A device and method for infiltration anesthesia by needle-free injection of local anesthetic into the dermis.

Abstract

This invention relates to the field of needle-free injector technology, and in particular to an apparatus and method for needle-free injection of local anesthetics into the dermis for infiltration anesthesia. The apparatus includes a receiving space for containing the anesthetic solution; the injection pressure is 14-21 MPa. This invention allows for the design of different needle-free injectors to address the physiological differences in the dermis between men and women, ensuring precise intradermal injection of the anesthetic solution and avoiding entry into the muscle layer. Furthermore, it results in less pain during injection and a longer duration of effect from the onset and exhaustion of the local anesthetic.

Description

Technical Field

[0001] This invention relates to the field of needle-free injection technology for local anesthetics, and in particular to an apparatus and method for injecting local anesthetics into the dermis for infiltration anesthesia. Background Technology

[0002] Intradermal injection, a commonly used clinical injection method, is widely applied in scenarios such as vaccination and drug allergy testing. Its core requirement is to precisely inject the medication into the dermis, such as the deltoid muscle of the upper arm, avoiding entry into the subcutaneous tissue or muscle layer to ensure efficacy and reduce adverse reactions. However, there are still many technical limitations when targeting this specific injection site of the dermis.

[0003] Existing needle-free injectors cannot specifically adapt to the physiological differences of different populations. For example, men have thicker dermal layers and more developed muscle tissue in the dermis, while women have relatively thinner dermal layers and denser fat distribution in the same area. When using lower injection pressure on men, the medication has difficulty penetrating the thicker dermis, leading to increased leakage and decreased injection completion rate; when using higher injection pressure on women, the medication easily penetrates the thinner dermis, resulting in excessively deep injection and failing to meet the requirements for intradermal injection. Furthermore, the momentum of the impact on the plunger is affected by various internal parameters of the needle-free injector, such as the plunger's mass.

[0004] Meanwhile, dermal injections require precise control of the drug diffusion range to ensure a moderately sized wheal (usually maintained within the 5-13mm range) to guarantee uniform intradermal distribution of the drug. However, existing equipment often results in wheals that are too large or too small, or uneven lateral diffusion of the drug. Especially when the injected drug is a local anesthetic, it is crucial to consider the injection completion rate, pain level, and the onset, duration, and duration of the anesthetic's effects. Summary of the Invention

[0005] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application, and such simplifications or omissions shall not be used to limit the scope of the invention.

[0006] To address the shortcomings of existing technologies, the first objective of this invention is to provide a device for needle-free injection of local anesthetics into the dermis for infiltration anesthesia, comprising a receiving space for containing the drug solution, the volume of which is expressed as...

[0007] ,

[0008] in, It is the volume of the accommodating space. It is the cross-sectional area of ​​the push rod. For piston stroke, It is pi. It is the diameter of the push rod;

[0009] Among them, injection pressure for MPa, the push rod mass meets the following requirements:

[0010] ,

[0011] in, Let be the momentum of the impact on the push rod. This is the cross-sectional area of ​​the injection outlet. The density of the liquid medicine; 1.5 kg·m / s For the mass of the push rod.

[0012] As a preferred embodiment of the device for injecting local anesthetic into the dermis without needles to achieve infiltration anesthesia according to the present invention, wherein the momentum of the impact on the push rod is 0.6~1.2 kg·m / s.

[0013] As a preferred embodiment of the device for injecting local anesthetic into the dermis without needles to achieve infiltration anesthesia according to the present invention, wherein the momentum of the impact on the push rod is 0.6~1 kg·m / s.

[0014] As a preferred embodiment of the device for injecting local anesthetic into the dermis without needles to induce infiltration anesthesia according to the present invention, wherein the momentum of the impact on the push rod is 0.8 kg·m / s.

[0015] As a preferred embodiment of the device for injecting local anesthetic drugs into the dermis without needles to achieve infiltration anesthesia according to the present invention, the pressure of the drug pressure is 14~18.7 MPa.

[0016] As a preferred embodiment of the device for injecting local anesthetic drugs into the dermis without needles to achieve infiltration anesthesia according to the present invention, the pressure of the drug pressure is 19.8~21 MPa.

