Computer controlled drug delivery system with dynamic pressure sensing

[0001] The present invention relates generally to drug delivery systems, in particular to a new and useful device and method for delivering drug to a patient via a needle.

[0002] US Publication No. US 2006/0122555 entitled Drug Infusion Device ..., is held by the rights holder of the present application, Milestone Scientific Inc., and was invented by the inventor of the present invention. This application is not prior art for the present application, but discloses an actuator with a mechanism for detecting and for reporting feedback the reaction force encountered by the rod moved through the actuator to control actuation of the actuator in response to that reaction force.

[0003] In published US patent application US 2004/0215080 to Lechner, a device for locating an anatomical cavity in the body is disclosed. This reference document is interesting because of the use of a continuous audible signal in the solution that indicates the pressure of the liquid in the reservoir to be injected into the patient's body via a needle. When the needle reaches the well you are looking for, an audible signal indicates to the operator the corresponding pressure drop in the tank. Fluid pressure in the reservoir, and not at the tip of the needle, is measured and used in this published application. It does not disclose or suggest a correlation between tissue type and the minimum or desired threshold pressure as well as the importance of considering or calculating the pressure at the needle tip.

[0004] Other important differences between the Lechner application and the present invention are illustrated in paragraph [0035] of the graphic version of the Lechner application, where it has been found that "calibrating pressure measurement is not critical because the user acts on the basis of changes that he detects in an audible signal" . The Lechner solution uses a relative scale to determine the identification of a "depression" or structure. In paragraph [0063] of the document Lechner goes to the extension of the use of the device to "localize the area" or "a tumor in a person's body" based on the observation that the tumor has essentially different properties from the surrounding tissue, and thus indicates the importance of changes in relative pressure, in which it is located, and especially the tumor will show a different resistance to fluid penetration compared to the surrounding tissue.

[0005] The Lechner device therefore requires detection of a relative pressure change in order to distinguish and distinguish it from the environment. Therefore, it is therefore a system based on a relative change and therefore requiring continuous delivery of acoustic feedback, otherwise the user will not notice such a relative change. The Lechner device cannot identify any particular tissue based on absolute pressure, but can only distinguish when there is a substantial change in relative pressure.

[0006] US Patent 6,200,289, which was developed, inter alia, by the inventor of the present invention, related patents US 6,786,885; US 6,945,954; and US 6 887 216; as well as related published US patent applications US 2005/0004514; US 2006/0102174; and US 200610122555, disclose and claim devices that control the output pressure for fluid injected into a patient's body.

[0007] The handle and system offered on the market by the assignee regarding the invention, under the registered trademark THE WAND, can be used to administer medicaments in general, and especially dental anesthetics. This handle and other aspects of the entire system for administering anesthetics in a controlled manner while reducing pain for the patient are disclosed in US Patent Nos. 4,747,824; US 5 180 371; US D422 361; US D423 665; US D427 314; US 6,132,414; US 6,152,734; and US 6,652,482.

[0008] US Patent 6,296,623 discloses a needle holder and anesthetic carrier assembly for delivering anesthetic under pressure to the patient's body, while US Patent 6,629,958 discloses a hypodermic needle structure that can be used, for example, for injection administered to the periodontal ligaments (PDL injection), which is also referred to as intra-ligament injection.

[0009] The PDL area is where the gingival tissue contacts the tooth at the thin band of the ligament that connects the tooth to the bone. However, this injection is extremely difficult to perform properly and is often painful for the patient due to various factors, including unusual hardness or high density of PDL tissue.

[0010] The technique of injection into the periodontal ligament was first described in the early 1900s by Dr. Guido Fischer and Cassamani. This technique used a standard dental syringe and "blind" placement of an axial metal needle into the gingival furrow, as well as pushing the needle into the periodontal ligament located between the root surface (cementum) and the bone tooth pocket. When the needle was placed in the periodontal ligament, the doctor generated maximum pressure on a standard dental syringe or on a high-pressure pistol lever syringe. The total recommended volume of the anesthetic solution was 0.2 mL to 0.4 mL using this method.

[0011] The location of the needle tip inside or at the entrance to the periodontal ligament as well as the generation of high pressure was of key importance for this technique

- 3 or typically between 600-1200 psi to drive the anesthetic to this dense tissue. Both of these features of this technique hide serious pitfalls. The authors have described in the past century the difficulties associated with the correct positioning of the needle in the desired place, due to the obvious lack of direct visualization and identifying anatomical landmarks, and thus the "blind" attempt to position the needle. In addition to placing the tip of the needle, maintaining proper positioning during drug delivery is difficult to obtain and confirm.

