WO2008086560A1

WO2008086560A1 - Vibrating medical device and method of performing medical procedures

Info

Publication number: WO2008086560A1
Application number: PCT/AU2008/000019
Authority: WO
Inventors: John Alfred Marx
Original assignee: John Alfred Marx
Priority date: 2007-01-15
Filing date: 2008-01-11
Publication date: 2008-07-24

Abstract

The Inventor provides a device for, and methods of, performing medical procedures by causing vibration in a medical instrument, in particular, a medical instrument having a cutting edge, where the vibration is in a direction transverse to the axis of movement, longitudinal axis, or direction of fluid flow associated with the instrument.

Description

VIBRATING MEDICAL DEVICE AND METHOD OF PERFORMING MEDICAL

PROCEDURES

Field of the Invention The present invention relates to a device and methods of performing medical procedures, more particularly, to a device for causing vibration of a medical instrument, such as at the cutting edge of the instrument, and the performance of certain medical treatments using a vibrating instrument. It will be convenient to describe the invention with particular reference to use in conjunction with a needle and syringe, although the invention has wider applications.

Background of the Invention

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was, in Australia, known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Introduction of fluids into the body for medical purposes using a syringe and needle is well known. Although patient discomfort and pain associated with injections can be reduced in some circumstances by use of small gauge needles and good technique, pain cannot always be adequately eliminated. Many patients suffer from phobias about receiving injections and may avoid medical treatment due to the fear of injections.

Modern manufacturing techniques are able to produce extremely sharp cutting edges on the tips of needles and other medical instruments such as scalpels, however these sharpened surfaces still require a force to be applied to penetrate bodily tissues. Many of those body tissues, such as the skin or, in the case of intravenous injection, the walls of a vein, may require a reasonable force to penetrate tough connective tissue or tissue layers, yet the tissue may easily be stretched or deformed from its usual shape because of its compliance or delicateness. For example, if a force is applied to delicate skin tissue in certain areas of the face such as the lips or around the eyes, particularly with more mature skin which may have lost some of its elasticity, during injection in such areas, the skin will be deformed by the pressure of the needle required to penetrate that skin. Similarly, in the case of intravenous injection, particularly to treat diseased or abnormal veins such as varicose or spider veins, the vein walls may be unduly deformed by the force required for the needle cutting tip to penetrate the wall. This may be exacerbated in the case of diseased veins because the condition of those vein walls may already be impaired. Also, despite the sharpness of the cutting edge, a threshold of force is required for the needle tip to initially penetrate the tissue. Following needle tip penetration, the shaft of the needle is in frictional contact with the bodily tissue through which the needle tip has penetrated and in engineering terms, the phenomenon is referred to as "stiction", or "static friction". In the case of for example, skin or a vein wall, because these tissues are effectively visco-elastic, such tissues will generally deform until the force applied to the needle tip is sufficient for tip penetration to occur. In addition, as the needle advances through a tissue, static friction between the exterior walls of the needle shaft and the tissue may cause the needle to drag and thus deform the surrounding tissue in the direction of the advance.

In at least several cosmetic restorative procedures, for example sclerotherapy, or wrinkle reduction, or administration of dermal fillers, it is highly desirable to reduce the deformation of the subject area caused by penetration resistance and stiction. Sclerotherapy involves injecting a solution, called a sclerosing solution, through the vein wall and into the vein with a fine needle. The sclerosing solution irritates the lining of the vein and causes it to swell and the vein walls then stick together. In a more advanced technique, the needle is guided using ultrasound imaging. This enables far more accurate placement of the needle. Although a fine gauge needle is used, the vein wall still may become distorted and the accuracy of needle placement may frequently be compromised. Furthermore, inaccurate placement of the needle may cause trauma to the vein wall, in particular, stripping of the intima layer.

During facial injections for wrinkle reduction and dermal filler administration, muscle relaxants and/or fillers such as collagen or visco-elastic gels are injected subcutaneously along or around wrinkle lines. Fillers may be used to "plump out" the overlying tissue and reduce or eliminate the wrinkle. A challenge for the practitioner administering such injections is that the delicate skin may be deformed due to penetration resistance and stiction, potentially making it difficult to visualise the wrinkle and ensure that the injection is given at the most appropriate location. Also, some of the substances to be administered in facial injections are relatively viscous. It is undesirable to use a large gauge needle to administer such substances because the associated pain would not be acceptable and this would create a greater penetration resistance and stiction problem. Indeed, even with fine gauge needles, practitioners regularly administer a local anaesthetic prior to giving the cosmetic treatment for patient comfort.

