Abstract:
An infusion pump has a base and a holder for a syringe extending along a longitudinal axis and having an axially shiftable plunger. The holder is pivotal on the base about a first axis substantially perpendicular to the longitudinal axis of the syringe. A first actuator connected between the base and the holder can oscillate the holder about the first axis relative to the base. A pusher is displaceable linearly on the base transversely of the first axis by a second actuator that can press this pusher against the plunger and thereby slide the plunger of the syringe and empty the syringe&#39;s contents. A controller is connected to the first and second actuators for moving the pusher out of engagement with the plunger during oscillation of the syringe and for operating the second actuator only when the first actuator is not oscillating the syringe to express the contents of the syringe.

Description:
FIELD OF THE INVENTION 
     Infusion pumps for syringes, which are used in the therapeutic field for the controlled and automated infusion of drugs, are known. 
     BACKGROUND OF THE INVENTION 
     Known pumps are substantially constituted by a supporting frame with which means for locking the cylindrical body of a syringe and means of the linear automated type for actuating the sliding of the plunger of the syringe are associated. 
     An electronic circuit controls and actuates the actuation means in order to dispense the drug contained in the syringe according to an infusion program (time, flow-rate, speed etc.) that can be set from the outside by a health operator by means of a keypad and a display. 
     These known types of pump are not free from drawbacks, including the fact that if the fluid to be infused is constituted by a plurality of components they do not allow them to mix adequately as required. 
     Currently, mixing is performed manually by health operators, who shake the syringe into which the components of the fluid have been introduced, with consequent disadvantageous labor costs and long execution times and producing a homogenization that is imperfect and inconstant since it depends on the experience and dexterity of the operators. 
     Another drawback of known pumps is that they practically cannot be used to infuse fluids that contain microbubbles of air or gas, such as for example the contrast media used in imaging diagnostic methods, such as in particular echocontrast imaging. 
     The expression “echocontrast imaging” designates a sonogram that uses contrast media and utilizes the reflection of ultrasound by microbubbles entrained together with the contrast medium. 
     The infusion of these fluids must in fact follow immediately their mixing in order to prevent the microbubbles from distributing unevenly inside them, and therefore to prevent the fractions of fluid that are infused in succession from containing too many or too few microbubbles, compromising the quality of the sonograms. 
     For this reason, the operator assigned to mixing them manually also then injects them manually immediately thereafter into the line for infusion to a patient; the time required to prepare a known type of pump would in fact eliminate the effects of mixing. 
     Currently, therefore, the mixing and infusion of these fluids that contain microbubbles of air or gas, as well as the immediate successive infusion of a physiological solution, are entirely manual, and this accordingly entails a further disadvantageous increase in labor costs and in execution times as well as inevitable and unpredictable inaccuracies and errors in execution due to the experience and dexterity of the operators. 
     Moreover, it should be noted that the contrast media of this type have high intrinsic costs, and therefore their incorrect mixing and/or their incorrect infusion, such as to compromise for example the quality of the resulting sonogram and prevent correct diagnosis, entail a waste of material that is disadvantageously onerous. 
     OBJECTS OF THE INVENTION 
     The aim of the present invention is to eliminate the above-mentioned drawbacks of known pumps, by providing an infusion pump for syringes that allows the components of a fluid to be mixed and then infused uniformly and constantly, to reduce labor use and costs, to reduce the time required, and to limit errors in mixing. 
     Another object of the present invention is to provide a pump that can be used easily to mix and infuse fluids that contain air or gas microbubbles uniformly, precisely and constantly and that reduces waste of material. 
     Another object of the present invention is to provide an infusion pump that can be used particularly to infuse contrast media and optionally physiological solutions for echocontrast imaging. 
     Within this aim, another object of the present invention is to provide an infusion pump that is simple, relatively easy to provide in practice, safe in use, effective in operation, and that has a relatively low cost. 
