Contrast agent injection system and method for prestressing tubing

Abstract

The present application discloses a contrast agent injection system that injects a contrast fluid into a patient using a relatively large inner diameter conduit. Contrast agent injection systems of embodiments presented herein take advantage of the elastic properties of conduits to "pre-stress" smaller inner diameter conduits into larger inner diameter conduits prior to injection of contrast agent into a patient. Contrast agent injection systems of these embodiments can thus reduce the risk of injection disruption caused by system pressure limits, improve maximum flow rates, and reduce the use of plastic.

Description

BACKGROUND

[0001] In some imaging modalities, contrast fluid is used to enhance the contrast of target features within a patient. A contrast media injection system can inject contrast fluid into a patient at a flow rate and volume (via tubing). In some injection systems, a syringe pump is used to inject the contrast fluid, while in other injection systems, a peristaltic pump is used to inject the contrast fluid. BRIEF DESCRIPTION OF DRAWINGS

[0002] Figure 1 is an illustration of an example syringeless injection system suitable for a single use scenario embodiment.

[0003] Figure 2 is an illustration of an example syringeless injection system suitable for a multiple use scenario embodiment.

[0004] Figure 3 is an illustration of an example syringe-based injection system embodiment.

[0005] Figure 4 is an illustration of an experimental setup of an embodiment.

[0006] Figure 5 is a graph illustrating peak syringe pressure drop of an experimental setup of Figure 4

[0007] Figure 6 is a flowchart of a method for pre-stressing tubing of an embodiment.

[0008] Figure 7 is a graph illustrating various example ways of limiting the distal end of a patient line.

[0009] Figures 8A to 8C is a block diagram of an example injection system embodiment.

[0010] Figure 9 is a flowchart of a method for pre-stressing tubing of an embodiment. DETAILED DESCRIPTION

[0011] INTRODUCTION

[0012] As mentioned above, an injection system can inject contrast fluid into a patient during a scan procedure to enhance the contrast of target features within the patient. Image quality of the contrast enhancement is closely related to the contrast media delivery output or injection performance, and can require a relatively large inner diameter plastic tubing to deliver the contrast fluid at a consistent desired flow rate without exceeding the pressure limits of the injection system.

[0013] ​The following embodiments can be used to allow the use of smaller inner diameter plastic tubing. By requiring the use of less plastic, these embodiments are more cost effective and environmentally sustainable than the systems discussed above. In general, these embodiments recognize that tubing for injection systems has elastic properties that allow the inner diameter of the tubing to expand when under pressure for a certain period of time, and to retain that expanded state even after the pressure is removed. Utilizing this phenomenon, the injection systems of these embodiments can be used to expand the inner diameter of tubing before the tubing is used to inject fluid into a patient, thereby transforming tubing that has a relatively small inner diameter into tubing that has a relatively large inner diameter. In one embodiment, the injection system performs this "pre-stressing" procedure after (or as part of) performing an air purge procedure on the tubing, since fluid (e.g., saline) has already been applied to the tubing under pressure. The pressure in the tubing can advantageously be increased to induce stress on the tubing. To achieve the increased pressure in the tubing, for example, the distal end of the patient line can be restricted to partially or completely block air flow, to allow pressure to build up in the tubing. Various restriction mechanisms are provided.

[0014] In one embodiment, an injection system is provided that includes one or more processors, a non-transitory computer-readable medium, and program instructions stored on the non-transitory computer-readable medium. When executed by the one or more processors, the program instructions cause the one or more processors to: perform an air purge operation by supplying fluid at a first pressure into tubing connected with the injection system; and perform a pre-stressing operation on the tubing by increasing the pressure in the patient line to a second pressure that is greater than the first pressure. The pressure in the patient line can be increased to the second pressure in any suitable manner. In one example, the pressure can be increased to the second pressure by supplying fluid at the second pressure (e.g., to expand the inner diameter of the tubing by 5%, a pump can fill an additional 10.25% of the original volume of the tubing to increase to the second pressure). In another example, the pressure can be increased to the second pressure by restricting the distal end of the tubing so that fluid pressure increases inside the tubing without necessarily increasing the pressure of the fluid supply.

[0015] In another embodiment, a method for pre-stressing a patient line is provided that is performed in an injection system prior to injecting fluid into a patient. The method includes applying fluid at a pressure to purge air from the patient line; increasing the pressure in the patient line to expand the inner diameter of the patient line; and after the inner diameter of the patient line has been expanded, injecting fluid into the patient through the patient line.

[0016] In yet another embodiment, an injection system is provided that includes: means for priming tubing for use with the injection system; and means for deforming the tubing by expanding the inner diameter of the tubing prior to the tubing being used by the injection system to inject fluid into a patient.

[0017] Other embodiments are possible, and each of the embodiments can be used alone or in combination.

[0018] Example injection system

[0019] Fluids are injected into patients for a number of medical procedures. For example, a contrast agent (or contrast medium) can be injected into a patient to enhance the contrast of a target (body) feature during a scan to make the target feature more apparent. For example, iodine-based contrast agents (e.g., containing Iopamidol) are commonly used in computed tomography (CT) applications, such as angiography examinations. The contrast agent is typically injected into the patient’s vasculature by an injection system. The injection system pressurizes the contrast agent and injects it into the patient’s vasculature or organs under predetermined injection conditions (e.g., at a predetermined flow rate and volume).

[0020] Power injection systems (sometimes referred to herein as injector systems or injectors) can use either a syringe or syringeless (e.g., using a peristaltic pump with rollers to sequentially and alternately squeeze a tube to control fluid flow). The following paragraphs provide a brief overview of these two types of systems. It is important to note that the specific type of system (e.g., syringe or syringeless) and the details presented below should not be interpreted into the claims unless explicitly recited in the claims.

