WO1997003602A1

WO1997003602A1 - Transilluminator for use in human and veterinary medicine

Info

Publication number: WO1997003602A1
Application number: PCT/EP1996/003249
Authority: WO
Inventors: Vibeke Elisabeth Hjortdal
Original assignee: Vibeke Elisabeth Hjortdal
Priority date: 1995-07-24
Filing date: 1996-07-23
Publication date: 1997-02-06
Also published as: AU6786796A

Abstract

A transilluminator (10) for use in human and veterinary medicine, in particular for back lighting veins, arteries, urethras and other fluid conducting organs or vessels of the animal or human bodies comprises a light source (12) provided at one end of a light conducting rod (14) which in turn comprises a rod of transparent material with a reflective coating (16) applied to the surface of the rod to ensure reflection of light within the rod and an aperture (32) in the coating at at least one position, in particular a position adjacent an end of the light conducting rod (14), with the aperture (32) permitting the emergence of light from the rod. The transillumination of, for example, an artery permits the surgeon to see that the artery is smooth inside and does not have excessive steps at a joint which could lead to the formation of a thrombus. Moreover, it permits the surgeon to observe the organ over a longer period of time, for example to check whether a thrombus is forming or if a thrombus which has formed is dissipating.

Description

TRANSILLUMINATOR FOR USE IN HUMAN AND VETINARY MEDI'CINE.

The present invention relates to transilluminator for use in human and vetinary medicine, in particular for diagnostic and monitoring purposes.

Many medical instruments are available to enable medical practitioners to view or otherwise investigate the organs of the body, for example when conducting surgery.

For example, increasing use is being made of fibre optic light guides to illuminate organs of the body during an operation so that the surgeon can see the organ while conducting surgery. With such instruments the light source typically serves simply to illuminate the organ on which surgery is being carried out and the parts of the body tissue around the organ.

Particular problems arise when conducting operations on fluid conducting vessels of the animal or human body, for example veins or arteries. At the present time medical practitioners use very complex systems for measuring blood flow (Doppler systems etc.) which are relatively expensive. Moreover, the output signal from such systems is normally simply a number which the medical practitioner then has to correlate to a certain flow pattern.

The present invention starts from a new concept that further information could be obtained from fluid conducting vessels of the body if it would be possible to visualise what is going on inside them. To date systems for visualising flow within body vessels do not exist.

One possibility would be to use an optical fibre lighting system to directly backlight the fluid conducting vessel, for example a vein or artery. That is to say, the optical fibre would be used to transmit light to the back of the vein or artery and to direct light from the back through the artery for viewing from the other side. This could be termed a transilluminating system. However, there are substantial problems in using an optical fibre arrangement in such a transilluminating system. Since many of the vessels of interest are small veins or arterties, particular in the field of heart surgery and neurosurgery, it is frequently necessary to magnify the vein or artery under investigation in a microscope. This results in a magnification of the optical fibres themselves which are typically of 50 to 70 microns diameter. If some of these fibres are broken, or if they are not evenly lighted then one sees a light source behind the vein with a very uneven light distribution. This light distribution is so uneven that one cannot see what is happening inside the vein.

The object underlying the present invention is to provide an improved transilluminator which results in an excellent light distribution and enables a skilled medical practitioner to visualise the flow of blood within the vein or artery. Clearly the transilluminator also has application to other fluid conducting vessels of the body, for example to the urethra, and it also has more general application to human parts that may be transplanted or reconstructed.

In order to satisfy the above object the present invention provides a transilluminator comprising a light source provided at one end of a light conducting rod, the light conducting rod comprising a rod of transparent material, a reflective coating applied to the surface of the rod to ensure reflection of light within said rod and an aperture in said coating at at least one position, in particular a position adjacent an end of said light conducting rod, said aperture permitting the emergence of light from said rod.

A transilluminator of this kind has the substantial advantage that the light conducting rod smooths out the distribution of light received from the fibre optic light guide so that a truly homogenous light beam emerges from the said aperture and thus results in uniform back lighting of the vein, artery or body organ under investigation. Moreover, the light conducting rod can be sterilised without the risk of breaking single fibres of an optical fibre light guide (since none are present in the light conducting rod) , so that there is no danger of broken fibres destroying the important light distribution.

