WO2011064615A1

WO2011064615A1 - Drip device for medicinal fluids and the like

Info

Publication number: WO2011064615A1
Application number: PCT/IB2009/055318
Authority: WO
Inventors: Renzo Soffiatti; Mario Zocca; Massimo Grazioli; Denis Faccioli
Original assignee: Tecres S.P.A.
Priority date: 2009-11-24
Filing date: 2009-11-24
Publication date: 2011-06-03

Abstract

Infusor device for medicinal liquids and the like, comprising a frame (2) with which at least one tank (3) of medicinal liquid, syringe-operated infusion means (4) of the liquid selectively communicating with said tank (3) and at least one linear actuator (5) of said syringe-operated infusion means (4) are associated, characterised in that said linear actuator (5) is supported by said frame (2) through floating coupling means (7) to recover the axial clearances.

Description

"DRIP DEVICE FOR MEDICINAL FLUIDS AND THE LIKE"

TECHNICAL FIELD OF THE INVENTION

The present finding concerns an infusor device for medicinal liquids and the like. More specifically, the invention concerns an infusor device for medicinal liquids, like for example drugs, anaesthetics, chemotherapy chemicals, etc..

STATE OF THE ART

In the field of infusion devices for medicinal liquids for example drugs, anaesthetics, chemotherapy chemicals and the like, devices are currently used that comprise pumping means that dispense a certain flow rate of liquid along a duct usually communicating with an infusion needle.

One of the critical aspects of such devices consists precisely of the aforementioned pumping means, and in particular the flow rates that they manage to dispense, the precision with which they dispense, and also the constancy over time of the infusion pressure. With regard, in particular, to the flow rates to be dispensed, it needs to be considered that such pumping means must be designed and sized so as to be able to dispense flow rates of liquid even of very small amounts: for example, in some therapies, such a flow rate must be of the order of a few thousandths of a millilitre per hour.

Some types of infusion devices found on the market incorporate pumping means consisting of a diaphragm pump, actuated by a motor. This type of pump, as well as not being particularly suitable for dispensing such small flow rates, has the serious drawback of not managing to keep the infusion pressure of the liquid constant over time: during operation, indeed, errors are detected that can reach 25%, and that are therefore totally unacceptable for critical applications like those relating to the infusion of medicine.

Other types of infusion devices found on the market have pumping means consisting of a peristaltic pump, actuated by a motor. This type of pump is undoubtedly more precise, in operation, than the diaphragm pump: nevertheless, its precision is not such as to satisfy the current requirements of the field, and moreover the flow rate that can be dispensed is never less than one tenth of a millilitre per hour.

Another typical drawback of peristaltic pumps is the ratio between minimum and maximum dispensing. A peristaltic pump sized to dispense very small amounts of liquid is not indeed able to dispense very high flow rates, which in some applications are needed just as much as very low ones.

A good alternative to the above types of pumping means consists of syringe- operated pumps, i.e. comprising a hollow body, containing the liquid, in which a plunger sealably slides that, actuated by a linear actuator, pushes the liquid itself out from a dispensing hole.

Although this type of pump allows some of the aforementioned problems to be solved, since it manages to ensure a certain constancy of infusion pressure and the dispensing of very small flow rates of liquid, it nevertheless is not without drawbacks of another kind, which jeopardise the precision of measurement of the flow rate of liquid dispensed: considering the fact that the flow rates dispensed by this type of pump are actually very small, such drawbacks give rise to errors that are in no way negligible.

In particular, it has been observed that this type of pump, but more generally also the other types, have a series of mechanical and/or hydraulic clearances and/or elastic deformations, due for example to the methods for fixing the pump itself, the actuator, and other component that, obviously added to one another in a chain, have a substantial influence upon the measurement of the flow rate dispensed.

