Injection system and method of measuring a distal pressure thereof

Abstract

An injection system comprises: a dispense line having a proximal end and a distal end; an injector in fluid communication with the proximal end of said dispense line; a vascular access device in fluid communication with the distal end of said dispense line; a return hydraulic line having a proximal end and a distal end, said distal end being in fluid communication with the distal end of the dispense line; a backstop positioned at the proximal end of the return hydraulic line, and a pressure sensor engaging the return hydraulic line, and positioned between the backstop and the distal end of the return hydraulic line. The present disclosure also relates to a method of measuring a distal pressure of the injection system, and to a vascular access kit to be used as part of such injection system.

Description

[0001] DESCRIPTION

[0002] Technical field

[0003] The present disclosure relates to an injection system and to a vascular access kit which can be used as part of the injection system, as well as to a method of determining a distal pressure of said injection system.

[0004] Background

[0005] The background of the present disclosure is introduced hereinafter with the discussion of techniques relating to its context. However, even when this discussion refers to documents, acts, artifacts and the like, it does not suggest or represent that the discussed techniques are part of the prior art or are common general knowledge in the field relevant to the present disclosure.

[0006] According to different situations and needs, a patient may require to receive specific fluids (like a contrast agent during a diagnostic procedure, or pharmaceuticals such as medicines, antibiotics, chemotherapy, or parenteral nutrition) by means of a vascular access device (VAD) which is inserted into the patient's vasculature. A typical VAD is a polymeric catheter (i.e., a polymeric tubing or sheath) that is inserted into a patient's blood vessel by means of a stainless hypodermic needle or stylet which is used for puncturing the patient’s skin and the blood vessel, and which is successively removed, thereby leaving the polymeric catheter in place partially inserted into the blood vessel and suitable for being fluidically connected to an injection system for administering a given fluid according to the desired patient treatment procedure. The catheter length may vary from a few centimetres in case of a peripheral access (e.g., radial artery, brachial artery, dorsalis pedis artery, posterior tibial artery) to many centimetres in case of a central access (e.g., superior vena cava, inferior vena cava, heart right atrium).

[0007] For example, diagnostic imaging procedures using Computed Tomography (CT) technology are often accomplished by administering to a patient a contrast agent (i.e., a substance used for enhancing the radiodensity of a targeted tissue by altering the way that electromagnetic radiation or ultrasound waves pass through the body) through a VAD. In this case, the VAD is a short, soft and flexible catheter, i.e. a narrow plastic tube, for example roughly 0.5 - 2.0 inches (1 - 5 cm) in length, and with a variable diameter, for example in the range of 24-16 gauge (0.5 - 1.4 mm). The VAD extremity that is located outside the blood vessel (while the other opposite extremity is positioned inside the patient’s blood vessel) usually comprises a connector for coupling with an intravenous line and with an injection system.

[0008] Typically, flow rate performance is one of the key injection performance specifications of diagnostic contrast injectors, such as CT (computed tomography) contrast injectors, angiography contrast injectors, MR (Magnetic Resonance) contrast injectors, and Ultrasound contrast agents injector. Generally, the flow rate requirement is determined by the specific procedural application. For example, in CT applications the contrast agent is traditionally injected into veins in the arm (e.g., antecubital vein) and the maximum flow rate is limited by what the vein system is able to handle / withstand. Most CT diagnostic contrast injectors on the market are indicated as being capable of providing flow rates in the range of 0.1-10 mb's.

[0009] However, in use the flow rate delivered by an injection system is further limited by a maximum allowed system pressure. That is. the injector of an injection system is commonly set or otherwise provided with a maximum system pressure. When the target flow rate is high or the VAD size is challenging, said maximum system pressure may be a limiting factor to the maximum flow rate performance of the injection system.

[0010] Moreover, the flow rate delivered by an injection system is also further limited by the more and more viscous contrast agents that are made available on the market, such increased viscosity generally decreasing the injector delivery perfonnance in terms of maximum flow rate possessed by the injected fluid. Even worse, sometimes said delivery performance is adversely affected also by the habit in some specific countries of injecting the fluid at room temperature, i.e. without pre-warming it at about body temperature before its injection, said pre-warming indeed advantageously contributing in reducing the viscosity of the fluid to be delivered and thus contributing in advantageously increasing the delivery performance of the injections system in terms of maximum flow rate being achieved.

[0011] Typically, VAD manufacturers are required to recommend a maximum injection system pressure limit according to ISO 10555-1 Standard. Applicant has noted that VAD manufacturers tend to recommend the VAD maximum rated pressure as the maximum injection system pressure limit. This recommendation is usually followed by the users and the users’ facility policies. The injection system pressure is usually defined at the injector pump or immediately distal of the injector pump which can be a few meters away from the VAD, separated by tubing(s) (i.e., fluid lines) and additional components. Therefore, the actual pressure at the VAD entrance is substantially lower than the maximum rated VAD pressure recommended by the VAD manufacturers because of the inevitable pressure drop occurring across the tubing(s) and any other component interposed along said tubing(s) upstream the VAD site. For example, for highly viscous contrast agents (such as lomeron® 400 or Isovue® 370 produced by Bracco Imaging) to be injected at a high injection flow rate (e.g., at about 8 - 9 ml / s), the pressure drop along a standard 150 cm long patient line can easily reach 75 - 100 psi (5 - 7 bar), which means that the pressure delivered at the inlet of the VAD will be much lower than the maximum rated pressure designed for that specific VAD. This results in limited and wasted injection system flow rate performance ability, thereby inhibiting to achieve the desired target flow rates, especially when high viscous contrast agents and high injection flow rates protocols are being used.

[0012] Therefore, the Applicant has perceived the need of determining (either by direct detection or by accurate estimation) the pressure of the injected fluid at a location as close as possible to the VAD entrance, i.e. as close as possible to the injection point at the patient site.