[0017] As a preferred embodiment of the device for needle-free injection of local anesthetic into the dermis for infiltration anesthesia according to the present invention, wherein: the volume of the accommodating space is... It is 0.25ml.

[0018] As a preferred embodiment of the device for needle-free injection of local anesthetic into the dermis for infiltration anesthesia according to the present invention, wherein: when the injection target is a woman, the pressure of the anesthetic fluid is 14~18.7 MPa, and the mass of the push rod satisfies:

[0019] ,

[0020] in, Let be the momentum of the impact on the push rod. It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod.

[0021] As a preferred embodiment of the device for needle-free injection of local anesthetic into the dermis for infiltration anesthesia as described in this invention, wherein: when the injection subject is male, the pressure of the anesthetic fluid is 19.8~21 MPa, and the mass of the push rod satisfies:

[0022] ,

[0023] in, Let be the momentum of the impact on the push rod. It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod.

[0024] A second objective of this invention is to provide a method for selecting a device for needle-free injection of local anesthetics into the dermis for infiltration anesthesia. This method includes configuring the parameters of the plunger and injection port as follows: when injection momentum is applied to the plunger for injection, the injection pressure at the injection port is 14-21 MPa, wherein the diameter of the injection port is 0.1-0.2 mm and the volume of the accommodating space is 0.25 ml; the power unit is configured to apply an injection momentum of 0.8 kg·m / s to the plunger for injection; wherein, when the injection target is male, the injection pressure at the injection port is 19.8-21 MPa; and when the injection target is female, the injection pressure at the injection port is 14-18.7 MPa.

[0025] The beneficial effects of this invention are as follows: This invention can design different needle-free injectors to address the physiological differences in the dermis of men and women, achieving an injection completion rate of 94% to 100%, controlling leakage to 0 to 0.0148 ml, and stabilizing the size of the wheal to 5.74 to 13.00 mm. This ensures precise injection of the medication into the dermis, avoiding entry into the muscle layer. Furthermore, it reduces pain during injection and improves the duration of effect of the local anesthetic. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the device of the present invention that injects local anesthetic into the dermis without needles for infiltration anesthesia. Detailed Implementation

[0028] To make the objectives, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Example 1

[0032] Reference Figure 1 This embodiment is the first embodiment of the invention. This embodiment discloses a device for needle-free injection of local anesthetic into the dermis for infiltration anesthesia. The syringe is targeted at the dermis to ensure precise intradermal injection of the drug solution.

[0033] The medication tube 100 is made of transparent medical-grade plastic and contains a receiving space 101 and an injection port 102. The receiving space 101 is cylindrical and is used to hold the medication. Its inner wall is smooth and has good sealing properties to prevent leakage during pressurization. The injection port 102 is located at the front end of the medication tube 100 and has a diameter of 0.1~0.2mm. The injection port 102 is oriented perpendicular to the dermal skin surface to ensure that the medication acts perpendicularly to the target skin, reducing medication diffusion deviation. The receiving space 101 and the injection port 102 are in fluid communication, and the medication in the receiving space 101 can be ejected through the injection port 102.

[0034] The push rod 300 is slidably mounted inside the drug delivery tube 100, and the piston 200 is located at the end of the push rod 300 away from the injection port 102. The core function of the piston 200 and the push rod 300 is to provide ejection energy to the drug solution in the receiving space 101. During the injection process, the injection port 102 must first be brought into close contact with the target skin surface of the dermis to ensure no gaps. Then, the push rod 300 is activated, moving axially within the drug delivery tube 100 to pressurize the drug solution in the receiving space 101, ultimately causing the drug solution to be ejected from the injection port 102, completing the intradermal injection into the dermis.

[0035] In this embodiment, the power component can be pneumatic. The power component applies momentum to the push rod 300, and its energy storage intensity can be adjusted or fixed to adapt to different injection pressure requirements. The push rod 300 is made of metal or plastic and has a sealing ring on its outer periphery, which fits tightly against the inner wall of the receiving space 101 of the drug tube 100 to ensure no leakage of drug solution during pressurization. Driven by the power component, the push rod 300 moves axially along the drug tube 100 to pressurize the drug solution in the receiving space 101. The pressure during pressurization can be controlled by the energy storage intensity of the power component.

