Abstract:
According to preferred embodiments and methods of the present disclosure, a medical injection system employs a single pump for the injection of multiple fluids, rather than employing a pump for each type of fluid, for example, like the prior art system described above. Embodiments of pumps disclosed herein preferably include a disposable pump cartridge configured to be contained within a hull of a medical injection system, wherein the hull may be formed when a pressure plate member is closed against a base plate; and, when the pressure plate member is opened with respect to the base plate, the disposable pump cartridge may be removed and replaced.

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure pertain to medical injection systems and more particularly to the pumps employed therein. 
     BACKGROUND 
       FIG. 1  is a perspective view of an exemplary medical injection system  100  (the ACIST CVO system) for delivering a contrast agent into a patient&#39;s vascular system for medical imaging.  FIG. 1  illustrates a first fluid reservoir  132  for supplying a syringe-type positive displacement pump of a pressurizing unit  130 , via a fill tubing line  27 -F, and an injection tubing line  27 -I coupled to unit  130  for injection of, for example, a radiopaque contrast agent, into a patient&#39;s vascular system via an inserted catheter (not shown), for example, coupled to a patient tubing line  122  at a connector  120  thereof.  FIG. 1  further illustrates a second fluid reservoir  138  from which a diluent, such as saline, is drawn by a peristaltic pump  106  through yet another tubing line  128  that feeds into tubing line  122 . A manifold valve  124  and associated sensor  114  control the flow of fluids into tubing line  122 , from pressurizing unit  130  and from tubing line  128 . 
     SUMMARY 
     According to preferred embodiments and methods of the present disclosure, a medical injection system employs a single pump for the injection of multiple fluids, rather than employing a pump for each type of fluid, for example, like the prior art system described above. Embodiments of pumps disclosed herein preferably include a disposable pump cartridge configured to be contained within a hull of a medical injection system, wherein the hull may be formed when a pressure plate member is closed against a base plate; and, when the pressure plate member is opened with respect to the base plate, the disposable pump cartridge may be removed and replaced. 
     The disposable pump cartridge preferably includes a shell and a piston, wherein the piston is contained within an inner surface of the shell and includes a bore that is adapted to be operably engaged by a drive member and a fixed gear of the injection system; each of the fixed gear and the drive member are inserted through a corresponding opening formed through the shell, when the cartridge is contained within the hull. The drive member is preferably coupled to a free end of a motor drive shaft, which extends through the base plate, and the fixed gear is preferably mounted to the pressure plate member. According to some preferred embodiments, the disposable pump cartridge is configured to function as a Limaçon-to-Limaçon machine, wherein sliding and rotational motion of the piston is driven by an eccentric drive member of the injection system to create expanding and contracting cavities during pump operation. The piston further includes a pressure seal that extends thereover and is configured to be in sliding and sealing engagement with the inner surface of the shell to seal the expanding and contracting cavities from one another within the shell, and to seal the cavities from the first and second openings of the shell. Fill and injection ports of the shell are preferably located at opposite ends of a long axis of the piston, when the piston is in a position where the contracting cavity is at a maximum volume and the expanding cavity is at a minimum volume. 
