WO1994023640A1

WO1994023640A1 - A fiberoptic endoscope

Info

Publication number: WO1994023640A1
Application number: PCT/US1994/004373
Authority: WO
Inventors: Pinchas Shalev; Steven Jackel
Original assignee: Helfgott & Karas, P.C.; The State Of Israel, Atomic Energy Commission, Soreq Nuclear Research Center
Priority date: 1993-04-20
Filing date: 1994-04-20
Publication date: 1994-10-27
Also published as: IL105466A0

Abstract

A light channel (27) for use in a cord of an endoscope (18) includes a sheathed cluster of optical fibers (4) consisting of a bundle of capillary tubes (1) made of a light transmitting material having an index of refraction n1. Each capillary tube (2) holds a body compatible, light transmitting liquid having an index of refraction n2 larger than n1. There are further described cords embodying at least one such light channel, and endoscopes fitted with such cords.

Description

A FIBEROPTIC ENDOSCOPE

FIELD OF THE INVENTION

The present invention is generally in the field of endoscopes and concerns more specifically endoscopes, serving as so-called videoscopes, for visualizing the interior of a targeted cavity of a subject's body and also, among others, for the injection of liquids into the body and withdrawal of liquids therefrom.

REFERENCES

1. B.A. Turkigton and W. Shannon, "Invasive Surgery, An Endoscopic Perspective", DR Reports June 1992, p. 111.

2. Hank Kelly, "Fiber continues to grow in Healthcare Treatments", Fiberoptic Product News, 5. 1992.

3. B.A. Turkigton and . Shannon, "Invasive Surgery, An Endoscopic Perspective", DR Reports June 1992, p. 5. 4. B.A. Turkigton and W. Shannon, "Invasive surgery, An Endoscopic Perspective", DR Reports June 1992, pp. 109-112.

5. B.A. Turkigton and W. Shannon, "Invasive Surgery, An Endoscopic Perspective", DR Reports June 1992, pp 113-116.

6. W.P. Siegmund, U.S. Patent No. 3,279,903 (1966). BACKGROUND OF THE INVENTION

Endoscopes are invasive medical instruments used to visualize and optionally to manipulate the interior of a cavity in a subject's body for diagnostic and therapeutic purposes. The optical system of an endoscope usually comprises a cord holding at least two clusters of optical fibers to be referred to herein as "light channels". Known endoscopes comprise, as a rule, dedicated light channels, at least one for illumination, i.e. for the transmission of light into a targeted cavity of the body, and at least one dedicated for the transmission of images from the cavity to an eyepiece, camera or display device.

An endoscope may further comprise at least one dedicated lumen for the injection and withdrawal of liquids, e.g. foj_. irrigation, injection of medicated aqueous solutions, withdrawal of samples of body fluids or tissues, and the like, and one or more additional lumens may be provided for other manipulations.

The need for dedicated lumens for liquid transfer such as injection or withdrawal of liquid additional to at least two dedicated light channels for light transmission in and out of the body, imposes lower limits on the outer diameter of the cord of known endoscopes which in case of two channels and one lumen cannot, as a rule, be reduced below about 1.5mm. In consequence, existing endoscopes are inherently precluded from a variety of desired applications for which an endoscope would have to be available that has a cord with a smaller outer diameter, examples of such desired applications being diagnosis and treatment of narrow blood vessels, injection of liquids to and withdrawal of body fluids and tissues from cavities between the spinal vertebrae, etc. SUMMARY OF THE INVENTION

It is one object of the present invention to provide for use in an endoscope, a small-diameter light channel comprising a cluster of optical fibers capable of transmitting images from the interior of a subject's body to the viewer's eye and of transferring liquids to and from the body with no need for a dedicated lumen.

It is a further object of the present invention to provide a bundle of capillary tubes for use in making a light channel of the kind specified. It is yet another object of the present invention to provide an endoscope with a cord embodying at least one such light channel, if desired together with at least one conventional light channel.