It would be desirable to provide a method and/or apparatus which would reduce the amount of deformation of tissue at and surrounding an injection site. It would also be desirable for such a method and apparatus to be used with a wide variety of existing medical instruments without the need for significant modification. It would further be desirable to provide a device which can be manufactured and supplied in a sterile form and which can be manufactured cheaply enough to be suitable for a single use and disposal. It would be further desirable to provide a method and/or apparatus which may alleviate or reduce the pain of administering substances into the body.

Summary of the Invention

The present invention utilises the effects of vibration to vibrate a medical instrument during medical procedures. Various benefits, as will be explained hereinafter, can be obtained through the use of vibration.

In one aspect of the invention there is provided a device for vibrating a cutting edge on a medical instrument, the cutting edge being moveable along an axis, the device including: vibration means for causing said instrument to vibrate when attached to said instrument such that said cutting edge is caused to vibrate in a motion substantially transverse to said axis. The invention extends also to a medical instrument which includes a device of the above described kind.

The device is configured such that, when attached to a medical instrument, it causes the medical instrument to vibrate in a motion substantially transverse to the axis of movement of a cutting edge on the medical instrument. For example, when the medical instrument is a needle and syringe, the axis of movement of the needle will be along the length of the needle, i.e. the needle would be inserted into or through a body tissue along its length.

Preferably the device, when attached to a medical instrument, causes the cutting edge to vibrate in a circular motion substantially transverse to the axis, although other types of motion, such as elliptical or linear motion transverse to the axis, may be acceptable to create the desired result. In the description and claims the term circular and/or substantially circular is intended to include elliptical motion.

The cutting edge on the medical instrument is preferably a bevelled edge of a needle, although this term should be understood in the description and claims to equally refer to a cutting edge of, for example, a scalpel blade, or a penetrating tip of a hypodermic needle, or a lancet.

In another embodiment of the invention, there is provided a device for vibrating a medical instrument having a body with a longitudinal axis, the device including: vibration means for causing the body of said instrument to vibrate when attached to said body in a motion substantially transverse to said axis.

In this embodiment, the device may be particularly suitable for facilitating improved mixing of the fluids prior to injection by creating a vortex in the flow of one fluid as it is dispersed into the other fluid.

Preferably the vibration means is a small, unobtrusive motor that causes vibration in the sonic range of frequencies, i.e. between 50Hz and 20,000Hz (or cycles per second), more preferably between 100Hz and 10,000Hz, or even more preferably between 200 and 500Hz. In one embodiment, the motor is powered remotely from the medical instrument when the device is attached to the instrument. Preferably it is powered through a controller where the frequency of vibration may be varied by the operator to a selected level. Preferably the motor includes a shaft bearing on eccentric weight, and the axis of the shaft is substantially parallel to the axis along which the cutting edge may be moved when the device is attached to the body.

In another embodiment, the device may be an internally powered device including a motor and battery located within a housing which is contained within resilient means made from a waterproof elastomeric material such as a rubber, for example, a latex or silicone rubber which is readily sterilisable. Suitable resilient materials are well known in the medical arts. Preferably the housing and resilient means are formed as a single integral component. Preferably the resilient means is extensible by more than 100%, more preferably by more than 300%, of its resting length without breaking. More preferably, the resilient means is one or more rings extending from said housing which can be stretched around the body of the medical instrument.

In this embodiment the battery operated vibrating motor is preferably a lightweight (between about 3 to 10 grams) electric motor having an eccentrically weighted shaft which transmits vibration to the housing. The motor may be contained within a shell, the whole assembly of which can be sterilized. Preferably the entire device is of a sufficiently simple design and has few parts such that it can be mass produced cheaply, packaged in an individual sterile package and is suitable for a single use only. Thus, the device is preferably sterilisable during manufacture, and can be disposed of after a single use. The battery is preferably a small, single cell, of a size similar to a watch battery, and which is capable of powering the motor at the desired rate of revolutions for at least 10 minutes.

A device according to the invention could take a variety of other forms. For example, the device could be other than externally powered or battery operated. In one embodiment, a motor as previously described may be powered from an external source, rather than an integral battery. A tuning fork or like device could be mounted to the instrument body, with the operator of the device manually striking the tuning fork as required to create the required vibrations. Alternatively, a capacitor could store electrical energy to drive a suitable vibrating motor. Still alternatively, a high frequency pulse generator could be employed. It is to be noted that pulses or vibrations could be generated in a unit which is attached to the medical instrument or the pulses or vibrations could be generated remote from the instrument and transferred to the instrument by any suitable arrangement, provided that the resultant vibration created would be substantially transverse to the axis of the medical instrument (e.g. needle or syringe barrel).