     SUMMARY OF THE INVENTION 
     This aim and these and other objects that will become better apparent hereinafter are achieved by the present infusion pump for syringes, characterized in that it comprises a supporting structure, means for supporting a syringe that can be rigidly mounted on the syringe and can be mounted on the supporting structure so that they can rotate alternately about an axis that is substantially perpendicular to the longitudinal axis of the syringe, first means for actuating the alternating rotation and second means for actuating the sliding of the plunger of the syringe, which cooperate functionally with the first actuation means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the present invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of an infusion pump for syringes, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
         FIG. 1  is a schematic axonometric view of an infusion pump for syringes according to the invention; 
         FIG. 2  is a schematic axonometric view of the pump of  FIG. 1  without the covering and protective housing; 
         FIG. 3  is a schematic enlarged-scale axonometric view of a detail of the holder and of the first actuation means of the pump according to the invention; 
         FIG. 4  is a schematic top plan view of the detail of  FIG. 3 ; 
         FIG. 5  is a schematic exploded view of the holder and of the first actuation means according to the invention; 
         FIG. 6  is a schematic axonometric enlarged-scale view of a detail of the means for locking the auxiliary syringe of the pump according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures, the reference numeral  1  generally designates an infusion pump for syringes. 
     The pump  1  comprises a supporting structure  2 , which is divided into a base  2   a  and a housing  2   b , means  3  for supporting a syringe  4  of the type constituted by a cylindrical body  4   a  inside which a plunger  4   b  slides, which can be rigidly mounted on the syringe  4  and can be detachably mounted on the supporting structure  2  so as to rotate alternately about a first axis A that is substantially perpendicular to a second longitudinal axis B of the syringe  4 . 
     The syringe  4 , which is rigidly coupled to the holder  3 , is therefore alternately rotated about the axis A with a so-called oscillating or rocking motion. 
     Further, the pump  1  comprises first actuation means  5  of the automated type for actuating the alternating rotation of the holder  3  and therefore of the syringe  4  that is rigidly coupled thereto. The first actuation means  5  cooperates functionally with second actuation means  6  of the automated type for sliding of the plunger  4   b.    
     Conveniently, the axis A lies on a substantially horizontal plane while the alternated rotation angle has a breadth of less than 2 πrad. 
     Further, the pump  1  comprises means  7  for locking an auxiliary syringe  8  of the type that is constituted by a cylindrical body  8   a  inside which a plunger  8   b  slides. This means  7  is mounted on the housing  2   b , and third actuation means  9  of the automated type for actuating the sliding of the plunger  8   b.    
     First sensing means  10  ( FIGS. 3 and 4 ) and second sensing means  11  ( FIG. 6 ), such as for example on/off switches, detect the presence of the syringe  4  and of the auxiliary syringe  8  respectively; first control means  12  and second control means  13  control the sliding of the respective plungers  4   b  and  8   b ; and means  14  for sensing the pressure applied to the plungers  4   b  and  8   b  are associated respectively with the second actuation means  6  and with the third actuation means  9 . 
     The second actuation means  6  and the third actuation means  9  are of the linear type. The first actuation means  5 , the second actuation means  6  and the third actuation means  9  can be, for example, of the mechanical, pneumatic, hydraulic (hydrodynamic), electric or electromechanical type. 
     The pump  1  is provided with ON/OFF control means shown schematically in  FIG. 1  at CM for activating and deactivating its operation and that can be advantageously be operated a foot and are constituted for example by a pedal, a pushbutton or the like, for transmitting start and stop signals over a cable, wirelessly or via infrared. 
     An electronic control and monitoring unit CU, such as an electric controller, advantageously of the programmable type, is functionally connected to the first actuation means  5 , with the second actuation means  6 , and optionally with the first means  10  for sensing the syringe  4 , with the first control means  12  for controlling the sliding of the plunger  4   b , and with the means  14  for sensing the pressure applied to the plunger  4   b.    
     If the auxiliary syringe  8  is also present, the electronic unit is also connected to the third actuation means  9 , with the second means  11  for sensing the auxiliary syringe  8 , with the second control means  13  for controlling the sliding of the plunger  8   b , and with the means  14  for sensing the pressure applied to the plunger  8   b.    
     The first actuation means  5 , may for example comprise a shaft  15 , which forms (extends along) the axis A and is supported, so that it can rotate in first supports  16  formed in the base  2   a  of the supporting structure  2 , first motor means  17 , which are coupled to the shaft  15 , and means  18  for coupling the holder  3  to the shaft  15 . Conveniently, the first motor means  17  are of the step motor type and comprise an inverter. 
     The holder  3  comprises a tubular element  19 , inside which it is possible to insert the cylindrical body  4   a  of the syringe  4 . Means for rigidly fixing the tubular element  19  to the cylindrical body  4   a , for example of the interlocking, adhesive-bonding, or interference-coupling type, are provided. In a particular embodiment, not shown, the gripping means may comprise a longitudinal slot, which interrupts the continuity of the tubular element  19 , the inside diameter of which, in the configuration in which it is disengaged from the cylindrical body  4   a , is substantially smaller than the outside diameter of the cylindrical body  4   a.    