The present invention makes use of a recently developed technology of making coherent clusters of essentially parallel capillary tubes with minuscule diameters of the order of microns. It has been realized in accordance with the invention that such a cluster can be converted into a light channel in which each capillary tube serves as cladding and the core is a body compatible, light transmitting liquid for injection into a subject's body for irrigation and, if desired, for diagnostic or therapeutic purposes. In this way light is transmitted and liquid is injected through one and the same capillary tubes, thus enabling the visualization of the interior of the body and the performance of a variety of diagnostic and medical manipula¬ tions by means of an instrument having a relatively small-diameter cord. It has now further been found that it is possible to fabricate in this manner light channels of less than 1 mm outer diameter which may hold a sufficiently large number of individual fibers to ensure good image resolution.

In accordance with the present invention, there is provided a light channel for use in a cord of an endoscope, comprising a sheathed cluster of optical fibers consisting of a bundle of capillary tubes made of a light transmitting material having an index of refraction ni, each holding a body compatible, light transmitting liquid having an index of refraction n₂ larger than n . The invention further provides a sheathed bundle of capillary tubes for use in making a light channel of the kind specified by introducing therein a body compatible, light transmitting liquid. Introduction of liquid into the capillary tubes may be done by injection or suction with the aid of any suitable manual or electric pumping or suction device. Still further the invention provides a cord for an endoscope comprising an envelope holding at least one light channel of the kind specified.

The light channel according to the invention may be enclosed within a rigid or flexible envelope to form a single channel cord of an endoscope. In such an application the sheath will, as a rule, be light transmitting and serve for the transmission of light from a light source for illumination inside the body, while the optical fibers serve for the transmis¬ sion of images from the body. To avoid interference between the incoming light and the outgoing images, no light should pass between the fibers and sheath. One way to achieve this is to make the index of refraction n₃ of the sheath larger than the index of refraction of the capillary tubes. Alternatively, a light barrier may be provided between the sheath and the cluster of optical fibers, e.g. in form of a light reflecting coat or layer of aluminum, silver and the like. If desired, a cord of an endoscope according to the invention may comprise several light channels at least one of which is a light channel according to the invention. In such an embodiment each light channel serves only for unidirectional light transmission that is either for illumination or for the transmission of images and the sheath of the light channel according to the invention need not be light transmitting. Also in such an embodiment the light channel according to the invention fulfills the double function of light transmission and the transfer of liquids.

Each optical fiber of a light channel according to the invention fulfills the double function of light transmission and of serving as lumen for the injection of liquid for irrigation and other purposes and, if desired, for the withdrawal of body liquid. In this way the need for a separate, dedicated liquid conducting lumen is obviated and endoscopes with a cord that embodies a light channel according to the invention may have a significantly smaller outer diameter than cords of prior art devices.

The inner diameter of each capillary tube in a light channel according to the invention may be extremely small, of micron order, whereby even a small diameter light channel has a large number of individual optical fibers and a satisfactory optical resolution is ensured. The present invention further provides an endoscope having a cord that embodies at least one light channel according to the invention. If desired an endoscope according to the invention may comprise a light source near the cord's proximal end.

To enable the ejection of the core forming liquid from a light channel according to the invention for irrigation and other purposes, the endoscope according to the invention comprises means for forcing liquid flow through the capillary tubes, e.g. a pump, a syringe type piston/cylinder assembly and the like. If desired, such flow forcing means may be associated with a reservoir for a body compatible, light transmitting liquid. Although liquid filled capillary tubes in a light channel according to the invention are capable of serving both for ambient light illumination and the transmission of images from the interior of the body, they are inappropriate for artificial light illumination. This is due to a so- called edge effect by which a fraction of the light impinging on the light channel's ends is reflected and thus gives rise to some dazzleness and distortion of the transmitted images. Consequently, when the light channel according to the invention is used alone, the illuminating light is guided through the sheath and the images are transmitted through the cluster of optical fibers in the manner specified.