[0012] Manually operating the maximum pressure on the dental syringe generates extremely high pressures. Although recommended for forced displacement of the anesthetic solution through dense tissues, the extremely high pressure of the syringe causes tissue damage, which is evident in histological studies, animal and human studies that have repeatedly demonstrated adverse tissue reactions resulting from such high pressures. Such tissue damage results in the patient experiencing pain, reported by dental patients, when an intramiginal or PDL injection is performed using a traditional technique and a mechanical dental syringe.

[0013] In addition to the position of the needle and the problems associated with high pressure in tissues, traditional syringes do not allow the clinician to obtain confirmation that the correct amount of anesthetic has been delivered, as both blockage and / or leakage during injection may occur. Due to these difficulties, prior technique may lead to an incorrect duration of anesthesia. Field workers reported a 10 to 20 minute duration of effective pulp anesthesia for the PDL technique they were testing. Various local anesthetics with different concentrations and vasoconstrictors were used in their studies. When performed at a larger volume, the PDL technique showed a longer effective working time, correlated with the higher dose administered. Limited volumes of anesthetic solution resulted in limited duration of anesthesia.

[0014] These traditional techniques and technologies used for routine intramiginal injections are therefore limited by the blind nature of such injections, the extreme pressures generated in local tissues during the procedure, and the relatively small volume of anesthetic that is reliably delivered. These factors resulted in limited duration of anesthesia and greater pain associated with tissue damage.

[0015] There is a need for an improved device and method for injecting drug into selected patient tissues, while increasing control, and more importantly, increasing feedback for the practicing specialist who manages the injection.

SUMMARY OF THE INVENTION [0016] The object of the present invention is to provide a device according to claim 1 for controlled injection of a drug into selected tissue of a patient by a practicing specialist.

[0017] The ability to precisely identify specific types of tissue based on dynamic pressure measurements has been published in both the medical and dental literature, but no device has yet been developed in which this relationship could be applied.

[0018] See, for example, the document Ghelber O, Gebhard R, Adebayo G, Szmuk P, Hagberg C, Ianucci D .: Utilisation of the CompuFlo ™ in determining the pressure of the epidural space: a pilot study. Anesth Analg 2005: 100: S-189. In this work, Ghelber et al. indicated the possibility of distinguishing specific types of tissue during subcutaneous injection, based on pressure.

[0019] The inventor of the present invention, Mark Hochman, as well as his associates, performed 200 dental injections, which showed the possibility of determining three specific categories of tissue type based on measurements of intraspinal pressure inside the oral cavity, namely periodontal ligament, connected gingival and non-attached ligaments Gingival mucosa (Hochman M, Friedman M, Williams W, Hochman C .: Interstitial tissue pressure associated with dental injections: A clinical study. Quintessence Int. 2006; 37: 469-476).

[0020] The many novel features that characterize this invention are indicated in particular in the claims attached to this disclosure and forming part thereof. For a better understanding of the invention, its practical advantages and the specific purposes achieved by its application, reference will be made to the figures of the attached drawing, and a description is given in which preferred embodiments of the invention are illustrated.

Brief description of the drawings [0021] In the drawing:

Fig. 1 is a cross-sectional view of a patient's tooth showing the initial placement of a PDL needle, a single injection of an anesthetic into a tooth, in accordance with the present invention;

Fig. 2 is a perspective view of one of the preferred embodiments of the device according to the present invention;

Fig. 3 is a vertical view of the front panel of the drive unit according to the invention during one operating phase; and

Fig. 4 is a side elevational view of the drive unit with the left housing portion removed to expose its internal structures.

Description of preferred embodiments

Tooling overview:

[0022] Referring to the figures of the drawings in which similar reference numerals have been used to indicate the same or similar elements, Fig. 2 shows the device generally indicated as 20 for performing a controlled infection of the drug for

- selected patient tissue by a practicing specialist, comprising a drive unit 22 for drug delivery with at least one flow rate, as well as a handle grip 24 for being gripped by a practicing specialist, the handle being connected via a flexible tube or hose 26 to the drive unit 22 to receive medication from a known dental anesthetic cartridge 28 that is coupled to a drive unit.