[0021] Turning now to the drawings, Figure 1 is an illustration of a syringeless injection system 100 of an embodiment. The injection system 100 can be located in a medical suite of a hospital, a health care facility, and / or any other facility. The medical suite can include a control room in which an operator of the injection system 100 can be stationed, and a procedure room (such as an imaging room) in which the injection system 100 and other equipment related to a medical imaging procedure can be located. In this embodiment, the injection system 100 is supported by a stand 160 that is provided with wheels to facilitate moving the injection system 100; further, the wheels can have foot brakes to secure the injection system 100 in place. Alternatively, the injection system 100 can include a boom mount that allows the injection system 100 to be mounted in the ceiling or wall of an imaging room, or even on the gantry of a CT scanner. The injection system 100 includes a control unit 155 that controls the operation of the injection system 100, and can include a touch screen and a number of buttons or other user interface elements that an operator can use to interact with the control unit 155.

[0022] As Figure 1As shown in the middle, in this embodiment, the injection system 100 comprises a first supply station 105a, a second supply station 105b, and a third supply station 105c for supplying fluid to be injected from corresponding reservoirs. In particular, the first and second supply stations 105a, 105b supply fluid from bottles 110a, 110b, respectively, and the third supply station 105c supplies fluid from a bag 110c. In one example, the first and second supply stations 105a, 105b both hold contrast medium, and the third supply station 105c holds a saline solution. In this example, when the contrast medium is depleted in the on-current station, the injector system 100 automatically switches from one of the first and second supply stations 105a, 105b as the on-current station to the other station. In another example, one of the first and second supply stations 105a, 105b holds contrast medium, while the other holds a saline solution. Other example implementations are also possible. Each bottle 110a, 110b can contain a single dose or multiple doses of different contrast medium or the same contrast medium. The bag 110c generally contains a large amount of saline that will be supplied before (pre-flush), after (post-flush), or between (inter-periodic) injections of contrast medium, or alternatively supplied sequentially in rapid succession with contrast medium (to achieve mixing of the contrast medium and saline solution within the patient's organ). In the latter case, the third supply station 105c can be eliminated.

[0023] In this embodiment, the first and second supply stations 105a, 105b comprise respective bottle holders 115a, 115b for housing and supporting the bottles 110a, 110b. Protective covers 120a, 120b can be mounted on the bottle holders 115a, 115b to cover the bottles 110a, 110b, thereby defining (enclosed) chambers for housing the bottles 110a, 110b. The protective covers 120a, 120b can serve as bottle insulators to help maintain a pre-warmed contrast medium temperature (in some cases, the contrast medium is injected warm, and the contrast medium bottles are pre-warmed). The supply station 105c comprises a hook 125c for suspending the bag 110c.

[0024] The injection system 100 of this embodiment also comprises a delivery arrangement 135 that determines a fluid pathway for delivering medical fluid from the reservoirs 110a, 110b, 110c to the pressurizing unit 140. The tubing of the delivery arrangement can be made of plastic material (e.g., PVC). In the first and second supply stations 105a, 105b, bottle connectors 130a, 130b are arranged in connection ports 132a, 132b of the bottle holders 115a, 115b. The bottle connectors 130a, 130b comprise a spike for connecting to the bottles 110a, 110b and a connection element (e.g., a septum or a male luer lock fitting) in fluid communication with the spike. The spike and the connection element are located at opposite longitudinal ends of the bottle connectors 130a, 130b.

[0025] The delivery arrangement 135 (sometimes referred to herein as a "day kit" or "transfer kit") connects all the supply stations 105a, 105b, 105c to the pressurization unit 140 for the transfer of the corresponding medical fluid from the reservoirs 110a, 110b, 110c to the patient kit assembly 400, which is received inside the pressurization unit 140. The delivery arrangement 135 comprises a transfer line for each supply station 105a, 105b, 105c. The transfer line of each supply station 105a, 105b comprises a flexible tubing 141a, 141b provided, at its distal end with respect to the pressurization unit 140, with a reservoir (or drip chamber) 142a, 142b and a connection element 143a, 143b for cooperating with the connection element of the bottle connector 130a, 130b. For example, in case the connection element of the bottle connector 130a, 130b is a septum, the connection element 143a, 143b can be a spike connector; alternatively, in case the connection element of the bottle connector 130a, 130b is a male luer lock fitting, the connection element 143a, 143b can be a female luer lock fitting.

[0026] During operation of the injection system 100, the reservoir 142a, 142b and the connection element 143a, 143b are arranged inside the bottle holder 115a, 115b. Similarly, the transfer line of the supply station 105c comprises a flexible tubing 141c provided, at its distal end with respect to the pressurization unit 140, with a reservoir (or drip chamber) 142c and a spike 143c for connecting to the bag 110c. The flexible tubing 141a, 141b, 141c is coupled, at its proximal end with respect to the pressurization unit 140, with a T-connector 144 comprising a plug for insertion into a corresponding port of the pressurization unit 140.

[0027] The pressurization unit 140 comprises an electric motor (not shown) acting on a peristaltic pump which pressurizes the medical fluid (received from the reservoirs 110a, 110b, 110c via the delivery arrangement 135) to inject it into the patient's body (e.g. up to 17 bar of pressure, or at a flow rate of 0.5 to 9.9 mL / s). The injection system 100 further comprises a patient set assembly 400 which connects the delivery arrangement 135 to the patient for delivering the pressurized fluid to the patient. The patient set assembly 400 comprises a delivery tube 405 provided (at its proximal end with respect to the pressurization unit) with a peristaltic pump component 401. The latter is introduced into a dedicated port provided in the pressurization unit 140 and also puts it in fluid communication with the T-shaped connector 144 of the delivery arrangement 135. The peristaltic pump component 401 houses a rotor having a plurality of pinch rollers into which a corresponding portion of a peristaltic tube is inserted, wherein the peristaltic tube is in fluid communication with the delivery tube 405.

