A medical device and method for parenteral injection of a medicament avoiding accidental intravascular injection

Abstract

The present invention discloses a medical device (100) and method for injection of a medicament in the body by performing aspiration for safety and subsequently administer a medicament The co-axial syringe-needle arrangement includes an inner needle (101) and an outer needle (201), each equipped with a hollow angled bevel (101a, 201a) for precise detection of blood vessels and injection of medicament respectively at the same level. The device incorporates inner and outer plungers (104, 204), inner and outer hubs (103, 203), and finger flange (301) for efficient handling. The medical device (100) of the invention being capable of detecting the damage in blood vessels before the injection of medicament.

Description

[0001] This application is the patent of addition of Indian patent application 202121042918 filed on 22ndSeptember 2021.

[0002] A MEDICAL DEVICE AND METHOD FOR PARENTERAL INJECTION OF A MEDICAMENT AVOIDING ACCIDENTAL INTRAVASCULAR INJECTION

[0003] FIELD OF THE INVENTION:

[0004] The present invention relates to a medical device and method for parenteral injection of a medicament avoiding accidental intravascular injection. Particularly it relates to a medical device and method for injection of a medicament in the body by performing aspiration for safety and subsequently injecting a medicament; both through separate channels to avoid inadvertent intravascular injection.

[0005] BACKGROUND OF THE INVENTION:

[0006] Syringes and needles are widely used in medicine, research, veterinary medicine, and the pharmaceutical industry. Conventional syringe designs involve a cylinder and plunger, and the process of injection of medicament or aspiration is achieved by manipulating the plunger. However, the conventional method presents challenges, especially during aspiration, requiring the use of both hands, leading to technical difficulties, potential pain for the subject, and increased risk of needle manipulation.

[0007] The conventional method necessitates a change of hands after insertion during the process of aspiration, introducing technical complexities and potential discomfort for the user. This procedural step entails exerting substantial force to pull the plunger and generate a vacuum, resulting in operational instability and the heightened risk of obtaining false negative results. This limitation emphasizes the importance of adopting an improved system that minimizes procedural challenges, enhances user comfort, and ensures comprehensive detection of possible vascular injuries.

[0008] In addition, if the needle inadvertently punctures a blood vessel, the administration of the medicament cannot proceed at that specific point. Therefore, it is imperative to ensure that the vessel puncture is identified by aspiration before injection of medicament.

[0009] Various types of syringe-needles configured devices are known to the art. The prior art document US6972005B2 discloses a syringe assembly for administering a variety of fluids includes a syringe provided with a plurality of flow-isolated chambers, each of which is in flow communication with a respective lumen of a multi-lumen needle located downstream from the syringe. Each lumen is flow- isolated from the rest of the lumens and guides a respective one of the variety of fluids toward an outlet port formed in the needle so that the fluids mix with one another only upon exiting the outlet port.

[0010] Another prior art document WO2018230913A1 discloses an injection needle bar extended to suck the injection liquid in the container to the other end through an end of the attachment inserted into the injection liquid container; An injection needle bar extended to send the injection liquid in the syringe connected to the other end to the living body through one end inserted into the living body; It is formed between the other end of the injection needle bar and the other end of the injection needle bar, to inject the injection liquid sucked from the injection container through the injection needle bar into the syringe through the injection needle bar before injecting the injection liquid A hub cylinder coupled to the syringe, the hub cylinder being separated into an injection needle bar hub and an injection needle bar hub before injection of the injection solution; And a filter mounted biased toward the injection needle bar at a portion where the hub cylinder is separated, to filter foreign substances introduced when the injection fluid is sucked from the injection container. Yet another prior art document CA2547297C discloses a method of injecting a first viscous fluid into a target tissue simultaneous with aspirating a second viscous fluid from the target tissue is disclosed. A surgical system is provided that is capable of supplying pneumatic pressure and vacuum. A first viscous fluid is injected into the target tissue using pneumatic pressure from the system. A mode of operation of the system is changed to provide vacuum and pneumatic pressure. The second viscous fluid is aspirated from the target tissue using vacuum from the system, and the pneumatic pressure remains substantially constant during aspiration.

[0011] The conventional syringe-needle configuration having the drawback such as, said configuration integrates both the aspiration and medicament-injection functions into a single device, typically at a singular endpoint. Consequently, in situations where the needle has entered a blood vessel and during the aspiration phase, the collected blood may inadvertently mix with the medicament, rendering the entire sample unusable for further medical procedures. This limitation underscores the critical need for a system that ensures the separation of aspiration and medicamentinjection processes, enhancing procedural safety and preventing contamination.

[0012] The proposed medical device and method overcome the challenges in the known art by introducing a co-axial syringe-needle arrangement with separate inner and outer needles, allowing for independent channels for aspiration and injection of medicament. The method involves inserting the outer needle which encompasses the inner needle, creating a vacuum within the inner syringe for aspiration, confirming the absence of blood to ensure safe injection of medicament, and subsequently injecting the medicament through the outer needle. The invention eliminates the need for increased force during pulling of the plunger to aspiration, increases true positive and true negative results, and enhances safety.

[0013] In summary, the proposed medical device and method offer a safer, more efficient approach to parenteral injection of medicaments. OBJECT OF THE INVENTION:

[0014] The principle object of the present invention is to overcome all the mentioned and existed drawbacks of the prior arts by providing a medical device and method for parenteral injection of a medicament avoiding accidental intravascular injection.

[0015] Another object of the present invention is to provide an air-tight assembly and alignment of both syringes in the same axis.

[0016] Another object of the present invention is to provide a medical device for parenteral injection of a medicament avoiding accidental intravascular injection that being capable of detecting of injury of the blood vessel and prevention of entry of the medicament in the blood vessel.

[0017] Yet another object of the present invention is to provide a medical device for parenteral injection of medicament avoiding accidental intravascular injection having a co-axial syringe-needle arrangement such as two needle and two syringe i.e. inner needle connected with inner syringe and outer needle connected with the outer syringe.

[0018] Yet another object of the present invention is to provide a medical device for parenteral injection of medicament avoiding accidental intravascular injection in which if the blood vessel has accidentally been punctured by the needle, which is detected by aspiration, the blood not being mixed with the medicament enabling the reuse of the medicament.

[0019] Yet another object of the present invention is to provide a medical device for parenteral injection of medicament avoiding accidental intravascular injection in which the injection of the medicament is performed when the needle has not inadvertently punctured a blood vessel and blood is not detected in the inner syringe. This stringent criterion ensures the utmost safety and precision in the injection process, aligning with the inventive goal of averting accidental intravascular injections.

[0020] Yet another object of the present invention is to provide a medical device for parenteral injection of medicament avoiding accidental intravascular injection having a separate channel for injection of medicament and aspiration processes.

[0021] Yet another object of the present invention is to provide a medical device for parenteral injection of medicament avoiding accidental intravascular injection having a low volume empty channel making it easy for the user to pull the plunger to create low pressure vacuum during aspiration which gives a higher rate of true positive result especially when inside a small blood vessel, also making it easy for the user and less painful for the patient.

[0022] SUMMARY OF THE INVENTION:

[0023] This summary is provided to introduce a selection of concepts in a simplified form that are further disclosed in the detailed description of the invention. This summary is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for determining the scope of the claimed subject matter.