In greater detail, these mechanical and/or hydraulic clearances and/or such elastic deformations typically determine a degree of uncertainty in identifying the "zero" dispensing point of the pump, or even the intake zero point from possible external supply sources: indeed, it is not possible to establish with precision which portion of the motion of the plunger, during the actuation of the pump, is due to possible recovery of mechanical clearances and elasticity, and which on the other hand corresponds to actual dispensing of liquid. This uncertainty therefore gives rise to a systematic error in the dosing of liquid dispensed - or taken in - that clearly is unacceptable in applications in which such a flow rate is of the order of thousandths of a millilitre per hour.

PURPOSES OF THE INVENTION The technical task of the present invention is therefore to improve the state of the art. Within such a technical task, a purpose of the present invention is to provide an infusor device for medicinal liquids and the like suitable for dispensing very small flow rates of liquid, with high precision.

Yet another purpose of the present invention is to provide an infusor device in which the dosing of the liquid dispensed and/or taken in does not suffer from systematic errors, in particular due to mechanical and/or hydraulic clearances and/or elasticity present in the system.

A further purpose of the present invention is to make an infusor device in which the dosing of the liquid dispensed and/or taken in does not suffer from errors relating to the true "zero" of the measurement itself.

Another purpose of the present invention is to provide an infusor device suitable for precisely dosing very small flow rates of liquid and that, at the same time, has a large reserve of liquid to be dispensed.

These and other purposes are all accomplished by the infusor device according to one or more of the attached claims.

An important advantage given by the infusor device according to the present invention consists of the fact that it allows very small flow rates of liquid - of the order of one thousandth of a millilitre per hour - to be dispensed with very high precision, and in particular so that micromovements of the pump correspond, in an accurate and repeatable way, to microdoses of liquid.

Another advantage given by the infusor device according to the present invention consists of the fact that the dosing of the liquid does not suffer from possible errors due to mechanical clearances and/or elasticity present in the system, with particular reference to the "zero" point of such dosing.

Yet another advantage given by the infusor device according to the present invention consists of the fact that it allows a substantial reserve of liquid to be kept, and at the same time allows it to be dosed in small amounts with very high precision, so as to be able to ensure autonomy of operation even for many days.

BRIEF DESCRIPTION OF THE DRAWINGS.

These and further advantages shall be better understood by any man skilled in the art from the following description and from the attached drawings, given as a non- limiting example, in which:

figure 1 is a diagram of the infusor device according to the invention;

figure 2 is a perspective view of the tank and of the infusion means of the device;

figure 3 is a section view of the tank and of the infusion means of the device carried out according to a vertical plane;

figure 4 is a front view of the tank and of the infusion means;

figure 5 is a front view of the actuation group of the infusion means;

figure 6 is a detailed view of the actuation group;

figure 7 is a section view of the actuation group carried out according to the plane VII- VII of figure 6;

figure 8 is a detail of figure 7;

figure 9 is a detailed rear view of the actuation group;

figure 10 is a side view of the pressure sensor associated with the actuator of the infusion means;

figure 11 is a front view of the pressure sensor;

figure 12 is a detailed perspective view of the actuation group of the infusion means.

EMBODIMENTS OF THE INVENTION.

With reference to the schematic representation of figure 1, an infusor device for medicinal liquids and the like according to the invention is wholly indicated with 1. The infusor device 1 comprises a frame 2 with which a tank 3 of medicinal liquid, syringe-operated infusion means 4 of the liquid selectively communicating with the tank 3 and a linear actuator, wholly indicated with 5, of the syringe-operated infusion means 4 are associated. More specifically, as can also be seen in figures 2, 3, 4, the tank 3 and the syringe-operated infusion means 4 are fixed to a common channel 6 for the passage of the liquid, for example configured substantially as a tray, or else with a circular section, with which they selectively communicate, as shall become clearer hereafter.

The linear actuator 5 of the syringe-operated infusion means 4 is supported by the frame 2 of the infusor device 1 through floating coupling means 7 that, during the actuation of the syringe-operated infusion means 4, allow the recovery of the axial clearances between the linear actuator 5 itself and the frame 2, obtaining important technical advantages that are better described hereafter.