     According to some embodiments, each of the fill and injection ports includes a channel and one or more apertures formed in the inner surface of a perimeter wall of the shell, wherein each channel extends from the corresponding one or more apertures to a corresponding opening in outside the shell. When the disposable cartridge is contained in the hull of the system, the fill and injection ports preferably extend through openings in the pressure plate member, and each has a fitting outside the hull for coupling to a fill and an injection tubing line, respectively, of the system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings are illustrative of particular methods and embodiments of the present disclosure and, therefore, do not limit the scope. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Methods and embodiments will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements, and: 
         FIG. 1  is a perspective view of an exemplary prior art medical injection system; 
         FIG. 2A  is a schematic depicting a medical injection system, according to some embodiments of the present disclosure; 
         FIG. 2B  is an exploded perspective view of a disposable pump cartridge that may be employed by the system depicted in  FIG. 2A , according to some embodiments; 
         FIG. 2C  is a perspective view of a pressure seal that may be incorporated in the disposable pump cartridge of  FIG. 2B , according to some embodiments; 
         FIG. 2D  is an exploded perspective view of a portion of a medical injection system, according to some embodiments; 
         FIG. 3A  is a cut-away plan view of an interior of a disposable pump cartridge, according to some embodiments; 
         FIGS. 3B-C  are schematics depicting exemplary expanding and contracting cavities of the pump cartridge; 
         FIG. 4A  is a cross-section view through section line A-A of  FIG. 3A , when the disposable pump cartridge is assembled into a hull of the system of  FIG. 4A , according to some embodiments; 
         FIG. 4B  is a cross-section view through section line B-B of  FIG. 3A , according to some embodiments; and 
         FIG. 4C  is an enlarged detail of a portion of a pump cartridge, according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the following description provides practical illustrations for implementing exemplary methods and embodiments. Examples of constructions, materials and dimensions are provided for selected elements, and all other elements employ that which is known to those skilled in the art. Those skilled in the art will recognize that many of the examples provided have suitable alternatives that can be utilized. 
       FIG. 2A  is a schematic depicting a medical injection system  200 , according to some embodiments.  FIG. 2A  illustrates system  200  including a single pump  230 , which is coupled between a fill tubing line  217 F and an injection tubing line  217 I, and which is formed by a hull  25  and a disposable pump cartridge  23  (shown with dashed lines) contained therein. Hull  25  may be formed by a base plate  42  and a pressure plate member  41  that may be opened and closed with respect to base plate  42  to remove and install disposable pump cartridges  23 .  FIG. 2A  further illustrates system  200  including a plurality of fluid reservoirs, for example, two types of contrast agent reservoirs  232 A,  232 B and a saline reservoir  238 , connected to fill tubing line  217 F via a manifold assembly  224  (i.e. an inlet stop cock valve) that couples each reservoir  232 A,  232 B,  238  to pump  230 . According to the illustrated embodiment, manifold assembly  224  is controllable to select one of reservoirs  232 A,  232 B,  238  for filling pump  230  and, once primed, pump  230  is operable simultaneously fill and inject fluid from the selected reservoir. 
       FIG. 2A  shows each of fill tubing line  217 F and injection tubing line  217 I preferably extending over a limited length, for example, less than approximately 25 mm, and injection tubing line  217 I transitioning into a dual lumen line  227 I wherein a first lumen is dedicated to contrast agent and a second lumen to saline. Dual lumen line  227 I is shown coupled to injection line  217 I via a stop-cock valve  274  that can be switched back and forth between the lumens of line  227 I, depending on the type of fluid that is being pumped, saline or contrast agent, so as to prevent excessive waste of contrast agent.  FIG. 2A  further illustrates a y-connector  265  coupling dual lumen line  227 I to a patient line  269 . According to the illustrated embodiment, y-connector  265  preferably includes a check valve to prevent backflow into dual lumen line  227 I. Furthermore, when a pressure transducer is incorporated in line  269  for patient blood pressure monitoring, the check valve helps to improve hemodynamic signal quality by isolating line  269  from line  227 I. 
