ES2956958A1 - Reusable device for intramuscular fluid injection (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Reusable device for the intramuscular injection of fluids comprising a housing (1) containing a syringe, needle protection means (5), locking means for the needle protection means (5), injection means, an inspection window (6) and suction means that move the plunger (4) of the syringe and that promote the return of a part of the injectable fluid for inspection. Applicable in those sectors in which health-related devices are designed, manufactured, produced or used. In particular, the device is especially suitable for use in hospitals, clinics, prisons, residential centers for the elderly, etc. and, in general, where it is required to apply therapies with intramuscular injections. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

Reusable device for intramuscular fluid injection

Technical sector

The present invention relates to a reusable device for the intramuscular injection of fluids, and preferably medications. The device contains a syringe with the injectable fluid and comprises injection means, suction means and an inspection window that makes it possible to evaluate the adequacy and safety of the injection process.

The invention is applicable in those healthcare sectors in which it is necessary to administer one or more active substances, or active ingredients, or drugs, prepared together with other products called excipients intramuscularly and especially in situations that require intramuscular pharmacological containment processes. and in those sectors where health-related elements or devices are manufactured.

Background of the invention

Intramuscular injection is one of the most used techniques for the indirect parenteral administration of fluids and medications, in which, using a needle and a syringe, a certain substance is injected into the muscle tissue. It is considered an indirect parenteral route because its administration is through the skin and requires absorption, requiring a certain time to reach the systemic circulation, allowing the administration of both aqueous and oily preparations (Polania Gutiérrez, J. J., & Munakoml, S. (2023).Intramuscular Injection.In StatPearls. Specifically, intramuscular injection is one of the most used techniques for pharmacological containment in situations of acute agitation due to metabolic, toxicological, neurological, infectious, traumatic and psychiatric causes, among others.

However, the intramuscular administration of fluids, and preferably medications, presents many problems from the point of view of patient and healthcare professional safety, some of them being: possible incomplete administration of the medication, inappropriate administration or biological risk. from the toilet due to punctures with an unprotected needle during administration. All of these inconveniences are also magnified in situations of psychomotor agitation.

For a safe practice of intramuscular injection, it is necessary to take into account several aspects (Wynaden, D., Tohotoa, J., Al Omari, O., Happell, B., Heslop, K., Barr, L., & Sourinathan, V. (2015).Administering intramuscular injections: how does research translate into practice over time in the mental health setting? Nurse education today, 35(4), 620-624):

• The accessibility of the area. The administration area is limited to the dorsogluteal, ventrogluteal, deltoid and vastus lateralis areas depending on the patient's clinical status (Walsh, L. & Brophy, K. (2011). Staff nurses'sites of choice for administering intramuscular injections to adult patients in the acute care setting. Journal of advanced nursing,67 (5), 1034-1040.); (Cocoman, A., & Murray, J. (2008). Intramuscular injections: a review of best practice for mental health nurses. Journal of psychiatric and mental health nursing, 15(5), 424-434); (Wynaden, D., Tohotoa, J., Al Omari, O., Happell, B., Heslop, K., Barr, L., & Sourinathan, V. (2015). Administering intramuscular injections: how does research translate into practice over time in the mental health setting? Nurse education today, 35(4), 620-624.).

• The amount of muscle mass/fat mass, being necessary to select the appropriate puncture area and the length of the needle to reach the muscle tissue, which can range between 38 mm and 51 mm in the adult population (Strohfus, P., Palma , S., & Wallace, C. T. (2022). Dorsogluteal intramuscular injection depth needed to reach muscle tissue according to body mass index and gender: A systematic review. Journal of clinical nursing, 31(19-20), 2943 2958.).

• The volume of administration depending on the selected anatomical area (Walsh, L., & Brophy, K. (2011). Staff nurses' sites of choice for administering intramuscular injections to adult patients in the acute care setting. Journal of advanced nursing , 67(5), 1034-1040.).

• The risk of nerve and/or vascular injury (Da Silva, Paulo Sérgio, & Vaz Vidal, Selma. (2013). The anatomical relationships involved in the administration of medications intramuscularly: a field of study for nurses. Global Nursing , 12(30), 156-169.); (Mraz, M. A. I., Thomas, C., & Rajcan, L. (2018). Intramuscular injection CLIMAT pathway: a clinical practice guideline. British journal of nursing (Mark Alien Publishing), 27(13), 752-756.).