[0028] When the patient set assembly 400 is of the single-use type (as in Figure 1 ), used only by a single patient, the delivery tube 405 can be rather long and (at its distal end with respect to the pressurization unit) provided with a connection element 407 for cooperating with a corresponding connection element (e.g. a plug) of a vascular access device (VAD) (not shown), e.g. an IV catheter, a peripherally inserted central catheter, etc., inserted through the skin into a peripheral vein of the patient to be treated. The delivery tube 405 can also be provided with a clamp 406 which clamps the tube and closes the delivery line during installation or uninstallation of the peripheral catheter.

[0029] When the patient set assembly 400 is of the multi-use type (as in Figure 2 ), intended for use with a plurality of patients, typically the delivery tube 405 (delivery line) is rather short and provided (at its distal end) with a connection element 407 for cooperating with a corresponding connection element 501 of an additional patient line 500, typically comprising a rather long flexible tube. The additional patient line 500 (at its distal end) terminates with a connection element 502 for cooperating with a corresponding connection element possessed by a VAD (not shown).

[0030] The patient set assembly 400 is a disposable element, which is completely used for a single patient in the case of single use ( Figure 1 ), and which is periodically replaced (e.g. every 12 hours) in the case of multiple use ( Figure 2 ), except for the additional patient line 500 which is intended only for a single patient and which, therefore, is discarded at the end of each injection procedure of a given patient, so as to be replaced by a new patient line when a new patient is ready to be treated.

[0031] In both Figure 1 And Figure 2 Each supply station 105a, 105b, 105c of the injection system 100 further comprises a clamping mechanism (not shown) for engaging the delivery arrangement 135 and thus blocking or unblocking the passage for fluid flow. In particular, the clamping mechanisms of the first and second supply stations 105a, 105b can be located inside the bottle holders 115a, 115b, while the clamping mechanism of the third supply station 105c can be located in a dedicated seat 153 housed in the front portion of the syringe body. Activation (e.g. clamping and unclamping) of the clamping mechanisms can be automatically controlled by the syringe software (e.g. as part of the injection steps performed by the syringe (according to the injection protocol loaded on the syringe, typically on a syringe remote console not shown in the figures)).

[0032] As mentioned above, the syringe system can use an injector pump (as an alternative to the absence of an injector) to inject fluids into the patient. Figure 3 An example of an injector system 115 based on an injector is illustrated in Figure 3 As shown in the The syringe system 115 of this embodiment comprises a syringe portion 210 (capable of operatively engaging at least two injectors 211, 213) and a controller device 220 configured to control dispensing operations of the dispensing medical device. The syringe portion 210 further comprises a pair of syringe pistons 215, 216 adapted to operatively engage a corresponding pair of injectors 211, 213. The injectors 211, 213 can be fluid-tightly attached to the syringe portion 210 of the syringe system 115 and can be configured to contain fluid media such as contrast media and / or flushing media.

[0033] As Figure 3As shown in FIG. 2, the injectors 211, 213 can also include luer locks 217a, 217b or other fluid-tight connections to allow fluid communication between the injectors 211, 213 and polymeric tubing 240a, 240b configured to deliver the media contained within the injectors 211, 213 to an injection site, such as an intravenous line, by extending the syringe pistons 215, 216 into the injectors 211, 213. In addition, the polymeric tubing 240a, 240b can be used to allow fluid communication between the injectors 211, 213 and a container filled with contrast media and / or flushing media, such that the injectors 211, 213 can be filled with such media by retracting the plungers 212, 214 into the injectors 211, 213 that are operably engageable with the syringe system 115. In addition, the syringe pistons 215, 216 can be configured to perform at least one dispensing function, such as extension and / or retraction, to correspondingly advance and / or retract the plungers 212, 214 concentrically disposed within the chambers of the injectors 211, 213 to dispense fluid media from or fill the injectors 211, 213 with fluid media. For example, the syringe pistons 215, 216 can be capable of performing dispensing functions including, but not limited to, extending fully into the injectors 211, 213 to initialize the injectors 211, 213 prior to filling the injectors with media; extending into the injectors 211, 213 to dispense media from the injectors; and retracting from the injectors 211, 213 to fill the injectors with media contained in a storage container (not shown).

[0034] The syringe system 115 of this embodiment also includes a controller device 220 configured to actuate the syringe pistons 215, 216 relative to the injectors that can be operably engaged with the dispensing medical device. The controller device 220 can include a microprocessor chip or other computer device suitable for controlling actuation of the syringe pistons 215, 216, data communication between various components of the syringe system 115 and other electronic devices via wired or wireless networks, and / or facilitating receipt of user input from a user interface 230. In one embodiment, the controller device 220 includes one or more processors configured to execute computer-readable program instructions stored in a non-transitory storage medium to perform various functions. The user interface 230 can include user input elements 235, such as real or virtual buttons, etc., to receive user input to, for example, control dispensing operations of the injection system 115. The injection system 115 can also include a manual controller 113 for saline test injections.

[0035] It is important to note that the injection systems discussed above are merely examples, and other configurations and types of injection systems can be used. Thus, the details presented herein should not be interpreted to limit the claims unless explicitly recited in the claims.