Where battery power is employed, the battery can be provided within the housing which contains the vibrating motor or it can be remote from the housing. For example, a battery pack might be provided remote from the housing and a suitable electric connection made through the housing with the vibrating motor. The battery pack could be rechargeable and therefore reusable. It could also be positioned sufficiently remote from the medical instrument so that it could be placed on an equipment table. By removing the battery from attachment to the medical instrument, or by providing an external source of mains power to energise the device, the bulk and weight of the attachment can be reduced.

Other devices for vibrating a medical instrument are within the scope of the invention. Mechanical arrangements, such as spring wound drives could, for example, be employed.

The benefits which have been discovered by use of the invention include that: (i) penetration of patient skin and other subsequent organs is less painful to the patient and causes minimal damage to surrounding tissues; (ii) penetration of patient skin and subsequent organs is far more accurate; (iii) the cutting edge of a medical instrument tends to have greater purchase, so that body tissues such as veins, which tend to shift under the pressure of a non-vibrating needle cutting edge for example, tend to remain in position rather than moving, so that the rate of successful penetration of such body parts, the so-called "strike rate", is much higher, resulting in greater patient confidence, shorter procedure time and reduced body trauma.

The above benefits are considered to result from reduction in the penetration resistance and stiction load experienced in some medical instruments such as hypodermic syringes. Thus, penetration occurs more readily and without, or with significantly reduced, deformation of the body tissue. Moreover, because stiction loads are reduced, instruments such as syringes or scalpels tend to pass through the body tissue more easily and so with reduced body tissue deformation and significantly less blunting. Accordingly, the number of needles required to be used in, for example, a sclerotherapy session, may be significantly reduced.

A further benefit, which has been discovered by the use of the invention, is that the vibration can have a positive effect on the flow characteristics of an injectable liquid and other characteristics such as solution density. Thus, the invention can provide for lowering of the viscosity of certain types of injectable liquids. In sclerotherapy, the sclerosant solution has been made to flow more easily from a syringe which is vibrated and to spread throughout a much wider area of the vein network. The ease with which the sclerosant solution flows from the syringe might also be attributed to a reduction in friction between the head of the plunger of the syringe and the internal wall of the chamber within which the plunger head is located. This reduction in friction can also improve the "feel" of the syringe for the syringe operator. Also during sclerotherapy, aspirational viscous retained blood from veins is improved in a similar manner.

During cosmetic procedures such as injection of facial fillers, the flow characteristics of such viscous fillers may be improved. This means that finer gauge needles may be used, resulting in less pain to the patient.

In a similar manner, injection of a foam sclerosant that has been mixed with added vibration has therapeutic benefits. Foam sclerosant is a different form of the normal liquid sclerosant which has advantageous properties for use in sclerosing larger varicose veins. The benefit of dispensing foam sclerosant subject to vibration is that a denser and superior quality foam can be produced, which is more stable and has a significantly longer survival time. Also, the foam mixes more quickly within the syringe and less finger pressure is required to dispense the foam from the syringe.

A yet further advantage of the present invention is that it causes a powerful spread or perfusion of an injected substance into the target, e.g. a vein, which is believed to be caused by the vortex created in the flow of the injected fluid by virtue of the vibration transverse the direction of flow of the fluid. In the preferred embodiment, where the transverse vibrational motion is circular, a vortex appears to be set up in the fluid as it is ejected from the needle. This vortex, and the increased perfusion in the target side, leads to the ability to reduce the required dosage of, for example, a sclerosing agent.

In a similar manner, during an aspiration procedure where, for example, blood is withdrawn from a blood vessel, the vortex created in the aspirated liquid gives rise to a more pronounced flashback in the syringe, signalling to the operator that blood is successfully being withdrawn.

The invention further includes within its scope a vibrating motor that is not connected to the medical instrument with which it is employed, but which is brought into contact with that instrument when the instrument is to be vibrated. In one embodiment of this kind, a vibrating motor can be applied to one or more fingers of the practitioner who is using the medical instrument, so that when the instrument is held by the practitioner, the vibrations transfer to the instrument and the vibrating effect of the invention is achieved.

As will be apparent from the discussion above, the medical instrument can be of any suitable kind, such as a hypodermic needle or a scalpel, although it is clear that the invention can have application in other medical instruments particularly where overcoming penetration resistance and/or stiction is advantageous, or the other benefits referred to above, such as improved mixing of fluids either outside or within the body, are desirable. Indeed, the present invention is highly versatile in that it may attach to or be applied to a wide range of medical instruments, thus its potential applications should be considered broadly. For example, the medical instrument of the invention could be a pair of forceps and employment of the invention could be made during suturing to increase the accuracy of skin alignment and thus to decrease scarring.

