17b) caused by movement of the piston (6) towards a lower end of the body (2).

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates generally to the injection of medical fluids, and more particularly to an injection device for injecting medical fluids from a medical fluid container into medical tubing. [Background technology]

[0002] Injection devices are typically used to inject medical fluids from a medical fluid container into medical tubing. Injection of medical fluids, such as iodine contrast media, is required in 70% of CT scan diagnostic cases. This injection is performed using an automatic contrast injector in approximately 70% of cases. Injection tubing is required to connect the automatic injector to the patient.

[0003] Patent application US Serial No. 13 / 453,335 (US Patent Publication No. 20120209111) discloses a bladder syringe for a fluid delivery system including a cylindrical body, a cap-bladder assembly, a plunger element disposed on the cylindrical body, and a mounting assembly for fixing the cap-bladder assembly to the cylindrical body. The cylindrical body has a distal end and a proximal end and defines a through hole. The cap-bladder assembly is adapted to connect to the distal end of the cylindrical body and includes a cap body and a bladder. The cap body defines an internal cavity and a distal discharge conduit and is adapted to engage the distal end of the cylindrical body. The disk-shaped bladder is disposed within the internal cavity and typically includes a central membrane portion. The plunger element is disposed in the through hole of the cylindrical body and is vented to allow evacuation of a space between the plunger element and the cap-bladder assembly of the cylindrical body.

[0004] Patent application US 10 / 986,416 (US Published Patent Application No. 20060249541) discloses a fluid dispensing device including a bottle for receiving a fluid, a discharge tube, and a pressurizing device coupled between the bottle and the discharge tube for pressurizing the fluid and causing the fluid to flow through the discharge tube without gravity. The pressurizing device includes a container coupled between the bottle and the discharge tube, a piston slidably received in the container, and a moving device for moving the piston in a reciprocating motion within the container. For example, a motor is coupled to the piston with a crank to move the piston in a reciprocating motion within the container.

[0005] Patent application U.S. Patent Application No. 10 / 810,686 (U.S. Patent Application Publication No. 20050215850) discloses a syringe pump including a syringe having a plunger that slides on a body having a discharge port, a drive mechanism including a cylinder connected to the syringe and in which a piston attached to a shaft slides, a biasing device that operates to apply a biasing force to the piston to drive the piston in a distal direction with the cylinder, and a safety catch that initially prevents the biasing device from moving the piston, the safety catch being removable to allow the biasing device to move the piston.

[0006] 1 illustrates an example of an injection system 100 for injecting medical liquid from a medical liquid container 104 into a common line 102. Those skilled in the art will appreciate that the medical liquid container 104 may be any type of container specifically adapted to contain medical liquid, such as, but not limited to, a vial, a bottle, a plastic container, and any type of container manufactured to contain medical liquid. The injection system 100 includes a first connector 106 configured to be connected to the medical liquid container 104, an injector 108 to which an injection device 110 having a medical tubing interface 112 is attached, a medical liquid supply line 114 configured to connect the first connector 106 to the medical tubing interface 112 to supply the medical liquid to the injection device 110, and a common line 102 connected to the medical tubing interface 112 and the patient line 116 and configured to inject the medical liquid into the patient line 116. More precisely, a first piping valve 130 connects the liquid supply line 114 to the common line 102 and only allows passage to the common line 102 under vacuum pressure. The common line 102 includes a second piping valve 140 downstream of the first piping valve 130 and only allows passage towards the patient line 116. The infusion device 110 typically includes a body defining an interior space and a piston actuated by a plunger rod and configured to move within the interior space to pump fluid into or expel fluid from the interior space.

[0007] In the illustrated example, two different types of medical fluid are to be injected into the patient, and as a result, the injection system 100 is configured to connect to two medical fluid containers 104 using two different first connectors 106 and two different medical fluid supply lines 114. However, the injection system 100 may be configured to inject only one medical fluid. For simplicity, the following description is made with reference to a configuration in which only one medical fluid is injected, since a double injection simply involves replicating the described features. Here, "double injection" is understood to mean injecting twice.

[0008] For economic and ecological reasons (less use of plastics), multi-patient practices are steadily gaining market share. In the so-called multi-patient practice, the plumbing for the infusion system 100 comprises two very separate parts: the day set 120 and the patient set 122. The patient set 122 is changed for each patient. The patient set 122 is typically used to limit the risk of cross-contamination between successive patients and thus protect the day set. Once installed and ready, the day set 120 remains connected to the power injector for several patient cases, as long as the same medical fluid is injected. If the medical fluid to be injected needs to be changed, the day set 120 is changed. This day set 120 comprises a medical fluid container 104 and a medical fluid supply line 114 connected to the common line 102. The patient set 122 comprises a patient line 116, which is supplied with the medical fluid by the common line 102 and is connected to a catheter or needle for injecting the medical fluid into the patient.

[0009] When the injection system 100 is set to inject a medical liquid into a patient, it is important to ensure that there is no gas present in the tubing prior to injection. Injecting a gas, such as air, into the patient's blood vessels can result in gas embolism, i.e., blockage of the blood vessel caused by one or more bubbles of air or other gas in the circulatory system. When the day set 120 or patient set 116 is in place, the tubing fills with air. Therefore, it is necessary to evacuate any gas present in the tubing prior to injection. Due to the length of the tubing, a large amount of gas will be evacuated from the injection system 100.

[0010] To purge the injection system 100 from any gas present before injection, the injection device 110 fills the medical liquid supply line 114 by aspirating or drawing medical liquid from the medical liquid container 104. Here, the injection device 110 is filled with a mixture of medical liquid and gas. The injection device 110 is then placed with the medical tube interface 112 facing upwards so that the gas is collected at said medical tube interface 112. It is noted that the filling of the injection device 110 causes turbulence in the medical liquid, generating microbubbles in the medical liquid. Due to the high viscosity of medical liquids (especially for contrast media), the microbubbles may take several minutes to reach the medical tube interface 112. Therefore, it is customary to wait at least 2 or 3 minutes with the medical tube interface 112 facing upwards. Then, by actuating the piston, the gas is expelled from the injection device 110 through the still upward-facing medical tube interface 112 to the common line 102. Medical fluid is then injected into the common line 102 to push the gas out of the common line 102 , thereby purging the infusion system 100 .