[0023] The micro-perforated tubing 26 preferably has an OD (outer diameter) of 0.078 "+/- 0.002" and preferably an ID (inner diameter) of 0.013 "+/- 0.002" at a hardness of 80, which is for example a polymer Alpha 222R. Other materials may be used, as is known to those skilled in the art. In the past, tubing with a hardness of 70 was used. Hardness and pipe ID can be important, as can pipe OD, as these features may have some effect on performance. The preferred range for OD is about 0.05 to 0.10 "or preferably about 0.07 to 0.09". The preferred range for ID is about 0.008 to 0.030 "or preferably about 0.010 to 0.017". The preferred range for hardness is about 60 to 90 or preferably about 65 to 85.

[0024] The handle 24 of the handle is designed to hold an injection needle 30 intended for insertion into selected patient tissue by a practicing specialist, to deliver the drug to the selected tissue at momentary pressure, which varies as a function of the type of tissue selected and the position of the needle tip 10 in the selected tissue. There is some minimum pressure that is beneficial for administering the drug to the selected tissue, so that the object of this invention is to advise the practicing specialist when this desired minimum pressure has been reached.

[0025] Referring now to Fig. 4, a pressure sensor or calculating unit 90, mounted to the linear plunger motor assembly 92, inside the drive unit 22, for example of the type disclosed in US patent application US 2006/0122555, detect or calculate this instantaneous absolute pressure at the tip or point of the needle, and feedback mechanism, such as the audible sound provided by the speaker 23 in unit 22, or a visual display, such as an illuminated scale 32, provides a perceptible signal to the practicing specialist.

[0026] This signal is designed to indicate instantaneous pressure, for example when a temporary increase in pressure occurs, the audible tone increases its height and / or intensity, and the lights of the visual scale 32 brighten, first at its smaller end on the left in fig And then gradually towards its larger end to the right. This signals to the practicing specialist that his manipulation and guiding of the needle tip or tip 10 into the selected tissue preferably increases the instantaneous pressure of the liquid drug at the needle tip 10. The perceived signal can alternatively be only a signal that indicates when the instantaneous pressure has reached the minimum desired pressure level. At this moment the tone sounds for the first time, or if there are changes when the pressure has increased, the tone changes in a distinct way, e.g. a pitch of sound or intensity occurs, or both,

- to indicate to the practitioner that the displacement of the needle through it has resulted in an effective minimum pressure being obtained, so that sufficient drug delivery to the selected tissue can be achieved. A visual signal, e.g. in the form of an increasing light scale 32 or even a digital readout, can also represent the pressure as it increases towards the desired pressure, with the fully illuminated scale 32 indicating that the desired pressure is being reached.

[0027] Returning to Fig. 4, the motor assembly 92 is mounted to the main component board 94 in the unit 22 and held in place by a bracket 96 and screws 98. Plate 94 is mounted on unit 22 with screws 100 and supports computer components 102, 104 and 106 to perform various drive unit functions, such as starting motor assembly 92 to move plunger 64, driving the loudspeaker, calculating absolute pressure at the tip of the needle, and other functions described herein . Energy is supplied through the supply module 108, which supports the power switch 54, while the seat 52 is supported by the cassette assembly 110, through which the plunger 64 can move and to which the cartridge housing 34 is attached.

[0028] In the event that the cassette assembly 110, which is a hermetically sealed assembly, leaks for any reason, it comprises an upper drain connector 112, which is connected via a schematically illustrated hose 114 to a lower drain connector 116 that is open downwards for removing the leaking liquid below the unit. Thereby the risk of leakage to the delicate electronic components of the drive unit 22 and the resulting damage are avoided.

[0029] Similarly, the leg control seat 46 will be explained in more detail below, connected via an air hose schematically depicted as 118 to the air connector 122 of the air switch 120, which has multiple actuation positions.

[0030] At the bottom of the unit 22, near the outflow 116, a standard fall-out mounting screw 124 is used to mount the unit on a bench, tripod, arm or the like. This is the same type of standard quarter-inch mounting screw as used on camera mounts, and therefore any standard tripod screw will fit. This is intended to facilitate the assembly and attachment of the unit according to the invention to a support arm or post. It can also be used to attach the unit to the top of a table or countertop.