[0036] Example setup procedure

[0037] As noted above, one or more plastic tubing sets can be used with the injection system. For example, one plastic tubing set (“day set” or “transfer set”) can connect one or more containers / reservoirs of fluid (e.g., contrast and / or saline) to the pressurizing unit in the injector system. Another tubing (“patient line”) can be used to deliver fluid from the injection system to the patient. More specifically, one end of the patient line can be connected to the output port of the injection system, and the other end of the patient line can be connected to a vascular access device (VAD) in the patient (e.g., a cannula or catheter inserted into a central or peripheral vein or artery, which can be implanted or inserted under the skin, allowing fluids and medications to be delivered into the patient’s vasculature). Whether a single-use or multi-use workflow, the patient line is replaced after each patient use. A benefit of the multi-use workflow for the injector-based system is that the injector is reused, whereas in the single-use workflow, the injector is replaced after each patient use. While peristaltic pump systems can not have a single-use workflow, the so-called “single-use” and “multi-use” patient sets for the peristaltic embodiments are design improvements that reuse the peristaltic pump originally designed on the single-use patient set. In the following examples, the multi-use workflow is used for the peristaltic pump embodiments. One benefit of the multi-use workflow is fast patient changeover (i.e., only the patient line is replaced rather than the patient line plus the injector and tubing). As another benefit, the multi-use workflow is typically cheaper, more environmentally friendly, and more convenient for the healthcare practitioner (“user”) because less plastic is consumed and replaced.

[0038] During the setup process, the user turns on the injection system and sets up the consumables / disposables. For example, at the start of the day, the user can set up a day kit (for a multiple-use workflow), install fluid containers (e.g., contrast bottle(s) and saline bottle(s) / bag(s)), and interact with the user interface of the injection system to fill corresponding injectors (in an injector-based system) that are part of the day kit with fluid. (While a multiple-use, injector-based system is used in this example, as noted above, the embodiments can be used with single-use systems and / or with non-injector-based systems.) Once the injectors are filled, the user connects one end of the patient line to the distal end of the day kit. Before the user connects the other end of the patient line to the VAD, the user primes (or purges) any air present in the tubing. An earlier vacuum process can be performed to remove small air bubbles trapped in the components of the injectors and day kit (e.g., manifold connecting the injectors).

[0039] The purge process can be manual or automatic, and can be performed in any suitable manner. For example, the user can position the distal end of the patient line (i.e., the end that will eventually be connected to the VAD) over a receptacle to capture any fluid that can flow out of the patient line during the purge process. The user then presses an appropriate button on the user interface of the syringe system to cause fluid (e.g., saline) to flow through the patient line and purge all of the air out of the line. As another example, the syringe system can have an input port to receive the open end of the patient line. In this example, the user simply arranges the open end of the patient line into the input port of the injection system. Automatically, upon detecting the insertion or in response to user input, the injection system can cause fluid to flow into the patient line to begin the priming process, and later notify the user when the air has been purged from the patient line. This eliminates the need for the user to hold the patient line over a receptacle and wait for the purge process to complete (thus, the user can attend to other tasks).

[0040] At the end of the purge process, the fluid completely fills the day kit and the patient line, and the user connects the patient line to the VAD. After the patient line is connected to the VAD, the user interacts with the user interface of the injection system to begin the flow of fluid (e.g., saline or contrast) into the patient.

[0041] Injection performance challenges

[0042] Generally, contrast-enhanced image quality is closely related to contrast delivery output or injection performance, and it is often desirable for an injection system to generate sufficient amount of pressure to deliver a volume of contrast to a patient at a flow rate (e.g., 8.5 mL / s) to help ensure accurate imaging. However, injection performance can be limited by many factors, which can be random or unmanageable by the syringe system manufacturer. Compromised injection performance can result in undesirable contrast delivery output, which can degrade image quality or even cause injection abort, which can disrupt workflow and can require the user to re-plan the entire procedure, which is undesirable for an imaging lab.

[0043] Several factors can constrain or limit flow rate, such as but not limited to fluid viscosity, tubing inner diameter and length, pump mechanism and capacity, system pressure measurement accuracy, VAD type, length, and gauge, and patient condition. For example, for high viscosity contrast fluids such as Iomeron 400 (28.9 cP @ 20°C) or Visipaque 320 (26.6 cP @ 20°C), and for patients with small veins requiring relatively small VADs (e.g., 22 or 24 gauge IV catheters or PICC lines), it can be challenging to achieve an injection rate of 8.5 mL / s for a coronary computed tomography angiography (CCTA) procedure. In this scenario, the injection system can need to generate higher injection pressure. However, the peak pressure of the injection system can be limited by factors such as pump capacity, consumable design, VAD rating, syringe control mechanism, and applicable standards / regulations.

[0044] Pump type can also affect syringe pressure capability. Generally, injector-based pumps can generate higher pressure (e.g., up to 325 pounds per square inch (psi) for CT syringes, and up to 1,200 psi for angiography syringes), while peristaltic pumps can have difficulty generating pressure higher than 200 psi. Therefore, in the case where the injection protocol requires high injection rate, injection performance (e.g., actual flow rate) can be compromised.

[0045] Another factor is the VAD type, as VADs can induce a relatively large pressure drop (e.g., 50 to 100-200 psi) due to their physical characteristics (e.g., one inch, 18-22 gauge hub). For safety purposes, the pressure at the VAD inlet is associated with a maximum pressure rating. In addition, the ISO 10555-1 standard requires that the VAD manufacturer give the user a recommendation for the maximum pressure limit setting of the power injector system, which effectively limits the power injector system pressure to be the same as the VAD pressure rating. Since the injector system pressure can be defined at the injector side, the pressure at the VAD inlet must be lower than its rated pressure (i.e., the pressure at the inlet of the VAD is equal to the pressure set at the system minus the pressure drop through the day kit and / or patient line).

