Pressure/force computer controlled drug delivery system and the like

The invention relates to a system for injecting or sucking in a fluid, with a container for the fluid, to which a fluid transport system is connected, which is provided at the end remote from the container with an element designed for insertion into a patient's body, preferably with an electrical element Drive mechanism for applying pressure to the fluid in the container for pressing out or sucking in fluid, and with a pressure or force sensor.

Such systems are used, for example, for subcutaneous injection of drugs or for sucking in body fluids, with intermittent, occasional or limited operation (as opposed to continuous drug supply) being provided.

Infusion pumps and similar systems for delivering a drug can have compact pump housings or they can be large, stationary pump units. When drugs are administered, the drug, for example intravenously, is supplied to a patient via an infusion line and a catheter or the like. These systems have been improved time and again with regard to line blockages. A line blockage inevitably increases the pressure in the system. In the prior art, it has been proposed here to identify a predetermined threshold value or to display the pressure in order to determine a clogging pressure within selected ranges and to ensure the safety of the patient, cf. for example US Pat. No. 5,295,967 A, US Pat. No. 4,731,058 A and No. 5 080 653 A. These known systems, however, do not disclose any drug delivery via a hollow needle. In addition, these systems do not relate to a device for aspirating drug delivery, which, however, is necessary with subcutaneous injection in order not to deliver the drug into a blood or lymphatic vessel.

Negative side effects such as pain, tissue damage and post-operative complications have long been tolerated using existing hypodermic drug injection systems. This is clearly documented in both dental and general medicine literature. Tissue damage and pain are a direct result of an uncontrolled flow rate in connection with excessive pressure that occurs within the tissue during the administration of the drug solution. Only the reaction of a patient to a subjective pain sensation gives an indication to reduce the flow rate during the drug administration. It has also been scientifically demonstrated that certain pressures (too high pressures without clogging) damage a certain type of tissue. It is therefore doubtful that a given flow rate in conjunction with a given pressure range maintained during the delivery of drugs with a subcutaneous injection can prevent a subjective pain response as well as tissue damage. It is necessary that the system permit priming at a controlled delivery rate and pressure in order to avoid these negative side effects during fluid movement. US Pat. No. 5,180,371 A discloses a rate-wise administration of a medicament via a hypodermic needle, but not how a determination, a measurement recording or a display of the pressure is possible during the administration of the medicament.

During the early 1980s it was shown variously (see, for example, Rood: "The Pressure Created by Inferior Alveolar Injections", British Dental J. 144: 280-282 1978; Walton and Abbot: “Periodontal Ligament Injection; a Clinical Evaluation, JADA “October 1981; Smith and Walton, “Periodontal Ligament Injection; Distribution of Injected Solution, Oral Surg 55: 232-238, 1983) that even a limited pressure generated by an injected fluid cannot necessarily prevent tissue damage and pain. Variability of different collagen types and densities in connective tissue results in different tissue flexibility and elasticity. These variations were confirmed both in different people and in different areas of a subject. Rood states in his 1978 article that “the relationship between injection rate and pressure increase, which was evident with smaller volumes, was lost with an injection of 2.0 ml. Various high pressures were recorded as well as some unexpected low pressures. Many experiments showed a pattern in which a tissue break could be inferred, and it is possible that these small breaks are due to the fact that the fluid was no longer contained in the pterygomandible space, because the volume injected corresponded to the volume previously estimated of the tissue space. Hence it seems that the flow rate is at

AT 412 837 B of an interstitial injection is in no direct relation to the pressure.

Smith and Walton described in their above-mentioned article that they have a histological

Animal (rabbit) study undertaken and used a technique to calibrate manually generated pressures. They concluded that “the injected volume and needle placement cannot always be attributed to the distribution ... an injection under medium to strong counterpressure resulted in deeper and more widely distributed paint penetration. This in turn confirms that the pressure is the critical variable in the distribution of the solution within the tissue and that the volume is not always related to the pressure generated.

Pashley, Nelson & Pashley showed in "Pressures Created by Dental Injections", J. Dent. Res. Io 1981, using a pressure transducer and a set flow rate generated by a motor drive for a conventional syringe, that different tissues have different tissue compliance. Changes in interstitial pressure, even at a fixed flow rate, were both statistically and clinically significant. From this it can be concluded that enormously different pressures can be brought about at a measured flow rate.

Pertot and Dejou described in their article “Effects of the Force Developed during Periodontal Ligament Injections in Dogs”, Oral Surg. Oral Med, Oral Pathol., 1992, how they used a syringe coupled to a miniature force transducer and found a positive correlation between the number of osteoclasts and the force applied to the syringe plunger, which shows that the pressure created in the PDL space increased osteoclastic activity. This experiment again showed that the pressure is a critical factor for tissue damage and depends on the opposing resistance, and not the flow rate at which the solution penetrates the tissue.

According to US Pat. No. 5,295,967 A, the pressure inside the syringe is measured. Specifically, in the medical syringe pump known from this, the injection pressure is continuously measured and displayed by means of a pressure transducer in order, among other things, to avoid occlusions in the infusion line, which can lead to tissue damage and pain in the patient. The sensor provided for measuring the pressure inside the syringe, however, only records the internal system pressure. It is not possible to adjust the flow rate and / or fluid pressure to compensate for changes in resistance throughout the system or depending on the outlet pressure (outlet pressure refers to the fluid pressure immediately downstream of the needle tip within the patient's body). A device for determining this outlet pressure is not known. A determination of a pressure caused by the system in the tissue is also not feasible, nor is a corresponding further processing of the determined value to optimize the flow of the fluid entering or exiting the tissue.

One of the goals in dentistry and general medicine should be to treat the patient in a humane and painless manner. Any treatment should aim to achieve the desired result without causing harm or pain to the patient. Thus, in all areas of surgery, there is a great need for an injection system which can be used to administer a fluid and which causes essentially no pain or tissue damage to the patient.