       FIG. 2B  is an exploded perspective view of disposable pump cartridge  23 , according to some embodiments.  FIG. 2B  illustrates cartridge  23  including a shell that has a first sidewall SW 1 , a second sidewall SW 2  and a perimeter wall PW, and a piston  28  configured to be contained within the shell and moved therein to form two dynamically expanding and contracting cavities for drawing in and injecting out, respectively, fluid from any of the aforementioned fluid reservoirs  232 A,  232 B,  238 . With further reference to  FIG. 2B , when the shell contains piston  28 , a first side  281  of piston  28  extends adjacent to an inner surface  211  of first sidewall SW 1 , a second side  282  of piston  28  extends adjacent to an inner surface  221  of second sidewall SW 2 , and an outer perimeter edge  83  of piston  28  extends adjacent to an inner surface  251  of perimeter wall PW. Furthermore an inner perimeter edge of piston  28 , which forms a bore  810  through piston  28 , includes a first portion  811 , located in proximity to a first opening  201  formed through first sidewall SW 1  of shell, and a second portion  812  located in proximity to a second opening  202  formed through second sidewall SW 2  of shell. According to the illustrated embodiment, first opening  201  allows insertion therethrough of a fixed gear  340  ( FIGS. 2D, 4A ) to mate with first portion  812  of the inner perimeter edge of piston  28 , and second opening  202  allows insertion therethrough of a drive member  442  ( FIGS. 2D, 4A ) to mate with second portion  812  of the inner perimeter edge, for the operation of pump  230 , which is described below. 
       FIG. 2D  is an exploded perspective view of a portion of pump  230 , wherein fixed gear  340  may be seen mounted on pressure plate member  41 , and drive member  442 , which is coupled to a free end of a motor drive shaft  441 , is illustrated with dashed lines on a side of base plate  42  that faces second opening  202  of the shell of pump cartridge  23  for the aforementioned engagement with piston  28 . It should be noted that suitable bearing supports, known to those skilled in the art of mechanical design, may be employed to support drive shaft  441  as it passes through base plate  41  and to support drive member  442  mounted on the free end of drive shaft  441 . With reference to  FIGS. 2A and 2D , base plate  42  may be part of a housing  24  that contains the motor from which drive shaft  441  extends, and pressure plate member  41  is coupled to base plate  42 , for example, by a hinge and pull action toggle clamp or a pull action cam clamp to form hull  25  that contains pump cartridge  23  and holds pressure during pump operation, and to allow opening and closing of hull  25  for the replacement of disposable pump cartridge  23 , for example, after the completion of each imaging procedure. According to preferred embodiments, drive member  442  is a roller bearing mounted eccentric adapted for a toothless engagement with second portion  812  of the inner perimeter edge of piston  28  that facilitates alignment when disposable cartridge  23  is assembled into hull  25 . 
     According to an exemplary embodiment, hull  25  may be formed of stainless steel, while piston  28  and first and second sidewalls SW 1 , SW 2  and perimeter wall PW of the shell are preferably formed, for example by injection molding, from a polycarbonate material, such as APEC® 1745. Each wall of the shell may have a nominal thickness of between approximately 0.070 inch and approximately 0.080 inch, which is preferably uniform along both sidewalls SW 1 , SW 2  and perimeter wall PW, for example, to avoid sink discontinuities from forming during injection molding of the shell. According to the illustrated embodiment, second sidewall SW 2  of shell may be formed independently of first sidewall SW 1  and perimeter wall PW and then attached about a facing edge  27  of perimeter wall PW, for example by tongue-in-groove engagement and ultrasonic welding or adhesive bonding, wherein the adhesive may be a cyanoacrylate or a UV cure adhesive, or any suitable adhesive known in the art. 
     With further reference to  FIG. 2B , piston  28  includes a pressure seal  288  formed thereover for sliding and sealing engagement with each of the aforementioned inner surfaces of the shell.  FIG. 2C  is a perspective view of pressure seal  288  separated from piston  28 .  FIGS. 2B-C  illustrate pressure seal  288  including a first seal ring portion SR 1  that extends about a perimeter of first side  281  of piston  28 , a second seal ring portion SR 2  that extends about a perimeter of second side  282  of piston  28 , and a pair of seal strip portions SS that extend between first and second seal ring portions SR 1 , SR 2  and along outer perimeter edge  83  of piston  28  opposite one another at either end of a long axis of piston  28 . The seal rings and strips of pressure seal  288  are preferably integrally over-molded onto the piston; and, according to an exemplary embodiment, are formed of 917CK silicone rubber (Minnesota Rubber &amp; Plastics of Minneapolis, Minn.) having a hardness of 75+5 on a Shore A scale. According to the illustrated embodiment, pressure seal  288  engages with the inner surfaces of the shell to seal expanding and contracting cavities, which are created by the movement of piston  28  within the shell, from one another and from openings  201 ,  202 . 