In the case of a hypodermic needle, the cutting edge is the piercing and cutting tip of the needle and the body of the instrument is the barrel of the syringe to which the needle is mounted. In another embodiment, the device could equally be mounted to the shaft of the needle if a sufficiently large needle is being used. Where the medical instrument is a scalpel, the handle of the scalpel may be the body to which the device is mounted.

A further medical instrument to which the present invention can be applied is one which is used in endovenus laser therapy. In such therapy, a small laser fiber is inserted through a needle into damaged vein and is guided within the vein by a U-shaped guide wire. The heat generated by pulses of laser light delivered into the vein causes the vein walls to collapse and seal shut. In this procedure, the U-shaped guide wire sometimes sticks into the vein wall as it is fed into the vein causing difficulty in feeding the guide wire to the correct position. The present invention can alleviate this difficulty by causing the guide wire to vibrate and thus to reduce or eliminate sticking of the guide wire into the vein wall.

In accordance with at least some of the discussion above, other aspects of the invention can be provided as follows.

In a further aspect of the invention there is provided a method of reducing the resistance to penetration of a body tissue by a cutting edge on a medical instrument, the penetration of said body tissue occurring along an axis, the method including causing said cutting edge to vibrate in a motion substantially transverse said axis. In yet another aspect of the invention there is provided a method of reducing the static friction between a cutting edge and a body tissue when said cutting edge is forced against said body tissue along an axis, the method including causing said cutting edge to vibrate in a motion substantially transverse to said axis.

Preferably the medical instrument is a hypodermic needle and the cutting edge is the tip of the needle. Preferably the means to cause the cutting tip to vibrate is a device according to one or more of the kinds described above.

In yet another aspect of the invention, there is provided a method of administering an injectable substance into a patient from a needle having a longitudinal axis, the method including causing said needle to vibrate in a motion substantially transverse to said axis during administration of said substance such that said substance is caused to flow in a vortex.

In yet another aspect of the invention there is provided a method of assisting the injection of a viscous fluid from a needle having a longitudinal axis into a patient, the method including causing said needle to vibrate in a motion substantially transverse to said axis during injection of said substance.

In yet another aspect of the invention there is provided the above method wherein said needle has a longitudinal axis and said needle is caused to vibrate in a motion substantially transverse to said axis. Preferably the means to cause the syringe to vibrate is a device described above. In a preferred embodiment the injectable substance is a cosmetic facial preparation.

In another aspect of the invention there is provided a method of performing sclerotherapy including connecting to the body of a syringe bearing a needle a sterilisable battery powered vibrating device and introducing the needle into a vein while said vibrating device vibrates said needle.

In yet another aspect of the invention there is provided a method of injecting a substance into the face of a patient with a hypodermic needle and syringe including mounting a vibrating device on the barrel of said syringe, then injecting the substance. In addition to reducing the effects of penetration resistance and stiction between the needle and the skin of the patient, it has been observed that this method has an advantageous benefit in reducing pain to the injection site.

In yet another aspect of the invention there is provided a method of mixing injectable substances at the time of injection, the method including: providing a first syringe containing a first injectable substance; providing a second syringe containing a second injectable substance, said second syringes being in fluid communication with said first syringe; and causing at least one of said syringes to vibrate in a motion.

It will now be convenient to describe the invention with reference to preferred embodiments illustrated in the accompanying drawings. It is to be understood that the drawings and the following description relate to preferred embodiments only and are not intended to limit the scope of the invention.

Figure 1 is a perspective view of a syringe and one kind of vibrating device suitable for use in accordance with the present invention.

Figure 2 is a perspective view of a disassembled vibrating device suitable for use in the present invention powered by a battery rather than an external power source.

Figure 3 is a perspective view of one kind of housing and securing arrangement for housing a vibrating device of the present invention.

Figure 4 is a perspective view of a vibrating arrangement for injection of foam sclerosant.

Figure 5 is a diagrammatic representation of the skin of a patient in cross section, shown when injected with a prior art needle. Figure 6 is a diagrammatic representation of the skin of a patient in cross section shown when injected with a needle of the present invention.

Figure 7 is a diagrammatic representation of a sclerotherapy procedure when using a prior art needle.

Figure 8 is a diagrammatic representation of the flow of fluid using a device of the present invention.

Figure 9 is a diagrammatic representation of the flow of fluid using a device of the present invention.

Figure 10 is a diagram showing flow of fluid using a device of the present invention.

In Figure 1 syringe (1 ) is a conventional syringe which consists of a barrel (3), a plunger (5) moveable in barrel (3), a Luer™ fitting (7) and a seal (9) attached to the end of plunger (5). Attached to Luer fitting (7) is a needle (11 ) which has a corresponding Luer fitting (13) at one end of a shaft (15) and a sharpened needle tip (17) at the other end of shaft (15). Syringe (1 ) and needle (1 1 ) may be of any size and shape suitable for the needs of the medical practitioner using the instrument and may be any syringe and needle combination as will be known in the art. Importantly, no modification to known syringes is needed to perform the present invention.

