Category: Stones: Ureteroscopy

VS1-4 - Ho:YAG laser lithotripsy in non-contact mode by using laser fibers with a stand-off jacket

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective :

We recently evaluated how variable working distances between the laser fiber tip and the stone influence single pulse laser lithotripsy efficiency. We found that highest efficiency was achieved with high energy and long pulses at a working distance of 0.4mm. Since specific distances are difficult to maintain during surgical interventions, these findings led to the development of new fibers.


Methods :

We analysed a new laser fiber of which the tip is covered with a stand-off jacket to ensure a constant stand-off range. It is characterized by a 9mm Soft Tip Stand-Off Jacked covering the distal 8.6mm of the laser fiber tip, in order that the distance between the laser fiber and the stone surface is 0.4mm in contact mode. We evaluated laser lithotripsy with this fiber in an in vitro model. We also evaluated its impact on flexible ureteroscope’s deflection and irrigation. Further, we evaluated if this fiber can be inserted in various fully deflected ureteroscopes and in case of a reduced diameter deflection. We also compared holmium cavitation bubbles of a standard fiber with a Soft-Tip fiber.


Results :

We found a significant mean difference of 15° for maximum upward and downward deflection loss, in favor of the Soft Tip fiber. The mean difference for irrigation loss was 1.4 ml/min. Passage of both fibers was feasible for all URSs, except for the SoftTip fiber in a reduced-diameter deflected Boa Vision and for all trials with Pusen ureteroscope. However, passage of worn SoftTip fiber through a reduced-diameter deflected URS resulted in fiber breakage within the stand-off jacket. In case of absence of a stone, we noticed no difference for various pulse durations and energies. In presence of a stone, the formation of a cavitation bubble was more pronounced for the standard fiber at 0.4 mm, compared to the Soft Tip fiber in contact mode. After laser lithotripsy of 10000 J, we noticed a shortening of the stand-off jacket of 0.1mm. However, the distance between the laser fiber tip and the jacket remained 0.4mm.


Conclusions :

Initial experiences with the Soft Tip Stand-Off Jacket laser fiber are promising. When the stand-off jacket is in contact with the stone surface, less pulse energy may be consumed for the cavitation effect and a greater amount of pulse energy may remain for ablation. SoftTip fibers had a smaller impact on deflection and irrigation compared to a standard fiber. The stand-off distance between the laser fiber tip and jacket seemed to remain unaltered after lithotripsy. However, further improvement is necessary since SoftTip wear may result in unrecognized fiber breakage within the stand-off jacket, which is of concern because the jacket cannot be cleaved.

Vincent De Coninck

Urologist
AZ Klina
Brasschaat, Antwerpen, Belgium

Vincent De Coninck graduated as a medical doctor from the Free University of Brussels, Belgium (VUB) in 2011. He became a certified urologist in 2017 after a training at the University Hospital of Brussels (Prof. Dr. Dirk Michielsen) and OLV Aalst (Prof. Dr. Alex Mottrie), where he developed a special interest in the minimal invasive treatment of benign and malignant pathologies. In the same year, he became Fellow of the European Board of Urology.
In 2018, he completed a one-year fellowship program of the Endourological Society in Paris, France under the supervision of Prof. Dr. Olivier Traxer. During that fellowship, he also obtained a diploma in urolithiasis, organized by Dr. Michel Daudon at the Sorbonne University in Paris, France. Afterwards, he was trained in HoLEP by Dr. Karin Lehrich in Berlin, Germany.
Currently, he is completing a three-month fellowship under the supervision of Dr. Guido Giusti in Milan, Italy. In December 2018, he will start working as an endourologist in AZ Klina, Brasschaat, Belgium. He will focus on the medical and surgical treatment of kidney stones and benign prostatic obstruction (HoLEP) and he will continue publishing articles relating to the management of patients with renal stone disease.

Etienne X. Keller

Fellow of the ES
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France

Paul H.L. Chiron

MD, FEBU
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Saint Mandé, Ile-de-France, France

Steeve S. Doizi

Urologist
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France

Laurent L. Berthe

Paris, Ile-de-France, France

Olivier O. Traxer

Professor
Sorbonne Universite, GRC n020 Lithiase Renale, AP-HP, Hospital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France