     According to some preferred embodiments, disposable pump cartridge  23  is configured to function as a Limaçon-to-Limaçon machine, wherein drive member  442  eccentrically engages with second portion  812  of the inner perimeter edge of piston  28  to cause a sliding and rotational motion thereof, which creates expanding and contracting cavities during pump operation.  FIG. 3A  is a cut-away plan view of an interior of disposable pump cartridge  23  in which fixed gear  340  is shown engaged with first portion  811  of the inner perimeter edge of the piston  28 ; and  FIGS. 3B-C  are schematics showing subsequent positions of piston  28 , relative to fixed gear  340  and the shell, as moved by drive member  442 —sliding per arrow S and rotating per arrow R ( FIG. 3A ), to create an expanding cavity E and a contracting cavity C. 
     With reference to  FIG. 3A , a profile of inner surface  251  of perimeter wall PW of the shell conforms to a shape defined by a Limaçon curve in an X-axis, Y-axis coordinate system, wherein the Limaçon is traced by end points of a cord that extends along the X-axis, through the origin of the X-Y coordinate system (over a length equal to twice the length L), and is divided in half by the origin. The Limaçon is represented by the following Cartesian equations:
 
 X=r ×sin(2θ)+ L ×cos(θ), and
 
 Y=r−r ×cos(2θ)+ L ×sin(θ);
 
wherein r is a radius of a base circle having a perimeter along which a center point of the cord slides as the end points of the cord rotate about the center point of the cord to trace the Limaçon; r divided by L is less than or equal to 0.25; and θ extends from 0 to 2π.  FIG. 3A  further illustrates the long axis of piston  28  being approximately the length of the cord (2×L) and having a shape symmetrical across the cord, wherein the curvature of the shape on each side of the cord also conforms to the Limaçon represented by the above equations, but wherein θ extends from π to 2π. Such a Limaçon-to-Limaçon machine is further detailed by Ibrahim A. Sultan in  Profiling Rotors for Limaçon - to - Limaçon Compression - Expansion Machines , Journal of Mechanical Design, July 2006, Volume 128, pp. 787-793, © 2006 by ASME, which is hereby incorporated by reference. With further reference to  FIG. 3A , an injection port IP is located at one end of the long axis of piston  28 , and a fill port FP is located at the opposite end of the long axis of piston  28 , when piston  28  is at the illustrated dead center position.
 
     With reference to  FIG. 3B , piston  28  has been moved counter-clockwise from the dead center position, which is shown in  FIG. 3A , to a position at which contracting cavity C is in fluid communication with injection port IP and is beginning to be compressed for injection of fluid, per arrow I, while expanding cavity E is in fluid communication with fill port FP and beginning to be enlarged to draw in fluid, per arrow F.  FIG. 3C  illustrates a subsequent position of piston  28 , having been moved through the position shown with dotted lines in  FIG. 3B , at which contracting cavity C is approaching a minimum volume and expanding cavity E is approaching a maximum volume at which it becomes the contracting cavity C of  FIG. 3A . The maximum volume of contracting cavity C may be between approximately 2 cubic centimeters and approximately 10 cubic centimeters, wherein a volume closer to 2 cubic centimeters may be preferred for less stress on the shell and piston  28 , and in order reduce a waste of fluid when switching from one type to another, for example, from a contrast agent  232 A or  232 B to saline  238  ( FIG. 2A ); yet, a volume closer to 10 cubic centimeters will allow the piston to move more slowly thereby reducing wear on pressure seal  288  and decreasing the possibility of fluid cavitation. It should be noted that the volume may be modified by changing the radius r and length L ( FIG. 3A ) and/or by modifying a height H of inner surface  251  of perimeter wall PW along with a corresponding increase in a thickness t of piston  28  ( FIG. 4C ). 