[0031] The USB 21 port is also available for loading and / or displaying instantaneous pressure readings to and on a personal computer or other computer appropriately programmed to collect pressure information and to record each injection with a time code so that useful information can be collected for needs of future research. USB port 21 can also be used

- 7 for remote display, for graphic representation and injection data. The USB port is also intended as a convenient means of recording data for documenting injection events, so that patient identification information can be entered to secure the record, which can be recalled at a later time.

[0032] Although the basic features of this invention can be used for a wide variety of tissues and drugs, the inventor has broadly confirmed the usefulness of this invention for single tooth anesthesia by intra-ligament injection (PDL).

Intra-ligament injection:

[0033] A single tooth anesthesia, intra-ligament injection or PDL technique according to the present invention differs fundamentally from the prior art procedure in that it uses dynamic real-time pressure feedback to both locate the ligament and ensure proper device operation. In addition, a precisely defined flow rate is used (e.g. 0.005 ml / s for PDL injection) and controlled "moderate" desirable minimum or threshold absolute pressure (eg, preferably 250 to 450 psi for PDL injection, or even in the range of 200 to 500 psi) for anesthesia.

[0034] As shown in Fig. 1, the injection of the present invention requires that the practicing specialist first locate the needle tip 10 near the target tissue, i.e., for example near the PDL (periodontal ligament) 12 between the patient's tooth root 14 and the maxillary bone 16 patient, and also physically guided the needle tip along the target tissue. This is achieved using dynamic real-time pressure detection technology, in the form of, for example, the device generally indicated as in Figure 2, and also using the principle that tissues in the body have different densities. The periodontal ligament, for example, has a range of intra-ligament pressure that is unique to surrounding tissues, namely bone 16, root 14 of the tooth, as well as connected and unconnected gingival tissues 18.

[0035] When the needle tip 10 is positioned correctly in the correct space, the device 20 provides real-time confirmation that the needle tip has not moved out of the target tissue during drug delivery. In addition to location, the device of this invention provides pressure detection feedback to ensure that no needle blockage occurs by an obstacle or blocked tissue. This dynamic pressure detection can also alert the practicing specialist if a leak occurs, which can sometimes be due to inaccurate needle placement, insufficient hand pressure on the handle, or internal leakage from the cartridge or tubing, which will be described in more detail in this disclosure. This invention informs the practicing specialist if any pressure loss has occurred as a result of any of the scenarios described.

[0036] By using the present invention, the dose of anesthetic administered can be higher than with previous intriginal injection techniques. This is due to both moderate pressures being used and controlled flow rate for the drug being administered.

[0037] The data considered by the inventor indicate that the volume of the injection solution is not limited by the intra-ligament route of administration when the intriginal injection is carried out according to the present invention. Therefore, the recommended dose of the anesthetic solution is in the range of 0.9 ml (for a single root tooth) to 1.8 ml (for a tooth with several roots) when using a 2% concentration solution for local anesthesia.

[0038] When using a 4% drug, such as articaine hydrochloride, half the dose, i.e. 0.4 ml (for a single root tooth) to 0.9 ml (for a tooth with several roots) is recommended. The practicing specialist should understand that the volume of anesthetic is related to the duration of anesthesia and plan according to specific procedural needs. It is possible to re-administer the dose during treatment, also by means of the injection technique of this invention.

Performing injections with the use of tooling:

[0039] The drive unit 22 is portable and approximately has the size of a small cable modem. The handle 24 grip is part of the disposable handle assembly. Drive unit 22 is powered by the standard AC electrical connection. The unit illustrated here, for example, has a power cable 36 with a unit plug 38, to plug into the rear of unit 22, and a wall plug 40 to an AC wall socket used, for example, in the United States.

[0040] The disposable, sterile handle assembly includes a handle 24, a micro-perforated tubing 26, and an anesthetic cartridge holder 34 that can accept any standard cartridge 28 with a dental anesthetic. Any standard medical needle 30 can be attached to the handle for use. Typically, a 30-inch 30 or 27-inch Luer needle 30 is attached to the holder 24 to perform intradigital or PDL injection in accordance with the present invention.

[0041] The drive unit 22 has three basic modes of operation:

a. STA mode - single speed mode (flow rate 0.005 ml / s);

b. Normal mode - two speed mode (0.005 ml / s and 0.03 ml / s);

c. Turbo mode - three-speed mode (0.005 ml / s, 0.03 ml / s and 0.06; and ml / s).

