SYSTEM AND METHOD FOR IMPROVED FLUID DELIVERY IN MULTI-FLUID INJECTOR SYSTEMS
A method of maintaining an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel includes delivering at least a first fluid into the patient’s blood vessel at a first flow rate, delivering at least a second fluid into the patient’s blood vessel at a second flow rate, and adjusting at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
This application is a continuation application of U.S. Application Serial No. 17/157,506, filed Jan. 25, 2021, which is a continuation application of U.S. Application Serial No. 16/081,202, filed Aug. 30, 2018, now U.S. Pat. No. 10,898,638, which is a 371 national phase application of PCT International Application No. PCT/US2017/020637, filed Mar. 3, 2017, and claims the benefit of U.S. Provisional Pat. Application No. 62/303,050, filed Mar. 3, 2016, the disclosure of which is hereby incorporated in its entirety by reference.
BACKGROUND Field of the TechnologyThe present disclosure is directed to a system and method for reducing the occurrence of spikes in flow rates for a fluid delivery system having a fluid pumping device for delivery of two or more medical fluids in applications in medical diagnostic and therapeutic procedures.
Description of Related ArtIn many medical diagnostic and therapeutic procedures, a physician or trained clinician injects fluid into a patient. For example, a physician may inject saline and/or an imaging contrast medium into a patient to help improve the visibility of internal body structures during one or more X-ray/CT imaging, MRI imaging, or other imaging procedure. To inject the saline and/or contrast medium, the clinician may use a manual injection syringe or may, alternatively, use a powered fluid injection system. A catheter is coupled to the manual injection syringe or injection device and is used to inject the saline and/or contrast medium into the patient (such as into a vessel in the patient’s hand or arm). The contrast medium and saline are provided from separate sources, such as bags, bottles, or syringes, and, in certain cases, may be mixed together before injection into the patient. However, several problems may develop during use of certain capacitive pressure injection systems and syringes, including spikes in fluid flow rates, extravasation and/or infiltration, saline or contrast medium contamination during injection due to backflow of the fluids, real-time injection ratio inaccuracies, or kick-back in catheter tubes that are inserted into patients.
A. Extravasation and InfiltrationExtravasation and infiltration are often characterized as an accidental infusion of an injection fluid, such as a contrast medium (extravasation) or saline (infiltration), into tissue surrounding a blood vessel rather than into the blood vessel itself. Extravasation and infiltration can be caused, for example, by a fragile vascular system, valve disease, inaccurate needle placement, sudden changes in fluid flow, or patient movement resulting in the injected needle being pulled from the intended vessel or pushed through the wall of the vessel.
Additional extravasation and/or infiltration issues may occur when using both a contrast medium and saline for a procedure. As shown in
With further reference made to
An additional factor that may contribute to the problem of inaccurate fluid mixing ratios is the backflow of fluid that occurs in injections where the viscous contrast medium 10 is injected at a higher ratio than the less viscous saline 12. In such a scenario, before a uniform fluid flow is established, the fluid pressure of the more viscous contrast medium 10 that is injected at a higher ratio may act against the fluid pressure of the less viscous saline 12 that is injected at a lower ratio to force the contrast medium 10 to reverse the desired direction of flow. After injection, pressures equalize and the fluid injection system achieves a steady state operation where the contrast medium 10 and saline 12 are injected at a desired ratio. However, in small volume injections, steady state operation may not be achieved prior to the completion of the injection process and the fluid mixing ratio of contrast medium 10 and saline 12 being delivered to the patient may not be accurately achieved. Thus, even though a desired ratio of contrast medium 10 and saline 12 may be 80% contrast medium 10 to 20% saline 12, the actual ratio due to backflow of contrast medium 10 into the saline 12 may be higher. This problem is further compounded with an increase in injection pressure. In one particular example of a fluid injector system, the syringes are typically always pointing upwards and are used for multiple patients throughout an entire day. Therefore, contrast medium 10 may backflow into the saline syringe and sink to the bottom of the saline syringe. By the time multiple patients have been treated and multiple injections have been performed, the saline syringe may be substantially filled with contrast medium thereby contaminating and reducing the amount of the saline fluid 12.