The tank 3 of the medicinal liquid is defined by rigid walls, and comprises a loading door 8 equipped with a tap 9; the tank 3 is also closed by a cover 10 with a hole equipped with an antibacterial filter Fl - i.e. a porous dividing wall that allows the passage of the gas and maintains aseptic conditions - and comprises a passive piston 1 1 that acts on the free surface of the liquid. The tank 3 is connected to the channel 6 for example with a screw-nut screw coupling, or with other equivalent attachment means, which can be permanent or removable.

A tank 3 devised in this way allows, in particular, the infusor device to work in any position, even upside down; moreover, air bubbles are prevented from forming during the emptying of the tank.

The syringe-operated infusion means 4 comprise a hollow body 12 in which a plunger 13 is able to sealably slide, equipped with an outer actuation head 14 suitable for being associated with the linear actuator 5.

The hollow body 12 is connected to the channel 6 for example with a screw-nut screw coupling, or with other equivalent attachment means, which can be permanent or removable.

The syringe-operated infusion means 4 also comprise a bellows casing 15, made from substantially yielding and elastic material, arranged between the hollow body 12 and the plunger 13, which allows the coupling between the aforementioned two components to be hermetically sealed, thus eliminating risks of contamination.

Indeed, since the plunger 13, during the operation of the device, repeats its path many times over, reloading the hollow body 12 at the maximum possible speed and pressing down at the dosing speed selected by the user, the syringe-operated infusion means 4 are exposed to the outside for most of the time, with the possibility that they may collect microbes or bacteria that could end up inside the seals thus compromising the aseptic conditions of the device.

The stem of the plunger 13 is equipped with a hole H for venting the air trapped between the bellows casing 15 and the stem itself; the stem of the plunger 13 is hollow, and communicates with a hole made in the head 14, at which an antibacterial filter F2 is mounted. Such venting of air is clearly necessary during the sterilisation process in an autoclave.

In an alternative embodiment of the device according to the invention, a protective casing is foreseen that encloses the entire device, thus eliminating the risks of contamination.

In the channel 6 for the passage of the liquid a first single-acting valve 16 is foreseen, which selectively places the tank 3 in communication with the syringe-operated infusion means 4; in particular, it places the tank 3 in communication with the hollow body 12 of the syringe-operated infusion means 4, i.e. it allows the passage of the liquid from the tank 3 to the hollow cylindrical body 12 and prevents it in the opposite direction.

In the channel 6, a second single-acting valve 17 is also foreseen that places the syringe-operated infusion means 4 in communication with a duct 18 for dispensing the medicinal liquid, i.e. it allows the passage of the liquid from the hollow cylindrical body 12 to the dispensing duct 18 and prevents it in the opposite direction.

The linear actuator 5 of the syringe-operated infusion means 4, illustrated in various views and details in figures 5-12, is incorporated in an actuation group A, defined by a support 19, with a substantially L-shaped cross section, which is rigidly fixed to the frame 2 of the infusor device 1 , and which, in practice, it constitutes an integral part of.

The support 19 defines an open seat 20, in which the linear actuator 5 is housed; in greater detail, said seat 20 defines a first shoulder 21 and second shoulder 22 that are both flat and opposite one another, which define the housing space of the linear actuator 5.

The linear actuator 5, in an embodiment of the infusor device according to the invention, consists of an electric motor; such an electric motor can, for example, be of the stepper type, since it is especially suitable for obtaining a high precision of movement of the plunger 13 of the syringe-operated infusion means 4, and therefore a high precision of infusion of the medicinal liquid. In particular, the choice of an electric stepper motor advantageously allows micromovements of the motor and microdoses of the syringe-operated infusion means 4 to precisely and accurately correspond to one another. Such an electric motor 5 can, however, also be of another known type, in relation to the specific application requirements.

Moreover, in other embodiments of the device according to the invention, linear actuators 5 of another type can be used, for example pneumatic, hydraulic, magnetic actuators, etc., should the application requirements allow it.

It is foreseen for there to be a screw 23, set in rotation by the electric motor 5, which is engaged in a through hole 24 made through the first shoulder 21 of the seat 20; the screw 23 has a bushing 25 coupled with it that is equipped with a nut screw 26 in its inner surface. The bushing 25 can, in turn, be coupled with the syringe-operated infusion means 4, as better described hereafter.