[0013] Being able to accurately determine the pressure value of the injected fluid in close proximity to the patient’s injection point allows the injector to maximize the flow rate of the injected fluid without exceeding the pressure rating of the VAD. This means that, by accurately determining the pressure value in close proximity to the injection point, it allows the injection system to reach the maximum rated VAD pressure (which is indicated by the VAD manufacturer and which depends on the VAD design) and thus to optimize the maximum flow rate performance of the diagnostic contrast injector of the injection system. In other words, an improvement of the diagnostic contrast injector maximum flow rate performance can be obtained by being able to deliver pressure at the VAD entrance that is as close as possible to the VAD maximum rated pressure. This improved ability is based on determining (either by directly detecting or by estimating) the in-line pressure at the VAD entrance and, taking into account said determined in-line pressure, on suitably tuning the injector pump pressure so that the determined in-line pressure is set to be equal to (or little less than) the VAD maximum rated pressure defined by the VAD manufacturer. Moreover, the Applicant has also perceived the need of providing an injection system which allows, if needed, to reach sufficiently high fluid pressures and to deliver the fluid at sufficiently high flow rates while avoiding, or at least significantly limiting, the necessity of setting up complex structural solutions of the injection system for guaranteeing that said sufficiently high fluid pressures and flow rates can be finally achieved.

[0014] Typically, an injection system pressure at the injection point (i.e., as close as possible to the VAD entrance) can be indirectly estimated from measuring the injector motor current and / or speed, e.g., by talcing into account the pushing force exerted by the plunger on the fluid contained within the syringe barrel in case a syringe injector is used. Therefore, the motor current is used to determine the pressure in the syringe barrel and the distal pressure (i.e., the injection system pressure at the injection point) is estimated based on calibration curves or lookup tables created from lab testing. Alternatively, syringe-less injectors typically calculate a pressure / flow based on the measured pump pressure, contrast viscosity, and flow rate. Therefore, an injection system pressure at the injection point (i.e., as close as possible to the VAD) can be indirectly estimated also by performing a pressure measurement directly at the powered injector by using a pressure sensor located at the injector head.

[0015] However, it is known that all these methodologies are not much accurate and they necessarily provide for rather approximate pressure values.

[0016] Moreover, the above mentioned solutions have several drawbacks. In fact, the fluid path (i.e., the tubing) connecting the powered injector to the VAD (and thus to the patient) is typically quite long (e.g., 150- 200 cm) and it also has a small inner diameter (e.g., in the range of about 2 - 3.5mm) in order to minimize the dead volume of contrast agent present in the fluid path, thereby causing a remarkable pressure drop to occur along the tubing. As already mentioned above, pressure drops are also further negatively impacted by viscosity and temperature of the fluid to be injected. As a result, the distal pressure of the injected fluid at the VAD entrance does not correspond to (i.e., it is lower, even remarkably lower, than) the pressure value possessed by the fluid at the powered injector. Theoretically, a powered injector can deliver a contrast agent at very different pressure values, but a generic high pressure value cannot be set at the powered injector site since, as already indicated above, the pressure value at the VAD entrance is requested to be limited to a maximum pressure rating which is designed for that specific VAD being used, typically in the range of 300 - 350 psi (20 - 25 bar).

[0017] Alternatively, an injection system pressure can be measured also by using an in-line pressure sensor, i.e. by positioning a distal pressure sensor next to the VAD entrance. However, this solution also has some drawbacks. In fact, a distal sensor would necessarily require an additional electrical cord for being operated, it would inevitably add additional time for the set up thereof, and it would also require cleaning and maintenance for its correct working.

[0018] Finally, an injection system pressure can be measured also by providing a pressure sensor directly coupled to the fluid dispense line, i.e. to what is typically called the “patient set”. However, since this fluid dispense line is disposed after use thereof (i.e., when a new patient is going to be injected), this solution is clearly too expensive because the pressure sensor coupled to the patient set would necessarily be disposed therewith.

[0019] Document US 2015 / 073274 discloses a medical fluid injection system including a powered injector and a fluid reservoir that contains a simulated contrast medium. The simulated contrast medium may exhibit a fluid flow property substantially equal to that of an active contrast medium but be devoid of any active contrast agent that provides contrast during diagnostic imaging. During operation, a syringe in the powered injector may be filled with the simulated contrast medium and then evacuated to discharge the simulated contrast medium from the syringe. The simulated contrast medium may be used to test and evaluate the performance of the powered injector prior to use in a medical procedure without exposing personnel to an active contrast agent or creating medical waste that contains the active contrast agent.

[0020] Document WO 2005 / 110007 discloses an injector system including a source of injection fluid, a pump device, a fluid path set disposed between the source of injection fluid and the pump device, and a fluid control device operatively associated with the fluid path set. The fluid control device is adapted to permit purging of air from the fluid path set and to stop flow of the injection fluid to a patient at substantially any pressure or flow rate generated by the pump device for delivering a sharp bolus of the injection fluid to the patient. The fluid control device is preferably part of the fluid path set between the source of injection fluid and the pump device. In another aspect, an injector system includes a powered injector, a pressurizing chamber in operative connection with the powered injector, a fluid path in fluid connection with the pressurizing chamber, and a manual control in fluid connection with the fluid path. The manual control includes at least one actuator for controlling the injector through application of force by an operator. The actuator provides tactile feedback of pressure in the fluid path to the operator via a fluid connection with the fluid path. A pressure isolation mechanism for use in a medical procedure includes a lumen, an isolation port in fluid connection with the lumen, and a valve having a first state and a second state. The first state occurs when the lumen and the isolation port are connected. The second state occurs when the lumen and the isolation port are disconnected. The lumen remains open for flow of fluid therethrough in the first state and in the second state. The valve is normally in the first state and is switchable to the second state when fluid pressure in the lumen reaches a predetermined pressure level. A pressure transducer can be in fluid connection with the isolation port of the pressure isolation mechanism. A fluid delivery system includes a manually operated syringe and a pressure isolation mechanism as described above.

