Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy

World Journal of Urology https://doi.org/10.1007/s00345-020-03481-9 TOPIC PAPER Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy Søren Kissow Lildal1 · Kim Hovgaard Andreassen2 · Joyce Baard3 · Marianne Brehmer4,5 · Matthew Bultitude6 · Ylva Eriksson4,5 · Khurshid R. Ghani7 · Helene Jung8 · Guido Kamphuis3 · Peter Kronenberg9 · Ben Turney10 · Olivier Traxer11 · Øyvind Ulvik12 · Palle Jörn Sloth Osther8 Received: 22 August 2020 / Accepted: 1 October 2020 © The Author(s) 2020 Abstract Purpose To summarize current knowledge on intracorporeal laser lithotripsy in flexible ureterorenoscopy (fURS), regarding basics of laser lithotripsy, technical aspects, stone clearance, lithotripsy strategies, laser technologies, endoscopes, and safety. Methods A scoping review approach was applied to search literature in PubMed, EMBASE, and Web of Science. Consensus was reached through discussions at the Consultation on Kidney Stones held in September 2019 in Copenhagen, Denmark. Results and conclusions Lasers are widely used for lithotripsy during fURS. The Holmium laser is still the predominant technology, and specific settings for dusting and fragmenting have evolved, which has expanded the role of fURS in stone management. Pulse modulation can increase stone ablation efficacy, possibly by minimizing stone retropulsion. Thulium fibre laser was recently introduced, and this technology may improve laser lithotripsy efficiency. Small fibres give better irrigation, accessibility, and efficiency. To achieve optimal results, laser settings should be adjusted for the individual stone. There is no consensus whether the fragmentation and basketing strategy is preferable to the dusting strategy for increasing stone-free rate. On the contrary, different stone scenarios call for different lithotripsy approaches. Furthermore, for large stone burdens, all laser settings and lithotripsy strategies must be applied to achieve optimal results. Technology for removing dust from the kidney should be in focus in future research and development. Safety concerns about fURS laser lithotripsy include high intrarenal pressures and temperatures, and measures to reduce both those aspects must be taken to avoid complications. Technology to control these parameters should be targeted in further studies. Keywords Laser lithotripsy · Ureteroscopy · Kidney stones · Endoscopes · Safety · Technology * Palle Jörn Sloth Osther 7 Department of Urology, University of Michigan, Ann Arbor, MI, USA 8 Department of Urology, Urological Research Center, Lillebaelt Hospital, University of Southern Denmark, Vejle, Denmark 1 Department of Urology, Aarhus University Hospital, Aarhus, Denmark 2 Department of Urology, Herlev‑Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark 9 3 Department of Urology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Department of Urology, Hospital CUF Descobertas, Lisbon, Portugal 10 4 Department of Surgery and Urology, Danderyd University Hospital, Stockholm, Sweden Department of Urology, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, UK 11 Department of Urology, Tenon Hospital, Paris, France 12 Department of Urology, Haukeland University Hospital, Bergen, Norway 5 Department of Clinical Sciences, Karolinska Institutet, Stockholm, Sweden 6 Urology Centre and Stone Unit, Guy’s and St. Thomas’ NHS Foundation Trust, London, UK 13 Vol.:(0123456789) World Journal of Urology Introduction Flexible ureterorenoscopy (fURS) has evolved as one of the major modalities for upper urinary tract stone management. This development is largely the result of continuing advancements in laser technology for intracorporeal lithotripsy, which is the focus of this review. Most daily clinical practices in the field of kidney stones, including lithotripsy techniques, are not supported by randomized trials and metaanalyses. This is not due to low research activity in this area, but rather to difficulties in designing meaningful trials that reflect daily clinical practice, because stone disease is so diverse. In this context, it is particularly important for practising experts to share their knowledge on clinical applications. The concept of the meeting “Consultation on Kidney Stones”, on which this review is based, was to create a forum for transfer and development of clinical expertise. Methods To evaluate lithotripsy in fURS regarding the balance between existing evidence, expert opinions, and safety and efficacy of new technological improvements, key opinion leaders in the field were invited to assess and discuss existing evidence at the 2-day meeting entitled “Consultation on Kidney Stones: Aspects of Intracorporeal Lithotripsy” held in Copenhagen, Denmark, in September 2019. The participating experts were assigned different topics and prepared presentations according to scoping reviews using PubMed, EMBASE, and Web of Science to search the literature. The first day of the meeting was open only to the experts, who individually presented their topics, which were then discussed by the whole group. The presentations were subsequently adjusted if necessary. The second day was an open meeting at which all presentations were given to an international audience, and this was followed by free discussions. lithotripsy [5]. Comparison of total fragmentation volume indicated little difference between fibres except at very low pulse energies (0.2 J), at which small fibres were more efficient [4]. These observations suggest that smaller fibres provide the following: better irrigation and thus improved visibility; better deflection and hence increased accessibility; and less retropulsion and thus higher ablation efficiency, and also an overall reduction in operating time [2, 6]. Laser fibre tips Laser fibres can have a standard flat tip or a polished or ballshaped tip. The ball-tip fibre is designed to reduce damaging friction forces generated within the working channel of the ureteroscope. It has been shown that this type of fibre can be safely passed through a deflected ureteroscope without causing liner perforation. The same advantage can be achieved by cleaving a standard fibre in such a manner that the coating protects the scope from the laser core [7]. Flat-tip fibres require greater insertion force at all angles and therefore can cause the ureteroscope liner to leak if it is deflected 45°or more [8]. An in vitro study comparing lithotripsy performance of different types of laser fibres found that the standard fibre functioned just as well as specially designed fibres [9]. Kronenberg et al. [10] noted that, compared to fibres stripped off the coating material, coated fibres achieved significantly higher ablation volumes, and there was no difference in performance between coated fibres cleaved with metal or ceramic scissors. However, Aldoukhi et al. [11] observed that single-use fi (...truncated)