The support 19 comprises a guide 27 along which a trolley 28 can slide, fixed to the bushing 25; the trolley 28 forms a seating 29 in which the head 14 of the plunger 13 of the syringe-operated infusion means 4 can be engaged. In particular, the seating 29 defines two opposite recesses 30 in which the collars 31 of the aforementioned head 14 are intended to engage, so as to make a secure but quickly removable coupling. In greater detail, the syringe-operated infusion means 4 - i.e. the disposable part of the device - and the seating 29 are sized so as to couple together perfectly, so as to obtain insertion by simply pressing and so as to avoid any connection or operation that is difficult for the user.

With this provision the difficulties of installation of the disposable part of the actuation group A are eliminated, which in known devices, for example those with peristaltic actuation, are due to the need to connect various lines, to insert the peristaltic tubes into the relative pressers and to close the whole thing up securely.

The support 2 also comprises an open cylindrical housing 32, situated substantially alongside the seat 20, in which the hollow body 12 of the syringeroperated infusion means 4 is intended to removably engage.

In the seating 29 and/or in the cylindrical housing 32, there can be sensor means, not represented in the attached figures but of the essentially conventional type, which make it possible to detect the presence of the syringe-operated infusion means 4. The floating coupling means 7 of the linear actuator 5 with the frame 2 of the device, i.e. of the electric motor with the support 19, comprise at least one pin 33, fixed to the support 19 with screw means 34, at the ends, and slidably engaged in a respective hole 35 foreseen in the electric motor 5. More specifically, the floating coupling means 7 comprise four pins 33, fixed to the support 19 and engaged in four respective holes 35 foreseen in the electric motor 5, in particular situated at the four side edges. The floating coupling means 7 also comprise a first spring 36 arranged between the first shoulder 21 of the support 19 and a first end portion of the electric motor 5. In greater detail, the first spring 36 is of the cup type and is mounted on a respective first spring-carrier 37, comprising a tubular portion and a flange that abuts on the first end portion of the electric motor 5; the tubular portion of the first spring-carrier 37 is, in particular, slotted along the screw 23 del electric motor 5, as can be seen in figure 8. The floating coupling means 7 also comprise a second spring 38 arranged between the second shoulder 22 of the support 19 and a second end portion of the electric motor 5, opposite the first end portion on which the first spring 36 abuts.

The second spring 38 is also of the cup type and is mounted on a respective second spring-carrier 39, which engages on the second shoulder 22.

More specifically, this second shoulder 22 comprises a plate 40 that is fixed, for example with screws engaged in holes 41, at a circular opening 42 foreseen in the second shoulder 22 itself; such an opening 42 thus communicates with the seat 20 for housing the electric motor 5, as can be seen in figure 7.

The second spring-carrier 39 is inserted in the opening 42, in which it is free to slide along the axis of the electric motor 5.

The plate 40 carries, on its inner face that communicates with the opening 42, a pair of pressure sensors 43, which are thus arranged between the second spring-carrier 39 and the plate 40 itself, i.e. the frame 2 of the device. Such pressure sensors 43 allow the infusion pressure of the medicinal liquid to be detected during the operation of the device, as shall be made clearer hereafter. In an alternative embodiment, a single pressure sensor 43 can be used.

The pressure sensor 43, or both of them if there are two of them, is suitably preloaded, i.e. the mounting of the electric motor 5 inside the seat 20 takes place with a certain pre-compression of the springs 36, 38.

In an embodiment of the infusor device according to the invention, for more safety it is possible to monitor the pressure existing between the two single-acting valves 16, 17 with a pressure sensor P fixed onto an elastic membrane M at the channel 6. This provision allows it to be verified with certainty that the disposable device - i.e. the system consisting of the syringe-operated infusion means 4 and the tank 3 - has been inserted and also allows to double in a redundant way the information coming from the pressure sensor 43 applied behind the motor 5. The two pressure sensors 43, P should, even with different detected values, have results having the same trend over time, ensuring further operating safety.