C. Catheter Kickback and Rapid MovementAn additional complication with known multi-fluid injector systems is a kickback or rapid movement of the catheter in the patient’s body as a result of the erratic flow of the contrast medium or saline. In many known multi-fluid injector systems, the saline and contrast medium tubing is connected to a catheter that is used for injecting the fluids into the patient. However, due to the backflow of the saline and/or contrast medium and the rapid acceleration of contrast medium or saline into the fluid line of the multi-fluid injector system during fluid transitions, the catheter may at least partially kick-back or otherwise change position within the patient vasculature. Fluid accelerations may be caused by nozzle effects in the catheter and rapid increases in flow rate during contrast medium-to-saline transitions. The nozzle on the catheter may accelerate the fluid from a lower flow rate in the tubing of the catheter to an increased flow rate exiting the catheter. The transition from a contrast medium injection to a saline injection causes a rapid flow rate increase. The force imparted to the catheter may cause undesired movement of the catheter. Complications related to extravasation and infiltration, inaccurate fluid mixing ratios, and catheter kickback and rapid movement may include unnecessary pain and discomfort to the patient. There is a current need for a system that provides accurate flow rates of saline and/or contrast medium to a patient, thereby reducing the risk of extravasation and/or infiltration. There is also a current need for a catheter design that reduces kickback and rapid movement of the catheter during injection of a fluid into a patient’s blood vessel.
BRIEF SUMMARYIn view of the foregoing, a need exists for an improved fluid delivery system for fluid delivery applications in medical diagnostic and therapeutic procedures. There is an additional need in the medical field for a fluid delivery system that provides a more precise and efficient flow rate or ratio of fluids during initial injection procedures compared to existing fluid delivery systems. Existing fluid delivery systems do not always provide accurate flow rates or mixing ratios of the desired fluids resulting in the risk of extravasation and/or infiltration. There is a current need for a fluid delivery system that allows an individual to quickly and accurately provide the necessary flow rate or ratio of fluids to a patient.
In one example, a method of maintaining a substantially uniform overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel includes delivering at least a first fluid into the patient’s blood vessel at a first flow rate, delivering at least a second fluid into the patient’s blood vessel at a second flow rate, and adjusting at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
In another example, the method further includes delaying the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate. The method may include adjusting one of the first flow rate and the second flow rate using a controller based on the other of the first flow rate and the second flow rate. The method may include pressurizing the first fluid using a check valve to a predetermined pressure before delivering the first fluid. The method may include pressurizing the second fluid using a check valve to a predetermined pressure before delivering the second fluid. The method may include pressurizing the first fluid and the second fluid using separate check valves to a first predetermined pressure and a second predetermined pressure, respectively, before delivering the first fluid and the second fluid.
The method may include over-delivering a predetermined volume of at least one of the first fluid and the second fluid during the delivery of at least one of the first fluid and the second fluid. The method may include diluting one of the first fluid and the second fluid with a predetermined volume of the other of the first fluid and the second fluid.
The method may include providing a multi-fluid injection system including a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel, and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel, and reducing a capacitance of at least one of the first syringe and the second syringe to prevent backflow of at least one of the second fluid into the first syringe and the first fluid into the second syringe. The method may include providing a pressure jacket around an outer circumference of at least one of the first syringe and the second syringe to reduce swelling of at least one of the first syringe and the second syringe under pressure.
The method may include providing a multi-fluid injection system including a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel, and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel, and wherein at least one of the first syringe and the second syringe includes a reduced inside diameter to correspond to a desired flow rate. The method may include providing an obstruction member within at least one of the first syringe and the second syringe to reduce the inner diameter of at least one of the first syringe and the second syringe.
The method may include providing a multi-fluid injection system including a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel, and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel, and providing an external restriction member on an outer circumference of at least one of the first syringe and the second syringe; and adjusting an inner diameter of the external restriction member to adjust a permitted swelling of at least one of the first syringe and the second syringe.
The method may include controlling one of the first flow rate and the second flow rate using an equalizing flow valve based on the other of the first flow rate and the second flow rate. The method may include adjusting at least one of the first flow rate and the second flow rate before delivery of at least one of the first fluid and the second fluid based on at least one of known operating fluid pressure and capacitance of a multi-fluid injection system used to deliver the first fluid and the second fluid. The method may include increasing a transition time between delivering one of the first fluid and the second fluid and delivering the other of first fluid and the second fluid.