• The risk of the coring effect, which consists of the appearance inside the vial, or the already loaded syringe, of small fragments of the rubber of the stopper, which in experimental studies in adults would only be detected visually in half of the cases, existing a risk of phlebitis, pulmonary granulomas, pulmonary dysfunction and even death in case of administration via the vascular route (Kordi, R., White, B. F., & Kennedy, D. J. (2017). Possibility and Risk of Medication Vial Coring in Interventional Spine Procedures .PM & R: the journal of injury, function, and rehabilitation, 9(3), 289-293.).

• Risk of injection of glass microparticles derived from the breakage of the upper part of the ampoule (Carraretto, AR., Curi, EF., Almeida, CED., Abatti, REM (2011). Glass Ampoules: Risks and Benefits. Rev Bras Anestesiol, 61(4): 280-284.).

All of these aspects pose a challenge to the skill of health personnel and also a technological challenge in situations with a high level of demand, such as those that occur when the safe administration of this type of injections is required in patients who present acute agitation ( for example, in children, adults, the elderly, or even in animals).

In terms of skills, to achieve safe de-escalation through pharmacological containment and intramuscular injection, action can be taken through specific training of the healthcare personnel involved. The assessment of the clinical picture, the implementation of non-pharmacological containment measures, the knowledge of the intramuscular technique itself or the protection of the patient and staff to minimize the biological risks due to accidental puncture, in a short period of time, make specialized training is necessary in handling these situations. To choose the area of administration of the injectable substance and carry out a safe practice, it is necessary to take into account the following aspects: the accessibility of the area in case of agitation, the volume administered, the amount of muscle mass/fat mass, the assessment of the state of the tissue, and the nervous and vascular risk of the area (Da Silva, Paulo Sérgio, & Vaz Vidal, Selma. (2013). The anatomical relationships involved in the administration of medications intramuscularly: a field of nursing study . Global Nursing, 12(30), 156-169.). On many occasions, in addition, the administration area is very limited to the dorsogluteal, ventrogluteal and vastus lateralis areas due to the patient's clinical condition (Gutiérrez Higueras T, Fuentes Callejón MC. (2013). Efficacy of the ventrogluteal area for administration of intramuscular medication in the patient during mechanical restraint. Health research monographs ISSN: 1988-3439 - YEAR VIl - N. 19).

However, despite improved skill among healthcare workers, there remains a high risk of needlestick injuries, with the corresponding biological risk of contracting infections such as hepatitis B virus (HBV), hepatitis C (HCV). ) and the AIDS virus (HIV) among others, during the management of agitation symptoms (Gabriel J. (2009). Reducing needlestick and sharps injuries among healthcare workers.Nursing Standard,23: 41-4.). Furthermore, despite all the biosafety measures adopted, healthcare professionals are the most exposed to this type of risk, considered one of the most serious occupational problems worldwide, with more than two million annual exposures in clinical practice and an overall incidence of needlestick injuries of 43% (Hosseinipalangi, Z., Golmohammadi, Z., Ghashghaee, A., Ahmadi, N., Hosseinifard, H., Mejareh, Z. N., Dehnad, A., Aghalou, S. ., Jafarjalal, E., Aryankhesal, A., Rafiei, S., Khajehvand, A., Ahmadi Nasab, M., & Kan, F. P. (2022). Global, regional and national incidence and causes of needlestick injuries: a systematic review and meta-analysis.Eastern Mediterranean health journal = La revue de sante de la Mediterranee oriéntale = al-Majallah al-sihhiyah li-sharq almutawassit, 28(3), 233-241.). It is difficult to know the magnitude of the problem due to their underreporting. One way to further minimize these risks, complementary to training, is through technology and more specifically through needle control, allowing preventive measures against biological risk to be achieved.

To reduce the risk of accidental punctures and increase the chances of safe administration, automatic injection devices for the administration of treatments are known, which may in some cases be applicable to agitated patients. In these devices, the needle is protected or collected within the system until the moment of puncture and they allow the administration of medication through the needle with different levels of automation. These are normally devices for self-injection of medications for the treatment of pathologies such as arthritis, sclerosis, diabetes, osteoporosis, etc., or designed to be used in situations that require a certain urgency, such as anaphylactic-type reactions.

If we take a look back through history, the first autoinjectors have military origins. The Syrette, introduced into the North American army in 1950 (Szinicz L. (2005). History of Chemical and biological warfare agents. Toxicology, 214(3), 167-181.), was one of the first. Consisting of a flexible metal tube similar to a tube of ophthalmic ointment, with a needle and its protector attached, it was developed for morphine injection, presenting major problems of sterility, stability and leaks.

