Piezoelectric lithotripsy of ureteral stones: Influence of shockwave frequency on sedation and therapeutic efficiency

Objective: The aim of this randomized study was to assess the relation betw een shockwave frequency, sedation, and efficiency in piezoelectric extracor poreal shockwave lithotripsy (SWL) for ureteral calculi. Methods: A random sample of 114 patients aged between 15 and 74 (mean 45) y ears were treated at the shockwave frequencies of 1 (N = 57) or 4 (N = 57) per second using the EDAP LT 02 lithotripter at maximum energy. The stones' largest diameter ranged from 5 to 18 mm (mean 7.6 mm). Lower ureteral ston es were treated with the patient in the prone position and upper ureteral s tones in supine position. The duration of SWL sessions and stone measuremen ts were statistically similar for patients treated at low and high frequenc ies. The levels of required sedation (none, intramuscular analgesia, intrav enous sedation-analgesia) and stone-free rates after one session were analy zed by Student's t-test or Fisher's exact test. Results: Sedation did not differ statistically with SWL frequency for mid a nd lower ureteral calculi. However, the use of intravenous sedation-analges ia was less common for patients with upper ureteral stones treated at low r ather than high frequency (19% and 100%, respectively; P < 0.0001), The suc cess rate was significantly lower (P = 0.04) for lower ureteral calculi tre ated at low v high frequency (65% and 89%, respectively) but was not statis tically affected by frequency for upper ureteral stones. Conclusion: We recommend high frequency for piezoelectric SWL of lower uret eral calculi, especially for stones with a maximum diameter greater than or equal to 8 mm. On the other hand, low-frequency SWL appears to be suitable for the treatment of upper ureteral stones.