[0011] During injection, it may occur that gas is present in the infusion set 110. For example, vaporization of the medical liquid may generate gas. Also, some gas bubbles generated during the initial filling of the infusion system 100 may be trapped against the tubing or walls of the infusion set 110 and may not be expelled during the initial purge. As a result, because the infusion set 110 is positioned with the medical tubing interface 112 facing downwards during injection, any gas present in the infusion set 100 is contained in the infusion set 100, away from the medical tubing interface 112, and is not injected into the common line 102.

[0012] This approach has several drawbacks. First, the medical tubing interface 112 must be oriented up or down and the injector 110 must be moved between two opposing positions. This requires that the injector 108 can rotate. Second, this purge takes a significant amount of time and the injector system 100 must be monitored by an operator during the purge. The operator must also assess the quality of the purge and whether it is complete. As with any human interaction, reliance on the operator can lead to errors. Third, the gas is pushed along the common line 102 by the medical liquid that is also exiting the injector system. This approach therefore involves wasting medical liquid and requires collecting the wasted medical liquid at the output of the injector system 100, with possible handling errors.

[0013] Also, gas still present in the infusion set 110 after purging can alter the operation of the infusion set, even if the gas is trapped in the infusion set 110. The dosage of medical liquid is usually controlled over the course of the piston of the infusion set 110. Gas is compressible, and therefore the change in the volume of the medical fluid inside the infusion set is imprecise. Also, the volume of gas trapped in the infusion set 110 must be small, otherwise there is a risk of it being injected into the common line 102.

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

[0015] 1. An injection device for injecting a medical liquid from a medical liquid container into a medical tube, comprising: a body defining a longitudinally extending interior space between an upper end of the body and a lower end of the body, the lower end of the body comprising a medical tubing interface through which medical fluid can pass from a medical fluid container through the interior space and exit said interior space to be injected into a medical tube; - a piston disposed within the interior space and configured to move within the interior space along a longitudinal direction, the piston defining an upper volume and a lower volume of the interior space, the lower volume being configured to receive a medical fluid; an exhaust path that passes longitudinally through the piston from a lower space to an upper space of the interior space; An injection device is proposed comprising: a peripheral seal arranged around a lower interface of the piston defining a lower space of the internal space, said lower interface having an inlet of the discharge path, said peripheral seal acting outwardly against the wall of the body and having a front surface facing the lower space, said front surface being at least partially inclined inwardly and upwardly towards the inlet such that when the peripheral seal is moved in a downward direction, the peripheral seal directs air from the wall of the body towards the inlet of the lower interface.

[0016] Other preferred, but non-limiting, aspects of the present invention are the following, isolated or in any technically feasible combination: at least one third of the front surface of the peripheral seal has a slope that forms an angle with a plane perpendicular to the longitudinal direction toward the inlet of at least 1.0°, preferably at least 3.0°, preferably at least 8.0°; at least a portion of the peripheral seal projects downwardly in the longitudinal direction relative to the lower interface; The front surface of the peripheral seal extends inwardly from the wall of the body of the injection device over a thickness of 3.0 mm to 5.0 mm; the lower interface comprises a frame surrounded by a peripheral seal, said frame defining at least one opening forming an inlet; the injection device further comprises a float disposed within the exhaust path between a lower portion of the exhaust path and an intermediate portion of the exhaust path, said lower portion of the exhaust path being fluidly connected to the lower space, the float being configured to selectively allow gas to move from the lower portion of the exhaust path to the intermediate portion, and the frame housing the float in the cavity in which the float is disposed; the float is configured to selectively prevent migration of medical liquid along a drainage path from a lower space to an upper space of the interior space; the frame comprises an outer ring, a central portion, and a connector connecting the central portion to the outer ring, and at least one opening is formed between the connectors; the injection device further comprises a float disposed within the exhaust path between a lower portion of the exhaust path and an intermediate portion of the exhaust path, said lower portion of the exhaust path being fluidly connected to the lower space, the float being configured to selectively allow gas to move from the lower portion of the exhaust path to the intermediate portion, and the central portion of the frame comprising a guide recess configured to receive and guide a portion of the float; the peripheral seal is made of a material having a Shore A hardness of 30 to 90, preferably about 70; the material of the peripheral seal comprises at least one of the following materials: nitrile, silicone rubber, liquid silicone rubber, styrene-ethylene-butylene-styrene, thermoplastic elastomer, elastomeric; and / or The body is made from a material having a modulus of elasticity greater than 2400 mPa.

[0017] In another embodiment, the present invention also proposes an injection device for injecting a medical liquid from a medical liquid container into a medical tube, said injection device comprising: a body defining a longitudinally extending interior space between an upper end of the body and a lower end of the body, the lower end of the body comprising a medical tubing interface through which medical fluid can pass from a medical fluid container through the interior space and exit said interior space to be injected into a medical tubing; - a piston disposed within the interior space and configured to move within the interior space along a longitudinal direction, the piston defining an upper volume and a lower volume of the interior space, the lower volume being configured to receive a medical fluid; an exhaust path that passes longitudinally through the piston from a lower space to an upper space of the interior space; a selector disposed within the exhaust path between a lower portion of the exhaust path and an intermediate portion of the exhaust path, the lower portion of the exhaust path being connected to the lower space, the selector configured to selectively allow gas to pass through the selector and travel along the exhaust path from the lower portion to the intermediate portion, and the selector configured to selectively prevent medical liquid from passing through the selector and traveling along the exhaust path from the lower space to the upper space of the interior space; a purge valve disposed in the exhaust path between an intermediate portion of the exhaust path and an upper portion of the exhaust path and configured to move between a blocking configuration in which the purge valve closes the exhaust path and a passing configuration in which the purge valve keeps said exhaust path open, the passing configuration of the purge valve requiring an overpressure in the intermediate portion of the exhaust path caused by a piston moving towards a lower end of the body.