In general, they are pre-filled and ready-to-use devices so that they only accept one single dose after which they are discarded. For example, a device of this type is described in publication ES 2 548 175 T3 by Brereton, S. et al., where the apparatus is for the subcutaneous application of a small dose of medication preloaded from the laboratory. This generates several problems, the most obvious being the management of biological waste and the environmental impact of single-use devices. There are also alternatives for autoinjectors capable of incorporating a syringe loaded with the medication and that can be mounted inside, such as the one described in patent CA 2637147 A1.

However, a particularly relevant problem that is not solved by any of the known alternatives, and that is especially important in situations in which the patient presents with agitation, is the verification of the correct administration of the intramuscular dose itself, ensuring that Indeed, the injection is performed at the muscular level and is not subcutaneous (under the skin) or intravenous. If this verification is not possible, there is a risk that the administered substance does not reach the muscle tissue and remains lodged in the subcutaneous tissue or is introduced into a blood vessel, so that the administration of the medication does not have the desired effect. or what is worse, that an undesirable effect on the health or risk to the patient's life occurs. There are many reasons why intramuscular administration can be incorrect: due to the lack of skill of the healthcare personnel, due to the patient's own agitation, due to the lack of depth of the needle penetration, due to a needle that is too short or due to from an inadequate needle penetration path, etc. (Zaybak, A., Güne§, U. Y., Tamsel, S., Khorshid, L., & E§er, I. (2007). Does obesity prevent the needle from reaching muscle in intramuscular injections? Journal of advanced nursing, 58 (6), 552-556.).

Explanation of the invention

The object of this invention is a reusable device for the injection of fluids, and preferably medications, intramuscularly, improving the effectiveness and safety in the administration of the fluid and also avoiding the risks of contamination for the user who applies it. .

Therefore, an object of the present invention is a reusable device for the intramuscular injection of fluids that comprises:

- A casing containing a syringe. Said syringe comprises a needle that penetrates the skin of a subject through which the injectable fluid circulates, a cylinder with at least a portion of the transparent cylindrical side surface containing the injectable fluid, and a plunger that pushes the fluid through the needle. For the purposes of this invention and its description, the term transparent should be understood as that which can be observed through, and to fulfill this function various strategies can be used, such as, for example, using materials permeable to visible light, or materialize gaps or holes in a component through which visible light passes.

- Needle protection means that cover or uncover the needle.

- Locking means for the needle protection means that block or unlock the movement of the needle protection means.

- Injection means that induce the displacement of the piston to inject the fluid. - An inspection window arranged in the housing, aligned with the transparent portion of the cylindrical side surface of the syringe barrel.

- Suction means that move the plunger and promote aspiration through the needle towards the cylinder after the puncture has been performed in the patient's body. These suction means, together with the inspection window, allow the user of the device to ensure that the fluid injection is of the intramuscular type. After the needle is punctured into the subject's body, the activation of the suction means promotes aspiration through the needle, so that by observing the inspection window it can be seen if blood refluxes when aspirating and, therefore, the puncture is being performed in a suitable area or not. If blood is seen, discharge of the fluid should not continue in that area of the subject's body and the procedure should be started again at another site. If no blood is seen, administration of the fluid to the patient can continue.

One way to use the device includes the following steps:

a) House the syringe with the fluid to be injected in the device housing.

b) Unlock the locking means of the needle protection means.

c) Perform a puncture in the selected area of the subject's body.

d) Activate the suction means to promote aspiration and check by observing the inspection window that there is no blood in the syringe to decide whether to continue with the application of the injectable fluid.

e) Activate the injection means that induce the displacement of the plunger to inject the fluid.

f) Remove the device from the subject's body after administration and lock the locking means of the needle protection means once the needle is protected.

g) Remove the syringe safely from the device, thus being prepared for new use.

In a preferred embodiment, the suction means is a lever mechanism comprising a lever and a fulcrum disposed in an intermediate portion of the lever and in the wall of the housing. One outer end of the lever is a push button operable with the fingers of one hand and the other inner end of the lever is associated with the syringe plunger. With this configuration, the pivoting movement of the lever pushes the plunger, moving it in a movement opposite to that of injection, promoting aspiration through the needle. The outer end of the lever is user-activatable so that it can be pressed with your fingers. For example, you can hold the device with one hand and use your thumb to press the outer end of the lever to encourage aspiration through the needle.

In another preferred embodiment, the needle protection means are movable and comprise a second cylinder movable on the inside of the housing. The second cylinder comprises at least a portion of the transparent cylindrical side surface alignable with the inspection window. It also comprises a first spring with a fixed end associated with the casing and another free end associated with the second cylinder and which pushes the second cylinder. In this way, the natural tendency of the protection means is to cover the needle with the second cylinder due to the tension of the first spring, which maintains it in this position. When the user releases the locking means and presses the device against the body of the subject, the elastic tension of the spring is overcome and the second cylinder of the needle protection means retracts into the interior of the housing, allowing the needle to be uncovered, facilitating the resulting puncture through the patient's skin.