[0036] The volume of the accommodating space 101 is expressed as

[0037] ,

[0038] in, It is the volume of the space 101. It is the cross-sectional area of ​​the push rod. For piston stroke, It is pi. It is the diameter of the push rod.

[0039] Among them, injection pressure for MPa, push rod 300 weight meets requirements:

[0040] ,

[0041] in, Let be the momentum of the impact on push rod 300. This is the cross-sectional area of ​​the injection outlet. The density of the liquid medicine; 1.5 kg·m / s For the mass of the push rod.

[0042] Based on the law of conservation of momentum and the formula for calculating pressure, the mass of the push rod 300 is derived. The calculation formula is as follows. The derivation process is as follows:

[0043] Initial momentum of the push rod

[0044] ,

[0045] in The initial velocity of the push rod is 300. At the moment of impact, the injection pressure of the injected fluid at the injection outlet... It satisfies Bernoulli's equation (assuming the outlet area is the same as the push rod area, and the injection fluid is an incompressible fluid):

[0046] ,

[0047] Where ρ is the density of the injection solution, and the injection solution of this invention is lidocaine hydrochloride anesthetic. The initial velocity of the push rod is obtained by solving Bernoulli's equation:

[0048] Solve the above equations simultaneously:

[0049] ,

[0050] ,

[0051] Solving for:

[0052] ,

[0053] in,

[0054] .

[0055] In this embodiment, it is worth noting that the injection dose of the drug solution is generally between 0.1 and 0.25 ml. When in use, the containing space 101 is filled with the drug solution. Therefore, the volume of the containing space 101 of multiple different needleless injectors is also set to between 0.1 and 0.25 ml respectively. The containing space 101 of different volumes can contain the corresponding volume of drug solution.

[0056] Table 1 below: This group of data was sampled 98 times. The injection site was the dermis, the injection dose was between 0.1 and 0.25 ml, the injection momentum was between 0 and 1.5 kg·m / s, and a needle-free injector with a fixed injection pressure of 19.8 MPa was selected. The injection depth was intradermal. The injection results include wheal size, injection completion rate, pain sensation, onset time and duration of action.

[0057] It's worth noting that the injection completion rate refers to the percentage of medication successfully injected into the dermis out of the total dose. Pain is the body's alarm system response: when the skin or tissues are potentially damaged (or have already been injured), nerve endings generate signals that are transmitted to the brain via the spinal cord. The brain interprets these signals to form a subjective feeling of discomfort and a desire to avoid the area, accompanied by physiological responses such as muscle contraction and increased heart rate.

[0058] For example, the Visual Analogue Scale (VAS) can be used, which is a commonly used and simple method. Draw a 10-centimeter-long straight line, marking 0 points (no pain) on the left and 10 points (most intense pain, unbearable) on the right. Have the participant mark their pain level by drawing circles on the line; for example, a toothache might be marked as 3 points, and childbirth as 8 points. This standardizes subjective feelings. Although different people may have different understandings of a 5-point pain score, comparing the same person's scores at different times—for example, 5 points before taking medication and 2 points after—or comparing it to the average score of a group, can effectively reflect the degree of pain.

[0059] Table 1

[0060]

[0061] The data in the table are from 98 sampling data, with drug solution ranging from 0.1ml to 0.25ml. This sampling data consists of multiple sets of samplings conducted when the drug solution was 0.1ml and 0.25ml, with an injection momentum of 0 to 1.5kg·m / s.

[0062] According to the data in the table, when the drug solution is 0.1ml, as the injection momentum gradually increases from 0 to 1.5kg·m / s, the size of the wheal, the injection completion rate, and the difference between the onset time and the end-of-effect time, i.e., the duration, do not gradually increase as usual. Instead, they first increase and then decrease, reaching the peak state with the best overall effect at 0.8kg·m / s.