[0018] The present invention allows gas to be purged from the injection device each time the piston moves to push medical fluid into the medical tubing, thus purging is performed automatically without the need for any operator intervention, ensuring that gas is not injected into the medical tubing.

[0019] Other preferred, non-limiting aspects of the present invention are the following, isolated or in any technically feasible combination: the purge valve is configured to be in a shutoff configuration when the piston moves towards the upper end of the body; a lower portion of the exhaust pathway configured to receive both medical liquid and gas, and a middle and upper portion of the exhaust pathway configured to receive only gas; the head space is configured to be maintained at a constant reference pressure, and the overpressure in the middle of the exhaust path corresponds to a pressure of gas exceeding the reference pressure; the piston has a lower interface defining a lower space of the interior space, said lower interface having an inlet of a discharge passage opening at the highest part of said lower interface; The lower interface has a convex surface when viewed from the lower space of the internal space, and the inlet of the discharge path opens in the center of the lower interface, or the lower interface has a concave surface when viewed from the lower space of the internal space, and the inlet of the discharge path opens around the periphery of the lower interface; the selector is a float configured to float on the medical liquid and disposed in a cavity, said cavity comprising at least one passageway belonging to a drainage path, said float configured to move longitudinally inside said cavity between a blocking configuration in which the float occludes the passageway, thereby closing the drainage path, and an open configuration in which the float moves away from the passageway, thereby opening the drainage path; the float has at least one obstruction and a floating part, the obstruction part being configured to obstruct the passageway, the floating part having an enlarged portion relative to the widest portion of the obstruction part; The float is configured to block the passageway by two distinct zones in contact with the sheet that defines the passageway.

[0020] The present invention also relates to an injection system comprising: an injection device according to any embodiment; a first connector configured to be connected to a medical fluid container; a medical fluid supply line configured to connect the first connector to a medical tubing interface to supply a medical fluid to an infusion system; a common line connected to the medical tubing interface and to the patient line and configured to infuse the medical fluid into the patient line.

[0021] Preferably, the overpressure corresponds to a pressure in the intermediate portion of the exhaust path exceeding a reference pressure in the headspace by at least a first pressure threshold; the common line includes a threshold valve at a second pressure threshold; The first pressure threshold is lower than the second pressure threshold.

[0022] The present invention also relates to a process for operating an injection device as described in any of the embodiments, the injection device being maintained with an upper end of the body facing upwards and a lower end of the body facing downwards, the process comprising: a filling step in which the piston moves longitudinally within the interior space toward the upper end of the body to allow medical liquid and gas from the medical liquid container to permeate into the interior space through the medical tubing interface, the purge valve being in a shutoff configuration; a purge step, in which the piston moves within the internal space along a longitudinal direction toward a lower end of the body, gas is discharged from a lower space to an upper space of the internal space through a discharge path that crosses the piston, the selector retains the medical liquid in the lower space, and the purge valve is in a passing configuration. [Brief description of the drawings]

[0023] Other aspects, objects and advantages of the present invention will become more apparent from a reading of the following detailed description of preferred embodiments thereof, given by way of non-limiting example and made with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a general diagram of an injection system with two medical fluid containers connected thereto. [Diagram 2] FIG. 13 is a cross-sectional view of the piston of an injection device with a float selector during the filling step before purging. [Diagram 3] FIG. 13 is a cross-sectional view of the piston of an injection device in which the selector is a float during the start of a purge. [Figure 4] FIG. 13 is a cross-sectional view of the piston of an injection device in which the selector is a float, at the end of a purge. [Diagram 5] FIG. 13 is a cross-sectional view of the piston of an injection device in which the selector is a float during the injection step after purging. [Figure 6] 1 is a cross-sectional view of the bottom of a piston of an injection device according to a possible non-limiting embodiment of the present invention. [Figure 7] FIG. 7 is a detailed view of a portion of the lower left portion of FIG. 6. [Figure 8]FIG. 13 is a perspective view of a lower interface of an example piston, according to a possible non-limiting embodiment of the present invention. [Figure 9] FIG. 2 is a detailed view of a portion of a peripheral seal according to an embodiment of the present invention when the seal is at rest. [Figure 10] 10 is a detailed view of a portion of the peripheral seal of FIG. 9 when the seal is assembled with an injection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Detailed Description of the Invention The injection device of the present invention may be used in injection system 100, as previously described in connection with Figure 1. Injection system 100, with the exception of injection device 110, will not be described further.

[0025] 2-5, the infusion device 110 includes a body 2 defining an interior space 4 extending longitudinally between an upper end of the body 2 and a lower end of the body 2, the lower end of the body having a medical tubing interface 112 through which medical liquid can pass from a medical liquid container 104 through the interior space 4 and can exit said interior space 4 to be infused into a common line 102. In contrast to previous infusion devices, the infusion device 110 according to the present invention is configured to stay down with the medical tubing interface 112. Terms relating to space such as "down", "up", "lower", "upper", "higher", "highest" and the like should be understood as defining commonly accepted relative positions to the vertical, i.e. the direction of local earth gravity. This is because gases and medical liquids are subject to gravity, and the present invention utilizes gravity to provide for proper gas evacuation. As a result, 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 cylinder made of, for example, glass or plastic material, also called a barrel.

[0026] The injection device 110 also includes a piston 6 arranged in the internal space 4 and configured to move in the internal space 4 along the longitudinal direction, i.e. between the upper end of the body 2 and the lower end of the body 2. The piston 6 defines an upper space 4b and a lower space 4a of the internal space. The lower space 4a is configured to receive a medical liquid, while the upper space 4b is not intended to receive any liquid. 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 peripheral seal 8, 10, for example made of rubber, preferably two peripheral seals 8, 10 at different heights along the longitudinal direction. Each peripheral seal 8, 10 is pressed against the wall of the body 2 to ensure a seal. As in the illustrated example, the peripheral seal 8, 10 may be a four-ring, but may also be, for example, an O-ring.