[0021] Document US 2015 / 209515 discloses an automated injection system which advantageously provides physicians with a simplified interface for selecting fluid sources, such as saline, contrast, or a mixture of both, to inject at high pressures. The injector system may comprise a multi-use subassembly, a single-use subassembly, a fitting to fluidly connect the multi-use and single-use subassemblies, a hand held controller, a user interface, and an injector housing.

[0022] In order to solve the above-mentioned drawbacks, the present disclosure is directed to an injection system as defined in claim 1 which is configured to accurately determine the distal pressure (possessed by the injected fluid) in close proximity’ to the patient’s injection point without the need of providing the injection system with a distal pressure sensor.

[0023] Summary

[0024] The present disclosure is set out in the appended claims.

[0025] A simplified summary of the present disclosure is herein presented in order to provide a basic understanding thereof; however, the sole purpose of this summary is to introduce some concepts of the disclosure in a simplified form as a prelude to its following more detailed description, and it is to be interpreted neither as an identification of its key elements, nor as a delineation of its scope.

[0026] The present disclosure also concerns a method of determining a distal pressure in an injection system, as well as a vascular access kit suitable for being used with said injection system.

[0027] Indeed, it can be pointed out that the present disclosure is applicable to any pressurized fluid flow path, where the pressurizing system is not even necessarily a pump. For instance, it can be a constant pressure system (e.g., an air pressure over a fluid reservoir) connected to a given dispense line. In case a pump is present, it can be not necessarily a syringe pump or a peristaltic pump, but it can also be a vane pump or a gear pump connected to a given dispense line. In other words, the present disclosure basically measures pressure drop across a fluid path, whatever pressurizing system is present and envisaged to act on this fluid path.

[0028] Dependent claims outline preferred and / or particularly advantageous aspects of the present disclosure.

[0029] Brief description of the drawings

[0030] The solution of the present disclosure, as well as further features and the respective advantages, will be better understood with reference to the following detailed description thereof, provided purely by way of a non-restrictive indication, with its explanations applying by analogy to every aspect thereof (irrespectively of the context in which they occur); the description is to be read in conjunction with the accompanying drawings (wherein, for the sake of simplicity, corresponding elements are denoted with equal or similar references and their explanation is not repeated, and the name of each entity is generally used to denote both its type and its attributes, like value, content and representation). In this respect, it is expressly intended that the drawings are not necessary drawn to scale (with some details that may be exaggerated and''or simplified) and that, unless otherwise indicated, they are merely used to illustrate the structures and procedures described herein conceptually. In addition, orientations and related position references (such as front, rear, upper, lower, lateral and so on) are to be understood in relation to a condition of use of the corresponding entities. Particularly:

[0031] Figure 1 is a schematic view- of an injection system according to the present disclosure; Figure 2 is a diagram showing the pressure values resulting from a first test conducted on the injection system according to the present disclosure, and

[0032] Figure 3 is a diagram showing the pressure values resulting from a second test conducted on the injection system according to the present disclosure.

[0033] Detailed description

[0034] Each example of the following description is herein provided merely as an illustration of the present disclosure and it is not intended as a limitation thereof. For example, the technical features illustrated or described as fonning part of one embodiment may be adopted over, or in association with, other embodiments to define a further form of implementation of the present disclosure. It is understood that the present disclosure will be inclusive of such modifications and variations.

[0035] In the present description the term “distal” is used to indicate a location or a direction that is close to the injection site, and thus close to the patient (and consequently far from the injector head). Analogously, the term “proximal” is used to indicate a location or a direction that is far from the injection site, and thus far from the patient (and consequently close to the injector head). Therefore, the term “proximal” indicates a direction that is opposite to the distal direction.

[0036] The subject matter of the present disclosure provides for an injection system, a vascular access kit and a method of determining a distal pressure within said injection system so that an increased flow rate performance of the injection system can be achieved while complying with the maximum pressure limit designed for the specific injection system being used. One application of the present disclosure is a computed tomography (CT) contrast injection system. An alternative application of the present disclosure is an angiography contrast injection system, an MR contrast injection system, a contrast enhanced mammography (CEM) injections system or an ultrasound contrast agent injection system. Moreover, the present disclosure can be applied to any fluid injection system that requires flow rate performance and pressure control. For simplicity, a fluid injector for delivering contrast agent to a patient will serve as an example embodiment of the present disclosure, but any fluid injector could equally apply with minor variations. If a diagnostic contrast injector cannot reach the desired target flow rate due to injection system maximum pressure limits, the contrast enhancement to a diagnostic imaging procedure may not be satisfactory, which can lead to poor image quality, disrupted lab workflow, increased patient contrast dosage from repeated procedures, and user and / or patient dissatisfaction. The subject matter of the present disclosure addresses this concern and it enables a diagnostic contrast injector of an injection system to provide flow rates that are higher than those provided by existing diagnostic contrast injectors with the same injection system maximum pressure limits.

[0037] In the embodiments of the present disclosure, the injection system includes at least one fluid container, a pressurizing mechanism such as a syringe pump or a peristaltic pump, at least one tubing for carrying the fluid from the fluid container and the pressurizing mechanism to a VAD at an injection site, and a controlling unit that, for example, may comprise a user interface, a computer, and software program(s) to set, cany out, and monitor the injection system performance prior to and during an injection procedure, or which may have a microcontroller, single board computer, or FPGA to cany out and monitor the injection system performance prior to and during an injection procedure.