The aim of the invention is to provide a system of the type mentioned at the outset with which pain or tissue damage can be effectively avoided in a patient when a fluid is supplied - or else sucked in.

The invention is thus aimed at minimizing the subjective pain response and the risk of possible tissue damage in patients resulting from inadequate pressure applied via a hypodermic needle during the administration of a drug. However, it should be possible to use a large number of different drug sources, for example standard syringes as well as anesthesia ampoules or cartridges. Furthermore, the system should be able to be used in a simple manner by a doctor with a minimal amount of practice. The system should also have a part that is essentially easy to dispose of or remove. Furthermore, not only injections, but also exact aspirations and / or biopsies should be possible with the system, whereby the flow rate and the pressure can be controlled. The outlet pressure (or inlet pressure) should be used as a control parameter for

AT 412 837 B any size and any combination of syringe, line and needle can be automatically determined and used.

The system according to the invention of the type mentioned at the beginning is achieved in that the pressure or Force sensor is set up to detect an internal parameter which is characteristic of the force generated by the drive mechanism and the internal resistances in the container and transport system, a control unit being connected to the sensor and to the drive mechanism, which contains a computing unit for calculating an input / output pressure at the end of the fluid transport system facing away from the container as a function of the internal parameter and generates commands for limiting the input / output pressure to a predetermined threshold value. With such a design, the above objective is met in an advantageous manner, and pain and tissue damage in patients in the course of administering drugs or sucking in body fluids are avoided, since the actually relevant pressure is monitored.

For pressure monitoring, it is advantageous if the control unit has a comparator for comparing the input / output pressure with the predetermined threshold value.

In order to adapt the system as best as possible to the subjective pain sensation of a patient, it is advantageous if the predetermined threshold value is selected according to a pressure level in the patient's tissue.

For high flexibility of the system according to the invention, it is advantageous if the container for the fluid and the fluid transport system are in a detachable connection with the rest of the system.

It is also advantageous if the computing unit has a memory unit for storing the physical properties of the container for the fluid and the transport system. The inlet / outlet pressure can then be optimally determined on the basis of these physical properties.

For setting the correct pressure, it is also advantageous if the input / output pressure can be determined on the basis of the fluid with the aid of the computing unit.

For simple operation and control of the system according to the invention, it is advantageous if an input element connected to the memory unit is provided for inputting data relating to the physical properties of at least the fluid, the container and the transport system. The input element can be formed, for example, by a keyboard, a touchscreen, a voice-activated device for receiving information from the operator, such as a doctor or a medical assistant.

It is particularly advantageous if the control unit has a main microprocessor for processing the physical properties and a microprocessor controlled by the main microprocessor for generating the commands.

In this connection it is also advantageous if the drive mechanism has a motor controlled by the controlled microprocessor and a coupling connecting the motor to the container. The pressure or force sensor is preferably arranged in the clutch. For example, the container for the fluid has a piston that can be pushed back and forth. The clutch can move the piston with the help of the motor, whereby the pressure or Force sensor can detect or measure the force generated by the motor and applied by the piston in the container.

To achieve a compact, protected unit, it is advantageous if the motor and the controlled microprocessor are arranged in a housing that accommodates the drive mechanism.

In order to avoid malfunctions, for example after or when replacing the container for the fluid, a position sensor can advantageously be provided which detects the container in position and which is connected to the control unit, which generates commands only after the container has been detected in position.

A syringe, a carpule or cartridge or the like can be used as the container for the fluid. In the case of a cartridge, it is advantageous if the container is assigned a cartridge with a side wall and a holding stop, the drive mechanism having an adapter with an element which is connected to the holding stop.

The aforementioned main microprocessor can be used as an independent computer unit in the form of a

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PC or a laptop can be provided, and it can form the interface to the doctor and collect the data from the mechanical device. The main microprocessor may be in communication with a display to provide instructions to an operator, such as a doctor. Furthermore, the main microprocessor can be connected to different databases, each database being able to be connected to at least one of the exchangeable parts, such as the container for the fluid and / or the transport system, as well as to other components of the system according to the invention.

During operation, the container for the fluid is filled and a setup process is started. Various process parameters are calculated that can be loaded or entered by the doctor. The physician determines the fluid flow rates, the syringe outlet or inlet pressure, and the total amount of fluid to be dispensed or ingested. He then operates a pneumatic control, such as a foot pedal, and starts the flow of fluid. Alternatively, the doctor's entries can also be made electronically or by voice. During the fluid discharge or suction, the current output or input fluid pressure is calculated from the output signal output by the force or pressure sensor. When this outlet or inlet pressure approaches a certain threshold, the fluid flow rate is automatically reduced to prevent excessively high outlet / inlet pressure. This can ensure that no pain is inflicted on the patient or the tissue is damaged. There are also various options

Features, including aspiration, flushing or admission of the medium with or without air, are provided.

As already indicated, the system can alternatively be operated in a biopsy mode in which the suction pressure and the dispensed or withdrawn fluid rate represent the relevant control parameters.

Throughout the procedure, the physician is constantly provided with information both visually and audibly about the process, including the instantaneous flow rate, total volume injected or aspirated, inlet and outlet pressure, and other parameters. The loop calculation microprocessor receives the commands from the main microprocessor and generates the drive signals required to operate the motor.