[0027] Due to the tight seal provided by the piston 6, the pressure can vary greatly between the upper space 4b and the lower space 4a of the internal space 4. The pressure inside the upper space 4b is roughly fixed and kept at a reference pressure that is substantially independent of the path of the piston 6. This reference pressure is typically atmospheric pressure, e.g. the pressure of the environment of the system. Preferably, the upper end of the body 2 is at least partially open so that the pressure inside the upper space 4b corresponds to atmospheric pressure, independent of the path of the piston 6. Conversely, the pressure inside the lower space 4a of the internal space 4 depends on the contents of said lower space 4a and the path of the piston 6. In the following description, overpressure is a pressure above the reference pressure and vacuum pressure is a pressure below the reference pressure.

[0028] The piston 6 is attached to the piston rod 12, for example by a protrusion 14 on the top of the piston 6 that engages said piston rod 12. The piston rod 12 is driven by an injector 108 to move the piston 6 along the longitudinal direction inside the interior space 4. The piston 6 can be formed by several parts assembled together. In the illustrated example, the piston 6 has a lower part 6a, a middle part 6b, and an upper part 6c. Connectors such as screws 16 can be used to assemble the piston parts.

[0029] The piston 6 has a discharge path arranged inside the piston 6. This path traverses the piston 6 in the longitudinal direction from the lower space 4a to the upper space 4b of the internal space 4. The discharge path is intended to discharge gas present in the lower space 4a to the upper space 4b. Typically, the discharge path is not linear, and can be opened and closed at different points depending on the components of the piston 6, as described below. More specifically, the discharge path includes a lower portion 17a, a middle portion 17b, and an upper portion 17c. The lower portion 17a of the discharge path is connected to the lower space 4a, and the upper portion 17c of the discharge path is connected to the upper space 4c. The middle portion 17b is between the lower portion 17a and the upper portion.

[0030] The piston 6 includes a lower interface 18 that defines a lower space 4a of the internal space 4, said lower interface 18 having an inlet 20 of the discharge path. Preferably, the inlet 20 opens at the highest part of the lower interface 18 in order to properly discharge all gas present in the lower space to 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 an apex toward the upper end of the body, and the inlet 20 of the discharge path opens at said apex. For example, the lower interface 18 has a convex surface as viewed from the lower space 4a of the internal space, and the inlet 20 of the discharge path opens in the center of said lower interface 18, as in the example shown. For example, the surface of the lower interface 18 may correspond to the surface of a cone, a truncated cone, or a pyramid facing upwards. Alternatively, the lower interface 18 may have a concave surface as viewed from the lower space 4a of the internal space, and the inlet 20 of the discharge path opens at the periphery of said lower interface 18. For example, the lower interface 18 may have a groove disposed about the periphery of the lower interface 18, and the exhaust passage inlet 20 may open in the groove.

[0031] The piston 6 includes a purge valve 22 arranged in the discharge path between the middle part 17b of the discharge path and the upper part 17c of the discharge path. The purge valve 22 is configured to move between a blocking configuration, in which the purge valve 22 closes the discharge path, and a passing configuration, in which the purge valve 22 keeps said discharge path open. The passing configuration of the purge valve 22 requires an overpressure in the middle part 17b of the discharge path relative to a reference pressure in the upper space 4b, caused by the piston 6 moving towards the lower end of the body 2. Since the upper space 4b is at a reference pressure (e.g. atmospheric pressure), overpressure means a pressure above the reference pressure. More precisely, the overpressure required for the passing configuration of the purge valve 22 corresponds to the pressure in the middle part 17b exceeding the reference pressure in the upper space 4b and the upper part 17c of the discharge path by at least a first pressure threshold. The purge valve 22 is configured to be in the blocking configuration when the piston 6 moves towards the upper end of the body 2. This is because there is no overpressure in the intermediate portion 17a relative to the reference pressure in the upper space 4b, but instead there is a vacuum pressure, i.e. a pressure below the reference pressure.

[0032] The piston 6 also includes a selector 24 disposed within the discharge path between the lower portion 17a of the discharge path and the middle portion 17b of the discharge path. The selector 24 is configured to selectively allow gas to pass through the selector 24 and travel along the discharge path from the lower portion 17a to the middle portion 17b of the discharge path. The selector 24 is also configured to selectively prevent medical liquid from passing through the selector 24 and traveling along the discharge path from the lower portion 17a to the middle portion 17b of the discharge path, and thus traveling along the discharge path from the lower space 4a to the upper space 4b of the interior space. As a result, the lower portion 17a of the discharge path is a mixed portion configured to receive both medical liquid and gas, and the middle portion 17b and the upper portion 17c are gaseous portions configured to receive only gas.

[0033] The purge valve 22 is disposed above the selector 24 in the longitudinal direction from the lower space 4a to the upper space 4b of the internal space. Therefore, the purge valve 22 is disposed in the gas portion of the discharge path and does not come into contact with any liquid.

[0034] In the shut-off configuration, the purge valve 22 seals the vent 26 between the middle portion 17b and the upper portion 17c of the exhaust path. In the through configuration, the purge valve 22 opens said vent 26. In the illustrated example, two vents 26 appear between the middle portion 17b and the upper portion 17c of the exhaust path. More or fewer vents 26 can be provided, as long as they can be sealed by the purge valve 22.

[0035] Preferably, as shown in the illustrated embodiment, the purge valve 22 is an umbrella valve having a diaphragm-shaped sealing disk 22a and a stem 22b. The stem 22b engages in a hole 28 arranged in a fixed part of the piston 6 and presents an enlarged lower part with an upper cross section than the cross section of the hole 28, thereby fixing the purge valve 22. The diaphragm-shaped sealing disk 22a is arranged above at least one vent 26 that is part of the discharge path and defines the upper part 17c to the middle part 17c of the discharge path. The umbrella valve can deformably and / or slidably move along the hole 28 arranged in the fixed part of the piston 6 to change its configuration (e.g. by deformation of the stem). In the passing configuration, the sealing disk 22a is away from the vent 26 due to the higher pressure of the gas inside the middle part 17b, thereby allowing the gas to pass through said vent 26. In the shutoff configuration, the higher pressure of the gas inside the upper portion 17c of the exhaust path causes the sealing disk 22a to press against the vent 26, thereby sealing said vent 26 and closing the exhaust path. For example, the umbrella valve can be made of a rubber-type elastomer, or silicone.