In another example, a controller for a multi-fluid injection system configured to maintain an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the system includes a processor configured to control the multi-fluid injection system to: deliver at least a first fluid into the patient’s blood vessel at a first flow rate, deliver at least a second fluid into the patient’s blood vessel at a second flow rate, and adjust at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
In another example, the processor is further configured to control the multi-fluid injection system to increase a transition time between delivering one of the first fluid and the second fluid and delivering the other of the first fluid and the second fluid. The processor may also be further configured to control the multi-fluid injection system to delay the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate. The processor may also be further configured to control the multi-fluid injection system to over-deliver a predetermined volume of at least one of the first fluid and the second fluid during delivery of at least one of the first fluid and the second fluid.
Further examples will now be described in the following numbered clauses.
Clause 1: A method of maintaining an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the method comprising: delivering at least a first fluid into the patient’s blood vessel at a first flow rate; delivering at least a second fluid into the patient’s blood vessel at a second flow rate; and adjusting at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
Clause 2: The method of Clause 1, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises delaying the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate.
Clause 3: The method of Clause 1 or Clause 2, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises adjusting one of the first flow rate and the second flow rate using a controller based on the other of the first flow rate and the second flow rate.
Clause 4: The method of any of Clauses 1-3, further comprising pressurizing the first fluid using a check valve to a predetermined pressure before delivering the first fluid.
Clause 5: The method of any of Clauses 1-4, further comprising pressurizing the second fluid using a check valve to a predetermined pressure before delivering the second fluid.
Clause 6: The method of any of Clauses 1-5, further comprising pressurizing the first fluid and the second fluid using separate check valves to a first predetermined pressure and a second predetermined pressure, respectively, before delivering the first fluid and the second fluid.
Clause 7: The method of any of Clauses 1-6, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises over-delivering a predetermined volume of at least one of the first fluid and the second fluid during the delivery of at least one of the first fluid and the second fluid.
Clause 8: The method of any of Clauses 1-7, further comprising diluting one of the first fluid and the second fluid with a predetermined volume of the other of the first fluid and the second fluid.
Clause 9: The method of any of Clauses 1-8, further comprising: providing a multi-fluid injection system comprising: a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel; and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel; and reducing a capacitance of at least one of the first syringe and the second syringe to prevent backflow of at least one of the second fluid into the first syringe and the first fluid into the second syringe.
Clause 10: The method of Clause 9, further comprising providing a pressure jacket around an outer circumference of at least one of the first syringe and the second syringe to reduce swelling of at least one of the first syringe and the second syringe under pressure.
Clause 11: The method of any of Clauses 1-10, further comprising: providing a multi-fluid injection system comprising: a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel; and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel; and wherein at least one of the first syringe and the second syringe includes a reduced inside diameter to correspond to a desired flow rate.
Clause 12: The method of Clause 11, further comprising providing an obstruction member within at least one of the first syringe and the second syringe to reduce the inner diameter of at least one of the first syringe and the second syringe.
Clause 13: The method of any of Clauses 1-12, further comprising: providing a multi-fluid injection system comprising: a first syringe for receiving the first fluid and a first plunger movable within a barrel of the first syringe to pressurize the first fluid for delivery to the patient’s blood vessel; and a second syringe for receiving the second fluid and a second plunger movable within a barrel of the second syringe to pressurize the second fluid for delivery to the patient’s blood vessel; providing an external restriction member on an outer circumference of at least one of the first syringe and the second syringe; and adjusting an inner diameter of the external restriction member to adjust a permitted swelling of at least one of the first syringe and the second syringe.
Clause 14: The method of any of Clauses 1-13, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises controlling one of the first flow rate and the second flow rate using an equalizing flow valve based on the other of the first flow rate and the second flow rate.
Clause 15: The method of any of Clauses 1-14, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises adjusting at least one of the first flow rate and the second flow rate before delivery of at least one of the first fluid and the second fluid based on at least one of known operating fluid pressure and capacitance of a multi-fluid injection system used to deliver the first fluid and the second fluid.