In a more preferred embodiment, the locking means of the needle protection means comprise a guide arranged on the surface of the second cylinder on which a protuberance arranged on the housing moves. Said guide comprises a portion parallel to the generatrix of the second cylinder and another portion substantially perpendicular to the previous one. The locking means prevent the needle protection means from accidentally moving and uncovering the needle. To unlock the movement of the needle protection means, the device can be rotated with the intention that there is a relative pivoting movement between the needle protection means and the housing, causing the protuberance to move along the portion substantially perpendicular to the guide. Once this position is reached, the configuration of the guide allows the needle protection means to move towards the interior of the housing, leaving the needle exposed. After use of the device, the needle protection means can be re-locked in the opposite process. Through this configuration, at the moment the puncture is going to be performed, the healthcare worker makes a small turn of the base, which allows the first spring to retract by applying pressure to the skin and leaving the needle available for the puncture.

In another preferred embodiment, the injection means comprise:

- A flat surface associated with the plunger.

- A second spring with a fixed end associated with the casing and another free end associated with the flat surface of the plunger, which pushes it due to the spring load.

- At least two walls with one end fixed on the flat surface and the other end free. Said walls comprise locking tabs associated with an edge of the housing. An edge of the housing may be, for example, an edge of a through hole provided at one end of the housing.

- A removable plug arranged between the walls and that limits the transverse movement of the walls towards the interior volume that is between them. When the plug is in a first configuration, not extracted, the walls cannot move transversely because the plug prevents them from doing so. In this way, the locking tabs associated with the edge of the housing are in contact with it and prevent the movement of the flat surface associated with the plunger and, therefore, of the plunger itself, locking it even if the second spring is loaded. When the stopper is in a second configuration, removed, the ends of the walls can be brought relatively closer together with the locking tabs, freeing the movement of the flat surface associated with the plunger, allowing the release of the dose of fluid contained in the syringe.

In another preferred embodiment, the injection means and the suction means of the device comprise a button associated with electronic means. Said electronic means comprise actuating means that, when the button is pressed the first time and once the needle is inserted, cause the actuating means to act on the suction means. At this point the device operator can check the presence or absence of blood through the inspection window and decide whether to continue with the process. When the button is pressed a second time, they cause the actuating means to act on the injection means to inject the fluid.

For representative purposes; electronic means, with actuator means and a control unit can be, for example, one or more electronically controlled servomotors that can also be associated with a set of mechanical couplings (a series of rigid links, with ligaments that form a closed chain or a series of closed chains) to transform rotary motion into another, or transform the delivery of work, power or energy. The control unit may be, for example, a microcontroller.

In a more preferred embodiment, the needle protection means are a movable carriage that includes the needle and that when it moves relatively inside the housing leaves the needle covered or uncovered. When the button is pressed the first time, the locking means unlock the movement of the needle protection means and the actuating means cause the carriage to advance inside the housing, exposing the needle. In an even more preferred embodiment, when the carriage moves it also pushes the needle and plunges it into the patient's body. After the second press, and once the fluid has been injected, the carriage moves again in the opposite direction, pulling the needle to hide it again inside the housing.

In another more preferred embodiment, the actuator means comprise at least one electric motor powered by a battery.

In another more preferred embodiment, the electronic means comprise actuator means and a control unit with a processor and a memory in which a program is stored that includes instructions that, when the button is pressed the first time, are executed by the processor. . Once the locking means of the needle protection means is released, the needle protection means can be moved to expose the needle. In an even more preferred embodiment, the needle is movable and the needle protection means also pushes the needle uncovered and plunges it into the patient's body. Once the needle is inserted, the instructions executed cause the actuating means to act on the suction means. At this point the device operator can check the presence or absence of blood through the inspection window and decide whether to continue with the process. When the button is pressed a second time, they cause the actuating means to act on the injection means to inject the fluid. In an even more preferred embodiment, once the fluid is injected, the needle protection means pull the movable needle to introduce it inside the housing and cover it.

For representative purposes, a control unit may be, for example, a microcontroller.

In another more preferred embodiment, the device comprises a first button that is pressed the first time and a second button that is pressed the second time. Through this configuration of the device, the safety of use of the device and risk prevention can be further increased through the redundancy of elements. In this way, the fluid injection event becomes independent of the previous check event through the use of two different buttons.