[0036] The selector 24 can be, for example, a float 24 configured to float on the medical liquid or a hydrophobic membrane. The membrane is configured to allow gas to pass and prevent the medical liquid from passing through. The membrane is, for example, made of a coated fabric. A process for operating an infusion device having a float 24 as a selector will now be described with reference to Figures 2 to 7.

[0037] In Fig. 2 the injection device 110 is shown before purging, e.g. during a filling step, during which the injection device 110 is filled with medical liquid and undesired gas. During this filling step the piston rod 12 is driven upwards, e.g. by an injector 108 acting on said piston rod 12, thereby moving the piston 6 longitudinally, i.e. upwards, in the interior space 4 towards the upper end of the body 2. The lower space 4a expands, as a result of which the pressure of the gas inside said lower space 4a falls below the reference pressure of the gas inside the upper space 4b, e.g. atmospheric pressure.

[0038] Since the selector 24 allows gas to move from the lower part 17a to the middle part 17b of the exhaust path, a reduced pressure in the lower space 4a is also found in the lower part 17a and in the middle part 17b of the exhaust path. However, since the purge valve 22 needs to bring the overpressure in the middle part 17b of the exhaust path to the passing configuration, the purge valve 22 is maintained in the blocking configuration. More precisely, the purge valve 22 is pushed downwards and seals the vent 26, thereby closing the exhaust path in the blocking configuration.

[0039] The combination of the closing of the exhaust path by the purge valve 22 and the expansion of the lower space 4a 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 piping valve 130, which is, for example, 0.2-0.5 bar below the reference pressure. The opening of the first piping valve 130 creates a suction of medical liquid to compensate for this vacuum pressure in the lower space 4a. The medical liquid is filled into the lower space 4a through the fill line 114 connected to the medical liquid container 104. Any gas present in the piping is also sucked into the lower space 4a.

[0040] Gradually, as the lower space 4a fills with medical liquid or gas, the pressure inside the lower space 4a rises and approaches atmospheric pressure. When the pressure inside the lower space 4a reaches the closing pressure (substantially similar to the opening pressure) of the first piping valve 130, the first piping valve 130 closes and filling stops. At the end of the filling step, the lower space 4a is filled with a certain amount of gas 32 that exceeds the certain amount of medical liquid 34. Because the pressure rise was stopped by closing the first piping valve 130 before the vacuum pressure was fully compensated, the pressure of the gas inside the lower space 4a is still lower than the pressure of the gas inside the upper space 4b. As a result, the purge valve 22 remains in the shutoff configuration.

[0041] As mentioned above, after filling the injection device 110, the gas in the lower space 4a must be evacuated during purging. This purging is performed by driving the piston 6 downwards, as shown in FIG. 3. The piston 6 moves inside the inner space 4 along the longitudinal direction towards the lower end of the body 2. The lower space 4a shrinks and the gas pressure in the lower space 4a increases until the pressure difference between the gas pressure in the middle part 17b that remains in communication with 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, i.e. until the pressure difference reaches a first pressure threshold.

[0042] As mentioned above, the purge valve 22 is configured to move to the through configuration in response to the overpressure in the lower volume 4a exceeding the reference pressure in the upper volume 4b by at least the opening pressure threshold of the purge valve 22 (e.g., the pressure difference between the overpressure and the reference pressure of 20-100 mbar). This causes the purge valve 22 to move to the through configuration, thereby opening the exhaust path. In the illustrated example, the sealing disk 22a moves away from the vent 26, thereby unsealing said vent 26.

[0043] Gas is discharged from the lower space 4a to the upper space 4b of the interior space 4 through a discharge path that crosses the piston 6. More specifically, the gas enters the discharge path through the inlet 20, then along the lower part 17a of the discharge path, then along the middle part 17b of the discharge path, then through the vent 26, and finally along the upper part 17c to reach the upper space. This is shown by the dotted arrows in FIG. 3.

[0044] When the piston 6 moves downwards while gas is being discharged through the discharge path, the piston reaches a certain amount of medical liquid in the lower space 4a. More specifically, the lower interface 18 comes into contact with the medical liquid and the gas is pushed back towards the inlet 20 of the discharge path as the inlet 20 opens at the highest part of said lower interface 18. This causes the gas to be discharged from the lower space 4a before the medical liquid reaches the inlet 20 of the discharge path. When all the gas is discharged, the medical liquid penetrates the inlet 20 of the lower interface 18 of the piston 6 and fills the lower part 17a of the discharge path.

[0045] As shown, the lower portion 17a of the drainage path may include a cavity 36 into which the selector 24 is positioned so that the medical fluid begins to fill the cavity 36. The selector is a float 24 configured to float in the medical fluid, and the cavity 36 is configured to allow the float 24 to move up and down the cavity 36 along a longitudinal direction. The cavity 36 includes at least a passageway 38 that forms a boundary between the lower portion 17a and the middle portion 17b of the drainage path. The passageway 38 is positioned at the top of the cavity 36. The float 24 is configured to move longitudinally within the cavity 36 between a blocking configuration in which the float 24 blocks (or blocks) the passageway 38, thereby closing the drainage path, and an open configuration in which the float 24 moves away from the passageway 36, thereby opening and not blocking the drainage path.

[0046] More precisely, when the cavity 36 is filled with gas 32, the float 24 remains at the bottom of the cavity 36, keeping the passageway 38 open and thereby not blocking the drainage path. When the medical liquid reaches the cavity 36, the float 24 starts to float on the medical liquid and therefore rises, carried by the medical liquid 34, according to the upward buoyant force exerted on the float by the medical liquid (Archimedes' principle). Under this force, the float 24 moves upwards until it reaches the top of the cavity 36, blocking the passageway 38.

