METHOD OF REDUCING STONE FRAGMENTS TO DUST DURING LASER LITHOTRIPSY

Abstract

A soft tip is used to trap and pulverize stone fragments between the stone and the end of a single fiber, fiber bundle or lenticular array during a pulsed laser lithotripsy procedure.

Claims

1. A method of optimizing a dusting effect resulting from the firing of laser pulses from a laser deliver device at stone during a lithotripsy procedure, comprising the steps of: placing a soft tip over a distal end of a laser delivery device, the soft tip extending between the distal end of the laser delivery device to provide a predetermined spacing between the stone and the distal end of the laser delivery device when the soft tip contacts the stone; and firing laser beams at the stone until the stone has been reduced to dust while the soft tip is maintained in contact with the stone so as to trap any fragments that have broken off the stone in a space between a distal end of the fiber and the stone.

2. A method as claimed in claim 1, further comprising the step of using a stone sensing method to maintain contact between the soft tip and the stone during the lithotripsy procedure.

3. A method as claimed in claim 1, wherein the laser delivery device is a single optical fiber.

4. A method as claimed in claim 1, wherein the laser delivery device directs multiple beams at the stone and trapped fragments.

5. A method as claimed in claim 4, wherein the laser delivery device is a fiber bundle that includes a plurality of optical fibers.

6. A method as claimed in claim 4, wherein the laser delivery device includes a lenticular array positioned in front of at least one optical fiber for splitting a laser beam emitted by the at least one optical fiber into a plurality of laser beams.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGS. 1A to 1C show the effect on stone fragments of a conventional pulsed laser.

[0017] FIGS. 2A to 2C show an embodiment of the invention that utilizes a soft tip to capture the fragments and subject them to multiple pulses.

[0018] FIGS. 3 and 4 show soft tips respectively fitted to a fiber bundle and lenticular array in accordance with the principles of preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] As shown in FIGS. 1A to 1C, a stone 10 in initially subjected to a first pulse emitted by the tip 11 of a fiber 12, resulting in the separation of fragments 14 from the stone 10. These fragments, like the stone is itself, are subject to retro-repulsion that, because of the lower mass of the fragments, tends to push them to the side or back behind the stone and out of reach of the laser. In order to dust these fragments, the operator must locate them and, in effect, chase them down by maneuvering the fiber tip into proximity to the fragments, even as the fragments continue to be pushed away from the fiber by retro-repulsion.

[0020] To solve this problem, a protective cap, spacer tip or standoff sleeve, preferably in the form of a compressible soft tip 15 of the type described in PCT Publ. No. WO/2017/192869, is secured to an end of the fiber such that the distal end of the protective cap extends beyond the end of the fiber, as illustrated in FIGS. 2A to 2C. As pulses are applied to the stone 10, the protective cap is maintained in contact with the stone, thereby trapping the fragments 14 that break off the stone so that the fragments are subjected to repeated pulses and reduced to smaller and smaller fragments 14. Contact may be maintained manually by relying on operator observation of stone position and manual adjustment, or with the assistance of a stone position detection by spectral analysis as disclosed in

[0021] The protective cap, spacer tip or standoff sleeve may be manually maintained in contact with the stone, or optionally with the assistance of a proximity feedback method such as the one disclosed in copending U.S. patent application Ser. Nos. 16/234,690, and 16/353,225, cited above.

[0022] As illustrated in FIG. 2, the single fiber of FIG. 1A may be replaced by a fiber bundle 1 that includes a plurality of optical fibers 2 surrounded by a jacket 3. A distal end of the fiber bundle 1 is fitted with a cylindrical soft tip 4. During a lithotripsy procedure, the fiber bundle 1 Is inserted through a scope or catheter (not shown). As in the embodiment of FIG. 1A, when the end of the soft tip contacts the stone, the end of the fiber bundle 1 is spaced by a predetermined distance from the stone. The laser is fired while the soft tip is maintained in contact with the stone. Maintaining contact with the stone may again be accomplished by conventional methods, or with the assistance of a stone proximity-sensing method such as the described in copending U.S. patent application Ser. Nos. 16/234,690, and 16/353,225. The lithotripsy procedure continues until the stone and all fragments have been reduced to dust, i.e., fragments that are small enough to easily pass through the patient's urinary tract.

[0023] As illustrated in FIG. 2, fiber bundle 1 may be replaced by a single fiber or a smaller number of fibers, and at least one lenticular array 5 for splitting the laser output into a plurality of beams that achieve the same dusting effect as the plurality of beams emitted by the fiber bundle of FIG. 1. As in above-described embodiments, a soft tip 4 is fitted to the lenticular array 5 in order to provide a predetermined spacing between the array and the stone for optimal dusting effect.