The light channel according to the invention is intrinsically flexible and may be contained either by itself or together with at least one other light channel within a flexible tube, such as a plastic tube or within a rigid tube such as a syringe needle. Where the light channel is contained in a flexible tube, for example when used as an optical catheter, it can be channelled through a pointed rigid tube, e.g. a syringe needle, which also serves for piercing the skin. Where the cord is contained within a syringe needle the needle itself may serve both for piercing and for advancing the cord to its target. Optical fibers can, as a rule, detect only light signals that originate from not more than 1-2 mm. away from their distal end. If it is desired to view sections in the interior of a targeted cavity that are more than 1-2 mm removed, a concave micro lens is mounted on the distal tip of the cord. When a lens is provided, the cord is fitted near the lens bearing tip with a chamber having radial ports for the egress and ingress of liquids. The diameter of each of the optical fiber forming capillary tubes and the diameter of the cord embodying a light channel according to the present invention, may be chosen in accordance with the desired image resolution, the diameter of the vessels through which the cord is to be channelled, the viscosity of the fluid to be transferred through the optical fiber forming capillary tubes and the size of any particle suspended therein, e.g. erythrocytes and leukocytes in case of blood withdrawal, and the like. The optical fiber forming tubes of a light channel according to the invention may have any desired cross-sectional shape e.g. circular or hexagonal, the latter being preferred since the resulting honeycomb pattern leads to a cluster without any voids between the individual capillary tubes. In addition to serving for viewing an interior cavity of a subject's body, an endoscope according to the invention may further be used for the injection of liquids into the body and the withdrawal of body fluids therefrom. For example, the said body compatible, light transmitting liquid may be an anaesthetic solution for injection between the spinal vertebrae as in an epidural injection at labor time; a liquid medicament for injection into blood vessels of the brain; various medicated solutions for injection to blood vessels of the liver; clear liquid injected to improve visualizing of blood filled cavities such as blood vessels, heart chambers or valves and the like. If the liquid to be injected is not transparent, it is possible to initially fill the light channel of the invention with a transparent body compatible liquid such as a solution of iodine, which enables viewing and monitoring the advancement of the endoscope to its target. Once the endoscope is properly positioned, the transparent liquid can be replaced by the liquid to be injected.

Examples of liquids that can be withdrawn for diagnostic purposes from the body by means of an endoscope according to the invention are blood and spinal cord fluid, and there may be many others.

The cord of an endoscope of the present invention may also be used for transmitting ultrasound waves to a target such as bile stones or bladder stones for disintegration, or for the transmission of a laser beam, e.g. for cutting or burning a targeted tissue. Furthermore, upon ejection of the liquid, the empty capillary tubes of the light channel may be used for the transmission of x-ray radiation for diagnostic or therapeutic purposes.

An endoscope according to the invention may comprise lumens dedicated to various manipulations such as the introduction of an inflatable balloon for dilating a blood vessel, introduction of a miniature scalpel for cutting away tissue and the like, all of which manipulations are monitored by means of an image transmitting channel.

By a further aspect the present invention further provides a method of endoscopy utilizing an endoscope of the kind specified.

BRIEF DESCRIPTION OF THE DRAWINGS

For better understanding, the invention will now be described, by way of example only, with reference to the annexed drawings in which:

Fig. 1 is an enlarged schematic cross-section of one embodiment of a bundle of circular capillary tubes serving for conversion into a light channel according to the invention;

Fig. 2 is a similar view of another embodiment with hexagonal capillary tubes;

Fig. 3 is a diagrammatic illustration of an endoscope according to the invention with light source;

Fig. 4 is a schematic axial section of a cord embodying a light channel according to the invention;

Fig. 5 is a diagrammatic actual section of a cord embodying a light channel according to the invention with a terminal lens; and Fig. 6 is a diagrammatic illustration of an endoscope according to the invention with a syringe type pumping device.