     Turning now to  FIGS. 4A-B , which are cross-section views through section lines A-A and B-B, respectively, engagement of the parts of pump  230  may be seen.  FIG. 4A  illustrates pressure plate member  41  in a closed position with respect to base plate  42  after disposable pump cartridge  23  has been mounted on eccentric drive member  442 , by insertion of drive member  442  in through opening  202  of second sidewall SW 2  of the shell to engage with second portion  812  of the inner perimeter edge of piston  28 . When pressure plate member  41  is closed with respect to base plate  42 , fixed gear  340  passes through opening  201  of first sidewall SW 1  of the shell to engage with the toothed first portion  811  of the inner perimeter edge of piston  28 , wherein the engagement of gear  340  and first portion  811  keep piston  28  ‘on track’ to slide about radius r ( FIG. 3A ) as drive member  442  rotates piston  28 .  FIGS. 4A-B  further illustrate the engagement of first and second seal ring portions SR 1 , SR 2  of pressure seal  288  extending outward from piston  28  to engage with inner surfaces  211 ,  221  of first and second shell sidewalls SW 1 , SW 2 . According to  FIG. 4B , in some embodiments, each of seal rings SR 1 , SR 2  is seated in a groove formed at the intersection of the corresponding one of the first and second sides  281 ,  282  of piston  28  with outer perimeter edge  83  of piston  28 , and a cross-section of each of seal rings SR 1 , SR 2  is preferably oval. The cross-section of seal strips SS may also be oval-shaped, and each may be seated in a corresponding groove extending along outer perimeter edge  83  between first and second sides  281 ,  282 . According to some embodiments each of seal rings SR 1 , SR 2  and seal strips SS extends out from the corresponding groove to contact with corresponding inner surfaces of the shell with a standard compression of approximately 20%, and pressure seal  288  preferably forms the only interface between piston  28  and the inner surfaces of the shell. According to a preferred embodiment, wherein piston  28  is formed from the aforementioned polycarbonate and pressure seal  288  of the aforementioned silicone rubber, pressure seal  288  is directly bonded to piston  28 , for example, within the above-described grooves, during the process of over-molding seal  288  onto piston  28 . 
       FIG. 4A  further illustrates injection port IP and fill port FP, according to some preferred embodiments, wherein each includes a channel  43  that extends from a corresponding one or more apertures  40 , preferably a plurality of apertures, formed in inner surface  251  ( FIG. 2B ) of perimeter wall PW, such that the above-described fluid communication between each port IP, FP and the corresponding cavity C, E is provided by the corresponding one or more apertures  40 . According to the illustrated embodiment, each channel  43  further extends through first sidewall SW 1  of the shell and through a corresponding opening formed through pressure plate member  41 . With further reference to  FIG. 4A , a first fitting  431  is coupled to channel  43  of injection port IP and a second fitting  432  is coupled to channel  43  of fill port FP, wherein first fitting  431  is adapted to couple with injection tubing line  217 I and second fitting  432  with fill tubing line  217 F outside hull  25  ( FIG. 2A ). Fittings  431 ,  432  are preferably different types to assist in the proper connection of injection tubing lines  217 F and  217 I. 
       FIG. 4C  is an enlarged detail view of one of channels  43  and the corresponding plurality of apertures  40 , according to some embodiments, wherein each aperture has an oval shape with chamfered edges to prevent damage to seal strips SS as each end of the long axis of piston  28  moves past apertures  40 . Channel  43  of fill port FP is preferably larger than that of injection port IP, and, according to an exemplary embodiment, a diameter of channel  43  for fill port FP is approximately 8 millimeters and each of the corresponding plurality of apertures  40  is approximately 2 millimeters by 6 millimeters, while a diameter of channel  43  for injection port IP is approximately 3 millimeters and each of the corresponding plurality of apertures is approximately 1 millimeter by 2 millimeters. 
     In the foregoing detailed description, disclosure subject matter has been described with reference to specific embodiments. However, it may be appreciated that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims.