Research Papers: Therapeutic

Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy

[+] Author Affiliations
Thomas C. Hutchens, David A. Gonzalez

University of North Carolina at Charlotte, Department of Physics and Optical Science, 9201 University City Boulevard, Charlotte, North Carolina 28223, United States

Pierce B. Irby

Carolinas Medical Center, McKay Department of Urology, 1023 Edgehill Road South, Charlotte, North Carolina 28207, United States

Nathaniel M. Fried

University of North Carolina at Charlotte, Department of Physics and Optical Science, 9201 University City Boulevard, Charlotte, North Carolina 28223, United States

Carolinas Medical Center, McKay Department of Urology, 1023 Edgehill Road South, Charlotte, North Carolina 28207, United States

J. Biomed. Opt. 22(1), 018001 (Jan 10, 2017). doi:10.1117/1.JBO.22.1.018001
History: Received October 17, 2016; Accepted December 20, 2016
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Abstract.  The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A “fiber muzzle brake” was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500  μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-outer-diameter, 360-μm-inner-diameter tube with a 275-μm-diameter through hole located 250  μm from the distal end. The fiber tip was recessed a distance of 500  μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40±4  mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25±4  s (n=10) without visible distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers, respectively. The muzzle brake fiber tip simultaneously provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

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© 2017 Society of Photo-Optical Instrumentation Engineers

Citation

Thomas C. Hutchens ; David A. Gonzalez ; Pierce B. Irby and Nathaniel M. Fried
"Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy", J. Biomed. Opt. 22(1), 018001 (Jan 10, 2017). ; http://dx.doi.org/10.1117/1.JBO.22.1.018001


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