Assessment of Factors Involved in Laser Fiber Degradation with Thulium Fiber Laser

Thibault Germain; Laurent Berthe; Frédéric Panthier; Cyril Gorny; Olivier Traxer; Steeve Doizi

doi:10.1089/end.2021.0387

Assessment of Factors Involved in Laser Fiber Degradation with Thulium Fiber Laser

J Endourol. 2022 May;36(5):668-673. doi: 10.1089/end.2021.0387. Epub 2021 Dec 29.

Authors

Thibault Germain^{1

2}, Laurent Berthe³, Frédéric Panthier^{1

2}, Cyril Gorny³, Olivier Traxer^{1

2}, Steeve Doizi^{1

2}

Affiliations

¹ Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, Hôpital Tenon, Paris, France.
² Sorbonne Université, Service d'Urologie, AP-HP, Hôpital Tenon, Paris, France.
³ PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151 bd de l'Hôpital, Paris, France.

PMID: 34806403
DOI: 10.1089/end.2021.0387

Abstract

Objectives: To assess the effect of various factors on laser fiber tip degradation with the thulium fiber laser (Tm-fiber): fiber stripping, adjustable laser settings (energy, frequency, peak power), and stone density. Methods: Two hundred seventy-three micrometer fibers were used with a 50W Tm-fiber. First, we assessed the evolution of power transmission with stripped and unstripped fibers submerged in saline. The laser was continuously activated for 5 minutes. The influence of each laser parameter (energy, frequency, and peak power) on fiber degradation was assessed by loss of power transmission and reduction of tip length. Second, we assessed the evolution of power transmission after 150 seconds of lithotripsy in a quasicontact mode against soft and hard BegoStones. The influence of lithotripsy with different laser settings on fiber degradation was assessed by loss of power transmission. Results: Power transmission was close to 100% with stripped fibers, while a power gain appeared for unstripped fibers after 5 minutes of laser emission. Thus, only stripped laser fibers were used during the second series of experiments. Regardless of laser settings, there was a constant loss of measured power transmission after lithotripsy with a significant difference between soft and hard stones, p < 0.0001. Power transmission was 67% and 78% against hard and soft stones, respectively. While there was no influence of peak power on power output against hard stones, there was a significant one against soft stones. Conclusions: The main determinant of loss of power transmission during lithotripsy in contact mode with Tm-fiber is the stone density. Higher loss of power transmission occurs against hard stones than soft stones. All peak powers may be used against hard stones without a difference, while high peak power appears as an additional factor of power loss against soft stones, but this decrease will not the reach the one obtained with hard stones.

Keywords: endourology; laser fiber; optical fiber; thulium fiber laser; ureteroscopy; urolithiasis.

MeSH terms

Calculi*
Humans
Lasers, Solid-State*
Lithotripsy*
Lithotripsy, Laser*
Thulium

Substances

Thulium