The invention described herein provides a device for the intramuscular injection of fluids designed to release the dose automatically, intramuscularly and safely for both the patient and the administrator, even in special situations of patient agitation.

Unlike other known technologies, the inspection window together with the suction means makes it possible to ensure intramuscular inoculation of the fluid, which is especially relevant for the efficient and safe administration of certain types of medications.

In some embodiments of the device, a list of technical characteristics is provided that allow it to be materialized in such a way that all its manipulation can be carried out using only one hand, regardless of whether the user is right- or left-handed.

Furthermore, the one-handed grip keeps the user's fingers away from the area near the tip of the needle, which, together with the needle protection means and the locking means, represents a doubly safe system.

Furthermore, from the point of view of sustainability, and unlike other automatic injection systems, a reusable device is presented, and can be used successive times simply by replacing the syringe with a new dose. In this way, the large amount of waste generated in healthcare environments is avoided, which is also difficult to treat due to its high biological risk.

The person responsible for administering the fluid can preload it according to the prescribed dose. As it is a controlled load, you can even use needles with filters that avoid the risk of the coring effect and the administration of glass microparticles derived from opening the ampoule.

The invention is applicable in those sectors in which health-related devices are designed, manufactured, produced or used. In particular, the device is especially suitable for use in hospitals, clinics, prisons, residential centers for the elderly, etc. and, in general, where it is required to apply therapies with intramuscular injections.

Brief description of the drawings

TheFig. 1 shows a general view of the device containing a syringe with a dose of medication. The device is shown with a hinged side cover (15) open to insert or remove the syringe, and the needle protection means (5) partially retracted, revealing the needle (2). The housing (1) has a window (6) to inspect the correctness of the puncture area. On the plunger (4) you can see a flat surface (11) on which the wings (12) are located, between which a plug (14) is arranged that blocks the wings (12).

TheFig. 2 shows a view of needle protection means (5) with at least a portion of the transparent cylindrical side surface and a guide (9) arranged on its surface.

TheFig. 3 shows a partial view of the device where the characteristics of the blocking, injection and suction means can be seen in detail. More specifically, in the figure you can see locking tabs (13) associated with an edge of the housing (1). This edge is constituted by two through semicircular slots in the casing (1) that cross the wings (12). You can also see a materialization of the lever (7) and the fulcrum (8) and a second spring with a fixed end associated with the housing (1) and another free end associated with the flat surface (11).

TheFig. 4 shows an embodiment of the device with the transparent casing (1) and comprising electronic means. In this device, actuator means act on the suction means and the injection means when the user presses a first or a second button. These buttons are arranged on a handle that the user can hold with one hand like a pistol. In the figure it can also be seen that the needle protection means (5) are a movable carriage that includes the needle (2) that moves when a button is pressed.

TheFig. 5 shows a partial detailed view of the interior of the device of Fig. 4. The actuating means that act on the suction means and the injection means are realized with a system of spindle and nut associated with the plunger (4) of the syringe. The movement of the spindle is produced thanks to an electric motor, which can also be controlled electronically. When the spindle rotates in one direction or the opposite, the displacement of the plunger (4) is promoted, either to allow suction and check the suitability of the puncture area, or to allow the injection of the fluid once the previous one has been secured. .

TheFig. 6 shows a schematic view of the device during some phases of use: b) unlocking the locking means of the needle protection means (5); c) perform a puncture in the selected area of the subject's body; d) activate the suction means; and e) activate the injection means that induce the displacement of the plunger to inject the fluid.

Preferred embodiment of the invention

For a better understanding of the present invention, the following examples of preferred embodiments are set out, described in detail, which should be understood without limiting the scope of the invention.

EXAMPLE 1

A device like the one represented in Fig. 1 was manufactured. To do this, 3D printing techniques were used for most of the components, except for the springs and the syringe, in which case commercial products were used. More specifically, Fused Deposition Modeling (FDM) was applied, using ABS (Acrylonitrile Butadiene Styrene) as a fuse material.

The device had to be light to be easily handled with one hand, but it also had to be resistant to withstand the stresses generated when performing the injection. For this reason, ABS was chosen (except for the springs and the syringe). ABS filament is a fairly common thermoplastic polymer in the industry, mainly known for its good resistance to low temperatures and light weight. It offers smooth, shiny surfaces and can be chemically welded with acetone. Little post-processing is required when printing ABS filament, saving time manufacturing complex parts. The design of the ABS parts was done in such a way that it also made them suitable for materialization through plastic injection molding.