Clause 16: The method of any of Clauses 1-15, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises increasing a transition time between delivering one of the first fluid and the second fluid and delivering the other of first fluid and the second fluid.
Clause 17: A multi-fluid injection system configured to maintain an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the system comprising: a processor configured to control the multi-fluid injection system to: deliver at least a first fluid into the patient’s blood vessel at a first flow rate; deliver at least a second fluid into the patient’s blood vessel at a second flow rate; and adjust at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
Clause 18: The controller of Clause 17, wherein the processor is further configured to control the multi-fluid injection system to increase a transition time between delivering one of the first fluid and the second fluid and delivering the other of the first fluid and the second fluid.
Clause 19: The controller as claimed in Clause 17 or Clause 18, wherein the processor is further configured to control the multi-fluid injection system to delay the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate.
Clause 20: The controller as claimed in any of Clauses 17-19, wherein the processor is further configured to control the multi-fluid injection system to over-deliver a predetermined volume of at least one of the first fluid and the second fluid during delivery of at least one of the first fluid and the second fluid.
These and other features and characteristics of the fluid injection system, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claim with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the disclosure. As used in the specification and the claim, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
For the purposes of the description hereinafter, spatial orientation terms, if used, shall relate to the referenced example as it is oriented in the accompanying drawings, figures, or otherwise described in the following detailed description. However, it is to be understood that the examples described hereinafter may assume many alternative variations and examples. It is also to be understood that the specific systems illustrated in the accompanying drawings, figures, and described herein are simply exemplary and should not be considered as limiting.
Referring to the drawings in which like reference characters refer to like parts throughout the several views thereof, several systems and methods are provided for reducing incidences of infiltration and/or extravasation, reducing the occurrence of spikes or sudden changes in fluid flow rates during an injection procedure, ensuring accurate flow rates and mixing ratios of fluids are delivered to the patient, and reducing kickback and rapid movement of a catheter during a transition from one injected fluid to another fluid. In a typical multi-fluid injection procedure, an injection fluid, such as a contrast medium, is delivered from a contrast medium source to the patient using a powered or manual injector. The injected contrast medium is delivered to a desired site in a patient’s body through a catheter inserted into the patient’s body, such as the arm. Once the contrast medium is delivered to the desired site, the area is imaged using a conventional imaging technique, such as computed tomography (CT), angiography imagining, magnetic resonance imaging (MRI), or other imaging or scanning technique. The contrast medium becomes clearly visible against the background of the surrounding tissue. However because the contrast medium may comprise toxic substances, it is desirable to reduce contrast dosing to the patient, while maintaining an effective contrast amount necessary for accurate imaging. By supplementing an overall contrast medium delivery procedure with saline, the saline flushes the contrast medium to the area of interest and additional hydration of the patient occurs automatically and aids the body in removing the contrast medium. In addition to improved patient comfort level and less toxicity, introduction of saline at clinically significant pressures and flow rates also allows higher flow rates to be achieved at lower pressure settings on the injector.
In one example, as shown in
The injector 100 has a housing 108 formed from a suitable structural material, such as plastic or metal, that encloses various components for delivering fluid from the syringes 102. The housing 108 may have various shapes and sizes depending on a desired application. The injector 100 includes at least one syringe port 110 for connecting the at least one syringe 102 to respective piston elements. In some examples, the at least one syringe 102 includes at least one syringe retaining member for retaining the syringe 102 within a syringe port 110 of the injector 100. The at least one syringe retaining member operatively engages a locking mechanism provided on or in the syringe port 110 of the injector 100 to facilitate loading and/or removal of the syringe 102 to and from the injector 100.