[0047] The passage 38 is defined by a periphery forming a seat 40 for the float 24 facing said float 24. The float closes the passage 38 by pressing the seat. The seat 40 is made of metal or plastic, for example thermoplastic polyurethane, polyoxymethylene, polycarbonate, polyvinyl chloride, etc. Advantageously, the seat 40 is made of a material having a modulus of elasticity higher than 2500 mpa (megapascals). Preferably, the seat 40 has a cross section that decreases in the direction of the middle part 17b of the discharge path, for example the shape of the seat 40 is at least partially a hollow truncated cone. A reinforcing element 42, such as a washer, can be provided above the seat 40 to strengthen it, especially if said seat is made of a highly deformable material.

[0048] The float 24 has at least an obstruction configured to obstruct (e.g., block or block) the passage 38. Typically, the passage 38 has a circular cross-section, and the obstruction of the float 24 also has a circular cross-section. For example, the obstruction of the float 10 may have an at least partially elliptical shape, or a spherical or pine-tree conical shape. For example, the float 24 may simply be a ball. Preferably, the obstruction 24 of the float is coated with a deformable material to better seal the passage 38 when the float 24 is pressed against the seat 40.

[0049] Preferably, the float has a floating part with an enlarged portion relative to the widest portion of the occlusion, said floating part supporting the occlusion. The float may be in two parts or may be a single piece including an occlusion and a floating part. The occlusion of the float 24 is, for example, a ball. The floating part of the float 24 has a diameter larger than the widest diameter of the occlusion, i.e. the ball part, of the float. The larger the diameter of the floating part of the float 24 (perpendicular to the longitudinal direction), the more responsive the float 24 is to the low force exerted on it by the medical liquid 34. This improved response allows the medical liquid to push the float 24 upwards as soon as it reaches it, thus ensuring that the medical liquid cannot reach the passage 38 before said passage is blocked by the float 24.

[0050] When the medical liquid 34 comes into contact with the float 24, for example with the floating part of the float 24, the float 24 starts to float and thus moves upwards until it reaches the seat 40. The shape of the float 24 and the shape of the seat 40 are adapted so that a continuous seal is created when the float 24 presses against the seat 40. Now, the passage 38 is blocked and neither the gas nor the medical liquid can pass through the blocked passage 38. A small amount of gas can be trapped inside the cavity 36 between the blocked passage 38 and the surface of the medical liquid 34, i.e. in the lower part of the drainage path. This small volume makes it possible to keep the seat dry and to avoid any accumulation of material on the seat 40. The small volume can be, for example, a volume of less than 10 ml at atmospheric pressure. This small amount of air can be sufficient to dry the float 24. The density of the float 24 and the complementary shapes of the blocking part and the seat 40 are selected to minimize the volume of trapped air while keeping the surface of the medical liquid away from the seat 40. For example, the cross section of the sheet may decrease in the direction of the middle portion 17b of the ejection path.

[0051] When the passage 38 is blocked, gas can no longer reach the middle part 17b escaping the overpressure in the lower part 17a of the exhaust path. As a result, the pressure in the middle part 17b above the blocked passage 38 drops until the difference between the pressure in the middle part 17b and the reference pressure reaches the closing pressure threshold of the purge valve 22, which is slightly above the reference pressure since the upper space 4b is at said reference pressure. For example, the closing pressure threshold of the purge valve 22 can correspond to a positive pressure difference between the pressure inside the middle part 17b and the reference pressure of 20 to 100 mbar. Preferably, the closing pressure threshold and the open-close valve threshold are substantially the same, but they may also be different. As a result, the purge valve 22 is now closed in a shut-off configuration (FIG. 5). In this example, the sealing disk 22a covers the vent 26. The purge step is finished. A small amount of gas 32 with a residual overpressure (i.e. slightly higher than the reference pressure) is retained in the middle part 17b. The residual overpressure is not high enough to force the purge valve 22 to open the vent 26. This residual overpressure ensures that air at atmospheric pressure coming from the head space 4b cannot penetrate the middle part 17b of the exhaust path, thus avoiding non-sterile air entering the sterile area where the medical fluid circulates.

[0052] The process may include a complementary filling step, which is performed after the purging step and before the injection step, allowing the lower space 4a to be filled with a precise predetermined medical liquid volume 34, which was not possible in the first filling step due to the volume of gas 32, which resulted in an erroneous volume measurement (usually based on the course of the piston 36).

[0053] The process may include an injection step, in which the piston moves in the inner space along the longitudinal direction toward the lower end of the body, and the medical liquid leaves said lower space of the inner space and is injected into the medical tube. When the discharge path is closed, the pressure inside the lower space 4a increases when the piston 6 is pressed down. When the pressure in the lower space 4a reaches the opening pressure of the second piping valve 140, the second piping valve 140 opens, and the medical liquid 34 can leave the lower space 4a and travel through the common line 102 to reach the patient line 116. This allows the medical liquid to be injected without any gas. During injection, the float 24 comes into contact with the medical liquid.

[0054] Note that the opening pressure threshold (i.e. the first pressure threshold) of the purge valve 22 is lower than the opening pressure threshold (the second pressure threshold) of the second line valve 140, so that the purge valve 22 opens before the second line valve 140 opens when gas is exhausted. However, during this injection step, the blockage of the passage 38 by the selector (float 24) means that pressure increases in the lower space 4a but not in the isolated middle part 17b of the exhaust path. The purge valve 22 is therefore kept in the shutoff configuration.

[0055] In the embodiment of Figures 2 to 5, the peripheral seal 8 is conventional in that it is designed to collect air adjacent to the wall of the body and to hold it against the piston 6 and the wall. Indeed, air bubbles may remain attached due to surface tension to the wall. These air bubbles are complicated to remove and may be a cause for concern if they remain in the interior space 4, as they tend to accumulate. As the piston 6 descends, the air bubbles break off and are collected around the piston 6. Thus, they gradually become larger and more visible. Even if the risk of injecting these air bubbles is minimal, they may be a cause for concern, and this air must be removed by purging, i.e. by turning over the head of the injection device 110 and losing the product.