Vibrating device (19) consists of a casing (21 ) which contains a motor (not shown) which causes vibration. In the embodiment shown, protruding from casing (21 ) is a slidable switch member (23) which is moveable between on and off positions. In another embodiment a power lead may protrude from the casing of a similar location, the power cord being connected to a remote source of power. The remote source of power may include means for selectively varying the frequency of vibration, e.g. by selectively varying the voltage applied to the motor. The casing (21 ) is contained within a resilient housing (25) which substantially envelops casing (21 ) except for switch member (23). An alternative form of housing is illustrated in Figure 3 by reference numeral 325 unattached to a syringe. In Figure 3, housing (325) is shown to have a casing accommodating portion (327) which is connected to a syringe attachment portion (329). Accommodating portion (327) consists of a substantially cylindrical sheath (331 ) and a chamber (333) which accommodates casing (21 ). Attachment portion (329) is preferably formed integrally with accommodating portion (327) and comprises an annular resilient band (335) which can be stretched and wrapped around barrel (3).

Reverting to Figure 1 , band portions (35a) and (35b) are wrapped around barrel (3) and extend through the housing (25) to hold vibrating device (19) securely against syringe (1 ). The vibrating device (19) is secured so that its longitudinal axis is substantially parallel to the longitudinal axis of the syringe (1 ). In this configuration the plane of vibration created by the vibrating device (19), which is perpendicular to the axis of rotation of shaft (45), is also perpendicular to the longitudinal axis of needle (1 1 ). In other words, by orienting vibrating device (19) along the barrel (3) of syringe (1 ), the needle tip (17) is caused to vibrate in a plane perpendicular to its longitudinal axis, i.e. transverse to the longitudinal axes of both the syringe and the vibrating device. The vibrating motion of the needle tip may be circular and parallel to the direction of advance of the needle through a body tissue.

In Figure 2 the components of vibrating device (19), which is battery powered, can be seen. Casing halves (37a) and (37b) contain the internal components consisting of an electric cell (39), a motor (41 ) with an unbalanced weight (43) attached to shaft (45) of motor (41 ), a conductive spring plate (47) and an insulator (49) to which switch member (23) is attached. Casing halves (37a) and (37b) may snap together to contain the internal components. In use, cell (39), motor (41 ), spring plate (47) and insulator (49) are contained within casing halves (37a) and (37b). A terminal (not shown) of cell (39) abuts contact (51 ) of motor (41 ) and contact (53) of spring plate (47) abuts terminal surface (55) of cell (39). Insulator (49) can be positioned either in an off position or an on position. In the off position, insulating platform (55) is drawn beneath contact (57) of spring plate (47) to separate contact (57) from conductive body (59) of motor (41 ). In the on position, switch member (23) is pushed to move platform (55) away from contact (57) so that contact (57) touches conductive body (59) to complete an electrical circuit and activate motor (41 ). This causes shaft (45) to rotate, and weight (43) is also rotated. Because weight (43) is unbalanced, its rotation causes a vibration which is transmitted throughout vibrating device (19).

The resilient housing (25) and attachment portion (329) are preferably made from a thermoplastic elastomer, more preferably a highly extensile styrene- ethylene/butylene-styrene block copolymer. A suitable copolymer is made by Ever Polymer Co., Ltd and sold under the trade name Everlon. Such copolymers have excellent elongation tensile strength resilience, are readily sterilisable, and are FDA approved for certain medical applications.

Individual vibrating devices may be provided in a vacuum foil package, which can be torn open ready for mounting on the medical instrument immediately prior to use. A particularly suitable vibrating device is currently commercially available. This device is manufactured and sold by Vicon Healthcare International, lnc and is described in US Patent 6907883.

During experimental trials, the applicant has observed a marked increase in the accuracy of placement when a device of the present invention has been used during sclerotherapy treatments, of the needle tip using ultrasound guidance, and a lessening of distortion to the subject vein wall when the needle tip is being passed therethrough. The applicant has further found that penetration resistance and stiction between facial skin and needle during penetration is reduced, as is the pain encountered by patients during such procedures. The apparent viscosity of thick injectables used in such procedures is also reduced, thus improving their administration.