At least one fluid path set 112 may be fluidly connected with the at least one syringe 102 for delivering medical fluid from the at least one syringe 102 to a catheter, needle, or other fluid delivery device (not shown) inserted into a patient at a vascular access site. Fluid flow from the at least one syringe 102 may be regulated by a fluid control module. The fluid control module may operate various pistons, valves, and/or flow regulating structures to regulate the delivery of the medical fluid, such as saline solution and contrast medium, to the patient based on user selected injection parameters, such as injection flow rate, duration, total injection volume, and/or ratio of contrast medium and saline. An example of a suitable front-loading fluid injector 100 that may be modified for use with the above-described system including at least one syringe 102 and at least one syringe interface loading and releasable retaining of the at least one syringe 102 with the fluid injector 100 described herein with reference to
To enable effective simultaneous flow delivery of first and second injection fluids, such as contrast and saline, substantially equal pressure must be present in each delivery line. In a powered injection systems described herein, in a dual flow mode it is desirable to actuate the plunger elements substantially simultaneously in simultaneous flow delivery applications to equalize the pressure in each line. Alternatively, in a single flow mode, one plunger element is actuated to deliver the desired fluid while the other plunger element is held in place. If the injector is operated with differential pressure in each delivery line of the fluid path set, fluid in the lower pressure line may be stopped or reversed until sufficient pressure is achieved in the lower pressure line to enable flow in a desired direction. This time delay could reduce the image quality. The fluid in the lower pressure side may also begin to store fluid pressure energy against the fluid in the higher pressure line. As the stored fluid pressure energy in the lower pressure side continues to build, the lower pressure will eventually achieve the same pressure as the higher pressure fluid as it exits into the catheter tubing. Due to the stored fluid pressure energy in the lower pressure side, the flow rate of the lower pressure fluid can rapidly accelerate into the catheter tubing, particularly when the pressure in the high pressure fluid is reduced.
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Further, the fluid mixing ratio of contrast medium-to-saline may become inaccurate due to the stored fluid pressure energy in the lower pressure saline syringe or line. The contrast medium may be injected at a significantly higher ratio relative to saline, such as 80% contrast medium to 20% saline injection protocol. The flow reversal may be exacerbated at high injection pressures. In small dosage injections at a high injection pressure, flow reversal may effectively stop the delivery of saline such that up to 100% contrast medium is injected, rather than the desired 80% contrast medium to 20% saline ratio. Similar inaccuracies may occur at various other injection protocols, including, but not limited to 20% contrast medium to 80% saline ratio.
The above-described situation of flow reversal during powered injections at high contrast medium-to-saline ratio may occur at least in part due to injection system capacitance. Total system capacitance (also referred to as compliance or the ability to store a fluid volume and/or hydraulic energy) represents the amount of suppressed fluid (i.e., backflow volume) that is captured in the swelling of the fluid injector system components or compression of fluid injector system components, such as the fluid lines and/or syringe(s) due to pressure applied to a medical fluid during an injection process. Total system capacitance is inherent to each fluid injection system and depends on a plurality of factors, including injector construction, mechanical properties of materials used to construct the syringe, plunger, pressure jacket surrounding the syringe, fluid lines delivering the contrast medium and saline to a flow mixing device, size or surface area of the syringe, plunger, pressure jacket, compression or deflection of syringe injector components, etc. The amount of back or reverse flow increases when the relative speed difference between the two plungers is large, the simultaneous fluid flow is through a small restriction, the speed of the total fluid injection is large, and/or the viscosity of the fluid is high. The back or reverse flow can prevent different ratios of simultaneously delivered fluid from occurring in certain injections, which can be a detriment for two-syringe type fluid injector systems.
In general, capacitance is directly correlative to injection pressure and inversely correlative to volume of contrast medium and saline in the syringes. For example, in one example, capacitance during an injection at 1200 psi with 150 mL of contrast medium and saline remaining in certain medical injector syringes is around 10 mL. In another example, the capacitance volume can be from about 5 mL to about 9 mL. Capacitance is also a function of the ratio at which the first and second injection fluids, such as contrast and saline, are injected. At a 50%-50% ratio, where contrast and saline are injected in equal amounts, backflow volume is minimized because the capacitance on the contrast medium side is equal to the capacitance on the saline side of the fluid injection system such that substantially equal pressures are present in each delivery line. Backflow may occur in situations where first and second injection fluids are delivered through long fluid conduits. However, as the injection ratio of contrast and saline changes, backflow volume increases corresponding to the increase in the ratio.