A position sensor of the syringe-operated infusion means 4 is also foreseen, wholly indicated with 44, which detects the movement of the head 14 of the plunger 13 of the syringe-operated infusion means 4. In greater detail, the position sensor 44, for example of the linear potentiometric type, comprises a resistive band 45 fixedly connected to the support equipped with a protective sheet, and a contact roller 46 on said band 45 that is rotatably supported by the trolley 28. In greater detail, the pressure of the roller 46 on the protective sheet creates an electrical contact between the latter and the underlying band 45, thus closing an electrical circuit. The position sensor 44 can, however, be of another known and equivalent type, like for example of the optical or magnetic type, provided that it allows sufficiently precise and accurate measurements to be taken for this type of application. Such a position sensor 44 has the function of checking that every step commanded to the motor 5 is actually carried out by the plunger 13, as well as of unequivocally keeping the information on the position of the plunger 13 itself even when there is no power supply.

The electric motor 5, the pressure sensors 43, the position sensor 44 and the possible sensor means for detecting the presence of the syringe-operated infusion means 4 are operatively connected to a processing and control unit, not represented in the figures but of the type essentially known in the field, which manages the entire operation of the device, obviously according to parameters set by the users through a suitable control interface, not represented but of the known type.

The processing and control unit, and in particular its control interface for the user, can, in an embodiment of the device, be equipped with vocal indication means, for example concerning the type of therapy, how long it lasts, and whatever else; moreover, the same indication means can also be used to send alarm messages to the user and/or patient in real time when there is a malfunction of the device, and/or other messages relating to the method of administration of the medicinal liquid.

Moreover, in an embodiment of the device, the processing and control unit can be provided with an interface that can be connected to an external computer to make it easier to program the therapy, or else it can be equipped with information transmission means, of the so-called "Wi-Fi" type, for constantly monitoring the operation of the device.

In practical use, it is presumed that the tank 3 of medicinal liquid is initially empty: in this situation, the passive piston 11 is substantially in the end stop position close to the channel 6. During the loading of the medicinal liquid in the tank 3, the passive piston 11 is pushed towards the opposite end stop, and still always remains in contact with the free surface of the liquid, while the air comes out through the filter Fl : in this way, the liquid can be immediately dispensed from the tank 3, irrespective of the amount present inside of it.

At this point, it is possible to proceed to the loading step of the syringe-operated infusion means 4, by drawing the liquid from the tank 3.

At the start of such a step, the trolley 28 is in the position represented in particular in figure 12, i.e. the plunger 13 is completely inserted in the hollow body 12. Therefore, the motor 5 is started, setting the screw 23 in rotation: this determines a small displacement of the trolley 28 towards the opposite end stop position of the plunger 13, which causes all of the mechanical and hydraulic clearances present in the device to be recovered. At the end of this small displacement, which, as stated, is necessary for the recovery of the clearances, the pressure sensors 43 pick up an increase, in absolute value, in pressure. The passing of a certain predetermined pressure value thus indicates that the intake of liquid taken from the tank 3 has actually started: in other words, the processing and control unit of the device in this way records that the previous small displacement, also detected by the position sensor 44, did not produce any intake of liquid, but only a recovery of clearances. In this way, therefore, the processing and control unit is able to establish a sort of "zero" of the liquid intake step, i.e. it is able to calculate with a high degree of precision, taking into account the mechanical and hydraulic clearances of the device, the amount of liquid actually taken out from the tank 3. This, obviously, makes it possible to dose with very high precision, suitable for the requirements, the amount of medicinal liquid that has to be administered, for example, to a patient in a given time period.

Once the loading step of the syringe-operated infusion means 4 has ended, it is possible to start the actual dispensing step of the medicinal liquid.

Also when this step begins, therefore, the rotation of the screw 23 controlled by the electric stepper motor 5 determines a small displacement of the trolley 28, and therefore of the plunger 13, which is recorded by the position sensor 44, but not by the pressure sensors 43, which do not register any increase, in absolute value, in the pressure itself. As made clear earlier, this small displacement thus corresponds to a mechanical and hydraulic clearance recovery stroke, which therefore does not actually correspond to any dispensing of medicinal liquid to the patient.