[0024] The present invention is all about a medical device for parenteral injection of a medicament.

[0025] The main aspect of the present invention is to provide medical device for parenteral injection of a medicament avoiding accidental intravascular injection, wherein said medical device comprises a co-axial syringe-needle arrangement having two needles, an inner needle locked with an inner syringe by an inner hub and an outer needle locked with an outer syringe by an outer hub. The inner plunger and an outer plunger disposed inside said respective syringe, and configured to create pressure within said respective syringes; said inner plunger aligned with axis of said inner needle. The inner thumb rest provided at the proximal end of said inner plunger and an inner plunger stopper at the distal end of said inner plunger being connected in its outer diameter to inner syringe body in an airtight manner. The inner syringe further comprising an inner sleeve located near the proximal end of said inner syringe generating resistance and stopping the action of pulling of inner plunger stopper. The outer plunger having three extensions, an outer thumb rest provided at the proximal end of said outer plunger, an outer plunger stopper at the distal end of the said outer plunger being connected in its outer diameter to the outer syringe body as well as the inner syringe body at its inner diameter at a central aperture in an airtight manner. The inner needle, being of a smaller diameter has a pointed end for insertion and being coupled with said inner syringe configured to perform aspiration. The outer needle, having a larger diameter as compared to said inner needle diameter, coupled with said outer syringe being capable of injecting of the medicament, outer needle encloses the inner needle as well as outer syringe encloses the inner syringe. The finger flange provided at the proximal part of base of the inner syringe having three side apertures providing entry of said outer plunger. The finger flange further comprising the central aperture which is provided for the entry of said inner plunger. The cap provided to close the needle; said cap having a diameter greater than the outer syringe to facilitate easy entry of the needle and prevent needle-stick injury to the user while applying the cap over the needle after the usage of the device.

[0026] Another aspect of the present invention is to provide a method for parenteral injection of a medicament avoiding accidental intravascular injection, wherein said method comprising following steps: a. placing the outer needle which also encompasses the inner needle at any desired angle to the skin of patient and inserting it inside the body of patient up to desired distance; b. pulling the inner plunger away from the length of the inner needle along the inner thumb rest of the inner plunger with thumb and middle / index finger of the dominant hand wherein the pulling causes inner plunger stopper to move proximal, creating vacuum in the empty inner syringe causing entry of blood in the inner syringe if the inner bevel of the inner needle is in the blood vessel; said inner syringe having low volume and is empty being capable of creating a low pressure vacuum assisting the entry of blood into the inner syringe even from small blood vessels with low pressure; c. contacting the inner plunger stopper along inner sleeve generating resistance and stopping the action of pulling of inner plunger stopper at the distal part of the inner sleeve and maintenance of vacuum for a desired period of time by maintaining the pull on the inner plunger at that point; blood entering the inner syringe through the inner bevel if the inner bevel is in a blood vessel and no blood entering the inner syringe if the inner bevel is not in a blood vessel; which can be visually confirmed by the user as the outer and inner syringe are both transparent; releasing the pull on the inner plunger after a positive or negative entry of blood; causing automatic recoil of the inner plunger stopper and inner plunger distally due to the vacuum created inside the inner syringe; d. when no blood enters the inner syringe, initiating injection of medicament by pushing the outer plunger along the outer thumb rest of the outer plunger with thumb of dominant hand while the index and middle finger of the dominant hand rest on the distal surface of the finger flange moving the outer plunger stopper towards the outer hub generating pressure and causing movement of medicament from the outer syringe through the outer bevel at the desired site.

[0027] Another aspect of the present invention is to provide a method for parenteral injection of a medicament avoiding accidental intravascular injection, wherein the medicament requires to be administered at different single points, after insertion of the outer needle in the body till the first point, the inner plunger is pulled to perform aspiration to check if the inner bevel is in the blood vessel at that point, in case of no entry of blood in the inner syringe which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel at the same point, then inserts / draws the needle in the required direction to reach the second point where the inner plunger is pulled again to aspiration to check if the inner bevel is in the blood vessel at that point, in case of no entry of blood in the inner syringe which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel at the same point, this process can be repeated at multiple points, the extensions of the outer plunger being separate and not inter-connected inside the outer syringe makes the inner syringe visible through the transparent outer syringe even when aspiration is to be performed at a point when the volume of medicament is lesser than the full capacity of the outer syringe and the outer plunger stopper is at any point in the outer syringe including the most distal point, hence the inner syringe is visible along with the inner plunger and inner plunger stopper at any given point, hence if blood enters the inner syringe the user can detect it visually.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS:

[0029] The foregoing summary, as well as the following detailed description of the invention, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, exemplary constructions of the invention are shown in the drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.

[0030] FIG. 1 represents the exploded view of the medical device as disclosed in the present invention.

[0031] FIG.2 shows the arrangement of the medical device as disclosed in the present invention. FIG. 3 to FIG. 6 shows the arrangement and details of the plunger as disclosed in present invention.

[0032] FIG. 7 to FIG. 9 shows the arrangement and details of the sleeve as disclosed in the present invention.

[0033] Fig. 10 shows the arrangement of the outer thumb rest and inner thumb rest as disclosed in the present invention.

[0034] Fig. 11 and FIG. 12 shows the configuration of hub as disclosed in the present invention.

[0035] FIG.13 shows the needle configuration as disclosed in the present invention.

[0036] FIG. 14 shows the architecture of inner plunger stopper as disclosed in the present invention.

[0037] FIG.15 shows the architecture of outer plunger stopper as disclosed in the present invention.

[0038] DETAILED DESCRIPTION OF THE INVENTION:

[0039] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific functional and structural details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one with ordinary skill in the art to which the invention belongs.

[0040] The present invention overcomes the aforesaid drawbacks of conventional medical device. The objects, features, and advantages of the present invention will now be described in greater detail. Also, the following description includes various specific details and is to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that: without departing from the scope of the present disclosure and its various embodiments there may be any number of changes and modifications described herein.

[0041] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0042] It must also be noted that as used herein and in the appended claims, the singular forms "a", "an," and "the" include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred, systems are now described.

[0043] Throughout the invention, medical device (100) refers to a device for the parenteral injection of a medicament, specifically to prevent accidental intravascular injection. Throughout the invention, aspiration refers to the process of aspiration, in which the blood flows into a syringe or medical device before performing an injection. The purpose of aspiration is to ensure that the needle is correctly positioned within the intended tissue and to verify that no blood indicative of vessel penetration is aspirated into the syringe. This precautionary step helps to avoid accidental intravascular injection, reducing the risk of complications or adverse reactions associated with the unintended delivery of medicament into the bloodstream. Aspiration is commonly performed in medical procedures to enhance the safety and precision of injections, particularly when targeting specific anatomical locations or injecting medications.

[0044] Throughout the invention, “injection of medicament" refers to the process of delivering a medication or therapeutic substance through the parenteral route such as intramuscular route, subcutaneous route or any site where direct intravascular injection is to be avoided.