In the following, the invention is explained in more detail with reference to the exemplary embodiments shown in the drawing. 1 shows a schematic perspective view of a system according to the invention; Figure 2 is a perspective view of a drive mechanism for the system of the present invention; 3 shows a perspective view of the drive mechanism according to FIG. 2, but now without the housing; FIG. 4 is a perspective view of the drive mechanism according to FIG. 2 and 3 with the housing broken open; FIG. 5A shows a plan view of the housing according to FIG. 2 or 4; FIG. FIG. 5B shows a schematic perspective view of the housing according to FIG. 5A; FIG. 6 shows an enlarged schematic view of a bracket for holding and fixing a syringe on the housing; 7A shows a plan view of an actuating plate for actuating the syringe in the system according to FIGS. 1 and 2; FIG. 7B is an enlarged view of the actuating plate according to FIG

Figures 1, 2 and 7A; 8 is a sectional view of a prior art fluid cartridge; 9 is a schematic side view of an adapter for using the cartridge shown in FIG. 8 in the system according to FIGS. 1 to 7; 10 shows a block diagram of an electronic control for the system according to the invention; Fig. 11 is a flow chart showing the operation of the controller of Fig. 10; Fig. Figure 12A is an example of a display panel showing various choices for the detachable parts of the system according to the invention; 12B shows an example of a typical display field in which the optional properties and parameters for setting the system according to the invention are summarized; 13 is an example of a typical display panel for display during a setup process; Fig. 14th a graphical representation of the pressure curve as a function of the actuation of a foot pedal; Figures 15A and 15B are graphs showing fluid flow and outlet pressure versus time; Figures 16A and 16B are respective graphs of fluid flow and outlet pressure when it exceeds a threshold value; 17 shows a flow chart to illustrate the sequence during an aspiration; Fig. 18th a flowchart showing the procedure for loading a syringe; 19 shows a syringe and associated equipment for filling the syringe; and Fig. 20 is a flow chart showing the procedure for determining the

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Outlet pressure using a typical component.

The structural components of the system 10 according to the invention are shown in FIGS. An electronic control unit 150 is explained in more detail with reference to FIGS. 10 to 18. The system 10 has a drive mechanism 12, a container 90, such as a syringe, cartridge or the like (hereinafter simply referred to as a syringe 90) and a fluid transport system 14 with a handle 16 connected to the syringe 90. The transport system 14 ends in an element designed for insertion into a patient's body, such as a needle 17. The syringe 90 is arranged on the drive mechanism 12. The syringe 90 has a plunger 94 which can be pushed back and forth with the aid of the drive mechanism 12 in order to selectively transfer a fluid through the

Transport system 14 to dispense through the handle 16 and through the needle 17 or alternatively to suck in a fluid. The drive mechanism 12 is connected to an external control unit 18, for example in the form of a computer, for selecting various operating parameters, which are explained below. This external control unit 18 can be provided on a housing 22 of the drive mechanism 12 or as a separate computing unit that is associated with the drive mechanism

12th is connected via a cable 20. The control unit 18 can be, for example, a PC or laptop. Alternatively, the control unit 18 can also be arranged internally, ie in the housing 22.

Details of the drive mechanism 12 are shown in FIGS. 1-5. 2 and 5B, the housing 22 of the drive mechanism 12 has a top surface 24 and an intermediate surface 26 disposed below the top surface 24. A slide 28 is provided on the intermediate surface 26 which extends along the longitudinal axis of the housing 22. An actuation plate 30 can be moved back and forth along the longitudinal axis of the housing 22, namely along the rail 28, as will be described in detail below.

In the upper surface 24, as can be seen more clearly in FIG. 5A, two parallel slots 32, 34 extending along the housing 22 are provided, between these slots 32,

34 a groove 36 is formed. The ends of each of these slots 32,34 have side extensions 38 which face one another. The end of the groove 36 facing away from these extensions 38 adjoins a transverse slot 54.

A bracket 40 (FIG. 4) can be moved in the slots 32, 34. As shown in FIG. 6, the bracket 40 is formed by an essentially C-shaped body 42 which has a web 46 and ends in two inwardly directed legs 44 or towards one another. A screw 48 with a screw head 50 is guided through a threaded opening (shown in dashed lines) in the web 46 and has a stop cushion 52 at its end facing away from the screw head 50.

According to FIGS. 5A and 6, the bracket 40 is constructed and arranged in such a way that its legs 44 engage in the extensions 38 of the slots 32, 34 in order to enable the bracket 40 to be displaced horizontally along the slots 32, 34 will.

In FIGS. 7A and 7B it is shown in detail that a further slot 56 is formed in the upper surface 58 of the plate 30, which slot is formed on one side with a stepped lock track 60. According to FIGS. 3 and 4, a motor 66 is arranged in the housing 22. By the engine 66 is one

Spindle 72 out. The spindle 72 is arranged such that it depends on the motor 66

The direction of rotation is moved in one direction or the other parallel to the longitudinal axis of the housing 22. One end of the spindle 72 is connected to a punch 74 on which a plate 76 is arranged. A load cell 78 is arranged between the plate 76 and the punch 74 in order to measure and transmit the force occurring between the punch 74 and the platform 76. The load cell 78 is designed to be bidirectional so that it can measure both a compressive force and a tensile stress, depending on whether the spindle 72 is moved to the left or to the right according to FIG. 3. Two short rods 80 connect the punch 74 to the plate 76 and prevent the rotational forces applied to the platform 76 by the motor 66 from being transmitted.

The plates 30 and 76 are connected to one another by rods 82, 84. These rods 82, 84 are slidably held on the housing 22 by two bushings 68, 70. With the exception of the bushings 68, 70, the plates 76 and 30 slide inside and outside the housing 22. The rods 82, 84 are guided through a wall 86 which extends through holes between the surfaces 24, 26 (see FIG. 2) (not shown) extends. The rail 28 (see Fig. 2) is hollow and aligned parallel to the spindle 72 in order to be able to move the spindle 72 in the longitudinal direction along its axis through the housing 22. The syringe 90 typically has a syringe body or barrel 92 which is shown in FIG

AT 412 837 B of the groove 36 (see FIG. 5A) is arranged, the bearing surface 95A (see FIG. 6) being received in the slot 54. The syringe 90 has a piston 94 which can be moved back and forth within the cylinder 92 with the aid of a piston rod 93. The piston rod 93 ends in a finger support surface 96. When the syringe 90 is inserted into the groove 36, the finger support surface 96 is located in the slot 54 of the plate 30. In this position, the syringe 90 is secured to the housing 22 by inserting the legs 44 of the bracket 40 into the slot widenings 38 and sliding the bracket 40 to the right over the syringe 90 until it reaches the end of the syringe body 92 adjacent to the slot 54. In this position the screw 50 is tightened, whereby the stop pad 52 moves downwards and the syringe body 92 of the syringe 90 is held in place. The groove 36 helps position the syringe 90. The syringe 90 ends with a LUER cone 95 to which the transport system 14 can be connected.