[0038] In general, an injection system uses one of the two main pump techniques (syringe pump and peristaltic pump, thereby distinguishing between syringe injectors and syringe-less injectors, respectively) to pressurize a fluid (e.g. contrast agent, saline, a mixture thereof, etc.) and relies on the pressure gradient to push the fluid through the VAD into a patient’s blood vessel. Through this process, the flow rate performance of the injection system is determined by the following factors:

[0039] • fluid viscosity; which is further determined by contrast type and concentration, possible contrast / saline co-injection ratio and temperature;

[0040] • injection system pressure;

[0041] • pressure drop between the pressurized chamber of the injector and the VAD entrance, which is further determined by the fluid pathway design such as the dispense line inner diameter, length, wall thickness, material, additional components present along the fluid pathway (e.g., check valve, anti-dripping connector, Luer fitting, etc.); • VAD type (e.g. short cannula, midline catheter, PICC (Peripherally Inserted Central Catheter), CVC (Central Venous Catheter)) and specifications, especially pressure rating, flow rate rating, inner diameter, length, and material;

[0042] • characteristics of the tubing present between the injector pressurized chamber and the VAD (e.g., length, inner diameter, valves and connectors along the tubing, etc.);

[0043] • patient ’ s blood vessel conditions.

[0044] The present disclosure is independent of the pump technology that the injection system uses. Therefore, the term "‘pump” used herein may refer to the various pump mechanisms that are suitable for pressurizing a given fluid. A diagnostic contrast injector typically uses a pressurized chamber (for example a syringe or a peristaltic pump) in order to push the fluid (particularly a contrast agent and / or saline in CT imaging procedures) downstream through the dispense line into a patient’s vasculature via a VAD, the latter being a short IV (intravenous) catheter, a midline catheter, a PICC (Peripherally Inserted Central Catheter), a CVC (Central Venous Catheter), or any other device depending on the procedure to be performed. Both 18G and 20G IV catheters are common VADs used in CT imaging procedure for adult patients, wrhile 20G and 24G IV catheters are typically used for elder patients, pediatric patients, or patients with poor vascular conditions.

[0045] Figure 1 shows an injection system 1 according to an embodiment of the present disclosure. In detail, the injection system 1 comprises a dispense line (also called “patient line”) 20 (typically a polymeric tubing) having a proximal end 22 which is fluidically connected to an injector 10, e.g. a syringe pump or a peristaltic pump. Preferably, the injector 10 is a powered injector having a pressurizing chamber and an outlet port (not shown in Figure 1 ) for fluidically connecting the proximal end 22 of the dispense line 20. The injector 10 is configured to be connected to a fluid reservoir 12 by means of an inlet line 13, said fluid reservoir 12 containing the fluid (e.g. a contrast agent) to be injected into the patient. Generally, the inlet line 13 is provided with a check valve 14 in order to properly regulate the fluid flow from the reservoir 12 to the injector 10 and also to avoid any fluid back flow from the injector into the reservoir.

[0046] The dispense line 20 also comprises a distal end 24 that is fluidically connected to a

[0047] VAD 30, and thus to a patient (not shown in Figure 1). According to the present disclosure, the injection system 1 further comprises a return hydraulic line 50 that is in fluid connection with the dispense line 20. The return hydraulic line 50 (typically a polymeric tubing) has a distal end 54 which is fluidically connected to the dispense line 20, preferably at the distal end 24 of the dispense line 20.

[0048] According to the embodiment shown in Figure 1, the injection system 1 further comprises a connector 26 that is fluidically connected to the distal end 24 of the dispense line 20 and to the distal end 54 of the return hydraulic line 50. Preferably, the connector 26 is an “Y” or “T” fitting connector.

[0049] According to the embodiment shown in Figure 1, the connector 26 is fluidically connected also to a vascular access device (VAD) 30 which is configured to be inserted into a patient’s vasculature (not shown). As per the embodiment of Figure 1, the injection system further comprises an additional dispense line 80 fluidically connecting the connector 26 to the VAD 30. The length of this additional dispense line 80 is kept as short as possible so as to limit the pressure drop along it.

[0050] As mentioned above, the connector 26 is in fluid communication with the distal end 24 of the dispense line 20, with the distal end 54 of the return hydraulic line 50, and with the vascular access device 30 (or with the additional dispense line 80, in case the latter is envisaged). Therefore, the connector 26 allows and promotes a continuous (i.e., uninterrupted) fluid passage through the dispense line 20, the return hydraulic line 50 and the vascular access device 30 (or the additional dispense line 80) so that the return hydraulic line 50 is continuously kept filled of fluid during operation of the injector 10. As a consequence, since no fluid flow occurs along the return hydraulic line 50, the return hydraulic fine 50 can be advantageously used to measure the actual pressure (of the pressurized fluid being delivered) in proximity’ of the connector 26, and thus of the vascular access device 30, as better explained in the following of the present description.

[0051] The injection system 1 further comprises a backstop 60 in fluid connection with the return line 50, preferably located at the proximal end 52 thereof. The backstop 60 can be a check valve, a luer-lock or any other means configured to block the fluid flow inside the return hydraulic line 50 so that the fluid contained therein is not allowed to exit the injection system 1. Moreover, backstop 60 can be used for purging air from return line 50. The injection system 1 further comprises a pressure sensor 40 which engages the return hydraulic line 50 at a location situated between the backstop 60 and the distal end 54 of the return hydraulic line 50. Preferably, the pressure sensor 40 is positioned in close proximity to the backstop 60. Preferably, the pressure sensor 40 is a non-contact pressure sensor, for instance a diaphragm pressure transducer or an "over the tube" sensor which is installed externally to the return hydraulic line 50 and which is configured to interact with an outer surface of the return hydraulic line 50 in order to provide a pressure measurement of the fluid contained within the return hydraulic line 50. Preferably, the pressure sensor 40 is positioned at the injector head, thereby constituting a single and specific component of the injector itself. Alternatively, the pressure sensor 40 is a distinct component, i.e. separate from the injector, and it is configured to interface with the return hydraulic line 50, preferably this pressure sensor 40 being positioned in proximity of the proximal end 52 of the return hydraulic line 50. Depending on the selected configuration and on the pressure sensor technology, mechanical features may be envisaged for an effecti ve and reliable interface of the pressure sensor 40 with the return hydraulic line 50.