With reference to
While several different factors that can affect the overall flow rate or an individual flow rate of one of the fluids in the injector system have been described, it is also contemplated that other factors may also affect these flow rates. The state of the particular flow of fluid through the injector system and the particular flow transition physics (laminar versus turbulent flow) during fluid mixing, fluid flow past fluid path components, and exiting from the catheter into the patient’s blood vessel, the temperature of the contrast medium may increase the viscosity of the contrast medium, and the higher flow rates for cardiac CT and other advanced imaging applications may also affect these flow rates.
A. Solutions for Reducing Spikes in Fluid Flow Rates and Providing Accurate Mixing Fluid RatiosSolutions to the problem of reducing backflow to compensate for system capacitance, for example in a high contrast medium-to-saline ratio, and thereby reducing undesired spikes in fluid flow rates and providing more accurate mixing ratios of fluids to the patient are described herein. In all of the examples described herein, a fluid flow profile of at least one of a first fluid 30 and a second fluid 32 is adjusted based on a function of the flow rate of one of the first fluid 30 and the second fluid 32 to minimize or dampen the spike or increase in the overall flow rate of fluid exiting from the catheter during a transition between delivering one of the first fluid 30 and the second fluid 32 to delivering the other of the first fluid 30 and the second fluid 32.
In one embodiment, one solution for improving (i.e., reducing) the overall capacitance of the injector system is to increase the stiffness of one or more of the components of the injector system subject to capacitance, to reduce swelling and/or compression in the one or more components. In one example, the stiffness of one of the catheter tubing 200, the catheter 210, the syringe 220, the syringe interface 230, the piston head 240, the piston 250, the polymeric cover 260, and the strain gauge cap 270 may be increased to reduce swelling and/or compression in the components of the injector system. In another embodiment, a pressure jacket may be placed around an outer surface of syringe 220 to reduce radial swelling under injection pressure.
The various embodiments of the methods described herein may be applied to injection procedures including simultaneous injection of fluid from two or more syringes or, alternatively, to reduce pressure and fluid flow spikes associated with transition from one fluid to another fluid during sequential injection of two or more fluids from two or more syringes, for example when transitioning from a contrast injection to a saline injection, or vice versa.
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With reference to
In another example, after pressure has been applied to the first fluid 30 and the second fluid 32, the flow rate of each fluid 30, 32 is measured. In the event the flow rates are not equal to one another, the fluid injection system may pause or hold the injection procedure, or pause injection or one or both fluids, to allow both fluids 30, 32 to achieve a steady-state pressure to reduce any stored energy in the fluid injection system. In one example, as the flow rates of the fluids 30, 32 are being measured, in the event it is determined that the flow rate of first fluid 30 is not equal to the flow rate of the second fluid 32 the fluid injection system can pause or hold the injection procedure while pressure is applied to either the first fluid 30 or the second fluid 32 to equalize the flow rates of the fluids 30, 32. In another example, the overall flow rate of the fluid exiting the catheter is measured during the injection procedure. The information regarding the overall flow rate is sent as real-time feedback information to the controller 38 to permit the controller 38 to adjust the pressures applied to the first fluid 30 and/or second fluid 32 to equalize the flow rates through the fluid injection system to ensure a consistent overall flow of fluid is exiting from the catheter into the patient’s blood vessel. As shown in
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In a similar fashion, as shown in
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(Where: C1 = -0.811; C2 = 0.039; C3 = -0.00035; C4 = 9.05E-7; C5 = 0.0269; C6 = -4.43e-5; C7 = 2.607e-8; x axis = pressure; y axis = position) To receive the desired volume of the first fluid 30 from the fluid injection system, the plunger 34 must be over-traveled the same amount and then the plunger 34 is pulled back in reverse to compensate for release of the capacitance volume of the first fluid 30 syringe.
