Shock Wave Lithotripsy: A Randomized, Double-blind Trial to Compare Immediate Versus Delayed Voltage Escalation

Comparison of treatment outcomes according to output voltage during shockwave lithotripsy for ureteral calculi: a prospective randomized multicenter study

“…Second, because rapid symptom relief and ureteral decompression were our treatment policy for UC, patients were evaluated at 1 week after SWL (much earlier than previous studies on renal calculi). Finally, SWL was performed at 2 Hz, which is similar to the study of Honey et al [12]. Meanwhile, previous studies [7][8][9][10][11] favoring voltage escalation used 1 Hz.…”

“…A previous study of Korean patients reported no significant difference in SFRs according to output voltage [13]. Although the reason for negative results in the two aforementioned studies [12,13] remains unclear, different study protocols, including voltage setting, shockwave numbers at low voltage, and frequency, may have contribute to conflicting results among the studies [7][8][9][10][11][12][13].…”

“…Thus, increasing power may be effective in constant stone fragmentation to compensate for screening effects caused by fine fragments which scatter and attenuate subsequent shockwaves [8][9][10][11], and reinforce cavitation bubble formation which is the main mechanism of stone disintegration at later stages of SWL [20,21]. However, Honey et al [12] reported negative results from 160 patients with renal calculi. In their study [12], the immediate voltage escalation SWL group (i.e., immediate voltage escalation from 14 to 23 kV) had a significantly higher overall success rate at 3 months after a single SWL than the delayed voltage escalation SWL group (i.e., 1,500 shocks at 15 kV followed by delayed voltage escalation to 23 kV) (72.5 vs. 54.5 %, p = 0.021).…”

“…However, Honey et al [12] reported negative results from 160 patients with renal calculi. In their study [12], the immediate voltage escalation SWL group (i.e., immediate voltage escalation from 14 to 23 kV) had a significantly higher overall success rate at 3 months after a single SWL than the delayed voltage escalation SWL group (i.e., 1,500 shocks at 15 kV followed by delayed voltage escalation to 23 kV) (72.5 vs. 54.5 %, p = 0.021). Although their study was based on one-time voltage escalation but not gradual voltage escalation, it suggested that voltage escalation may be inferior to conventional fixed voltage.…”

“…In vitro [7,8], animal [9], and two clinical trials [10,11] have shown better success rates using escalating voltage, compared to fixed voltage. In contrast, other randomized clinical trials showed no difference in treatment outcomes between fixed and escalating voltage [12,13]. The majority of subjects enrolled in the abovementioned studies were patients with renal calculi.…”