The motor 66, the punch 74, the load cell 78, the spindle 72 and the plate 76 are in

Housing 22 arranged and the plate 30 outside the housing 22. When the motor 66 is driven, as described below, it drives the spindle 72 in one direction or the other. The spindle 72 in turn presses on the plates 30, 76 and the rods 82, 84 to move them together, whereby the piston 94 in the syringe body 92 of the syringe 90 is moved. The only elements that move in and out of the housing are the rods 82,84. Thus, most of the critical elements of the system 10 within the housing 22 are protected from exposure or any fluid splash. In addition, the drive mechanism 12 is designed in such a way that it can accommodate syringes with different diameters and different lengths and can cooperate with them. The transport system 14, the handle 16 and the needle 17 can also have any size.

In the embodiment explained so far, it was assumed that a fluid is being dispensed from the syringe 90, whereby the syringe 90 can be supplied by the manufacturer, the clinic or by a

Operator must be recharged with a fluid before each operation. However, it may also be desirable to provide the fluid in a cartridge, such as the cartridge 100 shown in FIG. 8. Such a cartridge 100 has a cylinder 102 in which a piston 104 made of rubber or similar elastic material can be pushed back and forth is to optionally dispense the liquid contained therein. The cartridge 100 is provided with a seal which is formed from a membrane 106 which is to be pierced to release the contents of the cartridge 100.

FIG. 9 shows an adapter 110 which can release the fluid in such a cartridge 100 by means of the drive mechanism 12 shown in FIGS. 1 to 7. The adapter 110 has a holder 112 for holding the cartridge 100. The holder 112 has a first end with a connecting part 114 (for example a LUER cone) for connecting the adapter 110 to the transport system 14. An inwardly directed mandrel 116 is arranged on the inside of the connection part 114 in order to pierce the membrane 106 of a cartridge 100 inserted into the holder 112. At the end opposite the connection part 114, the holder 112 is provided with radial projections 118 in order to be able to fasten the holder 112 to the drive mechanism 12.

The adapter 110 also has a coupling element 118 which is designed with a shaft 120 which ends at one end in a point or a hook 121 and at the opposite end in a thumb punch 122. The shaft 120 runs through a cap 124 for fastening to the holder 112 with the aid of the projections 118, the projections 118 engaging in corresponding recesses (not shown) in the cap 124. The cap 124 is with a handle

126 which extends radially and approximately the shape of the bearing surface 95A (Fig. 6A) of a standard syringe 90 has.

In order to attach the cartridge 100 to the drive mechanism 12, it is first inserted into the holder 112 via the rear end thereof. When the cartridge 100 is inserted in the holder 112, the shaft 120 is aligned longitudinally to the axis of the holder 112 and advanced, whereby the hook 121 is pressed into the piston 104 until it is firmly engaged in this.

The cartridge 100 is then pushed in the direction of the connecting part 114, so that the mandrel 116 pierces the membrane 106 and thereby creates an outlet opening for the fluid contained in the cylinder 102 of the cartridge 100. To ensure that the fluid does not splash, this can

Transport system 14 are fastened in advance to the connection part 114, the transport system 14

AT 412 837 B has been omitted in FIG. 9 for reasons of clarity.

Instead of the hook 121, a piston 121A can also be arranged on the shaft 120, so that when the piston 121A is inserted into the holder 112, a vacuum / pressure connection is established between it and the piston 104 of the cartridge 100. As a result, the

Movement of the piston 121A in both directions so that the piston 104 follows this movement and thereby either presses fluid into the system or sucks it out of the system.

The cap 124 is then connected to the holder 112 by pressing the projections 118 into the recesses in the cap 124. In this arrangement the cartridge 100 with the adapter 110 now has a structure similar to a syringe 90 and can be arranged on the drive mechanism 12 according to FIGS. 1 to 7 exactly like a syringe, the bracket 40 grasping the cap 124 and the handle 126 itself extends in slot 54 and thumb punch 122 engages slot 56 of plate 30. In this position of the adapter 110, the motor 66 can be activated to move the shaft 120 and the piston 104 into or out of the cartridge 100, with fluid being dispensed via either the hook 121 or the piston 121A or after

Desire is sucked in. The hook 121 (or the piston 121A) can ensure precise engagement and a firm mechanical connection of the shaft 120 with the piston 104, whereby the piston 104 follows the movement of the shaft 120 and the plate 30 in any direction.

FIG. 10 shows a block diagram of an electronic controller 150 (18 in FIG. 1). The controller 150 has two microprocessors, a main (master) microprocessor 152 and one

Slave microprocessor 154. The slave microprocessor 154 is used to provide signals that drive the motor 66 and to receive information regarding the position of the plates 30,76.

The main microprocessor 152 is used to receive information regarding the remainder of the system 10, including the syringe 90 and its contents, the transport system 14, the handle 16, etc., and to generate control signals for the microprocessor 154 to operate the motor 66, so that the contents of the syringe 90 can be dispensed.

The microprocessor 154 and the circuitry connected to it are arranged in the housing 22. The main microprocessor 152 is integrated in the control unit 18, which is connected to the housing 22 by a cable 20, as shown in FIG.

According to FIG. 10, a main microprocessor 152 is connected to a memory unit 160, to input elements 162, to a display device 164 and to an interface 166.