[0052] According to the injection system 1 of the present disclosure, the pressure sensor 40 is provided for measuring (i.e., detecting) the actual pressure value of the pressurized fluid while being delivered (i.e., injected) by the injection system 1.

[0053] Moreover, the placement of the connector 26 to fluidically coupling together at least the dispense line 20 and the return hydraulic line 50, as well as the continuous (i.e., uninterrupted) presence of fluid along the return hydraulic line 50 (thereby, fully filling it) allow that the pressure sensor 40 engaging the return hydraulic line 50 is continuously and in real-time measuring the pressure value of the pressurized fluid during delivery (i.e., dispensing or injection) thereof, the pressure value of the pressurized fluid being remarkably higher than the patient hemodynamic pressure (i.e., the pressure of a patient blood vessel). Indeed, it should be noticed that the hemodynamic pressure can be measured by the pressure sensor 40, but this is possible only if: a) the return hydraulic line 50 is fully filled with fluid, b) the vascular access device 30 is connected to the patient, and c) no pressurized fluid is delivered (and thus no pressurized fluid is injected into the patient’s vasculature).

[0054] Analogously, also the backstop 60 is designed to be a specific component of the injector

[0055] 10, or, alternatively, a distinct component, separate from the injector. According to the embodiment shown in Figure 1 , the return hydraulic line 50 is coupled with the dispense line 20 in a sort of "twin-tube" configuration, with their respective ends (i.e., the proximal ends 22, 52 and the distal ends 24, 54) separated for their dedicated terminations. Alternatively, the return hydraulic line 50 and the dispense line 20 are configured as a single bilumen tubing wherein a first lumen (i.e., conduit) is used as the dispense line 20 and a second lumen is used as the return hydraulic line 50. Alternatively, the return hydraulic line 50 and the dispense line 20 are two separate tubings.

[0056] According to the embodiment shown in Figure 1 , the dispense line 20 comprises a check valve 70 that is in fluid connection with the distal end 24 of the dispense line 20, said check valve 70 being provided for preventing backflow of the fluid towards the injector 10. Check valve 70 also prevents the fluid from flowing / dripping out of the dispense line when not in use. Moreover, check valve 70 also acts as a bio barrier to prevent cross-contamination in a multiuse system. Preferably, the check valve 70 is positioned at the distal end 24 of the dispense line 20 and directly upstream of the connector 26.

[0057] In operation, the return hydraulic line 50 is filled with fluid, and since the return hydraulic line 50 is capped (i.e., "dead-headed"} at its proximal end 52 with the backstop 60, no fluid flow occurs inside the return hydraulic line 50. Therefore, since there’s no fluid flow inside the return hydraulic line 50, this means that there is no pressure drop along the return hydraulic line 50, and thus the full delivery pressure of the injected fluid present at the distal end 24 of the dispense line 20 can be transferred back (as a pressure wave) to the proximal end 52 of the return hydraulic line 50 and, thus, to the pressure sensor 40. Therefore, in accordance with the present disclosure, the pressure sensor 40 is able to detect (and consequently to provide to the operator or to the processor of the injection system) a pressure measurement (i.e., a pressure value) which indeed substantially corresponds to the actual pressure value of the injected (i.e., pressurized) fluid at the distal end 24 of the dispense line 20, and thus in close proximity’ to the VAD and to the patient. As mentioned above, the injection system according to the present disclosure allows the injection system operator / processor to obtain a realistic indication (or at least a substantially realistic indication) of the pressure possessed by the pressurized fluid at a location that is not at the injector level or close to the injector, but advantageously close to the VAD and thus close to the patient. This aspect is of particular relevance since detecting (i.e., measuring) the actual pressure value of the pressurized fluid in proximity of the VAD (and thus as close as possible to the patient) allows the injection system parameters to be set by an operator so as to guarantee that the pressurized fluid is delivered at the highest possible flow rate which is requested to properly accomplish a desired interventional procedure according to a predetermined injection protocol.

[0058] According to a first operative methodology of the injection system I . the same (first) fluid (typically a contrast agent) that is contained in the fluid reservoir 12 is also filled into the return hydraulic line 50. The filling of the return hydraulic line 50 can be performed through the dispense line 20 by making the fluid flowing through the dispense line 20, then through the connector 26 and finally back into the return hydraulic line 50, since, as mentioned above, the connector 26 allows and promotes the fluid passage there through and along the lines in fluid communication with the connectors itself. Alternatively, the filling of the return hydraulic line 50 can be performed by fluidically connecting an additional pump (e.g., a peristaltic pump or a syringe pump, the latter being manually or automatically actuated) (not shown in Figure 1) to the proximal end 52 of the return hydraulic line 50. In case the backstop 60 is a cap (and not a check valve), removing thereof is needed before filling the return hydraulic line 50 with the fluid.. It can be noted that the step of filling the return hydraulic line 50 with the fluid is performed also for purging air from the return hydraulic line before the injection system is connected to a patient. When the fluid (i.e., the first fluid contained in the reservoir 12) is injected into the dispense line 20, since the return hydraulic line 50 is in fluid connection with the dispense line 20 through the connector 26 and the return hydraulic line 50 is fully filled with fluid with no flow thereof within the return hydraulic line 50, the pressure of the pressurized fluid can be detected and measured at the distal end of the dispense line by using the pressure sensor 40, thanks to the wave pressure moving from the dispense line 20 into the return hydraulic line 50 and up to the proximal end 52 thereof.