The casing (1) was materialized in a cylindrical shape, open at one end and with two slots at the other. These slots allowed the walls (12) of the injection means to pass through them, so that the locking tabs (13) could rest on the edge of these slots. The housing (1) also included an inspection window (6), through which the contents of the syringe could be observed, which included a completely transparent cylinder (3). The housing (1) also included a hinged side cover (15) on an upper portion, closer to the end with the slots, which allowed the syringe loaded with the fluid to be injected to be inserted and removed once used. In the vicinity of the open part, on the inside of the housing (1), a protuberance (10) was located that could move along a guide (9) located in the needle protection means (5).

The needle protection means (5) were materialized by another cylinder that could slide inside the casing (1), concentric to it. The needle protection means (5) also included a transparent portion, so that, even if it was retracted inside the housing (1), the contents of the syringe could be seen through the inspection window (6). .

Between the housing (1) and the needle protection means (5), a first spring was arranged that exerted a compression load on the needle protection means (5), so that for the needle protection means (5) moved internally in the housing (1), this load had to be overcome by pressing the device on the patient's skin.

The needle protection means (5) also included locking means to avoid accidentally exposing the needle (2). These locking means served to keep the needle protection means (5) immobilized while the device was not going to be used and had to be unlocked by the person who was going to manipulate it at the time of use. The solution that materialized was to arrange a guide (9) on the surface of the needle protection means (5) in the shape of an "L" with the longest portion parallel to the generator of the cylinder and the other, shorter portion, perpendicular to the previous one. Through this guide, the protuberance (10) arranged inside could be relatively moved.

of the casing (1).

This lock worked so that the person who was going to use the device had to rotate the needle protection means (5) a little with respect to the housing (1) so that the protuberance (10) moved over the short section of the "L" and remained aligned with the long section and thus the needle protection means (5) could move inside the casing (1). In this way it could also be ensured that the unlocking was carried out consciously and not there would be accidental punctures. To ensure a more fluid movement, it was also decided to round the right-angled corners of the guide (9).

The injection means, except for a second spring, were also printed in ABS and consisted of the following parts: a flat disc-shaped surface (11) that could move inside the housing (1) and a second spring with a fixed end associated with the casing (1) and another free end associated with the flat surface, which pushes it. This flat surface (11) was associated with the plunger (4) of the syringe, so that when it came into contact with the free end of the plunger (4) it could push it to inoculate the fluid into the patient thanks to the load of the second spring. The function of the flat surface (11) was to ensure thrust and shape compatibility between the end surface of the plunger (4) of any syringe with the second spring. The flat surface (11) could be moved inside the housing (1) through second interior guides that prevented unwanted movements and ensured movement while maintaining the transverse position.

Two walls (12) started from the flat surface (11), with one end fixed on the flat surface (11) and the other free end, which passed through the slots at the end of the casing (1). These walls (12) included locking tabs (13) that could rest on the edge of the upper slots, retaining the injection means by a wedge effect, despite the load of the second spring. Between the free ends of the walls (12), a removable plug (14) was placed that limited the transverse movement of the walls (12) inwards, that is, towards the volume that was between both walls (12). When a user is willing to apply the intramuscular dose to the patient after following the previous preparation steps, he only has to remove the removable cap (14) so that the walls (12) can move transversely and that the tabs (13) leave to retain the flat surface (11). Then, thanks to the load of the second spring, a displacement of the flat surface (11) will occur, which in turn will push the plunger (4), thus administering the fluid intramuscularly.

The intramuscular dose is ensured by checking the existence or absence of blood inside the cylinder (3) of the syringe through the inspection window (6).

To carry out this verification, suction means have been developed that promote aspiration once the needle (2) has been inserted into the patient's body. The suction means comprised a lever (7) with an intermediate fulcrum (8) that was located on the wall of the housing (1). The outer end of the lever (7) was a button operable with the thumb of the same hand with which the device is held. The other inner end of the lever (7) was associated with the plunger (4) of the syringe so that when it came into contact with it it could move it to promote this aspiration. The intermediate fulcrum (8) divided the lever (7) into two portions, one outside the casing (1) and the other inside, so that the outside portion was longer than the inside portion in order to obtain a mechanical advantage that It will facilitate the movement of the plunger (4) with the pressure of the thumb.

The plunger (4) could move to produce aspiration, but simultaneously the accidental triggering of the dose was prevented until the cap (14) was intentionally removed. This was achieved thanks to the arrangement of the locking tabs (13) associated with the edge of the housing slots (1). The position of the tabs (13), on the outside of the casing (1), allowed the movement of the plunger (4) in the suction direction, but not in the injection direction, at least until the plug was removed. (14) removable arranged between the walls (12) and that limited its transversal movement.