Furthermore, the light conducting rod can be shaped in such a way that it does not take up much space and it can easily be inserted behind the vein, artery or organ under investigation during the operation without taking up a lot of space and without making it necessary to increase the size of the surgical incision or trokar used to introduce it.

In addition the use of such a light conducting rod makes it possible to position the actual light source outside of the body and indeed, if necessary, well away from the body. A whole variety of light sources could be used, for example a conventional light bulb, a fluorescent light emitting device, or a light emitting semi-conductor component, for example a light emitting diode. Such light sources can be arranged either directly at an end face of the light conducting rod or, preferably, can include a fibre optic light guide which transmits the light from the light source into the light conducting rod. It should be noted that breakage of fibres within such an optical light guide does not affect the perfect light distribution at the aperture of the light conducting rod, since the light conducting rod smooths out, i.e. homogenises the light flux entering it by multiple internal reflections.

Moreover, the ability to place the light source, even a light source in the form of a hot bulb, remote from the patient means that the light conducting rod itself is effectively a cold light source, i.e. the patient is not subjected to any unnecessary heating effect.

In addition, it is of particular advantage that the light conducting rod can be mechanically coupled to the light source or to the said fibre optic guide associated with the light source, since this enables a variety of different sizes of light conducting rods to be used depending on the precise organ under investigation. Moreover, it means that the light conducting rod can be separated from the light source for sterilisation. In addition, the ability to separate the light conducting rod from the light source or light guide makes it possible to leave the light conducting rod in place within the patient's body following an operation and to observe the flow of fluid through the organ under investigation over a period of time.

More specifically, investigations have been carried out to date with light conducting rods for the transillumination of arteries with diameters below 2 mm. These sizes of vessels correspond to the vascular supply for organs or human parts that would be sutured back in place after accidental amputation, such as a finger, hand, toe, foot, penis or nose. Moreover, the transilluminator of the invention can be used with other organs or human parts that may be transplanted or reconstructed such as the heart (coronary arteries) , pancreas, tissue flaps (skin, muscle, fascia, bone) , or to investigate muscular malformations in the brain. Larger vessels (arteries and veins) can be transilluminated using stronger light sources. The ability to transilluminate vessels with diameters up to 10 to 20 mm in diameter means that the vascular supply to almost all internal organs in the body, in the kidney, liver, brain, heart etc. can be illuminated and investigated.

One particular application of the invention is for the detection of thromboses in both arteries and veins in the living body (both the human body and the animal body) . If, for example, an artery is cut through and subsequently rejoined or rejoined to another piece of artery or an arteficial vessel then it is known that thromboses are more likely to occur if the joint is not smooth, i.e. if flow irregularities arise within the artery. Using the transilluminator of the invention it is possible to see the dynamics of a thrombus forming, growing, disintegrating and possibly stabilising. The use of the transilluminator has already been established in experiments with arteries and with veins, which are in fact easier to investigate since they have a thinner vessel wall.

A particular advantage of the invention is that the light conducting rod can have a variety of cross-sectional shapes, and indeed its cross-sectional shape can change along the length of the rod to enable ideal matching to the particular task. Thus, in a basic form, the light conducting rod can have a round cross-sectional shape. It is however preferable for it to have a shallower cross-sectional shape, for example in the form of an ellipse, in particular of a flattened ellipse. There is however no restriction to a light conducting rod with a fully rounded surface, it could for example have a cross-sectional shape representing a flat band or a new moon or a semi-circle or polygon, in particular a flattened polygon.

Moreover, no restrictions exist with respect to the surface of the light conducting rod. It can therefore have a structured surface, for example a roughened surface or a structured surface portion, for example it can incorporate a strip having a saw-tooth formation which facilitates the propagation of light within the light conducting rod, as is known per se from light conducting rods used in opto-electronics.

The rod can for example be a glass rod or a synthetic rod, for example of acrylic material.

Since a synthetic rod can be used it is also possible to conceive of a flexible material being used which can be bent to conform to the contours of the organ being monitored or diagnosed or to suit the conditions at the site of the operation.