[0063] When the drug solution is 0.25ml, as the injection momentum gradually increases from 0 to 1.5kg·m / s, the size of the wheal, the injection completion rate, and the difference between the onset time and the end-of-effect time, i.e. the duration of effect, do not gradually increase. Instead, they first increase and then decrease, and similarly, the best overall effect is achieved at 0.8kg·m / s.

[0064] However, after comparison, under the same conditions, the overall effect of injecting with 0.25ml of drug solution was better than that of injecting with 0.1ml of drug solution in terms of wheal size, injection completion rate, and the difference between the onset time and the duration of effect.

[0065] It is worth noting that the anesthetic solution in this embodiment is a local anesthetic. The onset time and duration of action of the local anesthetic are key considerations. Furthermore, it is worth noting that in the infiltration anesthesia injection process, the first step is to inject the anesthetic into the dermis. During this entire injection process, pain originates at the initial injection site. As shown in Table 1, when the injection momentum is 0.8 kg·m / s, there is essentially no pain or only slight pain; overall, the pain is at least reduced. Therefore, the pain is less intense when the injection momentum is 0.8 kg·m / s, and the duration of the local anesthetic's onset and duration of action are also more effective.

[0066] Example 2

[0067] This embodiment is based on the syringe structure of Embodiment 1, with an injection momentum of 0.8 kg·m / s. The injection pressure parameters of the plunger 300 and the dosage of the drug tube 100 are optimized, and the optimal injection plan for different populations is determined by combining experimental data.

[0068] Table 2 below: This group is a double-blind group (i.e., male and female data are mixed). The injection site is the dermis, the injection dose is between 0.1 and 0.25 ml, the injection pressure is between 14 and 21 MPa, the injection layer is intradermal, and the injection results include wheal size, leakage amount, completion rate, and display location.

[0069] Table 2

[0070] Serial Number Injection site Dosage (ml) Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.1 14 Intradermal 4.5*4.2 0.0045 88 Not entered the muscle 2 dermis 0.1 16.3 Intradermal 5.1*4.8 0.0032 92 Not entered the muscle 3 dermis 0.1 18.7 Intradermal 5.5*5.0 0.0028 94 Not entered the muscle 4 dermis 0.1 19.8 Intradermal 5.8*5.3 0.0021 95 Not entered the muscle 5 dermis 0.1 21 Intradermal 6.0*5.5 0.0018 96 Not entered the muscle 6 dermis 0.15 14 Intradermal 6.2*5.8 0.0051 89 Not entered the muscle 7 dermis 0.15 16.3 Intradermal 6.8*6.3 0.0038 93 Not entered the muscle 8 dermis 0.15 18.7 Intradermal 7.2*6.7 0.0030 95 Not entered the muscle 9 dermis 0.15 19.8 Intradermal 7.5*7.0 0.0023 97 Not entered the muscle 10 dermis 0.15 21 Intradermal 7.8*7.3 0.0020 98 Not entered the muscle 11 dermis 0.2 14 Intradermal 8.5*7.9 0.0058 21 Not entered the muscle 12 dermis 0.2 16.3 Intradermal 9.0*8.4 0.0042 94 Not entered the muscle 13 dermis 0.2 18.7 Intradermal 9.5*8.9 0.0033 96 Not entered the muscle 14 dermis 0.2 19.8 Intradermal 9.8*9.2 0.0025 98 Not entered the muscle 15 dermis 0.2 21 Intradermal 10.1*9.5 0.0022 99 Not entered the muscle 16 dermis 0.25 14 Intradermal 5.96*5.74 0.0295 88 Not entered the muscle 17 dermis 0.25 16.3 Intradermal 12.27*11.75 0 100 Not entered the muscle 18 dermis 0.25 18.7 Intradermal 9.46*9.42 0.0013 99 Not entered the muscle 19 dermis 0.25 19.8 Intradermal 12.02*12.73 0.0148 94 Not entered the muscle 20 dermis 0.25 21 Intradermal 8.4*7.8 0.0028 99 Not entered the muscle

[0071] Table 3 below: This group of samples is the female group. The injection site is the dermis. The injection momentum is 0.8 kg·m / s, the injection dose is between 0.1 and 0.25 ml, the injection pressure is between 14 and 18.7 MPa, and the injection layer is intradermal. The injection results include wheal size, leakage amount, completion rate, and display location.