EXAMPLE 2

An electronic injection system was manufactured where the components are substantially similar to those described in the previous example, although with the following differences in relation to the injection means, the suction means, the needle protection means (5) and the interlocking means.

The device consisted of a button, associated with a microcontroller with programmed instructions. The microcontroller was connected to two servomotors powered by a battery. A first servomotor was associated with the plunger (4) of the syringe through a screw and nut system, so that depending on the direction of rotation of the servomotor, the movement of the plunger (4) in a suction direction could be promoted. or in an injection direction. The controlled speed of rotation of the servomotor also allowed adjustment of the speed of suction and administration of the fluid dose.

On the other hand, the locking means of the needle protection means (5) were also governed by the microcontroller and could be controlled.

The needle protection means (5) consisted of a movable carriage that included the syringe with the needle (2) and the first servomotor with the nut and spindle assembly. The actuation means that acted on the carriage included a toothed crown that together with a belt moved the entire carriage. The belt could in turn move because it was geared with the other servomotor. When the carriage moved, the needle (2) was uncovered or covered and it was also possible to insert the needle (2) into the skin at the desired speed and withdraw it when the fluid had been injected, leaving the device with the needle. (2) fully covered. In this way, unlike the operation of the device described in example 1, the manual rotation movement that allowed the movement of the needle protection means (5) to be unlocked could be replaced by a controlled automatic movement.

The device also included a displacement sensor associated with the needle protection means (5) and the housing (1). This sensor sent a signal to the microcontroller when the needle (2) reached sufficient depth in the subject's body and activated the injection means to perform the safety check suction. If no blood appeared in the inspection window (6), the injection means were activated and the fluid was injected. Again, when the plunger (4) had supplied all the fluid to the cylinder (3), the displacement sensor activated the needle protection means (5), retracting the carriage and leaving the needle (2) completely protected inside. of the casing (1).

EXAMPLE 3

This example describes the application of an intramuscular dose of a medication to a patient using the device described in example 1. To do this, the following steps were followed:

a) The syringe loaded with the medication was placed inside the device through the hinged side cover (15). The top of the syringe plunger (4), which was flat, was fitted between the flat surface (11) and the inner end of the lever (7).

b) The locking means of the needle protection means (5) were unlocked to allow the needle (2) to move and to be able to insert the needle (2) into the patient's body. To do this, a rotation was manually made in the needle protection means (5) relatively with respect to the casing (1), causing the protuberance (10) to move transversely along the "L"-shaped guide (9).

c) The device was then pressed against the subject's body so that a puncture occurred in the selected area. This pressure manages to overcome the elastic force of the first spring, causing the second cylinder of the needle protection means (5) to move inside the housing (1), uncovering the needle (2) as it is introduced into the patient's body.

d) The suction means were then activated by pressing the lever (7) with the thumb to promote aspiration and check by observing the inspection window (6) the existence or absence of blood and decide whether to continue with the application of the injectable fluid. The cam mechanism that includes the lever (7) and the fulcrum (8) is responsible for the movement of the plunger (4) to cause the necessary suction in order to check through the inspection window (6) if the puncture has been carried out. on a blood vessel.

If signs of bleeding appear through the inspection window (6) of the device, this indicates that the puncture has been performed on a blood vessel, and the device must be removed and a new puncture must be performed on the patient, checking again that no puncture on a blood vessel has been performed. If blood does not flow back into the area during aspiration, the medication can then be administered.

e) Once it was verified that the insertion of the needle (2) was indeed intramuscular, the injection means that induce the displacement of the plunger (4) were activated to inject the fluid.

To do this, the plug (14) was removed with the thumb of the same hand that holds the device. Removal of the plug (14) unlocked the firing motion causing the second spring to extend and push against the flat surface (11) and the plunger (4). When the second spring has been fully extended, the plunger (4) is in the lower position and the fluid has been delivered.

f) After inoculation, the device was removed from the subject's body so that the needle protection means (5) was pushed by the first spring covering the needle (2) as it was removed from the body. Once covered, the locking means of the needle protection means (5) were locked with a manual rotation of the second cylinder.

g) Finally, the syringe was safely removed from the device through the hinged side cover (15), thus being prepared for reuse.

As can be seen, all device handling operations can be performed using only one hand. The activation of the injection means and the suction means can be carried out with the thumb of the hand that is holding the device, and even the locking means can be operated by supporting the housing (1) on the body of the subject and rotating device relatively. This way, the non-dominant hand can be free if needed for patient immobilization or other functions during administration.