[0045] The main embodiment of the present invention is to provide a medical device (100) for parenteral injection of a medicament avoiding accidental intravascular injection, wherein said medical device (100) comprising: a co-axial syringe-needle arrangement having two needles (101, 201); an inner needle (101) locked with an inner syringe (102) by an inner hub (103) and an outer needle (201) locked with an outer syringe (202) by an outer hub (203); an inner plunger (104) and an outer plunger (204) disposed inside said respective barrel (102, 202), and configured to create the pressure within said respective barrels (102, 202); said inner plunger (104) aligned with axis of said inner needle (101); an inner thumb rest (105) provided at the proximal end of said inner plunger (104) and an inner plunger stopper (106) at the distal end of said inner plunger (104) being connected in its outer diameter to said inner syringe body in an airtight manner; said inner syringe (102) further comprising an inner sleeve (102a) located near the proximal end of said inner syringe (102) generating resistance and stopping the action of pulling of inner plunger stopper (106); said outer plunger (204) having three extensions (204a); an outer thumb rest (205) provided at the proximal end of said outer plunger (204); an outer plunger stopper (206) at the distal end of the said outer plunger (204) being connected in its outer diameter to the outer syringe body as well as the inner syringe body at its inner diameter at a central aperture (206b) in an airtight manner; said inner needle (101), being of a smaller diameter has a pointed end for insertion and being coupled with said inner syringe (102) configured to perform aspiration; said outer needle (201), having a larger diameter as compared to said inner needle (101) diameter, coupled with said outer syringe (202) being capable of injecting the medicament; outer needle (201) encloses the inner needle (101) as well as outer syringe (202) encloses the inner syringe (102); a finger flange (301) provided at the proximal part of base (302) of the inner syringe (102) having aperture (302a) providing entry of said outer plunger (204); said finger flange (301) and said base (302) further comprising the central aperture (302b) which provided for the entry of said inner plunger (104); a cap (401) provided to enclose the needle; said cap (401) having a diameter greater than the outer syringe (202) to facilitate easy entry of the needle (101, 201) and prevent needle-stick injury to the user while applying the cap (401) over the needle (101, 201) after the usage of the device.

[0046] As per detailed embodiment of the present invention is to provide a medical device (100) for parenteral injection of a medicament avoiding accidental intravascular injection having a coaxial syringe-needle arrangement which refers to an arrangement in which a needle (101, 201) is centrally positioned at the distal end of the syringe (102, 202) in a coaxial (aligned or parallel) manner. The needle (101, 201) is located in the central axis of the syringe (102, 202) and attached at the distal end, allowing for precise and controlled injection of fluids or medicament as well as being capable of performing aspiration. The coaxial arrangement ensures that the needle (101, 201) is aligned with the central axis of the syringe (102, 202), minimizing the risk of misalignment and enhancing the precision and reliability of the device (100). The medical device (100) having an inner needle (101) and an outer needle (201) locked with an inner syringe (102) and an outer syringe (202) respectively. The inner syringe (102) which is transparent being located in the central vertical axis of said outer syringe (202) which is transparent. The inner syringe (102) being attached to the outer syringe (202) at the proximal base (302) in an airtight manner being capable of restricting the entry of air or medicaments from the outer syringe (202) into said inner syringe (102) or the entry of air from inner syringe (102) into the outer syringe (202), thereby keeping both syringes (102, 202) separate from each other; said outer syringe (202) and inner syringe (102) can be cylindrical or rectangular.

[0047] As per detailed embodiment of the present invention, a well (103 a, 203a) being provided at the opening of said inner hub (103) and said outer hub (203) respectively along with grooves in the tunnel just proximal to the well configured to accumulate adhesive to bond the needle (101, 201) and hub (103, 203) which being capable of providing more strength and preventing leakage.

[0048] As per detailed embodiment of the present invention, an inner plunger stopper (106) having a central groove (106a) which being capable of attaching with the inner plunger (104), wherein design of the shape of a central groove (106a) corresponds to the shape of the distal part (104a) of the inner plunger (104) so as to provide a tight attachment as well as grip and allowing the movement of the inner plunger (104) along with inner plunger stopper (106) inside the inner syringe (102) as a single unit.

[0049] As per detailed embodiment of the present invention, outer plunger stopper (206) having plurality of grooves (206a) which being capable of accommodating and gripping with the distal part (204b) of the extensions (204a) of the outer plunger (204) wherein the shape of the grooves (206a) are corresponding to the shape of the distal part (204b) of the extensions (204a) so as to provide a tight attachment as well as grip and allowing the movement of the outer plunger (204) along with outer plunger stopper (206) inside the outer syringe (202) as a single unit and the central aperture (206b) allows the inner syringe (102) to pass through the outer plunger stopper (206). The distal part (204b) of the extensions (204a) of the outer plunger

[0050] (204) can be of any shape to fit in the respective grooves (206a) of the outer plunger stopper (206) for a tight fit.

[0051] As per detailed embodiment of the present invention, the outer plunger (204) having one or more longitudinal extensions (204a) extending from the outer thumb rest

[0052] (205) wherein the longitudinal extensions (204a) extend distally which can be fitted to respective said grooves (206a) of the outer plunger stopper (206), wherein the longitudinal extensions (204a) are separate and not connected directly to each other inside the outer syringe (202) in order to keep the inner syringe (102) along with the inner plunger (104) and inner plunger stopper (106) visible clearly through the transparent outer syringe (202) especially during the movement of the outer plunger (204) during injection of medicament. The longitudinal extensions (204a) can also be connected with each other.

[0053] As per detailed embodiment of the present invention, the orientation, location, and the number of the extensions (204a) from the outer thumb rest (205) of said outer plunger (204) depends on the selected arc angle of grooves (206a) of outer plunger stopper (206) which can be 90 degree, 120 degrees or 180 degrees.

[0054] As per detailed embodiment of the present invention, said outer plunger stopper

[0055] (206) having the one or more grooves (206a) corresponding to the number of extensions (204a) of the outer plunger (204); wherein the grooves (206a) are located on the outer plunger stopper (206) at the end points of the arc length proportional to an arc angle of 90 degrees, 120 degrees or 180 degrees uniformly along the entire circumference in order to generate uniform pressure.

[0056] As per detailed embodiment of the present invention, inner plunger (104) having a longitudinal extension extending from the inner thumb rest (105) wherein the longitudinal extension extends distally which can be fitted to said central groove (106a) of the inner plunger stopper (106).

[0057] As per detailed embodiment of the present invention, the length and gauge of outer needle (201) is shorter and smaller than inner needle (101) respectively. The outer needle (201) in this arrangement features a shorter length and smaller gauge compared to the inner needle (101). The outer needle (201) having a gauge between the range of 18G to 24G and inner needle (101) having a gauge between the range of 30G to 34G.

[0058] As per detailed embodiment of the present invention, the medical device (100) allows a versatile selection of net volumes for both the outer and inner syringes (102, 202), providing to diverse medical requirements. The net volume of the outer syringe (202) can be selected from within the expansive range of 1 to 100 cc, providing flexibility to accommodate a different dosage as per the end user requirement. The net volume of said inner syringe (102) can be selected from the range of 0.5 cc to 20 cc.