With reference to
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Once forward longitudinal movement of the plunger 34 within the syringe is ceased, the plunger 34 may be rapidly driven back in order to compensate for the increased pressures within the fluid injection system resulting from the over-travel of the plunger 34. In order for the plunger 34 to retract to the retracted position, the controller 38 activates the motor 35, which causes transition of the plunger 34 from the third over-travel position P3plunger to the retracted position, thereby retracting the plunger 34 a corresponding retraction distance. This rapid backwards retraction of the plunger 34 relieves the swelling of the syringe and depressurizes the system. In one example, the rapid back-drive of the plunger 34 can be on the order of about 20 mL/s to 30 mL/s, for example 25 mL/s. This depressurization of the system allows the linear travel of the plunger 34 to coincide with the actual commanded location, irrespective of capacitance volume. In the example where the first fluid 30 is more viscous than the second fluid 32, the process described above in reference to
In typical fluid injection systems with saline and contrast medium fluids, the contrast medium has a higher viscosity than the saline. Due to this difference in viscosity, it is often difficult to apply the correct pressure to each fluid to achieve a uniform pressure between the two fluids to create a smooth flow of the mixture of the two fluids to the downstream location or sequential flow of the fluids without a flow spike at the fluid transition. As described herein, the higher viscosity of the contrast medium may cause backflow in the fluid injection system and/or swelling of the syringes holding the saline and/or contrast medium. Therefore, in one embodiment of the disclosure, the saline used in the fluid injection system may be replaced with an alternative fluid that has similar properties to saline but has a higher viscosity to substantially match the higher viscosity of the contrast medium. In one example, the saline may be replaced with a Ringers Lactate solution, which has a viscosity similar to blood or low viscosity contrast mediums. The pressure required to deliver the Ringers Lactate solution through the fluid injection system is higher than saline, which leads to a smaller difference between the pressure to move the Ringers Lactate solution and that needed to move the more viscous contrast medium resulting in lower spikes or jumps in the flow rates of the two fluids. The Ringers Lactate solution will also have a higher density than saline, which will reduce the density exchange between the Ringers Lactate solution and the contrast medium.
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Similar to the obstruction member 48 used in
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According to an embodiment, in a similar method, a test injection procedure using the first fluid 30 and second fluid 32 may be performed before the actual diagnostic phase, using the same flow rates as will be used from the diagnostic injection procedure. A pressure measurement of the first fluid 30 phase is obtained during the test injection procedure, which gives an indication of the expected pressure for the programmed flow rate under the current tubing and patient conditions. This measured pressure value is recorded and used during the diagnostic injection procedure to modify the flow rate of at least one of the first fluid 30 and the second fluid 32 to modify the flow rate and fluid flow profile of at least one of the first fluid 30 and the second fluid 32 to compensate for capacitance in the injector system. In one example, the flow rate modification is achieved by temporarily changing a pressure limit of one of the fluids 30, 32 in an adaptive flow algorithm used by a controller 38 to control the pressures of the fluid injection system. In another embodiment, a series of flow algorithms may be programmed into a controller 38 or processor based on set of pre-programmed injection protocols. Alternatively, one or more algorithms may be determined and programmed into the controller 38 that utilize various system parameters for a specific injection setup and protocol, such as, for example, fluid volumes and types, temperature, syringe volumes and types, desired flow rates, target organ or body part for imaging, patient information, etc., where the algorithms utilize the various parameters to calculate and appropriate injection protocol for the injection procedure.
With reference to
As shown in one embodiment in
In another example, the viscosity of the first fluid 30 or the second fluid 32 is adjusted to minimize or dampen the spike or increase in the overall flow rate during a transition between delivering one of the first fluid 30 and the second fluid 32 to delivering the other of the first fluid 30 and the second fluid 32. In one example, a volume of the first fluid 30 is added to the second fluid 32 to dilute the overall viscosity of the second fluid 32. Since the first fluid 30 has a lower viscosity, the first fluid 30 will dilute the second fluid 32 and reduce the overall viscosity of the second fluid 32. In another example, the viscosity of the first fluid 32 is increased to match the viscosity of the second fluid 32. By equalizing the viscosities of the fluids 30, 32, the transition of flow between the delivery of one of the first fluid 30 and the second fluid 32 and the delivery of the other of the first fluid 30 and the second fluid 32 does not create such a large spike or increase in the overall flow rate exiting from the catheter.
B. Solutions for Reducing Catheter Kickback and Rapid MovementWith reference to
As shown in
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With reference to
With reference to
While several examples of a fluid injection system and catheter are shown in the accompanying figures and described hereinabove in detail, other examples will be apparent to, and readily made by, those skilled in the art without departing from the scope and spirit of the disclosure. For example, it is to be understood that this disclosure contemplates that, to the extent possible, one or more features of any example can be combined with one or more features of any other example. Accordingly, the foregoing description is intended to be illustrative rather than restrictive.