Figure 4 illustrates a syringe arrangement (400) which is employed for mixing the foam sclerosant. The arrangement includes a pair of syringes (401 , 402). The syringes (401 , 402) are connected by a 3 way stopcock (404) which can be opened or closed by rotation of the lever (405). The syringes (401 , 402) are connected for the purpose of mixing air with liquid sclerosant solution and typically the mixture would be 3 ml of air in the syringe (402) to be mixed with 1 ml of 3% liquid sclerosant solution (sodium tetradecyl sulphate) in the syringe (401 ). Turbulence is created by the air negotiating a 90 degree turn into the liquid sclerosant solution and that turbulence causes a foam solution to be created. According to the invention, during a foam mixing procedure, the vibrating motor (409) is activated and applies a vibrating force to the syringe (402). The vibrations applied to that syringe transfer through to the valve (404) and subsequently to the syringe (401 ). It has been found that that vibration causes the sclerosant foam to compress into a much smaller volume (2.5 ml compared to 4.0 ml without vibration), while the foam is significantly faster to mix and requires less finger pressure to be exerted on the plungers (407) of both syringes for the mixing process. The characteristics of the foam also include that it is denser and therefore superior quality foam and it is a more stable foam with a significantly longer survival time.

When the sclerosant solution has been formed into a foam, each of the syringe (402) and the valve (404) are removed from connection with the syringe (401 ) and a needle is inserted into the discharge end of the syringe (401 ). Following this, a vibration device, such as the vibrating motor (409), is applied to the barrel of the syringe and it will be appreciated that the syringe thereafter takes the same or similar form to the syringe (1 ) of Figure 1. Referring to that syringe, the sclerosant solution is contained within the syringe between the plunger (9) and the Luer fitting (13) and the plunger (5) is retracted from the position shown in Figure 1.

When the sclerosant foam is to be discharged, the vibration device (19) is activated and the plunger (5) depressed. The benefits described earlier in relation to syringe discharge under vibration, all apply in this embodiment.

In Figure 5, syringe 501 and needle 51 1 are shown penetrating epidermis 512 overlying dermis 514. Needle 511 will initially depress and stretch epidermis 512 at the point of contact 516 until the penetration resistance offered by epidermis 512 is overcome by needle tip 518. In conventional needles the penetration resistance needed to be overcome is such that trauma of tissues and pain are likely to result. In Figure 6, syringe 601 has a vibration, device 619 attached to the barrel 603 which, when activated, causes vibration in syringe 601 and needle 611 in a direction transverse to the longitudinal axis I of the syringe and needle. The vibration reduces the penetration resistance of epidermis 612 and also reduces the amount of deflection or compression of the underlying dermis. The result is less trauma and less pain at the site of injection.

In Figure 7, a conventional needle is shown in a scenario which commonly occurs during sclerotherapy, and other procedures requiring the insertion of a needle into a vessel or opening. Needle 71 1 is inserted through tissue layers 701 a - d, which may be layers of epidermis, dermis and subcutaneous tissues towards blood vessel 703, for example, a vein. Due to the force required to be applied to the needle to overcome static friction and resistance to penetration, vessel wall 705 has been deformed so that lumen 707 is obliterated where the needle tip 718 has penetrated vessel 703. Needle tip 718 has not successfully been inverted with lumen 707 but instead has been passed right through the vessel walls 705 and out the other side of the blood vessel 703. Accordingly, the target zone (i.e. inside the blood vessel) has disappeared and the chance of administering an effective dose of a therapeutic agent, such as a sclerosing agent, is remote.

In Figure 8, a needle 81 1 is attached to a syringe 801 part shown with a vibrating device 819 attached. This time, when the needle 811 is inserted through tissue layers 801 a - d, by virtue of the vibration virtually eliminating static friction and resistance to penetration, significantly less force is required to pass the needle tip 818 through those layers. Once needle tip 818 has been advanced to vessel wall 805 with much reduced force, the blood vessel 803 is still relatively undeformed, and lumen 807 is still open. Again, due to the reduced static friction and resistance to penetration created by vibration device 819, needle tip 818 can be passed through vessel wall 805 into lumen 807 without collapsing vessel 803. Proper location of the needle tip 818 in lumen 818 can be assured either by aspirating blood from vessel 803 and watching for 'flashback' in the transparent syringe body, and/or by use of ultrasound or other imaging technology. The degree to which blood creates the 'flashback' signature in the syringe body is significantly enhanced by the vibration caused by device 819 because it causes improved mixing of the blood and fluid contents of the syringe, which in most cases will be a sclerosing agent.

When the practitioner is satisfied that the needle tip 818 is properly located, the contents of the syringe may be expressed into the lumen. As better seen in Figure 9, the injected liquid in this case, a sclerosant solution, 902, flows far more powerfully from syringe 901 and perfuses throughout blood vessel 903 in a much wider area than if no vibration were applied.