[0042] When performing intramiginal injection, only STA mode is used. All flow rates are controlled by a practicing specialist using foot control or pedal 42 connected to drive unit 22 through conduit 44 plugged below unit front panel 50 at leg control seat 46.

[0043] It should be noted that for all modes of operation and for obtaining pressure signals and generating perceptible signals, an on-board computer is introduced into unit 22, which has been programmed using techniques and technologies that are currently available to those of ordinary skill in this art. field. Additional details are also available from earlier patents and published applications for the invention of the assignee in this case, as well as the co-pending US patent application US 2006/0122555.

STA mode:

[0044] To make the injection, the subject or patient is placed in a supine position. The practicing specialist selects the appropriate anesthetic solution to achieve the desired result and places the insert 28 into the housing 34 of the insert in the handle assembly. The patient should be advised to hear audible noises emanating from the system throughout the procedure.

[0045] The cartridge housing 34 is then attached to the drive unit 22 by plugging the lower end of the housing 34, which has a pair of opposite tabs 35, into the housing 52 of the cartridge housing at the top of the unit. The housing 34 is then rotated about 90 degrees on its axis to engage the tabs 35 with complementary matching slots within the seat 52. This rotation both locks the cartridge housing with its insert in the slot, and also closes the switch in the slot 52, which performs other monitoring and security functions. See, for example, US Patent 6,132,414, for details about the housing of the cartridge and how it receives and pierces the cartridge to release liquid anesthesia.

[0046] The drive unit 22 was previously activated by pressing the power button 54 on the rear side of the unit. This causes the power indicator lamp 56 to light up. The STA 58 button is then pressed to start this operating mode and the STA mode lamp 60 also lights up. Fig. 3 shows the state of the indicators on panel 50 at this very moment.

[0047] The unit 22 will then automatically remove air from the handpiece and needle micro tube 26. This cleaning cycle is indicated by the automatic cleaning / retract indicator indicator lamp 62 being lit and is achieved due to the fact that the plunger 64 is linearly driven inside the cartridge 28 in a controlled manner and by setting the injection quantity of the liquid anesthetic from the cartridge, along the tubing and on the outside the needle tip 10 in a way that is well understood by the practicing specialist for the indication, that no air is left in the handle assembly. At this point, the indicator 66 of the remaining content of the cartridge indicates that the cartridge 28 is full by causing all or nearly all of its scale fields to light up. The highest fill scale field can be lit first and then blanked to indicate some use of the liquid for the cleaning cycle.

[0048] Holding the handle 24 like a pen, the practicing specialist will place the needle into the gingival furrow of the tooth to be anesthetized, as shown in Fig. 1. At the same time, the practicing specialist will start the first selected liquid flow rate (e.g. 0.002 ml / s or approximately 0.005 ml / s) by pressing foot control 42. It is important to gently and slowly move the needle tip inside the furrow, as in the case of the periodontal probe. The use of a finger rest to control the movement of the needle is highly recommended because it will allow the practicing specialist to carefully control and stabilize the movement of the needle. It is also recommended that the bevel of the needle points towards the root surface, and that the needle is positioned at an angle of approximately 30-45 degrees relative to the long axis of the tooth.

[0049] When the needle is inserted through the tissues, the system of the present invention provides a continuous audible and / or visible feedback signal to assist the work of a practicing specialist. The unit 22 has a visible scale 32 (i.e. indicator) of the detected pressure on the front 50 of the unit, which is made of a series of lights in the form of LEDs, which can be, for example, orange, yellow and green. The orange lights on the left, which are shown as glowing in Fig. 3, indicate minimal pressure, the yellow lights or compartments in the middle of the scale 32 indicate moderate pressure measurements, and the green lights on the right side indicate moderate pressures indicating intra-ligament tissue (PDL).

[0050] Acoustic feedback consists of a series of sounds with a pressure detection scale composed of rising tones to also lead a practicing specialist. When the practicing specialist hears the ascending sequence, this indicates that the pressure is increasing. When the periodontal ligament is identified, as a result of the fact that instantaneous real-time pressure becomes equal to the minimum desired pressure, the practicing specialist will initially hear the letters "PDL" actually spoken by the unit through the speaker, indicating that the correct position of the needle has been reached.

[0051] Such an audible signal may be continuous, but it should also be noted that it may be specific to the response to the absolute pressure, such as the indication "P-DL". The same can be done when STA detects ligaments Ligamentus Flavum, where the whole unit indicates "Flavum" and when specific epidural space pressure is identified, "Epidural space" will be indicated.