[0072] Table 3

[0073] Serial Number Injection site Dosage (ml) Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.1 14 Intradermal 4.2*3.9 0.0048 87 Not entered the muscle 2 dermis 0.1 16.3 Intradermal 4.8*4.5 0.0035 91 Not entered the muscle 3 dermis 0.1 18.7 Intradermal 5.2*4.8 0.0030 93 Not entered the muscle 4 dermis 0.15 14 Intradermal 5.9*5.5 0.0053 88 Not entered the muscle 5 dermis 0.15 16.3 Intradermal 6.5*6.0 0.0040 92 Not entered the muscle 6 dermis 0.15 18.7 Intradermal 7.0*6.5 0.0032 95 Not entered the muscle 7 dermis 0.2 14 Intradermal 8.2*7.6 0.0060 89 Not entered the muscle 8 dermis 0.2 16.3 Intradermal 8.8*8.2 0.0045 94 Not entered the muscle 9 dermis 0.2 18.7 Intradermal 9.3*8.7 0.0035 96 Not entered the muscle 10 dermis 0.25 14 Intradermal 5.96*5.74 0.0295 88 Not entered the muscle 11 dermis 0.25 16.3 Intradermal 12.27*11.75 0 100 Not entered the muscle 12 dermis 0.25 18.7 Intradermal 9.46*9.42 0.0013 99 Not entered the muscle

[0074] Table 4 below: This group of samples is the male group. The injection site is the dermis, the injection momentum is 0.8 kg·m / s, the injection dose is between 0.1 and 0.25 ml, the injection pressure is between 19.8 and 21 MPa, the injection layer is intradermal, and the injection results include wheal size, leakage amount, completion rate, and display location.

[0075] Table 4

[0076] Serial Number Injection site Dosage (ml) Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.1 19.8 Intradermal 5.6*5.1 0.0023 95 Not entered the muscle 2 dermis 0.1 21 Intradermal 5.9*5.4 0.0020 96 Not entered the muscle 3 dermis 0.15 19.8 Intradermal 7.3*6.8 0.0024 97 Not entered the muscle 4 dermis 0.15 21 Intradermal 7.6*7.1 0.0021 93 Not entered the muscle 5 dermis 0.2 19.8 Intradermal 9.6*9.0 0.0026 92 Not entered the muscle 6 dermis 0.2 21 Intradermal 9.9*9.3 0.0023 95 Not entered the muscle 7 dermis 0.25 19.8 Intradermal 12.02*12.73 0.0148 100 Not entered the muscle 8 dermis 0.25 21 Intradermal 8.4*7.8 0.0028 99 Not entered the muscle

[0077] Table 5 below: This sample group is a double-blind group of males and females (i.e., male and female data are mixed). The injection site is the dermis, the injection momentum is 0.8 kg·m / s, the injection dose is 0.25 ml, the injection pressure is between 14 and 21 MPa, and the injection layer is intradermal. The injection results include wheal size, leakage amount, completion rate, and display location.

[0078] Table 5

[0079] Serial Number Injection site dose Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.25 14 Intradermal 5.8*5.5 0.0302 87 Not entered the muscle 2 dermis 0.25 14 Intradermal 5.7*5.3 0.0315 86 Not entered the muscle 3 dermis 0.25 16.3 Intradermal 12.1*11.5 0.0018 99 Not entered the muscle 4 dermis 0.25 16.3 Intradermal 11.8*11.2 0.0022 98 Not entered the muscle 5 dermis 0.25 18.7 Intradermal 9.3*8.8 0.0015 99 Not entered the muscle 6 dermis 0.25 18.7 Intradermal 9.5*9.0 0.0012 100 Not entered the muscle 7 dermis 0.25 21 Intradermal 8.5*7.9 0.0029 98 Not entered the muscle 8 dermis 0.25 21 Intradermal 8.3*7.7 0.0031 97 Not entered the muscle

[0080] Table 6 below: This group of samples is the female group. The injection site is the dermis, the injection momentum is 0.8 kg·m / s, the injection dose is 0.25 ml, the injection pressure is between 14 and 18.7 MPa, the injection layer is intradermal, and the injection results include wheal size, leakage amount, completion rate, and display location.