The aperture through which the light emerges preferably comprises an elongate groove formed in a surface of the light conducting rod, and in particular an elongate groove disposed transverse to the longitudinal axis of the light conducting rod.

It is particularly advantageous if a curved recess is formed in the light conducting rod transverse to a longitudinal axis thereof, with the aperture being formed in a base portion of the recess. The curved recess may be formed by a curved tapering end portion of the light conducting rod. The curved recess is usefully matched in shape and curvature to the organ to be monitored or diagnosed.

Moreover, the elongate groove is usefully matched in size to the vessel to be monitored or diagnosed and has in particular a groove width less than half the diameter of the fluid conducting vessel to be monitored, but preferably more than one tenth of said diameter and in particular approximately one fifth thereof.

The transilluminator may comprise just one light source, or a plurality of light sources, each adapted for use with a plurality of light conducting rods which are in turn each adapted for use with a respective diameter of a fluid conducting vessel, or with a range of diameters of fluid conducting vessels, for example different light conducting rods can be provided to cover a total range of diameters of from 200 μm to 3 cm.

It is particularly advantageous if the transilluminator of the invention is used in combination with a coherent optical fibre read-out guide which is positionable to receive light from an vessel transilluminated by the transilluminator.

In this way the image of the vessel can be "taken back" through an optical fibre bundle so that visible access for the surgeon is no longer needed and the transilluminator and optical fibre monitoring system can be implanted and left covered with tissue or dressing until the surgeon is satisfied that the surgical wound is healing as desired and subsequently removes the transilluminator and the read-out guide.

Another possibility is to provide a second aperture for illuminating the vessel from an angle or position different from the illumination resulting from the first said aperture. If this is done means should be provided for viewing the vessel with respect to light emitted from both said apertures to form separate images of the illuminated vessel for each illuminating aperture. One way of doing this is to provide a beam deflecting element such as an inclined mirror or a prism in at least one of the beams so as to deflect one of the beams into a beam path alongside the other beam so that two images of the vessel can be formed alongside one another. The ability to investigate the vessel from two different directions of viewing enables the surgeon to have a complete picture of the conditions within the vessel.

Further advantageous embodiments of the invention are set forth in the subordinate claims which are incorporated herein by reference.

The invention will now be explained in further detail with reference to the accompanying drawings in which are shown:

Fig. 1 a perspective view of the transilluminator of the invention from the side,

Fig. 2 a view of the end of the light conducting rod of the transilluminator of Fig. 1 from above in the direction of the arrow II,

Fig. 3 an enlarged view of the curved end portion of the light conducting rod of Fig. 2 showing the gradual change in cross-section thereof, and

Fig. 4 a schematic illustration of the coupling of the light conducting rod to an optical fibre bundle.

Fig. 5 an enlarged view of the output end of the light conducting rod of Fig. 4, and

Fig. 6 the transilluminator of Fig. 1 in combination with an optical fibre read-out guide,

Fig. 7 a modified light conducting rod provided for illuminating an vessel from two different angular positions.

Fig. 8 an alternative arrangement to that of Fig. 7 using a prism in place of a deflecting mirror, and

Fig. 9 a view in the direction of the arrow IX of Fig. 8.

Referring now to Figs. 1 to 3 there can be seen a transilluminator 10 comprising a light source indicated generally by the reference numeral 12 and a light conducting rod 14 in the form of a rod or transparent material, in this case glass, with a reflective coating 16 applied to the surface of the rod 14 to ensure reflection of light within the rod. The coating is however omitted at the end face which receives light from the light source 12.

The light source 12 comprises an optical fibre bundle 18 of the kind well known for medical purposes for illuminating the inside of a body cavity, for example an optical fibre bundle such as is used in an endoscope. In the usual way this optical fibre bundle is connected at its input end 20 to a source of light 22, which may for example be a bulb, a fluorescent light emitting device, such as a neon tube, or a smaller light fluxes a light emitting semiconductor device such as a light emitting diode.