[0052] User feedback is not only audible at the absolute pressure value in the preferred embodiment, but is also visible because different coloration of the LED can be seen, which indicates achievement of PDL tissue. The minimum, desired or threshold pressure is an absolute value, but it may be within the discovered range for such tissue. The set point for the perceptible feedback signal may be higher or lower within the range depending on various factors, but this absolute pressure is analyzed.

[0053] For example, the STA injection works in the range of, for example, about 250 to 450 psi, since as soon as an absolute value of 250 psi (minimum threshold pressure or absolute pressure value) is reached, STA indicates that the site or tissue has been identified. The device and method of this invention do not seek coverage, although they still indicate "PDL" in this respect. Is based on absolute value detection for tissue identification. As already stated, STA may remain silent until it reaches the tissue, but in a preferred form informs the user that instead, the pressure increases in pursuit of the desired absolute pressure value.

[0054] The clinical application of this system has shown that it is not uncommon to re-adjust the needle to find the optimal position inside the intramural ligaments. This "search" is guided by feedback on the dynamic detection of real-time pressure, and is also what enables the practicing specialist to obtain a higher degree of predictability when performing this injection. The concept of a "blind" dental syringe is now transformed into a systematic way of finding the correct position of the needle relative to the intriginal position using the present invention. All this can be done in a practically painless and hassle-free way for the patient.

[0055] During injection, the practicing specialist is still aware that the correct position of the needle relative to the intracerebral region is maintained. This builds clinical confidence that effective and predictable intramural anesthesia will result from the use of this technology. A practicing specialist may find that slight displacements, be it the operator's hand or the patient's head, can result in rapid pressure loss, which may not be detected by using a dental syringe. If this happens, the system will notify the practicing specialist, through both audible and visible feedback, that the needle is no longer in the desired position. The practicing specialist should reposition or remove the needle from its current location and establish a new effective needle relation to the in-ligament area.

[0056] Real-time information from the device also informs the practicing specialist about the correct operating pressure to be used on the handle of THE THE WAND device. Heavy or forced pressure on the handle may block the flow of the anesthetic solution. Such blockage will be detected by the system and an "overpressure" condition will occur. The "overpressure" condition occurs when the pressures exceed the maximum pressure. The STA drive unit will generate an acoustic and visual alarm, e.g. a louder sound or lighting of the last red LED at the right end of the 32 scale, or "covering" the LED in a flashing sequence to indicate that an overpressure condition has occurred. The practicing specialist can then restart the injection. It may be necessary to re-position or move the needle to a new position.

[0057] If too low hand pressure is in effect when establishing the relation of the needle to the intramedullary area, then a proper seal between the needle and the intriginal tissue cannot be obtained. This leads to insufficient pressure or leakage of the anesthetic solution into the patient's mouth. The system with the technology of this invention will detect this before it becomes visually perceptible to the practicing specialist, by detecting instantaneous pressure and feedback signals, which in this case does not rise as expected, but may fluctuate to indicate that instantaneous Real-time pressure rises and falls uncontrollably.

[0058] This prevents the patient from sensing the typically bitter taste of the anesthetic because no timely leakage was detected when using a mechanical dental syringe. More importantly, this invention and its feedback system determine how a practicing specialist should operate with consistent hand pressure on the handle. This is becoming another feature that makes intra-ligament injection according to the present invention a predictable and simple alternative concept compared to injections and devices that cannot provide such information.

[0059] The practicing specialist should rely on his own judgment as to the choice of drug and volumes used. The information provided below is for guidance only, and practicing specialists are advised to analyze information from drug manufacturers for more specific guidance. In addition, practicing specialists are advised to review current literature in the field of dentistry and textbooks for guidance on recommended doses and recommended medications.

[0060] When using 2% xylocaine hydrochloride or other local anesthetics prepared at a concentration of 2%, the following recommendations are made. A volume of 0.9 ml is recommended for a single root tooth. A drug volume of 1.8 ml is recommended for a tooth with multiple roots. When using 4% articaine hydrochloride or other local anesthetics prepared at a concentration of 4%, the following recommendations are made. When using 4% articaine hydrochloride, it is strongly recommended that a 1: 200,000 vasoconstrictor concentration be used. A drug volume of 0.4 ml is recommended for a single root tooth, while a drug volume of 0.9 ml is recommended for a tooth with root age.