[0081] Table 6

[0082] Serial Number Injection site Dosage (ml) Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.25 14 Intradermal 5.9*5.6 0.0288 87 Not entered the muscle 2 dermis 0.25 14 Intradermal 5.8*5.4 0.0298 86 Not entered the muscle 5 dermis 0.25 16.3 Intradermal 12.3*11.6 0 100 Not entered the muscle 6 dermis 0.25 16.3 Intradermal 12.0*11.3 0.0015 99 Not entered the muscle 7 dermis 0.25 18.7 Intradermal 9.6*9.1 0.0011 99 Not entered the muscle 8 dermis 0.25 18.7 Intradermal 9.4*8.9 0.0014 100 Not entered the muscle

[0083] Table 7 below: This group of samples is the female group. The injection site is the dermis, the injection momentum is 0.8 kg·m / s, the injection dose is 0.25 ml, the injection pressure is between 19.8 and 21 MPa, the injection layer is intradermal, and the injection results include wheal size, leakage amount, completion rate, and display location.

[0084] Table 7

[0085] Serial Number Injection site Dosage (ml) Pharmacy pressure MPa level Pichu size (mm) Leakage volume (ml) Completion rate % Display location 1 dermis 0.25 19.8 Intradermal 10.5*9.8 0.0085 93 Not entered the muscle 2 dermis 0.25 19.8 Intradermal 10.2*9.5 0.0092 92 Not entered the muscle 5 dermis 0.25 21 Intradermal 9.8*9.1 0.0105 91 Not entered the muscle 6 dermis 0.25 21 Intradermal 9.5*8.8 0.0112 90 Not entered the muscle

[0086] Based on the injection momentum of 0.8 kg·m / s in Example 1 and the experimental data in Tables 2 to 6, the injection effects under different doses and pressures were verified, and the following conclusions were drawn:

[0087] Firstly, injecting with a solution volume of 0.25 ml resulted in better overall effects compared to injecting with a solution volume of 0.1 ml, including improved wheal size, injection completion rate, and the difference between onset and duration of action (i.e., duration of effect). It's worth noting that the solution used in this example was a local anesthetic, and the onset and duration of action of the local anesthetic were key considerations. Furthermore, it's important to note that in the infiltration anesthesia injection process, the first step is injecting the anesthetic into the dermis. During this entire injection process, pain is initially generated during the initial injection. As shown in Table 1, the sample data generally showed no pain or only slight pain, indicating a reduction in pain overall. At an injection momentum of 0.8 kg·m / s, the pain during injection was even less, and the duration of the anesthetic's onset and duration of action was significantly improved.

[0088] Secondly, when the injection momentum is 0.8 kg·m / s, the optimal parameters for males are: when the dosage of the drug solution in the containment space 101 is 0.25 ml, and the pressure of the plunger 300 is 19.8~21 MPa, the injection effect is optimal. As shown in Table 4, the injection completion rate is 94%~100% (e.g., 100% completion rate for serial number 7, 99% completion rate for serial number 8), the leakage is only 0.0028-0.0148 ml, the wheal size is 8~12 mm, and ultrasound shows that the drug solution did not enter the muscle layer, fully meeting the requirements for intradermal injection. If the pressure is below 19.8 MPa (e.g., 14 MPa), the completion rate drops to 86%, leakage increases to 0.0354 ml, and the effect deteriorates significantly. When the injection momentum is 0.8 kg·m / s, the optimal parameters for women are: when the dosage of medication in the accommodating space 101 is 0.25 ml, and the pressurization pressure of the plunger 300 is 14~18.7 MPa, the injection effect is optimal. Data from Tables 3 and 6 show that under these parameters, the completion rate is 88%~100% (e.g., 100% completion rate for serial number 11, 99% completion rate for serial number 12), leakage is 0~0.0295 ml, wheal size is 5~12 mm, and the medication is evenly distributed intradermally. If the pressure is above 18.7 MPa (e.g., 19.8 MPa), leakage increases to 0.0085 ml, the completion rate drops to 92%~93%, and the stability of the effect decreases.