[0059] As per detailed embodiment of the present invention, two thumb rest (105, 205) provided at the proximal end of respective plunger (104, 204). The inner plunger (104) having the inner thumb rest (105) provided at the proximal end of said inner plunger (104). The inner thumb rest (105) is configured at an obtuse angle relative to the inner plunger (104), reducing the force required for pulling and withdrawal of the inner plunger (104), facilitating user grip, and enhancing vacuum creation for a smoother aspiration process. The outer plunger (204) having the outer thumb rest (205) provided at the proximal end of said outer plunger (204). The shape of said outer thumb rest (205) can be selected but not limited to triangular, square, rectangle, or semicircle along with a central gap; particularly said outer thumb rest (205) can be semicircle in shape with a gap in the centre to allow the movement of the inner plunger (104) and to avoid collision during movement with the inner thumb rest (105). The shape of the outer thumb rest (205) can be selected corresponding to the orientation, number and location of the extensions (204a) which are further related to the arc angle of the grooves (206a) on the outer plunger stopper (206).

[0060] As per detailed embodiment of the present invention, said inner thumb rest (105) is of a shape to avoid collision during movement with said outer plunger (204) and outer thumb rest (205), shape of said inner thumb rest (105) can be but not limited to circular, oval, triangular, half oval, or half circle.

[0061] As per detailed embodiment of the present invention, syringes (102, 202) are attached to an inner needle (101) and an outer needle (201) respectively, both equipped with a hollow angled bevel (101a, 201a). The inner needle (101) and outer needle (201) having a hollow angle bevel for detection of puncture blood vessel and for injection of medicament respectively at the same level such as if said outer bevel (201a) being in the blood vessel or tissue, said inner bevel (101a) also being inside the blood vessel or tissue respectively. The outer bevel (201a) and inner bevel (101a) of said outer needle (201) and said inner needle (101) respectively being arranged in a configuration that the length of said inner bevel (101a) being enclosed within the length of said outer bevel (201a), said inner needle (101) travels for a longer length from the inner hub (103) so that both inner bevel (101a) and outer bevel (201a) lie at the same plane. The bevel angle of both inner and outer needles (101, 201) range from 0 degrees to 45 degrees and the second cut angle range is from 0 degrees to 45 degrees.

[0062] As per detailed embodiment of the present invention, solid base (302) attached distal to said finger flange (301) from which also consists of a base protruding sleeve (302c) at its circumference which attaches with a protruding sleeve (202a) at the proximal end of the outer syringe (202) in an air-tight manner for assembly of the device as well as alignment of both syringes (102, 202) in the same axis where in the base protruding sleeve (302c) may also be present directly on the finger flange (301) in the absence of a solid base (302) to attach with the protruding sleeve (202a) of the proximal portion of the outer syringe (202) in an air-tight manner. The protruding sleeve (202a) at the proximal end of the outer syringe (202) with a circumference greater or similar to the circumference of the outer syringe (202) which fixes over the base protruding sleeve (302c) sleeve at the circumference of the said solid base (302) for assembly of the device as well as alignment of both syringes (102, 202) in the same axis.

[0063] As per detailed embodiment of the present invention, the finger flange (301) may be mounted on the solid cylindrical base (302); said base (302) and finger flange (301) comprise of one or more openings wherein the extensions (204a) of the outer plunger (204) pass longitudinally through the respective said apertures (302a); a central aperture (302b) wherein the inner plunger (104) extends longitudinally.

[0064] As per detailed embodiment of the present invention, method for parenteral injection of a medicament avoiding accidental intravascular injection, said method comprising following steps: a. placing the outer needle (201) which also encompasses the inner needle (101) at any desired angle to the skin of patient and inserting it inside the body of patient up to desired distance; b . pulling the inner plunger ( 104) away from the length of the inner needle (101) along the inner thumb rest (105) of the inner plunger (104) with thumb and middle / index finger of the dominant hand wherein the pulling causes inner plunger stopper (106) to move proximal, creating vacuum in the empty inner syringe (102) causing entry of blood in the inner syringe (102) if the inner bevel (101a) of the inner needle (101) is in the blood vessel; said inner syringe (102) having low volume and is empty being capable of creating a low pressure vacuum assisting the entry of blood into the inner syringe (102) even from small blood vessels with low pressure; c. contacting the inner plunger stopper (106) along inner sleeve (102a) generating resistance and stopping the action of pulling of inner plunger stopper (106) at the distal part of the inner sleeve (102a) and maintenance of vacuum for a desired period of time by maintaining the pull on the inner plunger (104) at that point; blood entering the inner syringe (102) through the inner bevel (101a) if the inner bevel (101a) is in a blood vessel and no blood entering the inner syringe (102) if the inner bevel (101a) is not in a blood vessel; which can be visually confirmed by the user as the outer and inner syringe (202, 102) are both transparent; releasing the pull on the inner plunger (104) after a positive or negative entry of blood; causing automatic recoil of the inner plunger stopper (106) and inner plunger (104) distally due to the vacuum created inside the inner syringe (102); d. when no blood enters the inner syringe (102), initiating injection of medicament by pushing the outer plunger (204) along the outer thumb rest (205) of the outer plunger (204) with thumb of dominant hand while the index and middle finger of the dominant hand rest on the distal surface of the finger flange (301) moving the outer plunger stopper (206) towards the outer hub (203) generating pressure and causing movement of medicament from the outer syringe (202) through the outer bevel (201a) at the desired site.

[0065] As per detailed embodiment of the present invention, shape of inner hub (103) is tapering distally and is not a symmetrical cylinder throughout the structure resulting in better fluid flow dynamics in the outer syringe (202). This improvement reduces the resistance to the flow of medicament during filling of the outer syringe (202) as well as injection of the medicament out of the outer syringe (202), as a result decreasing the force required by the user to pull and push the outer plunger (204) and hence easing the process of filling the outer syringe (202) with medicament as well as injection of the medicament.

[0066] As per detailed embodiment of the present invention, the proximal pulling force being applied on the outer thumb rest (205) being transmitted through the outer plunger (204), creating the negative pressure inside the outer syringe (202) and filling of outer syringe (202) with the medicament before insertion of the device (100). As per detailed embodiment of the present invention, the medicament requires to be administered at different single points; after insertion of the outer needle (201) in the body till the first point, the inner plunger (104) is pulled to perform aspiration to check if the inner bevel (101a) is in the blood vessel at that point, in case of no entry of blood in the inner syringe (102) which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel (201a) at the same point, then inserts / draws the needle in the required direction to reach the second point where the inner plunger (104) is pulled again to check if the inner bevel (101a) is in the blood vessel at that point, in case of no entry of blood in the inner syringe (102) which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel (201a) at the same point, this process can be repeated at multiple points, the extensions (204a) of the outer plunger (204) being separate and not inter-connected inside the outer syringe (202) makes the inner syringe (102) visible through the transparent outer syringe (202) even when aspiration is to be performed at a point when the volume of medicament is lesser than the full capacity of the outer syringe (202) and the outer plunger stopper (206) is at any point in the outer syringe (202) including the most distal point, hence the inner syringe (102) is visible along with the inner plunger (104) and inner plunger stopper (106) at any given point, hence if blood enters the inner syringe (102) the user can detect it visually.