[0046] Yet another factor is the resistance of the fluid pathway through the day kit and / or patient line. For example, the internal diameter of the tubing can limit the flow rate, so tubing with a relatively large internal diameter can be required to limit the pressure drop from the injection system to the VAD. As another example, the patient line can be relatively long in multiple use workflows and in trauma workflows where the patient line is connected to the patient's head. In general, a relatively long patient line is required for certain CT scan procedures (e.g., whole body scans) or if the injector unit cannot be placed close enough to the patient. A longer patient line can result in a larger pressure drop, which can constrain the maximum flow rate of the contrast fluid. Another factor is the contrast agent type and temperature, as viscous, high concentration contrast agents can require additional pressure or larger tubing to deliver the contrast agent at the desired flow rate.

[0047] Use of the elastic properties of the tubing

[0048] The tubing used in the injection system is typically made of a polymeric material that possesses some elastic properties similar to a viscoelastic material. Due to these stress relaxation properties, the tubing can deform / expand when a stress is applied by injecting fluid into the tubing. At sufficiently high pressures of the fluid, the recovery of the strain can be minimal. That is, a partial recovery of the strain can be associated with an elastic deformation, and the unrecovered strain, which is a minimal recovery of the strain that occurs over a very long period of time, can be considered a plastic deformation. (It takes a long time for the plastic tubing to return to its original internal diameter, so for the uses discussed herein, the deformation can be considered permanent.) This effectively increases the internal diameter of the tubing and is similar to stress relaxation in polymers. That is, when a stress is applied to a constant strain condition to the extent that the stress changes with time, the stress decreases with time to maintain a constant strain state.

[0049] The following embodiments take advantage of this phenomenon by "pre-stressing" the tubing (e.g., patient line and / or day kit) prior to its use for injecting fluid into a patient. (The terms pre-stress, pre-tension, pre-strain, pre-deformation, pre-load, stress relaxation, and similar terms can be used interchangeably herein). That is, a sufficient amount and duration of pressure is applied inside the tubing prior to its use for injecting fluid into a patient to induce plastic deformation of the tubing. This pre-stressing effectively increases the internal diameter of the tubing (and can additionally result in a reduction of frictional losses along the tubing), which reduces the pressure drop across the tubing upon the first injection into a patient. This is because laminar fluid flow in the tubing follows Poiseuille's Law:

[0050]

[0051] where "ΔP" is the pressure drop,

[0052] "μ" is the dynamic viscosity,

[0053] "L" is the length of the tube,

[0054] "Q" is the flow rate of the fluid inside the tube, and

[0055] "d" is the internal diameter of the tubing.

[0056] As this equation shows, the pressure drop across the tubing is inversely proportional to the fourth power of the internal diameter of the tubing. Therefore, for a given flow rate, a small increase in the internal diameter of the tubing will exponentially reduce the pressure drop.

[0057] This technique of expanding the internal diameter of the tubing enhances the capacity and performance of the injection system without increasing the injection pressure set limit. Moreover, once the tubing is deformed to a larger internal diameter, the pressure drop can be lower for any given injection protocol. Other benefits include, but are not limited to: (1) reduced risk of system pressure limit triggering events, (2) predictable contrast fluid delivery rate performance, and (3) cost effective and sustainable (reduced plastic material usage) tubing design (i.e., tubing with an initially smaller internal diameter can be used, which can result in reduced costs and reduced plastic usage / waste).

[0058] Turning again to the drawings, Figure 4 is an illustration of an experimental setup 410 of the embodiments that will be described to illustrate the pressure drop advantages. As Figure 4As shown in FIG. 4, patient line 415 connects injector-based syringe 420 to 20 gauge VAD 425 via a male-to-male luer connection. Contrast collection bottle 430 is positioned below VAD 425 to collect contrast flowing out of VAD 425 (patient is not connected to VAD 425 in this experiment). First luer T-connector 435 connects first pressure sensor 440 to a portion of patient line 415 proximate to syringe 420, and second luer T-connector 445 connects second pressure sensor 450 to a portion of patient line 415 proximate to VAD 425.

[0059] This setup 410 was used for an experiment conducted to confirm the pressure drop benefit across a patient line 415 with pre-deformation by comparing pressure measurements 460 between first pressure sensor 440 and second pressure sensor 450 at a flow rate of 10 mL / s for non-deformed and pre-deformed versions of patient line 415. Patient line 415 was pre-deformed by performing an injection with a restriction (VAD 425) at the distal end of patient line 415 to achieve high injection pressures (close to the maximum injection pressure limit setting) within patient line 415 for about 10-12 seconds. The injection was performed by connecting an injector-based vascular syringe (ACIST CVi with 1200 psi injection pressure setting capability) to VAD 425 via patient line 415. To pre-deform patient line 415, an injection was performed with a 24 gauge VAD at 4.5-5 mL / s with high viscosity contrast fluid for 10-12 seconds (syringe pressure was about 450 psi at steady state). An injection was performed at 10 mL / s with a 20 gauge VAD on 10 tubes (5 pre-deformed and 5 non-deformed), and the average difference in pressure measurements was collected. Figure 5 The graph in FIG. 5 compares the results.