EXAMPLE 4

This example describes the application of an intramuscular dose of a medication to a patient using the device described in example 2. To do this, the following steps were followed:

1- . The syringe loaded with the medication was placed inside the device through the upper hinged cover (15). The upper part of the plunger (4) of the syringe, which was flat, was placed in line with the nut-spindle system, which will produce the thrust of the plunger (4).

2- . Next, the device was placed against the subject's body and the button was pressed, which triggered the immediate unlocking of the locking means and the needle protection means (5) advanced, inserting the needle (2) to the desired depth. for puncture on the patient's muscle.

3- . Simultaneously, the displacement sensor sent a signal that triggered an aspiration that made it possible to verify that there was no blood return through the inspection window (6).

4- . Once it was verified that the insertion of the needle (2) was indeed intramuscular, the button was pressed again, which triggered the activation of the injection means that induce the rotation of the servomotor and the displacement of the plunger (4) through the transformation. of the rotary movement into a linear movement through the nutscrew mechanism. With the displacement of the piston (4) throughout its entire travel, the fluid was injected.

5- . Finally, the needle protection means (5) were moved again, retracting the carriage carrying the syringe and the needle (2) was completely covered by the casing (1). The displacement sensor then sent a signal that defined the activation of the locking means of the needle protection means (5), leaving them locked and secured.

6-. Finally, the syringe was safely removed from the device through the hinged top cover (15), thus preparing it for reuse.

Claims (9)

1. Reusable device for intramuscular injection of fluids comprising: - a housing (1) containing a syringe, where said syringe comprises a needle (2) that penetrates the skin of a subject and through which the injectable fluid circulates, a cylinder (3) with at least a portion of the lateral surface transparent cylindrical tube that contains the injectable fluid, and a plunger (4) that pushes the fluid through the needle (2); - needle protection means (5) that cover or uncover the needle (2); - locking means for the needle protection means (5) that block or unlock the movement of the needle protection means (5); - injection means that induce the displacement of the piston (4) to inject the fluid; - an inspection window (6) arranged in the housing (1) aligned with the transparent portion of the cylindrical side surface of the cylinder (3); characterized in that it also comprises suction means that move the plunger (4) and that promote aspiration through the needle (2) towards the cylinder (3) after the puncture has been performed in the patient's body. 2. Device according to claim 1 characterized in that the suction means are a lever mechanism comprising a lever (7) and a fulcrum (8) arranged in an intermediate portion of the lever (7) and on the wall of the housing. (1), where one outer end of the lever (7) is a button operable with the fingers of one hand, and the other inner end of the lever (7) is associated with the plunger (4) of the syringe. 3. Device according to claim 1 characterized in that the needle protection means (5) are movable and comprise a second movable cylinder inside the housing (1) with at least a portion of the transparent cylindrical side surface alignable with the inspection window (6), and a first spring with a fixed end associated with the casing (1) and another free end associated with the second cylinder that pushes the second cylinder. 4. Device according to claim 3 characterized in that the locking means of the needle protection means (5) comprise a guide (9) arranged on the surface of the second cylinder on which a protuberance (10) arranged on the casing (1) where said guide (9) comprises a portion parallel to the generator of the second cylinder and another portion substantially perpendicular to the previous one. 5. Device according to claim 1 characterized in that the injection means comprise: - a flat surface (11) associated with the plunger (4); - a second spring with a fixed end associated with the casing (1) and another free end associated with the flat surface (11), which pushes it; - at least two walls (12) with one end fixed on the flat surface (11) and the other free end, where said walls (12) comprise locking tabs (13) associated with an edge of the housing (1); and - a removable plug (14) arranged between the walls (12) and which limits the transverse movement of the walls (12) towards the interior volume located between them. 6. Device according to claim 1 characterized in that the injection means and the suction means comprise a button associated with electronic means, where said electronic means comprise actuator means that, when the button is pressed the first time, cause, once the needle is inserted, the actuating means act on the suction means, and when the button is pressed a second time, they cause the actuating means to act on the injection means to inject the fluid. 7. Device according to claim 6 characterized in that the needle protection means (5) are a movable carriage that includes the needle (2) that moves when the button is pressed. 8. Device according to claim 6 characterized in that it also comprises a control unit with a processor and a memory in which a program is stored that includes instructions that, when the button is pressed for the first time, are executed by the processor and make that, once the needle is inserted, the actuating means act on the suction means, and that, when the button is pressed a second time, they cause the actuating means to act on the injection means to inject the fluid. 9. Device according to claim 6 characterized in that it comprises a first button that is pressed the first time and a second button that is pressed the second time.