The coupling between the optical fibre bundle 18 and the light conducting rod 10 is shown in more detail in Fig. 4. As shown there a length of tube 24 (not shown in Fig. 1) is placed over the end of the optical fibre bundle 18 so that the optical fibre bundle extends approximately half way into the tube 24. It may be retained there by an adhesive or by a mechanical clamp, or (for example) by an O-ring (not shown) .

One end of the light conducting rod is then pushed into the half of the tube 24 not occupied by the optical fibre bundle so that the exit end of the optical fibre bundle 18 lies immediately confronting the input end face 26 of the light conducting rod 10. The light conducting rod may be permanently or releasable retained with the tube 24, for example by adhesive bonding or by a mechanical connection or, for example by an O-ring (again not shown) . In any event the tube 24 will usually only be permanently fixed to one or other of the optical fibre bundle 18 or the light conducting rod 10 so that these items may be readily separated from one another. Alternatively the tube need not be physically connected to either of the optical fibre bundle 18 or the light conducting rod 10 so that all three items can be readily separated and separately sterilised as necessary.

The tube 24 can also be provided with one or more bayonet connection fittings which cooperate with corresponding bayonet connection elements (not shown) on one or both of the optical fibre bundle 18 and the light conducting rod 10.

It is also possible to introduce a coupling fluid, for example physiological saline solution which is readily available in medical facilities into the tube 24, to improve the coupling of light from the end of the optical fibre bundle into the light conducting rod 10, however this is not essential.

The output end of the light conducting rod 10, i.e. the end remote from the input end 26 is provided in this example with a curved recess 28 which is in fact formed in a tapered end portion of the light conducting rod. The curvature of this recess is matched, at least approximately, to the diameter of the body vessel to be investigated, for example the vein 30 of Fig. 5. A light output aperture in the form of a V-shaped groove or slot is provided in the base of the curved recess 28 directly behind the vein 30. This slot is preferably relatively narrow in relation to the diameter of the body vessel 30 under investigation. Thus, for body vessels of 2 mm diameter and below it has been found expedient to use a light slot having a width, i.e. a dimension along the longitudinal axis of the light conducting rod, in the range from 200 to 300 μm. The maximum width of the slot would normally be kept to below half of the diameter of the body vessel involved and it is expedient if the width does not go below one tenth of the diameter of the body vessel involved.

As can be seen from the examples of Figs. 2 and 3 the curved tapering tip of the light conducting rod has a length (for vessels of about 2 mm diameter and below) of approximately 15 mm and adjoins a light conducting rod of about 10 cm in length. The light conducting rod has a round cross-section of 4 mm and Fig. 3 shows how this round cross-section of 4 mm diameter gradually tapers from the circular cross-section of about 4 mm diameter through an oval and then through a semi-circular to flattened semi-circular cross-section to an approximately rectangular cross-section at the aperture 32 and subsequently broadens at a tip portion to an ellipsoidal section having a minor diameter of about 2 mm. An aperture is defined by the groove and is about 1 mm deep and 200 to 300 μm wide measured in the local longitudinal direction of the curved tapering end portion of the light conducting rod.

For larger vessels the size of the tip of the light conducting rod can be increased accordingly. It should be noted that the dimensions and shapes given here are not to be taken as restricting the invention to such dimensions and shapes, indeed the light conducting rods and the operating tips thereof can be made in a whole variety of cross-sectional shapes and dimensions, it only being important that the light emerging from the light source into the light conducting rod is subjected to multiple internal reflections to ensure homogeneity thereof.

Equally, although an elongate groove is a preferred shape for the aperture through which light emerges from the light conducting rod, the aperture need not take the form of a physical recess it can simply comprise a region of the light conducting rod where the surface coating has been removed (or is not applied in the first place) . Moreover, it is not essential for the aperture to be elongate in shape it could also, for example, simply be around the aperture. It is however preferable for the aperture to have a reasonable length dimension (for example the 2 mm of Fig. 2) so that it can illuminate a sufficient length of the vessel 30 on either side of the join or area under investigation.

Fig. 6 shows a particularly interesting variant of the invention where a coherent fibre optic light guide 34 is associated with the transilluminator 10 to enable a surgeon to view the transilluminated vessel with both the light conducting rod 14 and the coherent optical light guide 34 implanted in the patient.