DESCRIPTION OF A SPECIFIC EMBODIMENT

The bundle 1 shown in Fig. 1 comprises a plurality of circular capillary tubes 2 and is enclosed within a sheath 3. Bundle 1 may, for example, be made of silica having an index of refraction n_: and sheath 3 may be of doped silica having an index of refraction n₃, with the proviso that n₃ is larger than n_x whereby any illuminating light propagating through the sheath 3 remains confined therein. Alternatively, a light barrier e.g. a reflecting coat of aluminum, silver or the like may be interposed between sheath 3 and bundle 1.

For operation the sheathed bundle 1 is filled with compatible, light transmitting liquid having an index of refraction n₂ that is larger than n₃. The capillary tubes 2 are filled with this liquid by injection or suction of liquid utilizing an electrical or manual pump whereby bundle 1 is converted into a light channel with each capillary tube 2 forming a fiber cladding and the fiber core being formed by the said body compatible, light transmitting liquid.

In the bundle of Fig. 2 the individual tubes have a hexagonal profile which has the advantage that the resulting honeycomb pattern has no voids. Corresponding parts are numbered 1', 2' and 3'.

Attention is now directed to Fig. 3 which shows schematically a light channel 4 according to the invention having a light transmitting sheath 5 whose index of refraction is larger than that of the optical fiber forming capillary tubes, as shown in Figs. 1 and 2 and described with reference thereto. Bundle of optic fibers 6 serves for the admission of light from a light source that is not shown. Bundle 6 is coupled to sheath 5, which serves as a light guide within a coupling device 7. As shown, the attachment of bundle of optic fibers 6 to channel 4 is removed from the proximal end 8 of the channel which avoids any end effect and ensures that illumination occurs exclusively via the sheath 5 of channel 4.

Attention is now directed to Fig. 4 which shows schematically a light channel 10 according to the invention anchored in a fixture 11 connectable to the endoscope and having a distal end 12. Light channel 10 comprises a cluster of optical fibers made from a bundle of capillary tubes of a kind shown in either of Figs. 1 and 2 and described with reference thereto. In the embodiment of Fig. 4 the light channel 10 is assumed to be held within a needle 13. Alternatively, a light channel 10 may also be enclosed within a flexible envelope and in such a case a pointed tube such as a syringe needle will serve for piercing the skin and act as vehicle for the advancement of the flexible cord therethrough. During introduction the advancement of light channel 10 is monitored by observing the images transmitted therethrough. As the light channel 10 of Fig. 4 has no terminal lens the transmitted images are restricted to an area not more than 2 mm removed from the distal end 12.

Attention is now directed to Fig. 5 which shows a light channel 10 in which components equivalent to those of Fig. 4 are designated by the same numerals. As shown, the distal end 12 of channel 10 opens into a distributor/collector chamber 14 having a plurality of radial ports 15 and bearing a terminal lens 16. In operation, light arriving through light channel 10 via the optical fibers and/or the sheath 13 thereof is scattered inside the cavity under observation through lens 16 and the images of that cavity are focused by lens 16 onto the distal ends of the optical fibers of light channel 10. When liquid has to be discharged from light channel 10 into the body it is delivered via ports 15 of chamber 14 and any body fluid that has to be pumped out is sucked into channel 10 via ports 15. Attention is now directed to Fig. 6 which is a schematic illustration of an endoscope according to the invention. As shown, endoscope 18 has a syringe type head portion 19 comprising a cylinder 20 and manually operated piston 21 with integral shaft 22 and handle 23.

Inside cylinder 20 there is mounted a mirror 24 with a plurality of peripheral holes 25 for the passage of liquid. The head portion 19 further comprises a lens 26 which may be connected to an eye piece, a camera such as a CCD camera or a display device. A light channel 27 according to the invention is attached to the endoscope at 18 by means of a fixture 28 of the kind of fixture 11 shown in Figs. 3 and 4.