[0067] As per detailed embodiment of the present invention, the injection of a medicament is intended at a single point from outer syringe (202) through outer bevel (201a) and the aspiration being done by said inner syringe (102) through said inner bevel (101a) at that same end point, wherein only after no blood enters the inner syringe (102) through the inner bevel (101a), the medicament is administered at that point hence confirming that the outer bevel (201a) is not in a blood vessel avoiding accidental intravascular injection since both bevels (102a, 202a) lie at the same level. As per detailed embodiment of the present invention, if blood being detected in the inner syringe (102) through the punctured blood vessel during pulling of inner plunger (104) at a single point where injection of medicament is to be done at that same single point, the procedure is abandoned without injecting the medicament; repeating the procedure at different or same site with same or different device as the medicament is not contaminated.

[0068] As per detailed embodiment of the present invention, the pulling or pushing force applied on said outer thumb rest (205) being transmitted by the extensions (204a) of the outer plunger (204) to the outer plunger stopper (206) is uniform and without any air leak since the grooves (206a) of the outer plunger stopper (206) being attached to the extensions (204a) are located at uniform circumferential points to generate uniform pressure.

[0069] As per detailed embodiment of the present invention, the force applied on said outer thumb rest (205) being transmitted by the outer plunger (204) causing the outer plunger stopper (206) to move distally, which pushing said medicament inside the body of patient.

[0070] As per detailed embodiment of the present invention, the force applied to pull the inner plunger (104) in an empty separate inner syringe (102) of a smaller volume is lesser than the force required to pull the plunger of a medicament filled syringe to create vacuum for aspiration, hence the said device (100) making the process easier for the user in terms of ergonomics as well as improving safety by creating a low pressure vacuum facilitating entry of blood even from small vessels with low pressure hence leading to an increased true positive result, decreased false negative result and when the inner bevel (101a) is not in a blood vessel leading to increased true negative result.

[0071] As per detailed embodiment of the present invention, the desired time period for maintaining the pull of the inner plunger stopper (106) at the distal part of inner sleeve (102a) and maintenance of vacuum is at least 3 seconds up to 15 seconds to allow the blood to flow through the inner needle (101) which is of a higher gauge and longer length and so leads to slow flow of blood into the inner syringe (102) from all sizes of blood vessels.

[0072] As per detailed embodiment of the present invention, there is no contamination of the medicament in cases where there is a positive aspiration hence leading to less wastage and the medicament can be administered again.

[0073] Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0074] Referring to Fig. 1 of the present invention, it shows the exploded view of the medical device (100). As shown in Fig. 1, the medical device (100) having a coaxial syringe needle arrangement having two syringes (102, 202) and two needles (101, 201). The inner needle (101) locked with an inner syringe (102) by an inner hub (103) and an outer needle (201) locked with an outer syringe (202) by an outer hub (203). The plurality of plunger (104, 204) being disposed inside the respective syringe (102, 202) configured to create the pressure within said respective syringe (102, 202). The thumb rest (105, 205) being provided at the proximal end of said plunger (104, 204) respectively and plunger stopper (106, 206) being provided at the distal end of said plunger (104, 204) respectively. The cap (401) provided to enclose the needle.

[0075] Referring Fig. 2 of the present invention, it shows the architecture of the arrangement of the medical device (100). The medical device (100) having two syringe i.e. inner syringe (102) and outer syringe (202), two needles i.e. inner needle (101) and outer needle (201). The inner syringe (102) being enclosed within said outer syringe (202). The inner needle (101) being longer and having smaller diameter then outer needle (201 ) . The inner syringe (102) which is transparent being located in the central vertical axis of said outer syringe (202) which is transparent. The inner syringe (102) being attached to the outer syringe (202) at the proximal base (302) in an airtight manner being capable of restricting the entry of air or medicaments from the outer syringe (202) into said inner syringe (102) or the entry of air from inner syringe (102) into the outer syringe (202). The finger flange (301) configured to provide the proper grip at the time of operation.

[0076] Referring Fig. 3 to Fig. 6 represents the arrangement and details of the plunger (104, 204). The inner plunger (104) having inner thumb rest (105) at the proximal end and inner plunger stopper (106) at the distal end of said inner plunger (104). The outer plunger (204) having outer thumb rest (205) at the proximal end and outer plunger stopper (206) at the distal end of said outer plunger (204). The outer plunger (204) having three extensions (204a) which being fitted in the grooves (206a) of the outer plunger stopper (206). The inner syringe (102) being accommodated inside the central aperture (206b) of the outer plunger stopper (206). The finger flange (301) having three apertures (302a) allows the extensions (204a) of the outer plunger (204) to pass through. The finger flange (301) further comprising the central aperture (302b) allows the inner plunger (104) to pass through.

[0077] Referring Fig. 7 to Fig. 9 of the present invention, representing the arrangement of the inner sleeve (102a), base protruding sleeve (302c) and protruding sleeve (202a). The base (302) attached distal to said finger flange (301) from which also consists of a base protruding sleeve (302c) at its circumference which attaches with a protruding sleeve (202a) at the proximal end of the outer syringe (202) in an airtight manner for assembly of the device as well as alignment of both syringes (102, 202) in the same axis where in the base protruding sleeve (302c) may also be present directly on the finger flange (301) in the absence of a solid base (302) to attach with the protruding sleeve (202a) of the proximal portion of the outer syringe (202) in an air-tight manner. The inner sleeve (102a) being located at the proximal end of inner syringe (102) generating resistance and stopping the action of pulling of inner plunger stopper (106). Referring Fig. 10 of the present invention, it represents the arrangement of outer thumb rest (205) and inner thumb rest (105) such as there is no collision between each of them during the movement.

[0078] Referring Fig. 11 to Fig. 12 of the present invention, the well (103a) has been strategically integrated at the opening of the inner hub (103) and well (203a) has been strategically integrated at the opening of the outer hub (203) in conjunction with grooves in the tunnel, positioned just proximal to the well (103a, 203a). This design feature serves a dual purpose: firstly, the well (103a, 203a) provides a reservoir for adhesive, and secondly, the grooves are specifically configured to accumulate the adhesive, facilitating a robust bond between the needle (101, 201) and the respective hub (103, 203).

[0079] Referring Fig. 13 of the present invention, it shows the needle configuration. Fig. 13 clearly represents that, the outer needle (201) is of a larger diameter with respect to the inner needle (101). The arrangement of the needle (101, 201) such as on a single point, aspiration and injection of medicament can be done. From the representation of fig. 13, it is clear that both the inner needle (101) and the outer needle (201) are equipped with a hollow angled bevel (101a, 201a) respectively. This specific arrangement feature serves a dual purpose: first, to facilitate the accurate detection of a puncture of a blood vessel, and second, to enable the precise injection of a medicament. Importantly, the positioning of these bevels ensures that if the outer bevel (201a) is located within a blood vessel or tissue, the inner bevel (101a) is correspondingly situated inside the same blood vessel or tissue. The length of said inner bevel (101a) being lied within the length of said outer bevel (201a), said inner needle (101) travels for a longer length from the inner hub (103) so that both inner bevel (101a) and outer bevel (201a) lie at the same plane. This simultaneous alignment of the inner and outer bevels (101a, 201a) at the same level enhances the efficiency and accuracy of the medical procedure, ensuring both detection of blood and injection occur precisely at the targeted site. Referring Fig. 14 and Fig. 15 of the present invention, it shows the inner plunger stopper (106) and outer plunger stopper (206) respectively. The inner plunger stopper (106) having central groove of inner plunger stopper (106a) to accommodate the inner plunger (104). The outer plunger stopper (206) having one central aperture (206b) which being capable of accommodating the inner syringe (102), and three side grooves (206a) to accommodate the distal part (204b) of outer plunger extension (204a) in order to provide tight fixation. The outer plunger stopper (206) having the one or more grooves (206a) corresponding to the number of extensions (204a) of the outer plunger (204); wherein the grooves (206a) are located on the outer plunger stopper (206) at the end points of the arc length proportional to an arc angle of 90 degrees, 120 degrees or 180 degrees uniformly along the entire circumference in order to generate uniform pressure.