As soon as the processing and control unit records an increase, in absolute value, in the pressure through the sensors 43, i.e. that a certain predetermined value has been passed, it establishes a sort of "zero" liquid dispensing point, i.e. it can define, with a high degree of precision, how much liquid is actually dispensed from the moment when a certain predetermined pressure value has been passed.

The pressure sensors 43 also allow the force exerted on the infusion device, which is directly proportional to the resistance to the forward movement of the infused liquid, to be constantly monitored; the pressure sensors 43 also allow an alarm signal to be generated in the case of pressures that are too high, and/or a blocking signal of the infusor device to be generated in the case of accidental blockage at some point of the infusion ducts; the pressure sensors 43 also allow the depression generated during the reloading of the syringe-operated infusion means 4 to be constantly monitored; they also allow the reloading speed in relation to the desired depression value to be adjusted.

With this solution, important technical advantages are obviously achieved.

A first important technical advantage consists of the fact that possible clearances and/or elasticity present in the system are elastically absorbed by the floating coupling means 7, and such absorption is detected by the preloaded pressure sensors 43 that, once a predetermined pressure value has been passed, allow the processing and control unit to establish the "zero" in the liquid intake or dispensing measurement: in this way, therefore, the dosing of the medicinal liquid does not suffer from systematic errors due to such clearances and/or elasticity.

Moreover, with such a provision a very high precision of infusion— of a few thousandths of a millilitre per hour - is obtained, which is not influenced either by the aforementioned clearances or elasticity, or by the infusion pressure itself.

It is thus possible, with the infusion device according to the invention, to obtain a higher infusion pressure than what can be obtained with conventional devices, and this is advantageous since it allows the load losses encountered in the infusion ducts of the liquid to the patient to be compensated, and it thus always allows the correct dispensing of liquid.

A further technical advantage consists of the fact that the pressure sensors 43, mounted on the device in the described way, allow numerous other functions to be performed, for example the safety monitoring of the infusion pressure and the consequent blocking in the case in which a threshold value has been exceeded.

Yet another technical advantage consists of the fact that the presence of the tank 3 associated with the syringe-operated infusion means 4, which can also have a capacity of 200 millilitres, allows an operating autonomy even of many days to be obtained, with hourly doses of the order of thousandths of a millilitre.

In some applications of the device it is not necessary to completely program the motion of the syringe-operated infusion means 4, but it is sufficient to simply set the infusion speed. In order to save time and avoid pointless insertion of data, the device according to the invention can be set in advance at a single infusion speed so that the operator can load and operate the device itself by simply pressing a button, as if to simulate the operation of an elastomer type pump.

It should be noted that it is possible to vary the precision and the minimum dispensing value by varying the diameter of the infusion syringe, at the same time keeping the same dimensions of the tank. It has thus been seen how the invention achieves the proposed purposes.

The present invention has been described according to preferred embodiments, but equivalent variants can be devised without departing from the scope of protection offered by the following claims.

Claims

1. Infusor device for medicinal liquids and the like, comprising a frame (2) with which at least one tank (3) of medicinal liquid, syringe-operated infusion means (4) of the liquid selectively communicating with said tank (3) and at least one linear actuator (5) of said syringe-operated infusion means (4) are associated, characterised in that said linear actuator (5) is supported by said frame (2) through floating coupling means (7) for recovering the axial clearances.

2. Device according to claim 1, wherein said syringe-operated infusion means (4) comprise at least one hermetically sealed bellows casing (15) arranged between said hollow body ( 12) and said plunger (13).

3. Device according to claim 2, wherein the stem of said plunger (13) is hollow and comprises a vent hole (H) communicating with an antibacterial filter (F2) foreseen in the head (14) of said plunger (13).

4. Device according to one of the previous claims, wherein said floating coupling means (7) comprise at least one pin (33), fixed to a seat (20) of said frame

(2) at the respective ends, engaged so as to be able to slide in a respective hole (35) foreseen in said linear actuator (5).