The storage unit 160 is provided to store a program flow and data for the main microprocessor 152, in particular to store six or more databases which are intended for the following information: (a) syringes; (b) transport hoses; (c) needles;

(d) fluids; (e) control parameters; and (f) profiles consisting of a plurality of parameters for a particular process to be performed. Each of these parameters are used to determine the control signals generated for the microprocessor 154. Each database contains the appropriate parameters for various commercially available products, or alternatively, each database contains parameter data obtained from a special algorithm. the

Information regarding the various elements for a specific configuration of the system 10 is entered via the input elements 102 and confirmed on the display device 164. The input device 102 can have a keyboard, a touch screen, a “mouse”, but also a microphone. When a microphone is used, the acoustic commands are interpreted by a speech recognition circuit 162A.

The display device 164 is also used to display information and instructions for the operation of the system 10. The commands for operating the motor 66 are generated by the main microprocessor 152 and given to an interface 162. The main microprocessor 152 is also connected to a speaker 165 which plays various audible messages including spoken, recorded or synthesized words (generated by a speech synthesizer 165A), chimes, etc. to provide instructions to the doctor and other information about the current status of the entire system 10 and its elements without the doctor constantly having to look at the display panel.

The microprocessor 154 receives these commands via the cable 20 shown in FIG. 1 or via another connection and an interface 170.

With the microprocessor 154 are also one or more position sensors 172 as well as a

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Drive breaker circuit 174 connected. As already mentioned, the force applied between the plate 76 and the punch 74 is measured by the load cell 78. This print line can be, for example, a Model S400 print line manufactured by SMD, Inc. of Meridian Connecticut.

A foot switch or pedal 176 is also connected to the microprocessor 154. Pedal 176 preferably includes an air chamber with a flexible side wall, which side wall is intended to allow for a change in the volume of air and pressure in the chamber in response to operator actuation. A pressure sensor (not shown) is part of the pedal 176 and is intended to send information about the pressure to the microprocessor

154 output via a corresponding analog-to-digital converter 190. Pedals of this type are im

Prior art is known, so that a description of its details can be dispensed with.

A sequence of operations of the system 10 will now be described in connection with FIG. Beginning in step 300, the system 10 is started. Since this step 300 requires an exchange of information with the doctor and the environment, this step is performed by the main microprocessor

152 executed.

Step 300 initially includes the entry of the following information by the doctor: type of syringe 90 used, type (ie length and size) of the tubing of transport system 14, type of needle 17 used and name or corresponding identification of the fluid in syringe 90. These Information can be entered manually by the physician using the input device 162, such as a keyboard or a touch screen. Alternatively, a plurality of corresponding parameters (for example relating to syringes) can be taken from the database, displayed and offered to the doctor for selection. The doctor then uses a standard selection device, such as a mouse or touch screen, to select the correct syringe. Alternatively, a voice command can be used for this selection.

Fig. 12A shows a typical mask displayed on the screen for determining or selecting a syringe. For example, the physical properties, such as length, nominal volume, stroke length, injection force, are taken from the database and displayed after the syringe has been selected. After selecting a needle and a fluid, their properties are also read out from the database and displayed.

Some of the information, such as the length of the tubing, must be entered manually as it would be too difficult for the system to determine. Other information, such as various process parameters, can be determined automatically. For example, the identification of a syringe 90 can be encoded in a section of the syringe and read in by the system 10. As described below, one is required

Parameter is the cross-sectional area A of the syringe. This is determined by dividing the volume by the stroke or length of the syringe.

Once the information relating to the components of the system 10 has been entered or otherwise selected, a different display mask is presented to the doctor on the screen (see FIG. 12B) in order to either provide further information or to enable the

Physician can enter certain additional procedural parameters that are required to complete setup.

The display mask of FIG. 12B has five general areas labeled 502, 504, 506, 508 and 510. In area 502, general information is displayed or selected by the doctor, including a determination of the particular profile to be used, for example

"Periodontal Ligament Injection". In the area 504, the parameters of the display mask 12A are repeated in an abbreviated format, as a result of which information about the syringe 90, the needle 17, the tube and the fluid is reproduced.

In area 506, the physician selects the type of procedure (ie, injection) required, the high and low flow rates, and the optimal pressure limit. As mentioned, this one is the last

Parameters are very important because they are used to control pain and tissue damage that can be inflicted on the patient during the procedure. In addition, additional parameters such as filling flow rates, aspiration volume and flow rate, delivery volume and flow rate, etc., can be selected in this area.

In area 508, the doctor determines, for example, the total amount of fluid to be dispensed and whether (a) the syringe 90 is filled, (b) is to be supplied with air; or (c) should not contain air. Of the

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In this field, the doctor also selects whether or not to provide for aspiration. Finally, area 510 is used to display various parameters that are calculated based on the information previously acquired or selected, including system volume, maximum flow rates, maximum pressure, etc.

In one embodiment, the system 10, and in particular the main microprocessor 152, then uses these parameters to obtain a profile from the profile database, via which the sequence and program properties are determined which are required or optimized for the delivery of the fluid through the needle 17 Rate are required. The profile for each special syringe-hose-needle combination is calculated and stored in memory. These profiles io have uniform characteristics for each type of surgical procedure. For example, the profile for a PDL (periodontal ligament) is to be distinguished from a profile for a cranial subcutaneous anesthetic delivery. Only a group or family of profiles associated with the particular process can be stored in the memory of the main microprocessor 152 since other such profiles are unnecessary.

Alternatively, the main microprocessor 152 may be programmed to perform the calculations necessary to generate the profiles. It is assumed, however, that the profiles for most applications are calculated and programmed a priori or stored in the database as described above.