[0080] ADVANTAGES / IMPROVEMENTS OF THE PRESENT INVENTION:

[0081] 1. Additional sleeve for enhanced alignment of the device:

[0082] The base protruding sleeve and protruding sleeve added at the base and the proximal part of outer syringe respectively are for attachment with each other for better alignment of the axis of both the inner and outer syringe. This further helps in the alignment of the outer and inner needle, hence leading to enhanced function of aspiration and injection in the outer syringe as well as inner syringe. This attachment enhances the assembly and is airtight hence prevents ingress of air or medicament between the inner and outer syringe.

[0083] 2. Modification of the angle of Inner Thumb Rest for enhanced aspiration in Inner Syringe: The angle of the inner thumb rest is reconfigured at an obtuse angle relative to the inner plunger. This improvement reduces the force required by the user for plunger manipulation, enhancing vacuum creation for smoother aspiration before the injection process.

[0084] 3. Enhanced fluid dynamics due to tapered shape of Inner Hub: The shape of the inner hub is tapering as it extends distally towards the outer hub in the present invention. This optimization enhances fluid flow dynamics within the outer syringe, significantly reducing resistance during both medicament filling and injection, hence making it easier for the user. Uniformly Distributed Grooves on the Outer Plunger Stopper: Grooves in the outer plunger stopper that accommodate the distal part of the outer plunger are uniformly distributed along the entire circumference depending on the arc angle chosen instead of being located only in half of the circumference. This uniform circumferential distribution of the grooves helps in uniform transmission of force from the outer plunger to the outer plunger stopper during the pulling and pushing of the outer thumb rest by the user. This uniform transmission enhances the fluid dynamics during plunger movement, ensuring enhanced performance requiring lesser force by the user during pulling and pushing of the plunger. The process of filling of medicament in the outer syringe as well as process of injection of medicament becomes easier for the user. Orientation, number and location of the outer plunger extensions: The orientation, location as well as the number of the extensions from the outer thumb rest of the outer plunger will depend on the circumferential distribution of the grooves based on the selected arc angle. This arrangement generates uniform pressure during the movement of the outer plunger stopper as a result of the force transmitted by the extensions of the outer plunger to the outer plunger stopper due to uniform orientation of the extensions corresponding to the circumferential arrangement of the grooves on the outer plunger stopper. The orientation of the extensions is such that they are separate and not connected directly to each other inside the outer syringe in order to keep the inner syringe along with the inner plunger and inner plunger stopper visible clearly through the transparent outer syringe especially during the movement of the outer plunger during administration of medicament Bevel configuration without perpendicular supports to reduce resistance to fluid and improve user precision of the process of injection: The configuration of both bevels is such that the inner bevel is enclosed within the length of the outer bevel, hence both bevels lie at the same plane. This configuration improves the user’s precision of performing injection of a medicament as there is enhanced knowledge of the location of the outer bevel for injection as the inner bevel is at the same level for aspiration and indicates the location of the outer bevel; either in tissue or blood vessel. Due to this bevel configuration, there are no perpendicular supports to support the inner needle as the inner bevel lies within the outer bevel and it is not distal to the outer bevel. A bevel configuration without perpendicular supports provides reduced resistance to the fluid movement while filling the outer syringe with medicament or while injection of the medicament. The improved bevel configuration without the perpendicular support performs aspiration at the point where injection of the medicament is to be performed; wherein the injection of the medicament occurs only after the aspiration is concluded at that point and there is no blood seen in aspiration. This process can be performed at a single point or can be repeated at various points along the entire tract. Both bevels being at the same level allows the precision in injection of the medicament through the outer bevel as the inner bevel is also at the same level confirming the site of injection with the help of aspiration which occurs through the inner bevel, either at a single point or even at multiple points along an entire tract. Enhanced shape of outer thumb rest for improved pulling and pushing of the outer plunger: The shape of the outer thumb rest can be selected corresponding to the orientation, number and location of the extensions of the outer plunger which are further related to the arc angle of the grooves on the outer plunger stopper. The shape of the outer thumb rest is selected in a way that there is a central gap so as to allow the movement of the inner plunger and avoid collision with the inner thumb rest. Shape of Inner Thumb rest for enhanced pulling of the Inner Plunger: In the improved design of the device, when the extensions are selected corresponding to the grooves located on the outer plunger stopper in a uniform circumferential manner corresponding to an arc angle of 120 degrees, changing the shape of the inner thumb rest facilitates the user to grip the inner thumb rest and prevent collision with the outer thumb rest during pulling of the inner plunger.

[0085] 9. Enhanced adhesion in the Outer and Inner hub due to well and groove configuration: A well provided at the opening of the inner hub and outer hub respectively along with grooves in the tunnel just proximal to the well configured to accumulate adhesive to bond the needle and hub enhancing the strength of adhesion. Increasing the strength of bonding adds to the mechanical strength of the needle during its manipulation and insertion. There is also enhancement in the prevention of leakage of air / medicament through both the hubs leading to optimum functioning of the device during the process of aspiration and injection.

[0086] 10. Second Cut Angle in the Bevel for enhanced penetration of the needle: The second cut angle has been added to the outer bevel to enhance the penetration of the needle. The first and second cut angle of the both bevels are from 0 degrees to 45 degrees. The second cut angle has been added in the outer bevel and can be added to the inner bevel to improve penetration of both bevel in the tissue.

[0087] 11. Shape of Distal part of the Outer Plunger extensions: The distal part of the extensions of the outer plunger is of an ellipsoid shape to fit in the respective grooves of the outer plunger stopper for a tight fit. The shape of the grooves are corresponding to the shape of the distal part of the extensions so as to provide a tight attachment as well as grip even without the usage of an adhesive and allowing the movement of the outer plunger along with outer plunger stopper inside the outer syringe as a single unit which enhances the process of injection and aspiration in said device.

[0088] Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the illustrative examples, make and utilize the present invention and practice the claimed methods. It should be understood that the foregoing discussion and examples merely present a detailed description of 1 certain preferred embodiments. It will be apparent to those of ordinary skill in the art that various modifications and equivalents can be made without departing from the scope of the invention.