[0061] Intramural injection according to this invention is a unique single tooth injection technique that provides a certain level of safety, convenience and predictability previously unheard of.

[0062] This invention provides the practicing specialist with at least three different benefits that cannot be achieved with a standard dental syringe, high pressure pistol syringe or other systems

- 13 CCLADS. First, the invention provides the practitioner with objective means to determine tissue compliance and thus to determine the type of tissue into which the needle is inserted. Secondly, this system provides the practitioner with objective, continuous, real-time pressure feedback to ensure that the prescribed moderate pressure range is maintained within the injected fabric. And thirdly, this invention provides the practitioner with objective, real-time information regarding needle blockage and / or pressure loss due to leakage of anesthetic solution inside the mouth.

[0063] The unique nature of the device and method of this invention provides the opportunity to provide important clinical feedback in real time, and thus to allow adaptation and confirmation to be evaluated by a practicing specialist. This technology simplifies the intra-ligament injection process by introducing a new interactive injection system to practitioners. Nevertheless, it should be understood that this procedure still requires that users have in-depth knowledge of the basics of anatomy, the basics of technology, and fully understand the phenomenon of local dental anesthesia.

[0064] Intra-ligament injection performed with this invention eliminates previous subjectivity with respect to correct needle placement and leads to a higher level of trust as well as success in the case of dental anesthesia of a single tooth.

[0065] Although intramedullary injection has been disclosed as an example of this invention, other selected tissues that can be injected using the subject invention. One further example is the epidural space, which is part of the human spine located very close to the spinal cord and lies just outside the dura mater. With an epidural catheter, it is possible to administer both anesthesia and analgesia. Each type of tissue selected has its own desired pressure for the optimal efficacy of the drug to be administered, and therefore the benefits of providing a perceptible signal to a practicing specialist returning information about the desired pressure are obvious.

[0066] As noted above, the device and method of the present invention are based on the use of an absolute or specific objective value in real time, instantaneous pressure at the tip of the needle to identify a target location, e.g. a specific tissue. The method described in this document requires an objective rather than a relative pressure value to accurately identify the predicted tissue structure, such as PDL tissue (i.e. identified between 250 psi and 450 psi). You cannot rely on changes in relative pressure to identify PDL tissue, but you must first quantify the specific resistance of the ligament (e.g. exit pressure) at a given flow rate.

[0067] Another example of the specific tissue pressure and injection that can be used in the present invention is intra-gingival injection or PI (Palatal Injection) injection, which was presented in the study of Hochman et al. defined above as having an average pressure of 68.18 psi and in the range of about 50 to 75 psi objective or absolute pressure value to detect that the device and method have determined the correct location of the needle tip.

[0068] In the article by Ghelber et al. also specified above, specific baseline values ​​for Ligamentum Flavum ligament as well as two additional tissues are also theoretically given. These specific values, not relative values, are used to identify the epidural space.

Normal Mode:

[0069] For using the unit 22 according to the present invention for normal operation mode, the selection button 68 is pressed once. This causes the normal mode LED indicator or the 70 lamp to light up.

[0070] In this mode of operation, a purge cycle will occur when a new cartridge is installed. After this, pressing the foot control or pedal 42 will slightly cause the plunger 64 to move to the drug cartridge at a low speed for drug delivery at some first low flow rate, e.g. 0.005 ml / s. Further pressing the pedal to the second position will increase the plunger speed and drug delivery at a second higher speed, e.g. 0.03 ml / s.

Turbo mode:

[0071] The turbo mode is started by pressing the selection button a second time. The turbo mode indicator light 72 turns on and the 42 foot pedal has three depressed positions, corresponding to three plunger speeds and three corresponding flow rates, e.g. 0.005 ml / s, 0.03 ml / s and 0.06 ml / s. Turbo mode can be used to quickly remove drug residue in a cartridge that is no longer needed by the patient.

Other features of the invention:

[0072] The audible signal intensity control button 74 having an upper and lower functional end is used to increase and decrease the audible feedback signal from speaker 23, respectively.