     The coupling means  18  can be of the interlocking and/or contrast and/or friction type; they comprise for example a receptacle or seat  20  holding the holder  3 , which is formed in the shaft  15  and is provided with cavities  21  in which it is possible to insert corresponding protrusions  22  formed in the holder  3 . 
     Advantageously, the seat  20  has a profile that substantially duplicates the profile of the outer lateral surface of the holder  3 . 
     Further, the holder  3  has a contoured portion  23  that has a contoured profile P ( FIG. 5 ), which can mate with a complementarily contoured head  24   a  ( FIG. 4 ) of a stem  24  that is inserted so that it can slide axially, with the interposition of elastic means  25 , in a guide  26  that is formed at the free end of the shaft  15  at the seat  20 . The head  24   a  protrudes into the seat  20  in order to mate with the portion  23  and push, by way of the reaction of the elastic means  25 , against the holder  3  so as to fix them to the shaft  15 . 
     The stem  24  has an end  24   b  positioned opposite the head  24   a , which protrudes externally from the free end of the shaft  15 , proximate to which the first sensing means  10  are arranged. The sensing means are supported by a plate  27 , which is fixed to the corresponding first support  16 . 
     Insertion of the holder  3  in the seat  20  produces the sliding of the stem  24  toward the outside of the shaft  15 , so that the end  24   b  acts on the first sensing means  10 , which being thus activated report the presence of the holder  3  and therefore of the syringe  4  rigidly coupled thereto. 
     Each one of the second actuation means  6  and of the third actuation means  9  comprises straight guiding means  28 , along which a slider  30  is associated so that it can slide alternately by way of bushes  29 , driven by a screw  31 , which is substantially parallel to the straight guiding means  28  and is supported so that it can rotate by second supports  32  formed in the base  2   a  of the supporting structure  2  and is coupled to a female thread  33  formed in the slider  30 , and second motor means  34 , which are carry the screw  31 . 
     The slider  30  rigidly supports the end of a bar  35 . A pusher  36  is fixed to the opposite end of the bar and can contact the plunger  4   b  or  8   b , respectively, of the syringe  4  and of the auxiliary syringe  8 . Conveniently, the second motor means  34  are of the step motor type and comprise an inverter. 
     The pressure sensing means  14 , constituted for example by a load cell, are fixed to the face of the pusher  36  that makes contact with the plunger  4   b  or  8   b.    
     The means  7  for locking the auxiliary syringe  8  may be constituted for example by a receptacle, such as a slot  37  ( FIG. 1 ) formed in a block  38  that is fixed to the housing  2   b , inside which it is possible to insert wings  39  formed at the inlet end of the cylindrical body  8   a , and a clamp  40  for locking the cylindrical body  8   a.    
     The first control means  12  and the second control means  13  comprise respective proximity sensors  41 , switches or the like, which can detect the position of the corresponding slider  30  and/or sensors  42  for detecting the rotation of the corresponding screw  31 . 
     A keypad  43  ( FIG. 1 ) and a display  44  anchored to the housing  2   b  allow to the operator select/set and monitor the operating program of the pump  1 . 
     With particular but not exclusive reference to a setup wherein the pump  1 , which comprises not only the means  3  for supporting the syringe  4  but also the means  7  for locking the auxiliary syringe  8 , is used to perform sonograms with a contrast medium (echocontrast sonograms), the operation of the invention is as follows: 
     The echocontrast sonogram technique provides for the infusion in succession of a contrast medium that contains gas microbubbles and of a physiological solution, in quantities, with rates and with a time interval between the first infusion and the second infusion that can vary according to the type of diagnosis to be performed and according to the physical characteristics of the individual patient (weight, age, etc.) 
     The syringe  4 , to which the holder  3  is already rigidly anchored, and which is filled with a preset quantity of contrast medium, and the auxiliary syringe  8 , filled with a preset quantity of physiological solution, are purged manually, the term “purging” being understood to designate the action meant to eliminate any residues of air contained in the syringes. 
     Once the operating program has been selected by means of the keypad  43 , the two syringes  4  and  8  are anchored to the pump  1 . In particular, the holder  3  is rigidly coupled to the shaft  15 , while the cylindrical body  8   a  of the syringe  8  is anchored to the housing  2   b  by way of the locking means  7 . 