[0060] As Figure 5 As shown in FIG. 4, patient line 415 connects injector-based syringe 420 to 20 gauge VAD 425 via a male-to-male luer connection. Contrast collection bottle 430 is positioned below VAD 425 to collect contrast flowing out of VAD 425 (patient is not connected to VAD 425 in this experiment). First luer T-connector 435 connects first pressure sensor 440 to a portion of patient line 415 proximate to syringe 420, and second luer T-connector 445 connects second pressure sensor 450 to a portion of patient line 415 proximate to VAD 425.

[0061] Example techniques for pre-stressing a tube

[0062] The following embodiments take advantage of the elastic properties of tubing (e.g., patient lines and day sets) by expanding the inner diameter of the tubing (pre-stressing the tubing) prior to the tubing being used to inject fluid into a patient. In one embodiment, the injection system is used to pre-stress the tubing after an air purge process is performed (or as part of the air purge process) because fluid (e.g., saline) has already been applied under pressure in the patient line during the process, and the pressure can be increased (e.g., up to the pressure rating of the tubing) to induce stress on the tubing. To achieve the increased pressure in the tubing, in one embodiment, the distal end of the patient line is restricted to allow pressure to build up in the tubing. Various possible restriction mechanisms are discussed below, but any suitable type of restriction mechanism can be used.

[0063] As noted above, the tubing can be pre-stressed after or as part of an air purge process. Air is highly compressible, so if there is a large air column in the tubing, the pre-stress pressure can not be reached even if the entire injector volume is injected. Thus, in this case, the pre-stressing will be performed after the air purge process. However, from the user's perspective, the purging and pre-stressing can be done in one action (e.g., the user can view the pre-stressing as part of the air purge process). For example, as will be discussed below, the restriction mechanism can take the form of a small vent hole on a protective cap at the distal end of the patient line. During the purge process, air can flow through the small vent hole. Once the air is purged, the pressure drop through the hole increases due to the higher viscosity of the fluid than air, the pressure inside the line increases, pre-stressing the tubing. From the user's perspective, the pre-stressing is done in the same process / step as the air purge, even though the expansion of the tubing technically occurs after the air is removed.

[0064] Figure 6 is a flowchart 600 illustrating this embodiment. As Figure 6As shown in FIG. 6, the injection system purges air from the tubing (e.g., patient line and day kit, if used) by pushing fluid (e.g., saline) through the tubing at a first pressure ("priming") (act 610). A restriction mechanism is used to partially or completely occlude the fluid pathway on the patient line (act 620). The injection system then pushes fluid through the patient line at a second pressure higher than the first pressure for a duration (e.g., seconds to minutes) to pre-stress the tubing (act 630), the second pressure generated by the restriction mechanism. In one embodiment, the second pressure is lower than but close to the maximum rated pressure of the tubing, although any suitable pressure can be used. The pressure can be estimated by controlling the current / speed of the pump's motor, or measured by an external or in-line pressure sensor. After applying the prescribed pressure for the prescribed amount of time, the tubing is pre-stressed. The pressure in the tubing is then reduced (e.g., by the pump releasing the in-line pressure and / or by slowly opening the mechanism occluding the fluid pathway), and the distal end of the patient line is de-occluded (act 640). The distal end of the patient line is then connected to the VAD (act 650), and fluid is injected into the patient (act 660). As will be discussed below, one or more of these steps can be performed automatically or semi-automatically by the injection system.

[0065] The distal end of the tubing can be restricted in any suitable manner, and Figure 7 Sections 740, 750, and 760 in FIG. 7 show various example restriction mechanisms that can be used. It should be understood that these are merely examples, and other ways of restricting the distal end of the patient line can be used.

[0066] Before turning to these example restriction mechanisms, a brief overview of the injection system 700 used in these examples will be provided. As Figure 7 shown in FIG. 7, in these examples, the injection system 700 includes a fluid (e.g., saline) reservoir 705 connected to a pump 710 via a valve 715 to control the direction of the fluid. The valve 715 is also connected to a day kit tubing (not shown to simplify the figure). A patient line 725 having a male luer connector 730 at its distal end is connected to an output port 810 of the injection system 700 (see Figure 8A ). Optionally, a valve 735 is used to connect to other fluid reservoirs. Also, an optional pressure sensor 720 can be used. It should also be understood that Figure 7 FIG. 7 is a simplified diagram for illustration purposes, and other / different components can be used.

[0067] Figure 8A is a block diagram of the injection system 700 in this example. As Figure 8AAs shown in FIG. 7, in addition to the reservoir 705, pump 710, and pressure sensor 720, the injection system 700 of this embodiment also includes one or more volatile or non-volatile memories 800 (e.g., one or more non-transitory computer-readable media), one or more processors 802, a user interface 804 (e.g., a touchscreen display, a keyboard, and / or a mouse, etc.), and an output port 810 having an opening sized to accept the proximal end of the patient line 725. In one embodiment, the one or more volatile or non-volatile memories (e.g., RAM, flash drives, hard drives, etc.) 800 store program instructions that, when executed by the one or more processors 802, cause the one or more processors 802 to perform the functions described below, and possibly other / different functions if desired. In other embodiments, a purely hardware implementation (e.g., using logic gates, switches, application specific integrated circuits (ASICs), etc.) is used. Moreover, the "means" for performing a function can be implemented with one or more processors executing computer-readable program instructions and / or entirely with hardware.

[0068] As mentioned above, Figure 7 Sections 740, 750, and 760 in FIG. 7 show various example restriction mechanisms that can be used. Turning first to section 740, in this example, a protective cap 745 having a vent hole 747 is used as the restriction mechanism. Currently, some patient lines come shipped with protective caps on both the distal and proximal ends of the patient line, and are used during the sterilization process at the end of the manufacturing process and before the user receives the patient line. More specifically, patient lines often have protective caps on both ends to prevent contamination during handling. Small vent holes on the protective caps are used to allow EtO sterilization (provide a fluid path), which is a method of sterilization for disposable supplies. The vent hole 747 allows a passageway for the sterilization fluid to pass through. In this embodiment, the protective cap 745 is left on or placed on the distal end of the patient line 725 (if it was previously removed) for the pre-stressing process, and is used as a nozzle to partially block the fluid passageway in the patient line 725 to allow pressure to build up in the patient line 725 and pre-stress. Using the protective cap 745 as the restriction mechanism has the advantage of not adding capital or disposable costs, as the protective cap 745 is already supplied with the patient line 725.

[0069] Figure 9 is a flowchart 900 of an example method of pre-stressing the patient line 725 using the protective cap 745 as the restriction mechanism. As Figure 9As shown in the middle, the user connects the proximal end of the patient line 725 to the output port 810 of the injection system 700 (act 905). In this example, the distal end of the patient line 725 (the end that will eventually be connected to the VAD) is covered with a protective cap 745, and the protective cap 745 is left on the distal end of the patient line 725 during the air purge process. This example assumes that the vent hole 747 is large enough to allow air to purge from the patient line 725, although its limited flow rate can affect performance. Keeping the protective cap 745 on the distal end of the patient line 725 during the air purge process results in a more efficient workflow.

[0070] Next, the user initiates the purge / pretensioning protocol by interacting with the user interface 804 (act 910). Alternatively, the purge / pretensioning protocol can be triggered automatically by an event, such as the installation of the patient line. In response, the processor(s) 802 cause the pump 710 to pump fluid (e.g., saline) from the reservoir 705 into the patient line 725 at a pressure sufficient to purge air from the patient line 725 (act 915). In one example, the pressure is below about 50 psi. In another example, the pressure is sufficient to produce a flow rate of about 4-6 mL / s. During this process, the user can hold the distal end of the patient line 725 above a receptacle to capture any fluid that can flow out of the patient line 725 during the purge process.

[0071] After purging air from the patient line 725, the injection system 700 can automatically (or in response to input from the user via the user interface 804) transition to a pretensioning process and control the pump 710 to increase the pressure for a period of time to pretension the patient line 725 (act 920). In one embodiment, the pressure applied to pretension the patient line 725 is higher than the pressure applied to purge air from the patient line 725, but not greater than the upper limit of the tubing pressure rating determined by the manufacturer. In one example, the pressure is greater than about 50 psi. In another example, the pressure is greater than about 100 psi (e.g., about 300 psi) and is applied for about 30 seconds. In yet another example, the pressure is about 400 psi (e.g., when the VAD pressure rating is about 325 psi and the pressure measurement uncertainty is 50-75 psi). It should be noted that these are merely examples, and any suitable pressure can be used, and can be based on the type of limiting mechanism and patient line design. It should also be noted that while these embodiments are described in terms of a patient line, the pretensioning effect will also apply to the day kit tubing.

[0072] After the increased pressure has been applied to the patient line 725 for the prescribed period of time, the processor(s) 802 can cause the pump 710 to reduce the pressure in the patient line 725 (act 925). The processor(s) 802 can also take a pressure reading of the pressure sensor 720 to determine if there is any residual pressure in the patient line 725 at the time the protective cap 745 is removed that would cause a significant leak of fluid from the distal end of the patient line 725 (acts 930 and 935). If the residual pressure is above a threshold, the processor(s) 802 can automatically control the pump 710 to further reduce the pressure, e.g., by acting on the pump (act 940). For example, the residual pressure can be released by pulling the injector slightly back. If the limiting mechanism is a vent hole on the protective cap, no action can be needed because the residual pressure will gradually drop. If the limiting mechanism is a pinch valve, the residual pressure can be released by the pump side. After the pressure is released (or if the residual pressure is not above the threshold), the user removes the protective cap 745 from the distal end of the patient line 725 (act 945) and connects the distal end of the patient line 725 to the VAD (act 950). The injection system 700 will then begin injecting fluid into the patient (e.g., in response to a command from the user) (act 955).

[0073] During the purge and pre-stress process, the user can hold the distal end of the patient line 725 above the reservoir to capture any fluid that can flow out of the patient line 725. In another embodiment (shown in Figure 8B the input port 820 can have an adjustable female opening to account for either possibility. Other adaptations are possible. With any of these embodiments, the user can place the distal end of the patient line 725 in the input port so he can attend to other tasks during the air purge / pre-stress process. The injection system 800 can have a reservoir positioned to capture any fluid that can flow out of the patient line 725 during the air purge / pre-stress process.

[0074] As noted above, limiting mechanisms other than the protective end cap 745 can be used. For example, as shown in section 750 of FIG. 7B, a pinch valve 755 can be used. Although the pinch valve 755 is shown in FIG. 7B as being on the patient line 725, it can be on the output port 810. The pinch valve 755 can be controlled by the processor(s) 802 to limit the pressure in the patient line 725 during the air purge / pre-stress process. Figure 7 ​Figure 7 not shown as positioned at the very end of patient line 725, but is still considered to be "at the distal end of patient line 725" as that phrase is used herein. However, it can be desirable to arrange pinch valve 755 as close as possible to the very end of patient line 725 to help ensure that there is no significant reduction in the internal diameter of the tubing between pinch valve 755 and the very end of patient line 725. As yet another example (shown in section 760), a (disposable) valve (e.g., a stopcock valve) 765 is used that connects to luer connector 730 of patient line 725. In this alternative, valve 765 can be connected to patient line 725 prior to the air purge operation (with valve 765 open during the air purge operation and then closed for the pre-stressing operation), or valve 765 can be connected to patient line 725 after the air purge operation.

[0075] In one embodiment, the user manually closes pinch valve 755 or stopcock valve 765 after the air purge process and before the pre-stressing operation begins. In another embodiment (see Figure 8C ), a restriction mechanism 830 (e.g., a pinch valve, a stopcock valve, etc.) is part of injector system 800 and is actuated by a motor 840 controlled by processor(s) 802 in injector system 800. In some embodiments, the air purge and pre-stressing are performed automatically once the user inserts the distal end of patient line 725 into input port 820 of injector system 800. In other embodiments, the user interacts with user interface 804 of injector system 800 to initiate the process or to enable / disable the automatic function. Either way, the need for the user to hold and interact with patient line 725 and the restriction mechanism during the air purge and pre-stressing processes is eliminated, providing the user with an improved workflow as the user is able to attend to other tasks while these processes are performed.

[0076] CONCLUSION

[0077] Various examples of systems, devices, and / or methods are described herein. Unless otherwise stated, any example, embodiment, and / or feature described herein as "example" is not necessarily to be construed as preferable or advantageous over any other example, embodiment, and / or feature. Thus, other examples, embodiments, and / or features can be utilized, and other changes can be made without departing from the scope of the subject matter presented herein.

[0078] Accordingly, the examples described herein are not meant to be limiting. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in various ways.

[0079] Furthermore, the features illustrated in each of the figures can be used with one another in various combinations, unless expressly otherwise indicated. Thus, there can be any number of possible combinations. Figure 1 Generally, the described features can be regarded as aspects of one or more general embodiments, it should be understood that not all of the illustrated features are necessary to every embodiment.

[0080] Additionally, any listing of elements, blocks or steps in a method claim is intended to be illustrative and not restrictive. Thus, the listing of elements, blocks or steps should not be construed as requiring that the elements, blocks or steps be performed in a particular order.

[0081] Furthermore, terms such as "coupled" or "connected" and the like should not be construed as requiring direct coupling or connection between components. It should be understood that various intervening components can be present "between" components that are "coupled" or "connected" to one another.

[0082] Furthermore, terms such as "substantially" or "approximately" can be construed to mean that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, can occur.

[0083] The foregoing detailed description has been presented for purposes of clarity and description. It is not intended to be exhaustive or to limit the invention to the precise form described. Only the following claims, including all equivalents, are intended to define the scope of the invention. Finally, it should be noted that any aspect of any of the embodiments described herein can be used alone or in combination with one another.

Claims

1. An injection system, the injection system comprising: One or more processors; Non-transitory computer-readable medium; and Program instructions stored on the non-transitory computer-readable medium, which, when executed by the one or more processors, cause the one or more processors to: An air purging operation is performed by supplying fluid at a first pressure into a conduit connected to the injection system; and Prestressing is performed on the patient tubing by increasing the pressure in the tubing to a second pressure greater than the first pressure.

2. The injection system according to claim 1, wherein, The conduits include patient tubing and / or day kits.

3. The injection system according to claim 1, wherein, The conduit includes a patient tubing, and the injection system further includes a port configured to receive the distal end of the patient tubing.

4. The injection system according to claim 3, wherein, The port is sized to receive a protective cap at the distal end of the patient tubing.

5. The injection system according to claim 3, further comprising: motor; as well as A limiter that can be actuated by the motor; Wherein, the program instructions, when executed by the one or more processors, also cause the one or more processors to: The motor is controlled to actuate the limiter to restrict flow from the distal end of the patient line during the prestressed operation.

6. The injection system according to claim 5, wherein, The limiter includes a pinch valve.

7. The injection system according to claim 5, wherein, The limiter includes a plug valve.

8. The injection system according to claim 1, wherein, The injection system is based on an injector.

9. The injection system according to claim 1, wherein, The injection system is injectorless.

10. The injection system according to claim 1, wherein, When executed by the one or more processors, the program instructions also cause the one or more processors to: The air purging operation and / or prestressing operation are performed automatically, thereby allowing the user to perform another task during the air purging operation and / or the prestressing operation.

11. A method for prestressing patient tubing, the method comprising: Before injecting the fluid into the patient, the following procedures are performed in the injection system: A pressurized fluid is applied to purge air from the patient's tubing; Increase the pressure in the patient tubing to enlarge the inner diameter of the patient tubing; and After the inner diameter of the patient tubing has been enlarged, fluid is injected into the patient through the patient tubing.

12. The method according to claim 11, wherein the method further comprises: Restricting flow from the distal end of the patient line to increase pressure in the patient line.

13. The method according to claim 12, wherein, Restricting flow from the distal end of the patient line includes actuating a valve to at least partially close the distal end of the patient line.

14. The method according to claim 13, wherein, The valve includes a pinch valve.

15. The method according to claim 13, wherein, The valve includes a plug valve.

16. The method according to claim 12, wherein, A cap on the distal end of the patient tubing restricts flow from the distal end of the patient tubing.

17. The method of claim 11, wherein, The pressure in the patient's tubing increased to at least approximately 300 psi.

18. The method of claim 11, wherein, The pressure in the patient's tubing increased to at least approximately 400 psi.

19. An injection system, the injection system comprising: A filling device for filling a conduit used in conjunction with the injection system; and A deformation device that deforms the conduit by widening its inner diameter before the injection system uses the conduit to inject fluid into the patient.

20. The injection system of claim 19, further comprising: The deformation device for deforming the pipe includes a flow-limiting device for restricting the flow exiting the pipe.

Images