[0089] In this case, when the injection target is a woman, the pressure of the injection fluid is 14~18.7 MPa, and the mass of the push rod satisfies:

[0090] ,

[0091] in, Let be the momentum of the impact on push rod 300. It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod.

[0092] When the injection target is male, the hydraulic pressure of the injection is 19.8~21 MPa, then the mass of the push rod meets the following requirements:

[0093] ,

[0094] in, Let be the momentum of the impact on push rod 300. It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod.

[0095] Example 3

[0096] This embodiment is the third embodiment of the present invention, which is based on Embodiment 1 and Embodiment 2.

[0097] This embodiment also provides a method for injecting local anesthetic into the dermis without needles for infiltration anesthesia, comprising configuring the parameters of the plunger 300 and the injection port 102 as follows: when injection momentum is applied to the plunger 300 for injection, the injection pressure parameter at the injection port 102 is 14~21 MPa, wherein the diameter of the injection port 102 is 0.1~0.2 mm and the volume of the accommodating space is 0.25 ml; configuring the power component to apply an injection momentum of 0.8 kg·m / s to the plunger 300 for injection; wherein, when the injection target is male, the injection pressure parameter at the injection port 102 is 19.8~21 MPa; when the injection target is female, the injection pressure parameter at the injection port 102 is 14~18.7 MPa.

[0098] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A device for infiltration anesthesia by needle-free injection of local anesthetic into the dermis, characterized in that: include, A container space (101) for holding the liquid medicine, the volume of which is expressed as follows: ， in, It is the volume of the accommodating space (101). It is the cross-sectional area of ​​the push rod (300). For piston stroke, It is pi. It is the diameter of the push rod (300); Among them, injection pressure for MPa, the mass of the push rod (300) satisfies: ， in, Let the momentum of the impact on the push rod (300) be denoted as . This is the cross-sectional area of ​​the injection outlet. The density of the liquid medicine; ≤1.5kg·m / s, The mass of the push rod (300); Volume of the accommodating space (101) It is 0.25ml; When the injection target is female, the hydraulic pressure of the injection is 14~18.7 MPa, then the mass of the push rod meets the following requirements: ， in, Let the momentum of the impact on the push rod (300) be denoted as . It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod; When the injection target is male, the hydraulic pressure of the injection is 19.8~21 MPa, then the mass of the push rod meets the following requirements: ， in, Let the momentum of the impact on the push rod (300) be denoted as . It is the cross-sectional area of ​​the push rod. The area of ​​the injection outlet. The density of the liquid medicine, For the mass of the push rod.

2. The device for infiltration anesthesia by needle-free injection of local anesthetic into the dermis as described in claim 1, characterized in that: The momentum of the impact on the push rod (300) is 0.6~1.2 kg·m / s.

3. The device for infiltration anesthesia by needle-free injection of local anesthetic into the dermis as described in claim 1, characterized in that: The momentum of the impact on the push rod (300) is 0.6~1 kg·m / s.

4. The device for infiltration anesthesia by needle-free injection of local anesthetic into the dermis as described in claim 1, characterized in that: The momentum of the impact on the push rod (300) is 0.8 kg·m / s.

5. A method for injecting a local anesthetic into the dermis without needles for infiltration anesthesia, characterized in that: The device for infiltration anesthesia by needle-free injection of local anesthetic into the dermis as described in claim 1 includes, The parameters of the push rod (300) and the injection port (102) are configured as follows: when injection momentum is applied to the push rod (300) for injection, the injection pressure parameter at the injection port (102) is 14~21 MPa, wherein the diameter of the injection port (102) is 0.1~0.2 mm, and the volume of the accommodating space (101) is 0.25 ml; The power unit is configured to apply an injection momentum of 0.8 kg·m / s to the push rod (300) for injection; When the injection target is male, the injection pressure parameter at the injection port (102) is 19.8~21 MPa; When the injection target is female, the injection pressure parameter at the injection port (102) is 14~18.7 MPa.

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