[0073] The aspiration start button 76 is pressed to initiate the aspiration cycle function. When this feature is activated, the device will automatically suck when the user's foot is removed from the foot control during drug infusion. When this feature is turned off, the user can remove his foot from the foot control, and then the device will generally stop the infusion without further moving the plunger. The suction indicator 78 will be lit and the computer in unit 22 is programmed to pull the plunger 64 back slightly. Due to the plunger

- the 64 64 has an O 65 band around its end that seals the inside of the insert 28, when the plunger 64 is pulled backward, a partial vacuum is created in the space between the upper end of the plunger 64 and the lower end of the usual drug driving piston in the insert 28, which causes that the plunger also moves backwards, thereby drawing fluid from the patient's body at the injection site. Because the inner diameter of the tubing 26 is very small, very little suction movement is needed to make sure that no blood vessel has been damaged.

[0074] Unit 22 also includes an automatic purge and retract button 80 that is pressed momentarily to start only automatic purge, or is pressed and held for a few seconds to start the complete retraction of plunger 64 from the cartridge in preparation for removing the cartridge, example after it was used.

[0075] The button 84 for several cartridges, having the corresponding indicator 84 of several cartridges, is pressed for a moment to start the mode of operation of several cartridges, which allows the installation of a new cartridge but not being subjected to an automatic cleaning cycle. This is to avoid cleaning the handle when it is already filled with the medicine from the previous cartridge. Button 84 is pressed and held for a few seconds to start the verbal training mode, which causes the unit to verbally describe and state each operation and each cycle through the speaker 23, for training purposes. For example, when the selection button 68 is pressed to initiate the normal mode, with two available flow rates, the voice will say "Normal mode active", while when the pedal 42 is pressed to the first flow rate position, the voice will say "Low flow started." Similar verbal messages can be given for each mode of operation and for each phase, to support training and to facilitate the mastery of control by the absorbed specialist practicing the work effectively, allowing remembering and "working".

[0076] The unit 22 also includes a pair of opposing wings 86, each of which includes a handle tip holder 88 shaped to receive and be aligned with a highly frictional resilient material to hold the handle tip 24 as a pen holder for convenience.

[0077] Another characteristic feature of living tissue that can be used in accordance with the invention to improve the effectiveness of the injection is its compliance.

[0078] The device of this invention can be programmed for a specific tissue based on tissue compliance. Tissue compliance can be defined as a change in volume as pressure changes. Once a specific tissue compliance has been identified, then the device will notify the practicing specialist when it reaches the tissue with the tip of a needle manually guided by the practicing specialist.

[0079] Compliance means a change in volume required during pressure changes to allow identification of the desired tissue. Compliance differs from tissue resistance or also

- 16 intra-ligament pressure, which can be measured statically, while tissue compliance requires a dynamic state where the volume change occurs to change the pressure. According to this understanding, the system pressure sensor and method of this invention may be used to guide the hand of a practicing specialist. The change in volume parameter occurs due to the fluid flow, which must occur simultaneously with the pressure change to allow tissue identification.

[0080] As with the embodiment of this invention, which indicates that the selected tissue has been achieved by sending feedback to the practicing specialist as a perceptible signal that indicates that the desired pressure has been achieved, the pressure measurement for the sake of identification based on susceptibility is based at the instantaneous fluid outlet pressure, i.e. the fluid pressure at or near the tip of the needle itself.

[0081] The invention can also be used for guiding or tactile control of the handle, which is different from the actual identification of the tissue, i.e. stronger pressing or lighter holding. This can be independent of identifying the target tissue.

[0082] The pressure sensor or calculator for this embodiment of the invention is a pressure sensor for detecting instantaneous pressure, comprising means for determining the pressure change (²-Ρ¹= ΔΡ) over a certain period of time, means for determining the change in volume (ν²-ν¹= Δν) over a certain period of time, as well as means for determining tissue susceptibility based on a change in volume for a change in pressure, wherein the calculated susceptibility is compared with the determined susceptibility for a given anatomical site or structure, and the practicing specialist is guided to a specific target tissues based on specific susceptibility determination.

[0083] Unit 22 also has a drainage feature for draining drug from the bottom of the unit. The mounting screw 124 in Fig. 4 is a mounting screw on the base of the unit, which also allows the unit to be mounted and secured near the work space of a practicing specialist.

[0084] Note that the terms used in this disclosure, such as cartridge, cassette and the like, are intended to represent their widest possible meaning. For example, the term cartridge is intended to include any container or vessel for containing the liquid to be injected.

[0085] Although particular embodiments of this invention have been shown and described in detail to illustrate the application of the basic features of this invention, it will be understood that this invention may be implemented differently, without departing from the scope of such features.

Anna Stenzel

Patent Attorney

Prepared and verified