[0056] As explained above, the exhaust path 17 and the selector 24 allow for purging air through the piston 6 without the need to invert the head of the injection device 110. It should therefore be advantageous to exhaust the air adhering to the wall of the body 2 also through the piston 6. Furthermore, if the selector is a float 24, the collected air against the wall contributes to keeping enough air in the cavity 36 to ensure that the top of the float 24 (the occlusion blocking the passage 38) remains dry. In this regard, an improved piston with an improved peripheral seal will now be described. All the elements discussed above are applicable to the embodiment of the improved peripheral seal, with the modifications indicated.

[0057] An injection device 110 having an improved peripheral seal 8 will be described with reference to Figures 6-8, which show a non-limiting example of a piston 6 in which the selector is a float 24. The piston 6 includes a peripheral seal 8 disposed about a lower interface 18 of the piston 6. The peripheral seal 8 is in contact with the piston 6 and therefore moves with the lower interface 18 of the piston 8. In an embodiment, the peripheral seal 8 may be connected to the piston 6.

[0058] The lower interface 18 defines the lower space 4a of the interior space 4, said lower interface 18 having an inlet 20 of the exhaust passage 18. The lower interface 18 may be referred to as the bottom of the piston 6.

[0059] In the following, "outer", "outward" and "outwardly" are used to define radial directions extending from the central axis of the inlet 110 towards the body 2, whereas "inner", "inward" and "inwardly" are used to define radial directions extending from the body towards the central axis. For example, in the drawings, the central axis is substantially perpendicular to the lower interface 18 and extends through the inlet 20. The central axis is parallel to the longitudinal direction.

[0060] The peripheral seal 8 exerts an outward pressure against the inner wall of the body 2 in the interior space 4 defined by said body 2. Typically, the peripheral seal 8 has an outer surface 86 that extends in front of the inner wall of the body 2. The outer surface 86 may be parallel to said inner wall. When moving downwards, the peripheral seal 8 wipes the inner wall of the body 2, thus pushing the air adjacent to the inner wall of the body 2 downwards. However, in contrast to conventional seals, the peripheral seal 8 is configured to direct the collected air radially inwards towards the center of the piston 6. More precisely, the peripheral seal 8 is configured to direct the air adjacent to the wall of the body 2 towards an inlet 20 formed in the lower interface 18 of the piston 6, so that this collected air is purged through the piston 6 without being trapped below the piston 6.

[0061] To do so, a front surface 80 of the peripheral seal 8, which faces the lower space 4a and extends radially and inwardly from the inner wall of the body 2 towards the centre of the interior space 4, is at least partially inclined inwardly and upwardly towards the inlet 20 of the lower interface 18. In other words, at least a part of the front surface 80 of the peripheral seal 8 forms an acute angle with a plane P perpendicular to the central axis X and with the inner wall of the body, such that this part of the front surface extends inwardly and upwardly.

[0062] In an embodiment, the entire surface of the front surface 80 of the peripheral seal 8 is inclined inwardly and upwardly towards the lower interface 18. Alternatively, only a portion of the front surface 80 is inclined. For example, at least one-third of the front surface 80 is inclined inwardly and upwardly towards the lower interface 18, more preferably at least half of the front surface 80 is inclined inwardly and upwardly, or at least two-thirds may be inclined inwardly and upwardly, as measured from the inner wall of the body 2 towards the center of the interior space 4. In an embodiment, the portion of the front surface 80 that is inclined inwardly and upwardly corresponds to an inner portion of the front surface 80, i.e., the portion that is closer to the inlet 20.

[0063] The inwardly and upwardly sloping portion of the peripheral seal front surface 80 may be flat, in which case a portion of the front surface 80 is substantially frustoconical, or the portion may be curved, e.g., concave.

[0064] The portion of the front surface 80 of the peripheral seal 8 that is inwardly and upwardly sloping slopes upwardly toward the inlet 20 of the lower interface 18 and has an acute angle β with the plane P of at least 1.0°, preferably at least 3.0°, and more preferably at least 8.0°. In an embodiment, the acute angle β is less than 45°.

[0065] In an embodiment, the front surface 80 includes a first portion 81 that is not inclined or slightly inclined inwardly and upwardly, and a second portion 82 that is inclined inwardly and upwardly at a slope β. The first portion 81 extends inwardly from the outer surface 86 of the peripheral seal 8 toward the inlet 20 of the discharge path of the lower interface 18 and forms a right angle with the wall of the body 2. Thus, the first portion 81 is generally parallel to the plane P. The second portion 82 extends inwardly from the first portion 81 and forms an acute angle β with the first portion 81. Thus, the first portion 81 surrounds the second portion 82.

[0066] At rest (outside the syringe), the peripheral seal 6 extends over a thickness t of 2.0 mm to 8.0 mm, more preferably 4.0 mm to 6.0 mm (see FIG. 9). When assembled to the body 2 (see FIGS. 8 and 10), the peripheral seal 6 is compressed such that the thickness t' of the peripheral seal 6 is on the order of 3.0 mm to 5.0 mm. The peripheral seal therefore deforms and maintains a compression ratio of 10% to 40%, more preferably 20% to 25%. This compression ratio varies due to the draft (the demolding angle of the part made by plastic injection) of the syringe body being wider at the inlet than at the bottom of the tank.

[0067] In an embodiment, the inclination of the front face 80 (more precisely, a first portion of the front face 80, see FIG. 9 ) of the peripheral seal 6 is obtained or increased during assembly, i.e. when the peripheral seal is compressed inside the body 2. Indeed, the deformation of the peripheral seal 6 is blocked at the top of the peripheral seal by the hard plastic zone 200, and the peripheral seal 6 has no choice but to deform downwards.

[0068] The perimeter seal 6 may be made of a flexible and deformable material having a Shore A hardness between 30 and 90, preferably about 70, to ensure a good seal. The perimeter seal may be made of at least one of the following materials: nitrile, silicone rubber, liquid silicone rubber, styrene-ethylene-butylene-styrene (SEBS), thermoplastic elastomer (TPE), elastomeric.

[0069] In an embodiment, the peripheral seal 6 may be a separate component assembled by deformation and mechanical hooks, or the peripheral seal 6 may be overmolded onto the piston body.