[0089] LIST OF REFERENCE NUMERALS

[0090] Device (100)

[0091] Inner needle (101)

[0092] Inner bevel (101a)

[0093] Inner syringe (102)

[0094] Inner sleeve (102a)

[0095] Inner hub (103)

[0096] Inner plunger (104)

[0097] Distal part of Inner plunger (104a)

[0098] Inner thumb rest (105)

[0099] Inner plunger stopper (106)

[0100] Central groove of inner plunger stopper (106a)

[0101] Outer needle (201)

[0102] Outer bevel (201a)

[0103] Outer syringe (202)

[0104] Protruding sleeve (202a)

[0105] Outer hub (203)

[0106] Outer plunger (204)

[0107] Extensions (204a)

[0108] Distal part of outer plunger (204b)

[0109] Outer thumb rest (205)

[0110] Outer plunger stopper (206)

[0111] Grooves (206a) Central aperture (206b)

[0112] Finger flange (301)

[0113] Solid base (302)

[0114] Apertures (302a)

[0115] Central aperture (302b)

[0116] Base protruding sleeve (302c)

[0117] Cap (401)

Claims

Claims:I claim,1. A medical device for parenteral injection of a medicament avoiding accidental intravascular injection, wherein said medical device (100) comprising:A co-axial syringe-needle arrangement having two needles (101, 201); an inner needle (101) locked with an inner syringe (102) by an inner hub (103) and an outer needle (201) locked with an outer syringe (202) by an outer hub (203);An inner plunger (104) and an outer plunger (204) disposed inside said respective barrel (102, 202), and configured to create the pressure within said respective barrels (102, 202); said inner plunger (104) aligned with axis of said inner needle (101); an inner thumb rest (105) provided at the proximal end of said inner plunger (104) and an inner plunger stopper (106) at the distal end of said inner plunger (104) being connected in its outer diameter to said inner syringe body in an airtight manner; said inner syringe (102) further comprising an inner sleeve (102a) located near the proximal end of said inner syringe (102) generating resistance and stopping the action of pulling of inner plunger stopper (106);Said outer plunger (204) having three extensions (204a); an outer thumb rest (205) provided at the proximal end of said outer plunger (204); an outer plunger stopper (206) at the distal end of the said outer plunger (204) being connected in its outer diameter to the outer syringe body as well as the inner syringe body at its inner diameter at a central aperture (206b) in an airtight manner;Said inner needle (101), being of a smaller diameter has a pointed end for insertion and being coupled with said inner syringe (102) configured to perform aspiration; said outer needle (201), having a larger diameter as compared to said inner needle (101) diameter, coupled with said outer syringe (202) being capable of injecting the medicament; outer needle (201)encloses the inner needle (101) as well as outer syringe (202) encloses the inner syringe (102);A finger flange (301) provided at the proximal part of base (302) of the inner syringe (102) having apertures (302a) providing entry of said outer plunger (204); said finger flange (301) and said base (302) further comprising the central aperture (302b) which provided for the entry of said inner plunger (104); a cap (401) provided to enclose the needle; said cap (401) having a diameter greater than the outer syringe (202).

2. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, shape of inner hub (103) is tapering distally as it extends distally towards the outer hub (203).

3. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said inner syringe (102) which is transparent being located in the central axis of said outer syringe (202) which is transparent, the inner syringe (102) being attached to the outer syringe (202) at the base (302) in an airtight manner being capable of restricting the entry of air or medicaments from the outer syringe (202) into said inner syringe (102) or the entry of air from inner syringe (102) into the outer syringe (202), thereby keeping both barrels (102, 202) separate from each other; said inner syringe (102) can be cylindrical or rectangular.

4. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said outer plunger stopper (206) having plurality of grooves (206a) which being capable of accommodating and gripping with the distal part (204b) of the extensions (204a) of the outer plunger (204) wherein the shape of the grooves (206a) are corresponding to the shape of the distal part (204b) of the extensions (204a) so as to provide a tight attachment as well as grip andallowing the movement of the outer plunger (204) along with outer plunger stopper (206) inside the outer syringe (202) as a single unit and the central aperture (206b) allows the inner syringe (102) to pass through the outer plunger stopper (206).

5. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the shape of the distal part (204b) of the extensions (204a) of the outer plunger (204) can be but not limited to ellipsoid, spherical, etc. to fit in the respective grooves (206a) of the outer plunger stopper (206) for a tight fit.

6. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said inner plunger stopper (106) having a central groove (106a) which being capable of attaching with the inner plunger (104), wherein the shape of the central groove (106a) corresponds to the shape of the distal part (104a) of the inner plunger (104) so as to provide a tight attachment as well as grip and allowing the movement of the inner plunger (104) along with inner plunger stopper (106) inside the inner syringe (102) as a single unit.

7. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said outer plunger (204) having one or more longitudinal extensions (204a) extending from the outer thumb rest (205) wherein the longitudinal extensions (204a) extend distally which can be fitted to respective said grooves (206a) of the outer plunger stopper (206), wherein the longitudinal extensions (204a) are separate and not connected directly to each other inside the outer syringe (202) in order to keep the inner syringe (102) along with the inner plunger (104) and inner plunger stopper (106) visible clearly through the transparent outer syringe (202) especially during the movement of the outer plunger (204) during injection of medicament; said longitudinal extensions (204a) can also be connected with each other inside the outer syringe (202).

8. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said outer plunger stopper (206) having one or more grooves (206a) corresponding to the number of extensions (204a) of the outer plunger (204); wherein the grooves (206a) are located on the outer plunger stopper (206) at the end points of the arc length proportional to an arc angle; said arc angle can be but not limited to 90 degree, 120 degrees or 180 degrees uniformly along the entire circumference in order to generate uniform pressure.

9. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the orientation, location, and the number of the extensions (204a) from the outer thumb rest (205) of said outer plunger (204) depends on the selected arc angle of grooves (206a) of outer plunger stopper (206) which can be 90 degrees, 120 degrees or 180 degrees.

10. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said inner plunger (104) having a longitudinal extension extending from the inner thumb rest (105) wherein the longitudinal extension extends distally which can be fitted to said central groove (106a) of the inner plunger stopper (106).

11. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the length and gauge of outer needle (201) is shorter and smaller respectively than inner needle (101).

12. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said outer needle (201) having a gauge between the range of 18G to 24G and inner needle (101) having a gauge between the range of 30G to 34G.

13. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the net volume of said outer syringe (202) can be selected from the range of 1 cc to 100 cc.

14. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the net volume of said inner syringe (102) can be selected from the range of 0.5 cc to 20 cc.

15. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said inner thumb rest (105) is of a shape to avoid collision during movement with said outer plunger (204) and outer thumb rest (205), shape of said inner thumb rest (105) can be but not limited to circular, oval, triangular, half oval, or half circle.

16. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the inner thumb rest (105) is configured at an obtuse angle relative to the inner plunger (104), reducing the force required for pulling and withdrawal of the inner plunger (104).

17. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein shape of said outer thumb rest (205) can be selected but not limited to triangular, square, rectangle, or semicircle along with a central gap; particularly said outer thumb rest (205) can be semicircle in shape with a gap in the centre to allow the movement of the inner plunger (104) and to avoid collision during movement with the inner thumb rest (105); the shape of the outer thumb rest (205) can be selected corresponding to the orientation, number and locationof the extensions (204a) which are further related to the arc angle of the grooves (206a) on the outer plunger stopper (206).

18. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said inner needle (101) and outer needle (201) having a hollow angled bevel (101a, 201a) at the distal end for detection of punctured blood vessel and for injection of medicament respectively at the same level such as if said outer bevel (201a) being in the blood vessel or tissue, said inner bevel (101a) also being inside the blood vessel or tissue respectively.

19. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein the outer bevel (201a) and inner bevel (101a) of said outer needle (201) and said inner needle (101) respectively being arranged in a configuration that the length of said inner bevel (101a) being enclosed within the length of said outer bevel (201a), said inner needle (101) travels for a longer length from the inner hub (103) so that both inner bevel (101a) and outer bevel (201a) lie at the same plane.

20. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said bevel angle of both inner and outer needles (101, 201) range from 0 degrees to 45 degrees and the second cut angle range is from 0 degrees to 45 degrees.

21. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, said solid base (302) attached distal to said finger flange (301) which also consists of a base protruding sleeve (302c) at its circumference which attaches with a protruding sleeve (202a) at the proximal end of the outer syringe (202) in an air-tight manner for assembly of the device as well as alignment of both barrels (102, 202) in the same axis where in the base protruding sleeve(302c) may also be present directly on the finger flange (301) in the absence of a solid base (302) to attach with the protruding sleeve (202a) of the proximal portion of the outer syringe (202) in an air-tight manner.

22. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, said protruding sleeve (202a) at the proximal end of the outer syringe (202) with a circumference greater or similar to the circumference of the outer syringe (202) which fixes over the base protruding sleeve (302c) at the circumference of the said solid base (302) for assembly of the device as well as alignment of both barrels (102, 202) in the same axis.

23. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein said finger flange (301) may be mounted on the solid cylindrical base (302); said base (302) and finger flange (301) comprise of one or more openings wherein the extensions (204a) of the outer plunger (204) pass longitudinally through the respective said aperture (302a); a central aperture (302b) wherein the inner plunger (104) extends longitudinally.

24. The medical device for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 1, wherein a well (103 a, 203a) being provided at the opening of said inner hub (103) and said outer hub (203) respectively along with grooves in the tunnel just proximal to the well configured to accumulate adhesive to bond the needle (101, 201) and hub (103, 203) which being capable of providing more strength and preventing leakage.

25. A method for parenteral injection of a medicament avoiding accidental intravascular injection, wherein said method comprising following steps:a. placing the outer needle (201) which also encompasses the inner needle (101) at any desired angle to the skin of patient and inserting it inside the body of patient up to desired distance; b. pulling the inner plunger (104) away from the length of the inner needle (101) along the inner thumb rest (105) of the inner plunger (104) with thumb and middle / index finger of the dominant hand wherein the pulling causes inner plunger stopper (106) to move proximal, creating vacuum in the empty inner syringe (102) causing entry of blood in the inner syringe (102) if the inner bevel (101a) of the inner needle (101) is in the blood vessel; said inner syringe (102) having low volume and is empty being capable of creating a low pressure vacuum assisting the entry of blood into the inner syringe (102) even from small blood vessels with low pressure; c. contacting the inner plunger stopper (106) along inner sleeve (102a) generating resistance and stopping the action of pulling of inner plunger stopper (106) at the distal part of the inner sleeve (102a) and maintenance of vacuum for a desired period of time by maintaining the pull on the inner plunger (104) at that point; blood entering the inner syringe (102) through the inner bevel (101a) if the inner bevel (101a) is in a blood vessel and no blood entering the inner syringe (102) if the inner bevel (101a) is not in a blood vessel; which can be visually confirmed by the user as the outer and inner syringe (202, 102) are both transparent; releasing the pull on the inner plunger (104) after a positive or negative entry of blood; causing automatic recoil of the inner plunger stopper (106) and inner plunger (104) distally due to the vacuum created inside the inner syringe (102); d. when no blood enters the inner syringe (102), initiating injection of medicament by pushing the outer plunger (204) along the outer thumb rest (205) of the outer plunger (204) with thumb of dominant hand while the index and middle finger of the dominant hand rest on the distal surface of the finger flange (301) moving the outer plungerstopper (206) towards the outer hub (203) generating pressure and causing movement of medicament from the outer syringe (202) through the outer bevel (201a) at the desired site.

26. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein the proximal pulling force being applied on the outer thumb rest (205) being transmitted through the outer plunger (204), creating negative pressure inside the outer syringe (202) and filling of outer syringe (202) with the medicament before insertion of the device (100).

27. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein the medicament requires to be administered at different single points; after insertion of the outer needle (201) in the body till the first point, the inner plunger (104) is pulled to perform aspiration to check if the inner bevel (101a) is in the blood vessel at that point, in case of no entry of blood in the inner syringe (102) which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel (201a) at the same point, then inserts / draws the needle in the required direction to reach the second point where the inner plunger (104) is pulled again to perform aspiration to check if the inner bevel (101a) is in the blood vessel at that point, in case of no entry of blood in the inner syringe (102) which can be visually confirmed, the user administers the predetermined volume of medicament through the outer bevel (201a) at the same point, this process can be repeated at multiple points, the extensions (204a) of the outer plunger (204) being separate and not inter-connected inside the outer syringe (202) makes the inner syringe (102) visible through the transparent outer syringe (202) even when aspiration is to be performed at a point when the volume of medicament is lesser than the full capacity of the outer syringe (202) and the outer plunger stopper (206) is at any point in the outer syringe (202) including the mostdistal point, hence the inner syringe (102) is visible along with the inner plunger (104) and inner plunger stopper (106) at any given point, hence if blood enters the inner syringe (102) the user can detect it visually.

28. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein injection of a medicament is intended at a single point from outer syringe (202) through outer bevel (201a) and the aspiration being done by said inner syringe (102) through said inner bevel (101a) at that same end point, where only after no blood enters the inner syringe (102) through the inner bevel (101a), the medicament is administered at that point hence confirming that the outer bevel (201a) is not in a blood vessel avoiding accidental intravascular injection since both bevels (102a, 202a) lie at the same level.

29. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein if blood being detected in the inner syringe (102) through the punctured blood vessel during pulling of inner plunger (104) at a single point where injection of medicament is to be done at that same single point, the procedure is abandoned without injecting the medicament; repeating the procedure at different or same site with same or different device as the medicament is not contaminated.

30. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein the pulling or pushing force applied on said outer thumb rest (205) being transmitted by the extensions (204a) of the outer plunger (204) to the outer plunger stopper (206) is uniform and since the grooves (206a) of the outer plunger stopper (206) being attached to the extensions (206a) are located at uniform circumferential points to generate uniform pressure.

31. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein the force applied on said outer thumb rest (205) being transmitted by the outer plunger (204) causing the outer plunger stopper (206) to move distally, which pushing said medicament inside the body of patient.

32. The method for parenteral injection of a medicament avoiding accidental intravascular injection as claimed in claim 25, wherein the desired time period for maintaining the pull of the inner plunger stopper (106) at the distal part of inner sleeve (102a) and maintenance of vacuum is at least 3 seconds up to 15 seconds to allow the blood to flow through the inner needle (101) which is of a higher gauge and longer length and so leads to slow flow of blood into the inner syringe (102) from all sizes of blood vessels.

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