After completing the setup process, a test is performed 20 as shown in step 302 of FIG. 11 to determine whether or not the physician wishes to fill the syringe 90 using the system 10. In many cases it can be expected that the doctor will fill the syringe 90 manually or use an already filled syringe 90 or cartridge 100. When the syringe 90 is refilled outside of the system 10, the main microprocessor 152 then sends a command to the microprocessor 154 in accordance with step 304 to move the platen 30 to an initial position.

As shown in FIG. 10, the microprocessor 154 is connected to the load cell 78 via an analog to digital converter 83, as well as to a RAM 182, an EEPROM 184 and a limit switch or sensor 172. The microprocessor 154 then controls the operation of the motor 66 using the information provided by these elements, described in detail below, and in response to commands issued by the main microprocessor 152 via the interface 170. In particular, the microprocessor 154 actuates the drive circuit breaker 174 which then generates step-shaped pulses for the motor 66 in order to rotate the motor 66 in one of the two directions according to discrete angular increments. The frequency of these pulses determines the speed of the motor 66. Separate speeds can be used for high flow rate, low irrigation flow rate, aspiration, or a

Filling can be used. The physician selects the values ​​for each of these speed parameters and the microprocessor 154 then calculates the appropriate motor speed (ie, step frequency) using the dimensions of the syringe 90 and transport system 14.

The microprocessor 154 monitors the position of the plates 30, 76 by counting the number of times that the

Motor 66 steps taken. Alternatively or in addition, another sensor switch can be provided in order to record and adjust the position of the plates, such as plate 76, at different locations along their path of movement. In the preferred embodiment, at least one sensor switch 172 is provided which determines the (initial) end position of the plate 76. All other positions of the plate 76 are calculated on the basis of this end position. For example, the end position can be the leftmost position, as shown in FIG. 4.

The motor 66 is preferably provided with permanent magnets of a rare earth metal, so that it can be made relatively compact and yet generate a large torque.

Referring to Figure 11, at step 304, main microprocessor 152 sends a command to instruct microprocessor 154 to move platen 76 to the end position. A list of all commands of this type is stored in the storage unit 61 as part of the control database. The microprocessor 154 activates the motor 66 until the plate 76 has reached the end position, and this position is verified by a signal from the sensor 172 and confirmed to the microprocessor 152. Then, in step 306, the main microprocessor 152 directs the plate 76 to be moved to the initial position. This initial position is a function of the selected syringe 90 and that in FIG

AT 412 837 B

Syringe 90 contained fluid quantity and is determined by the profile stored in the profile database.

The system 10 is now ready to receive a filled syringe 90. Figure 13 shows a typical mask 164 as may be shown to the doctor at this point in time. The display contains various soft or program buttons 198 which can be actuated by the doctor in order to activate certain commands and various display regions in which information is provided to the doctor. At that particular moment, the display shows the following selection buttons 198: Close, Print, Pedal. Other panels may be shown at other times.

In addition, the display according to Fig. 13 the following information areas: a message field 200 in which instructions for the next phase are issued or a message is displayed informing the doctor of the method step currently being carried out; two graphs 202, 204, in which the fluid flow and the outlet pressure are shown as a function of time, a syringe image 206, a pressure manometer 208, which shows the current outlet pressure as a percentage of the maximum allowable pressure (another parameter that is used as a part is obtained from the profile), and another set of measurement fields, which are jointly designated by 210 and characterize the following parameters: Location of the plate 76 (and thus the piston 94 within the cylinder 92) in a distance indication relative to the initial position, the volume of the already injected fluid (or the fluid collected in the case of a biopsy), the current flow rate (volume per time), the current one Pressure, the force applied, and the force applied by the pedal 176. At the beginning of step 306 (Fig. 11) the display areas 202, 204, 208 and 210 do not show values ​​for the corresponding parameters, and the image 206 includes a label 212 to show that a syringe 90 has not been determined. Message field 200 displays a message instructing the doctor to fill syringe 90 and to press pedal 176.

The doctor can now insert a filled syringe 90 into the groove 36, with the support surface 95A extending into the slot 54 and the finger support surface 96 being inserted into the slot 56 of the plate 30. As previously mentioned, the motor 66 has moved the plates 76, 30 to their initial positions. The initial position is defined as the position in which the syringe 90 contacts the in the

Slot 56 matching finger support surface 96 can be attached. It should be noted that the system 10 cannot accept any other syringe position. The program ensures that the correct syringe is inserted with the correct amount of fluid and that no other syringe can be incorrectly loaded.

The system 10 waits for the syringe 90 to be assembled in step 310. The physician can now see that the syringe 90 is attached by briefly activating the pedal 176 or by pressing the control panel 198 on the screen. The drug delivery process can now begin. First, a red “stop” symbol 212 is hidden. In step 312, the system 10 checks to see if the doctor has requested an irrigation. If so, flushing is carried out according to step 313, during which the transport system is freed of possible air bubbles. The volumes of the needle 17, the handle 16 and the needle 17 are known, whereby the volume of the irrigation fluid can easily be calculated.

As already mentioned, the pedal 176 preferably has an air bellows and an air pressure sensor (not shown). The output signal of the air pressure sensor is given to the analog-to-digital converter 190, and the corresponding digital signal from the pedal 176 is passed on to the microprocessor 154. The microprocessor 154 uses this sensor signal in conjunction with a check table stored in EEPROM 184 to generate a switching signal as a function of the position of the switch. It has been found that the switch position is translated into four different positions or states for the best response and sensitivity, using hysteresis. In other words it is

Switch or pedal 176 is initially in a rest position, as shown in FIG. As soon as the switch (pedal) is depressed, the internal pressure increases. When it reaches a first value “ON 1”, the microprocessor 154 generates the command for a “low flow”. If the pressure continues to rise but does not exceed a second ON 2 threshold, the low flow command is maintained. If the pressure is reduced within an "OFF 1" level, the rest position is displayed. Typically the “OFF 1” pressure is lower than that

AT 412 837 B "ON V-Druck. If the pressure exceeds the “ON 2” value, a “high flow” command is generated. This “high flow” command is not terminated until the pressure falls below an “OFF 2” pressure level that is less than the “ON 2” value.