The arrangement of Fig. 7 is also of particular interest in which two apertures are provided in the curved end of the light conducting rod so as to illuminate the vessel from two different perspectives, which, in this embodiment, are arranged at 90° to one another. A beam deflector (for example in the form of an inclined mirror is then used to direct the beam 42 from the aperture 32' into a position parallel to the beam of light 40 issuing from the aperture 30 so that both may be simultaneously viewed by the surgeon.

The viewing can, if necessary, be effected in all embodiments using a microscope so as to obtain optical magnification of the vein which facilitates the visualisation of the flow taking place therein.

An arrangement of this kind can also be used with a coherent optical light guide to permit viewing of the vessel under investigation after implantation of the light conducting rod, the light deflecting element and the coherent optical guide into the patient.

An improved version is shown in Fig. 8 where a prism 38* is substituted for the deflecting mirror and is arranged at the free end of the light conducting rod 14 on the same. The second aperture 32' is provided on the opposite side of the tip of the light conducting rod from that shown in Fig. 7. The prism can for example be adhesively bonded to the light conducting rod and it can have an associated part-cylindrical portion which surrounds the vein or vessel under investigation and includes the first and second apertures 38, 38' as shown.

Here the two beams 40, 42 are again separate. The 90° prism 38' simply turns the light beam from the second light slot so that the second image forms alongside the first image and both images can be surveyed.

Claims

Patent Claims

1. Transilluminator (10) for use in human and vetinary medicine, in particular for backlighting veins, arteries, urethras and other fluid conducting organs or vessels of the animal or human body, the transilluminator comprising a light source (12) provided at one end of a light conducting rod (14) , the light conducting rod comprising a rod of transparent material (14) , a reflective coating (16) applied to the surface of said rod to ensure reflection of light within said rod and an aperture (32) in said coating at at least one position, in particular a position adjacent an end of said light conducting rod, said aperture (32) permitting the emergence of light from said rod.

2. Transilluminator in accordance with claim 1 wherein said light source (10) comprises a light source directly positioned at an end face (20) of said light conducting rod (10) .

3. Transilluminator in accordance with claim 2 wherein said light source (12) comprises a bulb (22) , a fluorescent light emitting device or a light emitting semiconductor component, e.g. a light emitting diode.

4. Transilluminator in accordance with claim 1 wherein said light source (12) comprises a bulb (22) , a fluorescent light emitting device or a light emitting semiconductor component, e.g. a light emitting diode, disposed at one end of a fibre optic light guide (18) , said fibre optic light guide having a second end which communicates optically with an end of said light conducting rod, in particular an end face thereof.

5. Transilluminator in accordance with claim 4 wherein means (24) is provided for mechanically coupling said second end of said fibre optic light guide (18) to said light conducting rod.

6. Transilluminator in accordance with claim 5 wherein said mechanical coupling means (24) comprises a tube element disposed at said second end into which an end (26) of said light conducting rod is inserted.

7. Transilluminator in accordance with claim 5 or claim 6 wherein said mechanical coupling means comprises a threaded coupling.

8. Transilluminator in accordance with claim 5 or claim 6 wherein said mechanical coupling means comprises a bayonet coupling.

9. Transilluminator in accordance with any one of claims 5 to 8 wherein said mechanical coupling means includes a coupling liquid, e.g. a saline solution, in particular a physiological salt solution, disposed between said second end of said fibre optic light guide (15) and said end (26) of said light conducting rod, which is in particular an end face of said light conducting rod.

10. Transilluminator in accordance with any one of the preceding claims wherein said light conducting rod (14) has a round cross-sectional shape.

11. Transilluminator in accordance with any one of the preceding claims 1 to 9 wherein said light conducting rod has a cross-sectional shape in the form of an ellipse, in particular of a flattened ellipse.

12. Transilluminator in accordance with one of the claims 1 to 9 wherein said light conducting rod (14) has a cross-sectional shape representing a flat band or a new moon or a semi-circle or a polygon, in particular a flattened polygon.

13. Transilluminator in accordance with any one of the preceding claims wherein said light conducting rod (14) includes a structured surface, e.g. a roughened surface or a structured surface portion, e.g. a strip having a saw tooth formation.