5. Device according to one of the previous claims, wherein said floating coupling means (7) comprise at least one first spring (36) arranged between a first shoulder (21) of said seat (20) and a first portion of said linear actuator (5).

6. Device according to one of the previous claims, wherein said floating coupling means (7) comprise at least one second spring (38) arranged between a second shoulder (22) of said seat (20), opposite said first shoulder (21), and a second portion of said linear actuator (5).

7. Device according to one of the previous claims, wherein said first spring (36) is of the cup type and is mounted onto a respective first spring-carrier (37).

8. Device according to one of the previous claims, wherein said second spring (38) is of the cup type and is mounted on a respective second spring-carrier (39).

9. Device according to one of the previous claims, wherein said second shoulder (22) comprises a plate (40) equipped with at least one pressure sensor (43) on which said second spring-carrier (39) abuts.

10. Device according to the previous claim, wherein said pressure sensor (43) is pre-loaded by said second spring-carrier (39).

11. Device according to one of the previous claims, wherein said seat (20) is defined by a support (19) fixedly connected to said frame (2), provided with , a cylindrical housing (32) for said syringe-operated infusion means (4).

12. Device according to one of the previous claims, wherein said linear actuator (5) comprises an electric motor.

13. Device according to the previous claim, wherein said electric motor (5) is of the stepper type.

14. Device according to one of the previous claims, wherein said syringe-operated infusion means (4) comprise a hollow body (12) and a plunger (13) able to sealably slide in said hollow body (12).

15. Infusor device according to one of the previous claims, wherein said electric motor (5) is associated with a screw (23) in turn coupled with a bushing (25) provided with a nut screw (26), said bushing (25) being able to be coupled with said syringe-operated infusion means (4).

16. Device according to the previous claim, wherein said bushing (25) is associated with a trolley (28) able to slide along a guide (27) associated with said frame (2) and comprising a housing seating (29) for the head (14) of said plunger (13).

17. Device according to one of the previous claims, comprising a first single- acting valve (16) that places said tank (3) in communication with said syringe- operated infusion means (4).

18. Device according to one of the previous claims, comprising a second single- acting valve (17) that places said syringe-operated infusion means (4) in communication with a duct (18) for dispensing the medicinal liquid.

19. Device according to one of the previous claims, comprising at least one channel (6) that places said tank (3), said syringe-operated infusion means (4) and said duct (18) for dispensing medicinal liquid in communication.

20. Device according to one of the previous claims, comprising at least one position sensor (44) of said plunger (13).

21. Device according to the previous claim, wherein said position sensor (44) comprises a metallic band (45) fixedly connected to said frame (2), and a contact roller (46) on said band (45) that is rotatably supported by said trolley (28).

22. Device according to one of the previous claims, wherein said tank (3) is defined by rigid walls and comprises a passive piston (11), so as to allow the device to operate in any position and to prevent the formation of air bubbles during the emptying of said tank (3).

23. Device according to one of the previous claims, wherein said tank (3) comprises a cover (10) that is perforated and equipped with an antibacterial filter (Fl).

24. Device according to one of the previous claims, wherein said tank (3) comprises a loading door (8).

25. Device according to one of the previous claims, comprising a processing and control unit to which said linear actuator (5), said pressure sensor (43) and said position sensor (44) are slaved.

26. Device according to one of the previous claims, comprising a pressure sensor (P) fixed onto an elastic membrane (M) at the channel (6) between said two single- acting valves (16), (17), suitable for monitoring the infusion pressure.

27. Infusion method of a medicinal liquid, actuated with the infusor device according to one or more of the previous claims, characterised in that it comprises the following steps:

actuating said linear actuator (5);

detecting the absolute pressure value through said pressure sensor (43);

once a predetermined pressure value has been reached, zeroing the measurement of the amount and/or flow rate of liquid infused or sucked from said tank (3); starting the infusion or sucking of the liquid;

measuring the amount and/or flow rate of liquid infused or sucked.