Claims
1. A method of maintaining an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the method comprising:
- delivering at least a first fluid into the patient’s blood vessel at a first flow rate;
- delivering at least a second fluid into the patient’s blood vessel at a second flow rate, wherein the second fluid is less viscous than the first fluid; and
- adjusting at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
2. The method of claim 1, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises delaying the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate.
3. The method of claim 1, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises adjusting one of the first flow rate and the second flow rate using a controller wherein the adjusting is based on the other of the first flow rate and the second flow rate.
4. The method of claim 1, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises pulling back a plunger of a second fluid syringe containing the second fluid to reduce a capacitance volume of the second fluid syringe.
5. The method of claim 4, wherein pulling back the plunger of the second fluid syringe comprises pulling back the plunger a distance equal to the capacitance volume of the second fluid syringe.
6. The method of claim 4, wherein the pulling back of the plunger is controlled by a controller.
7. The method of claim 6, wherein the pulling back of the plunger by the controller is based on information based on one or more of fluid viscosities, catheter size, capacitance of the second fluid syringe and a volume of fluid in a fluid injection system.
8. A multi-fluid injection system configured to maintain an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the system comprising:
- a processor configured to control the multi-fluid injection system to: deliver at least a first fluid into the patient’s blood vessel at a first flow rate; deliver at least a second fluid into the patient’s blood vessel at a second flow rate wherein the second fluid is less viscous than the first fluid; and adjust at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
9. The multi-fluid injection system of claim 8, wherein the processor is further configured to control the multi-fluid injection system to increase a transition time between delivering one of the first fluid and the second fluid and delivering the other of the first fluid and the second fluid.
10. The multi-fluid injection system of claim 8, wherein the processor is further configured to control the multi-fluid injection system to delay the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate.
11. The multi-fluid injection system as claimed in claim 17, wherein the controller adjusts at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises the controller pulling back a plunger of a second fluid syringe containing the second fluid to reduce a capacitance volume of the second fluid syringe.
12. A method of maintaining an overall flow rate during a sequential delivery of at least two fluids to a patient’s blood vessel, the method comprising:
- delivering at least a first fluid into the patient’s blood vessel at a first flow rate, wherein the first fluid is less viscous than the second fluid;
- delivering at least a second fluid into the patient’s blood vessel at a second flow rate; and
- adjusting at least one of a first flow profile of the first flow rate and a second flow profile of the second flow rate to dampen a transient increase in the overall flow rate during a transition between delivering one of the first fluid and the second fluid to delivering the other of the first fluid and the second fluid.
13. The method of claim 12, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises delaying the delivery of one of the first fluid and the second fluid until the other of the first fluid and the second fluid reaches a predetermined flow rate.
14. The method of claim 12, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises adjusting one of the first flow rate and the second flow rate using a controller wherein the adjusting is based on the other of the first flow rate and the second flow rate.
15. The method of claim 12, wherein adjusting at least one of the first flow profile of the first flow rate and a second flow profile of the second flow rate comprises pulling back a plunger of a second fluid syringe containing the second fluid to reduce a capacitance volume of the second fluid syringe.
16. The method of claim 15, wherein pulling back the plunger of the second fluid syringe comprises pulling back the plunger a distance equal to the capacitance volume of the second fluid syringe.
17. The method of claim 15, wherein the pulling back of the plunger is controlled by a controller.
18. The method of claim 17, wherein the pulling back of the plunger by the controller is based on information based on one or more of fluid viscosities, catheter size, capacitance of the second fluid syringe and a volume of fluid in a fluid injection system.
Type: Application
Filed: Jun 9, 2023
Publication Date: Nov 2, 2023
Inventors: Michael Spohn (Fenelton, PA), Ralph Schriver (Tarentum, PA), Arthur Uber, III (Pittsburgh, PA), Ronald Heller (Monroeville, PA), Kevin Cowan (Allison Park, PA), Barry Tucker (Verona, PA), Edward Rhinehart (Murrysville, PA), Timothy Newing (Thornleigh)
Application Number: 18/208,021