In Figure 10, the effect of applying a circular vibrational motion transverse to the direction of flow of a fluid along a needle, i.e. along the longitudinal axis of the needle, can be seen. Needle 101 1 is shown with a representative vibration, device 1019, which applies a circular vibration motion transverse to the axis Il of needle 101 1. The direction of flow of fluid 1020 in needle 101 1 is along the axis II, as represented by arrows 1021 a, b, c, etc. The circular motion applied by device 1019 thus creates a vortex-like fluid flow in fluid 1020, as depicted by arrow 1022.

Accordingly, it has been found that by providing a device to create vibration in a medical instrument such as a syringe (and needle), the functioning of the instrument can be significantly enhanced in many ways. As has been described above, the most preferred type of vibration is a circular motion transverse to the longitudinal axis of the syringe, or direction of motion of the fluid flow in the instrument, or the direction of movement of a cutting edge of, say, a needle, although other vibrational movement substantially transverse will still create an improved effect. However, such movement is most likely to cause turbulent flow along the needle, whereas circular transverse vibration is more likely to create a laminar flow.

The gentle, unforced, eventually frictionless needle movement observed in the present invention creates significantly less pain and damage to surrounding tissues, and enables a practitioner to target the desired site, such as a vein, with improved skill and accuracy. The reduced forces of tissue resistance and static friction may reduce needle failure and reduce the blunting of needles during procedures where multiple needle insertions are required, such as in cosmetic procedures like injection of dermal fillers, or in sclerotherapy. The amount of needle blunting may correlate to the amount of pain and trauma inflicted on a patient. The reduction in needle blunting observed when using the present invention may then be a further indicator of reduced patient pain and trauma. Further, accuracy can be increased as a result of the need for less plunger pressure by the practitioner.

Accuracy has also been observed to increase in reticular vein strike rates when using a device of the present invention. Reticular veins, particularly around the ankle and shin regions, are notoriously difficult to sclerose and therapists are often forced to abandon attempts to sclerose these veins after having created significant trauma to surrounding tissues. These veins are very mobile, with a significant amount of inherent movement and are therefore difficult to stabilize. If the practitioner misses the vein on the first attempt a haematoma is likely to form, with an underlying vein spasm. With the present invention such veins are much easier to sclerose, and even if the practitioner misses the vein initially, only minimal damage is likely to have occurred to surrounding tissues and a second attempt may then be made.

The present invention has been seen to give rise to improved mixing and perfusion of an injected substance such as a sclerosant, improved mixing of an aspirated fluid such as blood from a blood vessel as demonstrated by flashback into a syringe, and improved vortex mixing of fluids such as foam sclerosants. With the present invention it has been found that a more dilute sclerosant solution may be used to achieve the same result as a conventional injection. In one example, a 0.1 % solution of FibroVein™ has successfully been used to achieve a therapeutic effect, compared to the conventional concentration of 0.6%. The reduced concentration may be significantly less painful to the patient, recovery may be quicker, and reduced levels of staining and trapped blood have been observed. Additionally, there is likely to be less wastage of sclerosant because it is more likely to be administered to the target site, rather than injected into surrounding tissue. The vortex mixing of the present invention can be used to create a denser, superior quality sclerosant foam, which may be faster to mix, requires less finger pressure on syringe plungers, and the sclerosant foam has been observed to be more stable and has an increased survival time compared to foams prepared using conventional methods.

There are significant benefits of improving the flow characteristics of viscous liquids such as dermal fillers by providing vibration. Effectively, the flow characteristics are improved, because the viscous liquids flow more easily when being vibrated. A liquid 'energised' by vibration is easier to inject (or aspirate). Accuracy of injection of viscous liquids can be improved with the present invention because less plunger pressure is required to deliver such liquids, and the patient is likely to encounter less discomfort during administration. Similarly, where a procedure requires aspiration of, for example, blood from a vein, it has been observed that significantly less negative suction pressure is required to draw blood from a vein because the present invention improves the flow characteristics of the blood, and as a result, smaller gauge needles may be used. Again, the finer the needle, the less discomfort to the patient.

Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to exclude other additives, components, integers or steps.

While the invention disclosed herein has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made by those skilled in the art without departing from the scope of the invention.

Claims

The claims defining the invention are as follows:

1. A device for vibrating a cutting edge on a medical instrument also having a body, the cutting edge being remote from said body and being moveable along a longitudinal axis, the device including: vibration means for causing the cutting edge of said instrument to vibrate when associated with said instrument such that said cutting edge is caused to vibrate in a motion substantially transverse to said axis.

2. A device according to claim 1 wherein when said vibration means is attached to said medical instrument, said device causes said cutting edge to vibrate in a substantially circular motion substantially transverse to said axis.