According to step 314 in FIG. 11, each position or each state of the Pe5 dals 176 is determined after the flushing. When a "low flow" command is received, the drug will be dispensed at a low flow rate. When a "high flow" command is received, the drug will be delivered at a high flow rate. The actual values ​​for a high and low flow were set beforehand, as shown above.

After the pedal 176 has been depressed, the motor 66 is started and operated at the required flow rate, see (step 316) in Fig. 11. A typical drug delivery is shown in Figs 202 and 204 occurs. As shown in FIG. 15A, the flow rate is built up relatively quickly to a first value “low” at T0 and then remains at a constant value. The outlet pressure p begins according to Fig. 15B to rise in a somewhat irregular manner as determined by tissue resistance to fluid flow and other factors. At time T1, the pedal 176 is activated to a high "high" level and the flow rate increases accordingly to the high level (FIG. 15A). The outlet pressure p also begins to rise. At the point in time T2, the pedal 176 can be relieved to the lower level “slightly”. As soon as this process starts, the main microprocessor 152 continuously monitors various printing parameters (see step 318 in FIG. 11), and it takes in the released total volume and compares this current volume with the desired total volume (step 320). If this has not yet been achieved, it is checked in step 322 whether the pedal 176 is still depressed. If so, step 314 is repeated. If not, it is assumed that aspiration is requested and accordingly an aspiration routine is performed as described in connection with FIG. 17 below.

In step 318, the instantaneous pressure displayed by load cell 78 is compared to a threshold value that represents the maximum safe value for system 10. This pressure level depends on the components selected for the system 10. In addition, in step 318, the outlet pressure is also monitored. As mentioned, the fluid pressure present during an injection is essential to the degree of pain felt by a patient and tissue damage during an injection. At low pressure levels, the pain is minimal, so the patient feels practically nothing. However, if the pressure rises above a certain level, the injection becomes very painful. The control of the flow rate in such a way that it ensures a low outlet pressure level therefore plays an important role in the invention.

In particular, in this regard, the flow rate is reduced in step 324 if in step

318 excessive pressure has been detected. In step 326 the pressures are checked again. If the pressure is then still too high, the flow rate is reduced again in step 324. If the conditions are acceptable, the flow rate is then assumed in step 328 and the method continues with step 320.

The flow rate and various other parameters are displayed to the doctor on the display panel shown in FIG. 13 so that he can easily monitor the process. In all likelihood, an increase in pressure as shown in Figures 16A and 16B at TX is caused either by a blockage or by the needle 17 striking a bone. Whenever an abnormal pressure is measured, both a visual and an audible alarm are triggered. The doctor is then able to do something to eliminate the high pressure. However, should a blockage persist and the pressure continue to rise, the flow rate will gradually decrease until the system 10 stops, as shown in Figure 16A.

After step 320, if the specific volume has been reached or a termination command has been issued by the doctor, an end subroutine is executed in step 330. During this subroutine, the forward movement of the syringe plunger 94 is halted and a message to withdraw the needle 17 is displayed. The doctor can now pull out the needle 17 and separate the transport system 14 from the syringe 90 and dispose of it together with the handle 16 and the needle 17. Optionally, an aspiration55 subroutine, explained below, is also executed to ensure that further fluid is not dispensed from the needle 17

AT 412 837 B becomes.

In many cases, aspiration during drug infusion is desirable. For example, when an anesthetic is infused, after the needle 17 has been inserted, suction is required in order to check whether the needle tip has entered a blood vessel. In this case, a little blood will be sucked into the blood vessel. This blood becomes visible in the handle 16 or in the needle 17.

As shown in FIG. 11, when a released pedal is determined in step 322, an aspiration routine shown in FIG. 17 is executed.

In detail, according to FIG. 17, step 400, it is checked whether the plunger 94 in the syringe 90 has been stopped at 10. If not, it is checked in step 402 whether the piston 94 is being advanced at a low speed. If so, a low speed stop routine is performed in step 404 to slow the motor 66 and then stop. Otherwise, in step 406, a high speed stop routine is performed to slow and stop the motor 66.

In step 408 it is checked whether there is sufficient space to carry out an aspiration. With reference to Fig. 3, the moment an aspiration command is received, the plunger 94 could be in its absolutely right position so that further withdrawal from the syringe 90 could mean falling out, which of course should not happen. Thus, in step 408, on the basis of the position of the plunger 94 and the length of the syringe 90, it is determined whether safe conditions exist in order to be able to safely carry out an aspiration without the plunger 94 falling out. If not, the method is stopped and an error message is issued to the doctor in step 410 to indicate that aspiration is currently unsafe.

Otherwise, in step 412, the motor 66 is reversed and operated in the opposite direction for a predetermined period of time in order to retract the piston 94. After the piston 94 has moved a predetermined distance, it is stopped (step 414). The piston 94 is then moved forward again (step 416) until it has returned to its initial position at step 408. Then the motor 66 is stopped (step 418).

Steps 416 and 418 can be omitted if aspiration is performed at the end of the procedure when the needle 17 is withdrawn from the tissue.

In this way, the present system 10 is used, for example, to deliver an anesthetic. For example, if the procedure concerns a periodontal ligature, the following parameters can be used:

Syringe Type: Dental Cartridge Tip Size: 29.5 cm³

Medicinal product: local anesthetic (lidocaine HCL 2% and epinephrene 1: 100,000)

Specific gravity of the drug: 0.0361 Inner diameter of the conduit: 0.0381 cm. Conduit length: 152.4 cm

Needle type: BD 30 G ¹/ s

Needle length: 1.27 cm

Inside diameter of the needle: 0.01524 cm. Low speed: 0.09668 cm³/ s High speed: 6,063cm³/ s Maximum pressure: 17.24 bar

When a normal syringe 90 and needle 17 of the dimensions described above are used to manually inject the same fluid, it has been found that an output pressure of up to 45.5 bar or more is generated.