If desired, cylinder 20 of head 19 may be filled with the same body compatible, light transmitting liquid as light channel 27, or with a different liquid, or alternatively be empty.

The endoscope shown in Fig. 6 may be operated with ambient light or else have a built-in light source of more intensive light (not shown). For example, mirror 24 may be of the beam splitter type and the light source may be mounted behind it.

In operation, light channel 27 of endoscope 18 is gradually introduced into the body to reach a targeted cavity thereof, the operation being facilitated by irrigation with the core forming liquid of the optical fibers. The insertion is monitored by the images arriving via light channel 27 and reflected by mirror 24 to an eye piece, camera or display device, as the case may be. During the introduction piston 21 is gradually advanced. When it is desired to utilize light channel 27 for a therapeutic treatment with some medicated liquid, which may be the same as or different from that contained in light channel 27 in the first place, such liquid is stored in cylinder 20. When the tip of light channel 27 has reached the desired target, piston 21 is further advanced whereby the liquid is forced via light channel 27 into the targeted body cavity.

If upon completion of the penetration it is desired to use light channel 27 for the transmission of ultrasound waves, the head portion 19 is removed and fixture 28 is connected to an ultrasound generator.

Where it is desired to utilize light channel 27 for treatment with electromagnetic x-ray radiation, cylinder 20 will not include any liquid and once the tip of the channel has reached its desired destination, the liquid thereof is forced out by driving piston 21 forward until the end of the piston step. When the capillary tubes of light channel 27 have been emptied the endoscope head portion 19 is removed and fixture 28 is connected to an x- ray generator.

As mentioned, the technology of making clusters of capillary tubes with minuscule diameters of the order of a few microns only, is known. Essentially such manufacture comprises the production by extrusion of a bundle of tubes with a much larger diameter and having each the desired profile, e.g. circular or hexagonal, and this bundle is drawn out in a drawing tower of the kind used in the manufacture of optical fibers, whereby the diameter is reduced to the desired extent while the initial profile is retained. For example, a one meter long bundle of several thousand capillary tubes of 1-2 mm diameter each may be drawn out into a 10-20 kilometer long bundle in which the individual capillary tubes have the desired minuscule diameter while retaining their initial profile. After drawing, the bundle resulting cut into pieces of desired length. The sheath may be provided prior to drawing and be drawn together with the bundle or alternatively, each stretch of bundle of capillary tubes may be sheathed separately.

Claims

CLAIMS:

1. A light channel for use in a cord of an endoscope, comprising a sheathed cluster of optical fibers consisting of a bundle of capillary tubes made of a light transmitting material having an index of refraction n^ each holding a body compatible, light transmitting liquid having an index of refraction n₂ larger than n_r

2. A sheathed bundle of capillary tubes for use in making a light channel according to Claim 1 by introducing therein a body compatible, light transmitting liquid.

3. A light channel according to Claim 1, wherein the sheath is light transmitting.

4. A light channel according to Claim 3, wherein the index of refraction of the sheath is greater than that of the bundle of capillary tubes.

5. A light channel according to Claim 3, wherein a light barrier is provided between the sheath and cluster of optical fibers.

6. A cord for an endoscope comprising- an envelope holding at least one light channel according to any one of Claims 1 and 3 to 5.

7. A cord according to Claim 6, having one single light channel.

8. A cord according to Claim 7, wherein the light channel is as defined in Claim 4.

9. A cord according to Claim 7, wherein the light channel is as defined in Claim 5.

10. A cord according to Claim 6, comprising at least one conventional light channel.

11. A cord according to any one of Claims 6 to 10, having at one end a distributor/collector chamber with radial ports and fitted with a terminal lens.

12. An endoscope fitted with a cord according to any one of Claims 6 to 11.

13. An endoscope according to Claim 12, fitted with a light source.