3. A device for vibrating a medical instrument having a body with a longitudinal axis, the device including: vibration means for causing the body of said instrument to vibrate when attached to said body in a motion substantially transverse to said axis.

4. A device according to any one of claims 1 to 3 wherein said vibration means causes vibration at a rate of between 100 and 10,000 cycles per second.

5. A device according to claim 4 wherein said vibration means causes vibration at a rate of between 200 and 500 cycles per second.

6. A device according to any one of claims 1 to 5 wherein said device further includes a controller for selectively causing said vibration means to vibrate at a selected frequency.

7. A device according to any one of claims 1 to 6 wherein said vibration means includes a shaft, said shaft having a drive axis, an eccentric weight associated with said shaft, and where the drive axis of said shaft extends in substantially the same direction as said longitudinal axis when said device is attached to said body.

8. A device according to claim 6 wherein said shaft is caused to rotate by an electric motor.

9. A device according to any one of claims 1 to 7 further including said attachment means adapted to attach said device to a range of medical instruments having differing sized bodies.

10. A medical instrument having a cutting edge and a body, said cutting edge being remote from said body and being moveable along an axis, the instrument including a device according to any one of claims 1 to 9 attached to said body.

11. A medical instrument according to claim 10 wherein said instrument is a syringe having a needle with a cutting edge, said needle having a longitudinal axis, and said device is mounted to cause said cutting edge to vibrate in a motion substantially transverse to said axis.

12. A medical instrument according to claim 1 1 wherein said cutting edge is caused to vibrate in a circular motion substantially transverse to said axis.

13. A medical instrument according to claim 1 1 or 12 including a needle having a distal end at which said cutting edge is located and a proximal end attached to said syringe, said syringe having a barrel and said device is associated with said barrel such that vibration of said syringe barrel by said device causes said cutting edge to vibrate in a motion substantially transverse to said axis of said barrel.

14. A medical instrument according to claim 13 wherein said cutting edge is caused to vibrate in a circular motion substantially transverse to said axis of said barrel.

15. A medical instrument according to any one of claims 1 1 to 14 wherein said syringe is capable of expressing a liquid and when liquid is expressed from said syringe when said device causes said syringe to vibrate, said liquid is expressed in a vortex.

16. A medical instrument according to any one of claims 10 to 15 when said device is a syringe and needle for targeting a vein.

17. A medical instrument according any one of claims 10 to 16 when said medical device is a syringe and needle for use in sclerotherapy.

18. A medical instrument according to any one of claims 10 to 16 wherein said instrument is a syringe and needle for administering a subcutaneous facial filler.

19. A medical instrument according to claim 3 for use in mixing a foam sclerosant.

20. A method of reducing the resistance to penetration of a body tissue by a cutting edge on a medical instrument, the penetration of said body tissue occurring along an axis, the method including causing said cutting edge to vibrate in a motion substantially transverse said axis.

21. A method of reducing the static friction between a cutting edge and a body tissue when said cutting edge is forced against said body tissue along an axis, the method including causing said cutting edge to vibrate in a motion substantially transverse to said axis.

22. A method according to claim 20 or 21 wherein said cutting edge is the tip of a needle.

23. A method of administering an injectable substance into a patient from a needle having a longitudinal axis, the method including causing said needle to vibrate in a motion substantially transverse to said axis during administration of said substance such that said substance is caused to flow in a vortex.

24. A method of assisting the injection of a viscous fluid from a needle having a longitudinal axis into a patient, the method including causing said needle to vibrate in a motion substantially transverse to said axis during injection of said substance.

25. A method according to claim 24 wherein said needle has a longitudinal axis and said needle is caused to vibrate in a motion substantially transverse to said axis.

26. A method of increasing the flow characteristics of a fluid forced into or out of a syringe, said syringe having an elongate axis, the method including: causing said syringe to vibrate in a motion substantially transverse said axis while said fluid is forced into or out of said syringe.

27. A method according to any one of claims 20 to 24 wherein said motion is a substantially circular motion substantially transverse to said axis.

28. A method of mixing injectable substances at the time of injection, the method including: providing a first syringe containing a first injectable substance; providing a second syringe containing a second injectable substance, said second syringes being in fluid communication with said first syringe; and causing at least one of said syringes to vibrate when said first injectable substance is caused to flow into said second injectable substance.

29.A method according to any one of claims 20 to 28 wherein said vibration is at a rate of between 100 and 10,000 cycles per second.

30. A method according to claim 29 wherein said vibration is at a rate of between 200 and 500 cycles per second.

31.A method according to any one of claims 20 to 30 for use in a sclerotherapy procedure.

32.A method according to any one of claims 20 to 27 for use in a facial injection.

33.A method according to any one of claims 20 to 27 for use in injection of a dermal filter.