Other syringes, drugs, lines, and / or needles are selected for other procedures.

As mentioned above, a critical parameter monitored by the system 10 is the fluid outlet pressure at the needle tip, ie the pressure in the tissue at which the fluid is released from the needle 17. This pressure is illustrated by the graphs of Figures 15B and 16B. However, it is very difficult to measure this pressure directly. According to the invention, an indirect measurement is therefore carried out instead of a direct measurement: the desired output or

Needle pressure Pn is derived from the force received by the load cell 78 and from the

AT 412 837 Β physical properties of the system 10 derived. In this regard, it was found in particular that the outlet pressure in a steady state (i.e. with a constant speed of movement of the piston) can be represented as follows:

Pn = Ps - dVhn + dVhl - d (Fl + Ft + Fn), where

Ps is the pressure at the interface of the piston 94 with the fluid due to the movement of the piston;

Vhn is the back pressure present in the needle 17; io Vhl is the back pressure present in syringe 90;

d is the specific gravity of the fluid; and

Fl, Ft and Fn represent frictional losses resulting from the flow from the syringe 90, the transport system 14 and the needle 17, respectively.

Further insignificant pressure losses present in system 10 are less than one percent and can be ignored.

The frictional losses are determined empirically and stored as part of the profile for each element. Typical values ​​Fl, Ft and Fn are for example:

Fl - 0.1%; Ft = 89%; Fn = 11% of the total loss.

The density of the fluid is known and is normally close to the density of water. the

Back pressures are calculated using the following equation:

Vhl = a * Q²d / [(π / 4)² D.⁴(2g)], where α is the kinetic energy factor related to the Reynolds number and has the value 2 for laminar flows;

Q is the corresponding fluid flow as shown in Figures 15A and 16A; g is the constant of gravity; and

D is the inner diameter of the respective element, see Vhl for the syringe and Vhn for the needle.

An additional acceleration factor is to be considered when the motor 66 is accelerating or decelerating. This factor is given by the following expression:

Ms * a / As + Mt * a / At + Mn * a / An; whereby

Ms, Mt and Mn are respective fluid masses in the syringe, conduit and needle, and

As, At, and An represent the corresponding cross-sectional areas.

As shown in the flow chart of FIG. 20, the friction losses in each section (the syringe, the line and the needle) are first determined as follows to calculate the outlet pressure. In step 700, the Reynolds number is determined from the flow rate, the diameter of the

Component and viscosity determined. If the Reynolds number is above 2000 (corresponding to turbulent flow), the kinetic energy factor is set to 1 (step 702) and the friction loss is calculated using the Reynolds number (step 704).

For R <2000 (step 706) the kinetic energy factor is set to 2 and the friction loss (step 706) is determined using another expression based on the fluid 45 viscosity, flow rate and diameter of the component. In the absence of flow, the friction loss and the kinetic energy factor are set to 0 (step 708). Subsequently, when the parameters of all of the components are calculated, the flow loss for each component and the stopping force are calculated, and these parameters are used to obtain the output or needle pressure (step 712).

At any time, the microprocessor 152 checks the pressure (step 318 in FIG. 11) and calculates the actual output or needle pressure Pn as shown above. Figures 16B and 17B show normal pressure and abnormal pressure, respectively, using these expressions.

According to step 302 in FIG. 11, a filling subroutine shown in FIG. 18 is started when the

Device for filling the syringe 90 is used. In step 600 of FIG. 18, the disk becomes

AT 412 837 B moved to its starting position. At step 602 a test is performed to determine whether the syringe 90 should be filled with or without air. If filling with air is required, in step 604 the plate 30 for the syringe head is arranged in the position in which the syringe 90 is completely filled. In step 606, the system 10 awaits the attachment of the syringe 90.

To fill a syringe 90, the system 10 must be connected to a source of fluid such as a glass vial or bottle. According to FIG. 19, the syringe 90 is filled in particular by connecting a three-way valve 700 to the line of the transport system 14. The valve 700 connects the system 10 to the fluid source 702 via a line 706. To fill the syringe 90, the valve 700 is set in such a way that the fluid source 702 is connected to the syringe 90. In FIG. 19, the fluid source 702 is shown upside down, so that an air space 706 remains. For filling with air, the injection plunger 94 is positioned as if the syringe 90 is full, ie in the position shown in FIG. 19. For filling without air, the syringe plunger is moved such that it comes as close as possible to the opposite end position, as shown at 94A. When the connections shown in FIG. 19 are complete, the doctor can arrange the syringe 90 in the groove 38 and fasten it with the bracket 40 and the plunger head engaging in the plate 30.

According to FIG. 18, the syringe 90 is detected in step 606, cf. also the field 606 ′ in FIG , thereby pressurizing the fluid source 702. In

In step 610, the position is returned to an initial position corresponding to the volume to be injected, as previously determined by the doctor. In step 612, the physician is reminded to switch the valve 700 to connect the syringe 90 to the transport system 14. The system 10 now returns to step 308.

If it has been determined in step 602 that filling is to be performed, in step 604 the

Plate 30 is moved to the empty position of syringe 90. The system 10 is then ready to place the syringe 90 in position in step 616, after which the system 10 begins with step 610.

The system 10 was described above for performing an injection procedure. For the person skilled in the art, however, it goes without saying that the system 10 can be used in a corresponding manner to carry out a biopsy, for example in order to carry out a spinal stitch or other similar anaerobic procedures. Essentially, the same parameters can be used for this procedure with some minor modifications. For example, the doctor specifies an inlet pressure instead of an outlet pressure. In addition, some subroutines, such as rinsing, filling and aspiration, are not necessary here.