Evolution of extracorporeal shockwave lithotripsy (ESWL)

Abstract

Much has changed since the introduction of extracorporeal shockwave lithotripsy (ESWL); however, in many ways the principles remain constant. This manuscript by Jagtap et al. [1] is a large series of patients over 25 years and encapsulates the changes in ESWL over that time. This paper has all the limitations inherent in a retrospective review but within this offers interesting data. In particular the use of two different machines and refinements in technique are eloquently described. This shows an improvement due to both the change in technology but also in the importance of modifications of technique. The particular factors improving stone-free rate (SFR) were; better localisation with ultrasonography and X-ray, better coupling and use of coupling gel, change in selection criteria for both the patient and stone, ramping up the power and a staff training programme. This emphasis on technique is especially pertinent in healthcare systems where mobile lithotripters are still in use. These are renowned to have lower SFRs than static machines, which may be due to the technical delivery of treatment as much as the efficacy of the lithotripter.What is the future for ESWL? The paper reflects the perception globally that whilst the incidence of urolithiasis is increasing, the use of ESWL is not increasing at the same rate, particularly for ureteric stones, and they cite the potential factors for this. This has also been noted in the UK and our own recent review of Hospital Episode Statistics (HES) data even suggest the rate of ESWL has plateaued for both ureteric (3000/year) and renal (19 500/year) stones in the last 3 years [2,3]. There has been discussion within the UK about centralising endourology services using the same model as for cancer, with provision of static lithotripters within those centres. This would potentially have the advantage of creating high-volume centres with quality being easier to standardise and monitor; however, this would have to be balanced against patients probably having to travel further to access ESWL. The use of Hounsfield units remains a topic of debate with conflicting data and limited clinical application [4,5]. Optimising targeting to minimise tissue damage with maximal stone fragmentation remains a challenge and modifications to lithotripters with dual-imaging modalities, dual heads, alterations in shockwave delivery rate, control of respiratory effort and novel feedback devices have had limited success. Increasing levels of obesity within developed countries are a factor in the utilisation of ESWL, as there is a limit on focal distance. All of these factors along with the continued improvement in the optics, miniaturisation of ureteroscopes and advent of holmium laser have contributed to a surge in the use of ureteroscopy, despite publications and guidelines showing similar success rates [6].

Shock wave lithotripsy (SWL): outcomes from a national SWL database in New Zealand

“…The European Association of Urology (EAU) guidelines recommend SWL as the first line management option for proximal ureteral stones <10mm, and an equivalent first line option to endourology for renal stones <20mm, proximal ureteral stones >10mm and distal ureteral stones <10mm [7]. In spite of this, reports indicate that the rate of SWL use has plateaued or decreased in recent years alongside a surge in the use of ureteroscopy with the holmium laser [8][9][10][11], and despite evidence suggesting similar success rates between management options [7]. The current evidence examining the use of SWL demonstrates wide variation in clinical outcomes, with overall stone free rates (SFRs) ranging from 40.2% to 96.8%, and is limited to studies reporting small cohorts or in which multiple models of SWL machine has been used [12].…”

Reduction of pre-procedural anxiety for repeat sessions in extracorporeal shockwave lithotripsy (ESWL) reduces pain intensity: A prospective observational study

“…Extra-corporal shockwave lithotripsy (ESWL) has revolutionized management of renal and ureteric calculi since its introduction. [ 4 ] ESWL is popular with patients because it is non-invasive, and it is an “office” procedure. However, ESWL requires more sessions to achieve stone clearance and might have a higher overall cumulative cost of treatment when compared to other methods of treatment such as ureterorenoscopy (URS).…”

Insights into the mechanism of a novel shockwave-assisted needle-free drug delivery device driven by in situ-generated oxyhydrogen mixture which provides efficient protection against mycobacterial infections

“…The emerging paradigms of present day shock wave research have opened up new horizons for interdisciplinary applications [ 10 ]. Shockwaves have been extensively used for various medical procedures like extracorporeal lithotripsy [ 11 ], treatment of avascular necrosis [ 12 ], accelerated bone fracture healing [ 13 ], angiogenesis [ 14 ] and tendinitis [ 15 ]. The use of shockwaves as a driving force for transdermal drug delivery has proved to be effective because of their ability to accelerate the drug particles to high velocities so that they can penetrate the skin [ 16 – 21 ].Shockwaves have also been demonstrated to generate high velocity projectiles for delivering nucleic acids into living cells [ 22 – 25 ].…”