     The first sensing means  10  and the second sensing means  11  report the presence of the syringe  4  and of the auxiliary syringe  8 , respectively, to the electronic control and monitoring unit CU. 
     The outlets of the two syringes  4  and  8  are connected to the inlets of a conventional infusion line of the Y-shaped type, the output of which is suitable to be connected to a tube for feeding to a patient. 
     By means of a command inputted at the keypad  43 , the shaft  15  is actuated by the first motor means  17  so as to oscillate about the axis A through a preset angle, as shown by the arrows F. The microbubbles of the contrast medium contained in the syringe  4  are thus mixed uniformly and distributed within it. 
     After a time interval that can be preset, the electronic unit CU stops the first motor means  17  and starts the second actuation means  6  and the third actuation means  9  to purge the infusion line, the outlet of which is not yet connected to the tube for feeding to the patient. 
     Once purging of the infusion line has ended and once its outlet has been connected to the tube for feeding to a patient, the electronic unit CU automatically restarts the first motor means  17  for another period of time during which the microbubbles of the contrast medium contained in the syringe  4 , which is oscillated about the axis A, are mixed and distributed uniformly inside it, the pusher  36  of the second actuation means  6  having been moved away beforehand from the plunger  4   b.    
     The medical personnel assigned to performing the sonogram, at its own discretion and despite having both hands occupied in operating the sonogram probe and in managing the processing of the images that it transmits to a monitor, then activates, by action on the foot pedal, the operation of the pump  1  to infuse the contrast medium and then automatically infuse the physiological solution without further interventions of any health personnel. 
     Once this time interval has elapsed, the electronic unit starts the second motor means  34  of the second actuation means  6  in order to infuse the contrast medium, as shown by arrow G. The end of the infusion is reported by the sensors  41 , which report to the electronic unit CU that the stroke limit has been reached by the corresponding slider  30 . 
     Once the second motor means  34  of the second actuation means  6  have stopped, the electronic unit CU starts the second motor means  34  of the third actuation means  9  in order to infuse in succession the physiological solution, as shown by the arrow H. As before, the end of this second infusion is reported by the corresponding sensors  41 , which report to the electronic unit CU that the stroke limit has been reached by the corresponding slider  30 . 
     Finally, the electronic unit reverses the rotation of the second motor means  34  and of the second and third actuation means  6  and  9  in order to return the corresponding pushers  36  to the beginning positions of their stroke, as shown by arrows L. 
     It should be noted that the initial position of the two plungers  4   b  and  8   b , which depends on the amounts of contrast medium and of physiological solution loaded in the corresponding syringes, is detected simultaneously by the pressure sensing means  14  and by the rotation sensors  42 . The former report the contact pressure with the plungers  4   b  and  8   b  and the latter report the number of turns made by the respective second motor means  34  before reaching the plungers  4   b  and  8   b.    
     The pressure sensing means  14  further allow the detection during infusion of any abnormal increase in pressure on the plungers  4   b  and  8   b , which indicates for example a venous occlusion. 
     This technique can be used for diagnosis for example in cardiology, neurology, gastroenterology, or for targeted therapeutic treatments. 
     The operation of the pump  1  in possible different applications can be deduced easily by the person skilled in the art. It can be used whenever it is necessary to mix the components of a fluid to be infused. 
     In practice it has been found that the described invention achieves the intended aim and objects. The pump according to the invention in fact allows one to automate not only the draining and infusion but also the mixing of the fluid to be infused, to mix the fluid homogeneously, precisely and in a short time without the intervention of auxiliary health personnel, and this accordingly entails a reduction of labor costs and of wastes of material, and allows medical personnel to perform mixing and infusion automatically and autonomously. 
     Finally, it should be noted that the alternated rotation of the syringe that contains the fluid to be mixed about an axis that is substantially perpendicular to the longitudinal axis of the syringe causes shaking and entrainment of the fluid between the two ends of the syringe, and this ensures uniform mixing, which cannot otherwise be obtained if the rotation of the syringe occurs about the longitudinal axis thereof. Due to the low viscosity of the fluids that are normally used, they in fact would not be entrained in rotation and therefore would not be stirred correctly. 
     The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. All the details may further be replaced with other technically equivalent ones. In practice, the materials used, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claim. 
     The disclosures in Italian Patent Application No, M02004A000028 from which this application claims priority are incorporated herein by reference.