[0059] According to an alternative operative methodology of the injection system 1, the return hydraulic line 50 is filled with a second fluid which is different from the (first) fluid contained in the fluid reservoir 12. For instance, the first fluid (within the fluid reservoir 12) is a contrast agent, while the second fluid, which is used for filling the return hydraulic line 50, is saline. This second fluid can be introduced into the return hydraulic line 50 by removing the backstop 60 if the latter is in the form of a cap (and then putting the cap back at its place when the filling of the return line 50 is completed), or simply by dispensing the second fluid through the backstop 60 if the latter is a check valve or a similar device. Then, an additional pump (e.g., a peristaltic pump or a syringe pump, the latter being manually or automatically actuated) (not shown in Figure 1) is fluidically connected to the proximal end 52 of the return hydraulic line 50 so as to fully fill the return hydraulic line 50 with said second fluid. Also according to this alternative operative methodology, when the fluid (i.e., the first fluid of reservoir 12) is pressurized and injected into the dispense line 20, since the return hydraulic line 50 is in fluid connection with the dispense line 20 through the connector 26 and the return hydraulic line 50 is fully filled with the second fluid with no flow thereof within the return hydraulic line 50, the pressure of the pressurized first fluid can be detected and measured at the distal end of the dispense line by using the pressure sensor 40, thanks to the wave pressure moving from the dispense line 20 into the return hydraulic line 50 and up to the proximal end 52 thereof.

[0060] The Applicant has conducted several tests to demonstrate that the pressure value measured by the pressure sensor 40 at the proximal end 52 of the return hydraulic line 50 substantially corresponds to the pressure value measured by a sensor which would be positioned at the distal end 24 of the dispense line 20.

[0061] To perform these tests, the injection system 1 was equipped with two additional pressure sensors, for example two pressure transducers: a first pressure sensor interposed between the connector 26 and the VAD 30, and a second pressure sensor positioned next to the proximal end 22 of the dispense line 20. Thanks to this configuration, the proximal pressure values (i.e., the pressure values measured by the additional first pressure sensor at the injector’s site), the distal pressure values (i.e., the pressure values measured by the additional second pressure sensor at substantially the entrance of the VAD), and the return hydraulic line pressure values (measured by means of the pressure sensor 40) wrere determined. In place of a VAD, the testing set-up was provided with a stainless steel dispense tip that was positioned at the distal end of the additional dispense line 80. This tip generated a sufficient restriction to build up a measurable pressure within the injection system 1.

[0062] First Test A first test was performed by filling with water both the dispense line 20 and the return hydraulic line 50, and then by injecting 20 ml of water at a flow rate of 6 ml / s.

[0063] Figure 2 shows a diagram reporting the pressure curve (in psi) over time (in seconds) measured during this first test by the three pressure sensors indicated above.

[0064] A maximum pressure value of 280 psi (i.e., 19.3 bar) was achieved. The variation among the pressure values measured by the three different pressure sensors was indeed negligible, as it can be clearly inferred from the three different represented curves that are substantially fully overlapping each other over their whole extension. More importantly, the curve representing the evolution (i.e., the profile) of the distal pressure substantially overlaps (i.e., lays on) the curve representing the evolution of the return pressure, thereby indicating that the pressure value measured by the pressure sensor 40 on the return hydraulic line 50 is substantially identical to the pressure value measured by the second additional pressure sensor positioned at the distal end 24 of the dispense line 20, and thus at a location in close proximity to the VAD 30, and thus to the patient. The profile of each represented line ( curve ) of Figure 2 indicates the pressure trend of the proximal, distal and return pressures detected by the respective three pressure sensors indicated above when the injection process is started. In fact, as the injection starts, the pressure rises as the flow rate increases. Successively, the flow rate reaches a steady state which is shown in the curves when the lines are steady out. Finally, the curves come down as the injection stops and the pressure returns to zero.

[0065] The diagram of Figure 2 also shows that, during the injection, the gap (i.e. the pressure drop) between the proximal pressure curve and the distal pressure curve (as well as between the proximal pressure curve and the return pressure curve), in correspondence of the maximum plateau of the three curves, is quite small, and thus that a very small pressure drop occurred along the dispense line 20 during the test. This is mainly due to the fact that the internal diameter of the dispense line was pretty “large" (i.e., 0.088 inches, which means about 2.2 mm), the fluid was water and thus with a viscosity of IcP (low viscosity), and finally the tested flow rate was quite low, i.e. 6 ml / s. Therefore, these conditions did not generate significant resistance to the fluid flow, thereby causing little pressure drop along the dispense line. This specific setting of the test was intentionally designed for demonstrating that all sensors could detect the same low pressure drop condition where the VAD was the sole restriction. Second test

[0066] A second test was performed by filling the return hydraulic line 50 with water and by filling the dispense line 20 with contrast agent lomeron® 400 (manufactured by Bracco Imaging) at room temperature (25°C). Then 60 ml of contrast agent lomeron® 400 at room temperature (25°C) was injected at a flow rate of 14 ml / s.

[0067] Since lomeron 400® is much “thicker” (i.e., more viscous) than water (which was used in the first test), the small internal diameter of the dispense tip used in the first test would have been too restrictive. Therefore, a dispense tip with a larger internal diameter was used in the second test, said needle internal diameter being 0.039 inches (i.e., 0.99 mm), thus equivalent to an l8G VAD.

[0068] Figure 3 shows a diagram reporting the pressure curves (in psi) over time (in seconds) measured during this second test by the three pressure sensors indicated above. Analogously to Figure 2, the profile of each represented line (curve) of Figure 3 indicates the pressure trend of the proximal, distal and return pressures detected by the respective three pressure sensors indicated above when the injection process is started. As represented in Figure 3, a maximum pressure value of 310 psi (i.e., 21.3 bar) was achieved by the proximal pressure, i.e. at the injector site (i.e., inside the syringe if a syringe injector is used). From the diagram it can be inferred that the curve representing the evolution (i.e., the profile) of the distal pressure substantially overlaps the curve representing the evolution of the return pressure, thereby demonstrating that the pressure value measured by the pressure sensor 40 on the return hydraulic line 50 is substantially identical to the pressure value measured by the second additional pressure sensor positioned at the distal end 24 of the dispense line 20 (and thus at a location in close proximity to the VAD 30, and thus close to the patient), even when a very viscous contrast agent (like lomeron® 400) is being used. This confirms that the zero-flow condition of the return hydraulic line does not cause any pressure loss (pressure drop) and this return hydraulic line delivers to the pressure sensor 40 a pressure measurement substantially identical to the distal pressure present at the VAD.

[0069] The diagram of Figure 3 also shows that, during the injection, the gap (i.e. the pressure drop) between the proximal pressure curve and the distal pressure curve (as well as between the proximal pressure curve and the return pressure curve), in correspondence of the maximum plateau of the three curves, is quite important, and thus that a large pressure drop (of about 100 psi, i.e. about 6.8 bar) occurred along the dispense line 20 during the test. This means that the injector could be driven 100 psi higher without exceeding the pressure rating (-300 psi) of the distal VAD.

[0070] This specific setting of the test was intentionally designed with a thicker fluid (e.g., by using a highly viscous contrast agent instead of water) and with a higher flow rate, thereby inducing a more significant drop prior to the VAD, which was detected (measured) by the setup of the present disclosure which was able to determine and evaluate (and thus to take into consideration) a real (or at least more realistic) pressure condition of the injection system if compared to what is typically detected at the injector level according to the known solutions described herein above.

[0071] It can be also highlighted that, since the dispense line 20 and the return hydraulic line are both sterile and disposable, there is no risk of cross-contamination among successive patients being treated with the same injection system 1. Moreover, since pressure sensing (i.e., pressure measurement) is performed from outside of the fluid path by using, for instance, over- the-tube sensors or diaphragm sensors, cross-contamination does not occur.

[0072] According to a further embodiment of the present disclosure, in addition of being used as a pressure detection tool as disclosed herein above, the return hydraulic line 50 is used as a secondary delivery line for delivering saline, or a contrast agent different from the contrast agent contained in the reservoir 12, or any other fluid (medicament, nutrient, etc) that is requested to be injected into a patient’s vasculature. In other words, according to the desired injection protocol selected by the operator for a given patient to be treated, the return hydraulic line 50 is fluidically connected to an additional dedicated pump (e.g., a peristaltic pump) (not shown in Figure 1) and a predetermined amount of a second fluid (typically, saline) is injected into the patient’s vasculature through the return hydraulic line 50, the connector 26, the additional dispense line 80 (if present) and the VAD 30. Then, when a new phase of the injection protocol requires that the first fluid (contained within the reservoir 12) has to be injected, the presence of the second fluid within the return hydraulic line 50 at zero flow rate allows the injection system I to determine the real pressure of the injected fluid at the distal end 24 of the dispense line 20 and thus to regulate and optimize in real time the injector parameters suitable for achieving the desired flow rate of the injected first fluid at the VAD site.

[0073] Therefore, according to a first aspect, the present disclosure relates to an injection system comprising: an injector acting on a fluid contained within a pressurizing chamber of said injector to deliver a pressurized fluid; a dispense line having a proximal end and a distal end, said proximal end being in fluid communication with said pressurizing chamber and with an outlet port thereof; a vascular access device in fluid communication with the distal end of said dispense line; a return hydraulic line having a proximal end and a distal end, said distal end being in fluid communication with the distal end of the dispense line; a connector in fluid communication with the distal end of the dispense line (20), with the distal end of the return hydraulic line and with the vascular access device, so that during delivery’ of the pressurized fluid said connector promotes a continuous fluid passage through the dispense line, the return hydraulic line and the vascular access device; a backstop positioned at the proximal end of the return hydraulic line to ensure that the return hydraulic line is filled with fluid and no fluid flow occurs along it while delivering the pressurized fluid through the dispense line and the vascular access device, and a pressure sensor engaging the return hydraulic line, and being positioned between the backstop and the distal end of the return hydraulic line, said pressure sensor measuring the actual pressure value of the pressurized fluid at the distal end of the dispense line, and thus in close proximity’ to the vascular access device.

[0074] As already anticipated, the present disclosure relates also to a vascular access kit whichs used in the injection system as previously described, said vascular access kit being a disposable component that is discarded when the injection procedure on a given patient is completed and a new patient is admitted to the intervention room (cath lab, CT room, MRI room, . . ..) for a new procedure to be performed.

[0075] In particular, the vascular access kit comprises: a dispense line having a proximal end and a distal end, said proximal end being configured to be connected in fluid communication with an injector of an injection system; a return hydraulic line having a proximal end and a distal end, said proximal end being terminated with a backstop and said return hydraulic line being configured to engage a pressure sensor of the injection system; a connector which is in fluid communication with the distal end of the dispense line, with the distal end of the return hydraulic line, and with the vascular access device, and a vascular access device which is in fluid communication with the distal end of the dispense line.

[0076] The vascular access kit further comprises an additional dispense line fluidically connecting the connector to the vascular access device.

[0077] The present disclosure also relates to a method of measuring a distal pressure of an injection system which comprises a dispense line and a vascular access device located at a distal end of the dispense line which is used for delivering a pressurized first fluid. The method of measuring comprises the steps of: providing a return hydraulic line having a backstop positioned at a proximal end of the return hydraulic line, the return hydraulic line being configured to engage a pressure sensor of the injection system; fluidically connecting the return hydraulic line to the distal end of the dispense line through a connector promoting a continuous (i.e., uninterrupted) fluid passage through the dispense line, the return hydraulic line and the vascular access device during delivery' of the pressurized first fluid; filling the return hydraulic line with a second fluid; dispensing the pressurized first fluid through the dispense line and the vascular access device, and measuring a pressure value of the pressurized first fluid in close proximity to the vascular access device by means of the pressure sensor.

[0078] As already indicated above, the first fluid and the second fluid can be different fluids, or they can be the same fluid. The method of measuring according to the present disclosure further comprises the step of regulating in real-time at least one parameter of the injection system based on the pressure value of the injected first fluid measured at the distal end of the dispense line, and the step of measuring by using the pressure sensor possessed by the injection system is performed thanks the pressure wave that propagates along the dispense line and the return hydraulic line, the latter, containing the second fluid at zero flow' rate, i.e. in a steady condition.

Claims

CLAIMS1. An injection system ( 1) comprising: an injector (10) acting on a fluid contained within a pressurizing chamber of said injector to deliver a pressurized fluid; a dispense line (20) having a proximal end (22) and a distal end (24), said proximal end (22) being in fluid communication with said pressurizing chamber and with an outlet port thereof; a vascular access device (30) in fluid communication with the distal end (24) of said dispense line (20); a return hydraulic line (50) having a proximal end (52) and a distal end (54), said distal end (54) being in fluid communication with the distal end (24) of the dispense line (20); a connector (26) in fluid communication with the distal end (24) of the dispense line (20), with the distal end (54) of the return hydraulic line (50) and with the vascular access device (30), so that during delivery of the pressurized fluid said connector (26) promotes a continuous fluid passage through the dispense line (20), the return hydraulic line (50) and the vascular access device (30); a backstop (60) positioned at the proximal end (52) of the return hydraulic line (50) to ensure that the return hydraulic line (50) is filled with fluid and no fluid flow occurs along it while delivering the pressurized fluid through the dispense line (20) and the vascular access device (30), and a pressure sensor (40) engaging the return hydraulic line ( 50), and being positioned between the backstop (60) and the distal end (54) of the return hydraulic line (50), said pressure sensor (40) measuring the actual pressure value of the pressurized fluid at the distal end (24) of the dispense line (20), and thus in close proximity to the vascular access device (30).

2. The injection system (1) according to claim 1, further comprising a fluid reservoir (12) that is in fluid communication with said injector (10).

3. The injection system (1) according to any of the preceding claims, further comprising a check valve (70) in fluid connection with the distal end (24) of the dispense line (20) and positioned upstream of said connector (26).

4. The injection system (1 ) according to any of the preceding claims, further comprising an additional dispense line (80) fluidically connecting the connector (26) to the vascular access device (30).

5. The injection system (1) according to any of the preceding claims, wherein the pressure sensor (40) is a non-contact pressure sensor, a diaphragm pressure transducer or an "over the tube" sensor.

6. The injection system (1) according to any of the preceding claims, wherein the connector (26) is an “Y” or “T” fitting connector.

7. A method of measuring a distal pressure of an injection system (1), said injection system comprising a dispense line (20) and a vascular access device (30) located at a distal end (24) of said dispense line (20) for delivering a pressurized first fluid, said method comprising the steps of: providing a return hydraulic line (50) having a backstop (60) positioned at a proximal end (52) of the return hydraulic line (50), said return hydraulic line (50) being configured to engage a pressure sensor (40) of the injection system (1); fluidically connecting the return hydraulic line (50) to the distal end (24) of the dispense line (20) through a connector (26) promoting a continuous fluid passage through the dispense line (20), the return hydraulic line (50) and the vascular access device (30) during delivery' of the pressurized first fluid; filling the return hydraulic line (50) with a second fluid; dispensing the pressurized first fluid through the dispense line (20) and the vascular access device (30), and measuring a pressure value of the pressurized first fluid in close proximity to the vascular access device (30) by means of the pressure sensor (40).

8. The method according to claim 7, wherein the first fluid and the second fluid are different fluids.

9. The method according to claim 7, wherein the first fluid and the second fluid are the same fluid.

10. The method according to any claim 7 to 9, further comprising the step of regulating in real-time at least one parameter of the injection system based on the pressure value of the pressurized first fluid measured at the distal end (24) of the dispense line (20), said step of measuring by means of the pressure sensor (40) being performed thanks to a pressure wave propagation along the dispense line (20) and the return hydraulic line (50) containing the second fluid at zero flow' rate.

11. The method according to claim 10, wherein the step of regulating in real-time at least one parameter comprises the step of varying the current voltage or the speed of the pump motor of the injection system (1).

12. The method according to claim 10 or 11, wherein said at least one parameter is the flow rate of the pressurized first fluid.

13. A vascular access kit comprising: a dispense line (20) having a proximal end (22) and a distal end (24), said proximal end (22) being configured to be connected in fluid communication with an injector (10) of an injection system (1); a return hydraulic line (50) having a proximal end (52) and a distal end (54), said proximal end (52) being terminated with a backstop (60) and said return hydraulic line (50) being configured to engage a pressure sensor (40) of the injection system (i); a vascular access device (30) being in fluid communication with the distal end (24) of the dispense line (20), and a connector (26) being in fluid communication with the distal end (24) of the dispense line (20), w'ith the distal end (54) of the return hydraulic line (50) and w-ith the vascular access device (30).

14. The vascular access kit of claim 13, further comprising an additional dispense line (80) fluidically connecting the connector (26) to the vascular access device (30).

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