14. Transilluminator in accordance with any one of the preceding claims wherein said light conducting rod (14) comprises a glass rod or a synthetic rod, e.g. of acrylic material.

15. Transilluminator in accordance with any one of the preceding claims wherein said light conducting rod (14) is of a flexible material and can be bent to conform to the contours of the vessel (30) being monitored or diagnosed.

16. Transilluminator in accordance with any one of the preceding claims wherein said aperture (32) comprises an elongate groove formed in a surface of said light conducting rod (14) transverse to a longitudinal axis thereof.

17. Transilluminator in accordance with any one of the preceding claims wherein a curved recess (28) is formed in said light conducting rod transverse to a longitudinal axis thereof, with said aperture (32) being formed in a base portion of said recess.

18. Transilluminator in accordance with claim 17 wherein said curved recess (28) is formed by a curved tapering end portion of said light conducting rod (14) .

19. Transilluminator in accordance with claim 18 wherein for use with vessels of about 2 mm diameter said tapering end portion (17) has a length of about 15 mm and tapers from a circular cross-section of about 4 mm diameter through an oval and then through a semicircular to flattened semicircular cross-section to an approximately rectangular cross-section at said aperture (32) and subsequently broadens at a tip portion to an ellipsoidal section having a minor diameter of about 2 mm, with said aperture being defined by a groove of about 1 mm depth and 200 - 300 μm width measured in the local longitudinal direction of said curved tapering end portion of said light conducting rod.

20. Transilluminator in accordance with claim 17 wherein said curved recess (28) is matched in shape and curvature to the vessel (30) to be monitored or diagnosed.

21. Transilluminator in accordance with claim 16 wherein said elongate groove (32) is matched in size to the vessel (30) to be monitored or diagnosed and has in particular a groove width less than half the diameter of the fluid conducting vessel to be monitored, but preferably more than one tenth of said diameter, and in particular approximately one fifth thereof.

22. Transilluminator in accordance with any one of the preceding claims comprising a light source (12) adapted for use with a plurality of light conducting rods (14) each adapted for use with a respective diameter of a fluid conducting vessel, or with a range of diameters of fluid conducting vessels, e.g. to cover a total range of diameters of from 200 μm to 3.0 cm.

23. Transilluminator in accordance with any one of the preceding claims in combination with a coherent optical fibre read-out guide (34) positionable to receive light from an vessel (30) transilluminated by said transilluminator (10) .

24. Transilluminator in accordance with any one of the preceding claims and comprising a second aperture (32) for illuminating the said vessel from an angle or portion different from the illumination resulting from the first said aperture (32) and means (36) for viewing said vessel (30) with regard to light emitted from both said apertures (32, 32') to form separate images (37, 37') of the illuminated vessel (30) for each illuminating aperture (32, 32').

25. Transilluminator in accordance with claim 24, wherein said second aperture (32') is provided in a curved region of said light conducting rod (14) at a position such as to illuminate the vessel at an angle of approximately 90° relative to the direction of the illumination by the first said aperature, and in that a beam deflection means, such as an inclined mirror (38) or a prism (38'), is inserted into at least one of the beams of light emerging from the vessel (30) and originating from one of said apertures (32') to deflect said light into a beam path alongside the beam path of another beam of light emerging from the vessel (30) and originating from the other one of said apertures (32) whereby to form two images of said vessel alongside one another.

26. Transilluminator in accordance with claim 25 wherein said prism (38') is disposed at the free end of the light conducting rod.

27. Transilluminator in accordance with claim 26 wherein the prism is bonded to the tip of the light conducting rod.

28. Transilluminator in accordance with one of the claims 25 to 27 wherein said prism (38') has an integral, part-cylindrical portion defining the recess (28) for receiving said fluid conducting vessel, with said apertures (32, 32') being formed in said part-cylindrical portion.

29. Method of observing the flow through vessels (30) of the body such as veins, arteries, comprising the steps of illuminating the vessel from behind with a transilluminator (10) having a uniform homogenous light flux, in particular a transilluminator in accordance with any one of the preceding claims, and viewing the illuminated vessel (30) from the front or side.