Badar M. Mian, MD, discusses a recent study about the use of external physical vibration lithecbole for treating residual stones after retrograde intrarenal surgery.
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External physical vibration lithecbole (EPVL) may be the ideal adjunct to retrograde ureteroscopic treatment of renal stones in trying to render patients free of stone fragments.
This is based on a prospective, randomized, controlled trial performed at eight different centers in China that demonstrated a 51% increase in the stone-free rate by week 5. The findings were published in the Journal of Urology (2017; 197:1289-95).
Several hundred thousand extracorporeal shock wave lithotripsy (ESWL) and ureteroscopic stone extraction procedures are performed each year in the United States. Depending upon the size, location, and composition of the original stone, residual fragments may be noted in as many as 50% of the patients and are a major risk factor for stone recurrence and stone growth. Residual stone fragments cause infection, pain, renal dysfunction, ER visits, and secondary procedures. Clearly, the removal of residual fragments is a major challenge in kidney stone management.
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In this study, Wu et al randomized 173 patients (128 men, 45 women) with residual stone fragments <4 mm in size, 1 week after ureteroscopy, including 87 patients who underwent EPVL and 86 patients who served as controls. Both groups were advised to increase their hydration and activity level, and to use inversion therapy in case of lower pole fragments.
The EPVL apparatus includes a table with a built-in oscillator (with adjustable frequency and magnitude of the vibration) that can be tilted. The second component is a handheld oscillator that can deliver multi-directional vibration of variable amplitude, frequency, and power. With the patients in supine or prone or lateral position, the fragment is repositioned with the help of multidirectional vibrations and is monitored real time with an ultrasound as it passes the ureter into the bladder. The entire procedure took about 20 minutes, and 41 patients (47%) required a second EPVL procedure if there were still some stones fragments noted by week 2.
There was a significant and sustained increase in the stone-free rates at weeks 2, 3, and 5 (based on KUB or US or computed tomography scan) between controls and the EPVL group at week 2: 31% versus 53%; week 3: 51% versus 71%; week 5: 59% versus 90%. Most of the benefit was noted in patients with lower pole, renal pelvis or with multiple fragments. There was no difference in stone-free rates for patients with upper or middle calyceal fragments, but the fragments were expelled earlier in the EPVL group.
In addition to the accelerated stone passage, the ongoing hematuria and urinary leukocytosis were lower in the EPVL group at week 3 and 5, presumably because there were fewer fragments left to cause these symptoms. The procedure requires no anesthesia as it is totally noninvasive and appears to be well tolerated as no side effects related to EPVL were reported.
Other studies have reported variable degree of success while using interventions such as inversion, activity, percussion, medications, and hydration. The current study appears to combine several of these measures into one and more importantly, EPVL appears to be an active intervention that monitors the propulsion of the fragments into the ureter/bladder during the procedure. These authors had previously reported similarly improved outcomes with use of EPVL after ESWL (J Urol 2015; 195:965).
While some questions remain about the use of imaging modality (KUB, US), the length of follow-up beyond 5 weeks, and any complications in the control group, this approach (once validated and externally reproducible) has the potential to significantly reduce the morbidity associated with upper tract stone management.