[0070] The piston body 6 may be made of a material with an elastic modulus of greater than 2400 mPa in order to withstand pressure and have limited deformation. The same is true for the syringe body 2, which must not deform under pressure or only deform within a small range.

[0071] At least a portion of the front surface 80 of the peripheral seal 8 protrudes downwards relative to the lower interface 18 in the longitudinal direction so as to contribute to evacuating all air from the inner wall of the body 2. Thus, a first portion 81 of the front surface 80 is involved in directing the air towards the inlet 20. Additionally or alternatively, at least a portion of the front surface 80 of the peripheral seal 8 is recessed relative to the lower interface 18.

[0072] In an embodiment, the lower interface 18 comprises a frame 90, which is surrounded by the peripheral seal 8. The frame 90 defines at least an opening forming the inlet 20. For example, the frame 90 may be disk-shaped and may include an outer ring 92, the outer surface of which is configured to receive the peripheral seal 8, a central portion 96, and a connector 94 connecting the central portion 96 to the outer ring 92. The lower interface 18 thus comprises a plurality of openings, each of which is defined by the central portion 96, two adjacent connectors 94, and the outer ring 92. The internal chamber 24 of the piston 6 is completely open so that no liquid is retained when air enters the system. The downwardly flared shape of the chamber 36 allows the free flow of liquid and the free rise of air to be discharged.

[0073] In the example of FIG. 8, the frame 90 includes four openings defined by four connectors 94 .

[0074] In an embodiment, the selector is a float 24. The piston 6 extends from a frame 90 and includes an outer wall defining a cavity 36, configured to accommodate the float 24. In an embodiment, the float 24 includes a keel 56 that projects downward toward the lower interface 18. Also, a guide recess 57 is formed in a central portion 96 of the frame 90. The guide recess 57 is then configured to receive the keel 56 from the float 24 to guide the float 24 as the piston 6 is moved up and down. In an embodiment, the guide recess 57 is a through opening.

[0075] Although the present invention has been described with respect to certain preferred embodiments, it is clear that the invention is in no way limited thereto, but includes all technical equivalents of the described means and combinations thereof. It will be clear to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention, in particular as defined in the appended claims.

Claims

1. An injection device (1) for injecting medical liquid from a medical liquid container into a medical tube, - A main body (2) comprising a main body (2) having a longitudinally extending internal space (4) between the upper end and the lower end of the main body (2), wherein the lower end of the main body has a medical tube interface (112) through which the medical liquid can pass from the medical liquid container into the internal space (4) and exit the internal space (4) so ​​as to be injected into the medical tube (112), - A piston (6) disposed inside the internal space (4) and configured to move within the internal space (4) along the longitudinal direction, 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 the medical fluid, - Discharge path (17), wherein the piston (6) moves through the longitudinal direction from the lower space (4a) to the upper space (4b) of the internal space, - An injection device (1) comprising: a peripheral seal (8) disposed around the lower interface (18) of the piston (6) that defines the lower space (4a) of the internal space (4), wherein the lower interface (18) has an inlet (20) of the discharge path (17), and the peripheral seal (8) acts outward with respect to the wall of the main body (2) and has a front surface (80) facing the lower space (4a), the front surface (80) being at least partially inclined inward and upward toward the inlet (20) such that when the peripheral seal (6) is moved in a downward direction, the peripheral seal (8) guides air from the wall of the main body (2) toward the inlet (20) of the lower interface (18).

2. The injection device according to claim 1, wherein at least one-third of the front surface (80) of the peripheral seal (8) has a slope (β) that forms an angle of at least 1.0°, preferably at least 3.0°, preferably at least 8.0° toward the plane (P) perpendicular to the longitudinal direction and the inlet (20).

3. The injection device according to claim 1 or 2, wherein at least a portion of the peripheral seal (8) protrudes downward in the longitudinal direction relative to the lower interface (18).

4. The injection device according to claim 1 or 2, wherein the front surface (80) of the peripheral seal (8) extends inward from the wall of the main body (2) of the injection device over a thickness (t') of 3.0 mm to 5.0 mm.

5. The injection device according to claim 1, wherein the lower interface (18) comprises a frame (90) surrounded by the peripheral seal (8), and the frame (90) defines at least one opening that forms the inlet (20).

6. The injection device according to claim 5, further comprising a float (24) disposed inside the discharge path (17) between the lower part (17a) and the intermediate part (17b) of the discharge path, wherein the lower part (17a) of the discharge path is fluidly connected to the lower space (4a), the float (24) is configured to selectively allow gas to move from the lower part (17a) to the intermediate part (17b) of the discharge path, and the frame (90) houses the float (24) in a cavity (36) in which the float (24) is disposed.

7. The infusion device according to claim 6, wherein the float is configured to selectively prevent the medical fluid from moving along the discharge path from the lower space (4a) to the upper space (4b) of the internal space.

8. The injection device according to any one of claims 5 to 7, wherein the frame (90) comprises an outer ring (92), a central portion (96), and a connector (94) connecting the central portion (96) to the outer ring (92), and the at least one opening is formed between the connectors.

9. The injection device according to claim 8, further comprising a float (24) disposed inside the discharge path (17) between the lower part (17a) and the intermediate part (17b) of the discharge path, wherein the lower part (17a) of the discharge path is fluidly connected to the lower space (4a), the float (24) is configured to selectively allow gas to move from the lower part (17a) to the intermediate part (17b) of the discharge path, and the central part (96) of the frame (90) comprises a guide recess (57) configured to receive and guide a portion (56) of the float (24).

10. The injection device according to claim 1 or 2, wherein the peripheral seal (6) is made of a material having a Shore A hardness of 30 to 90, preferably about 70.

11. The injection apparatus according to claim 10, wherein the material of the peripheral seal (6) includes at least one of the following materials: nitrile, silicone rubber, liquid silicone rubber, styrene-ethylene-butylene-styrene (SEBS), thermoplastic elastomer (TPE), and elastomer.

12. The injection device according to claim 1 or 2, wherein the main body (2) is made from a material having an elastic modulus greater than 2400 mPa.

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