Ng et al, 2012: A prospective, randomized study of the clinical effects of shock wave delivery for unilateral kidney stones: 60 versus 120 shocks per minute
Ng CF, Lo AK, Lee KW, Wong KT, Chung WY, Gohel D
Division of Urology, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, People's Republic of China
PURPOSE: We assessed the effects of different shock wave delivery rates in patients treated with shock wave lithotripsy for renal stones, particularly treatment success, degree of renal injury and pain experienced, and analgesic demand.
MATERIALS AND METHODS: A total of 206 patients with renal stones were prospectively randomized to receive shock waves delivered at 60 (group 1) or 120 (group 2) shocks per minute using a Sonolith® Vision at a single institution in October 2008 and August 2010. The primary outcome was successful treatment 12 weeks after 1 lithotripsy session. Secondary outcome measures included the degree of renal injury, as reflected by changes in urinary markers of renal injury, as well as patient pain scores and analgesia consumed during treatment.
RESULTS: Mean stone size in groups 1 and 2 was 8.95 and 9.28 mm, respectively (p = 0.525). The overall treatment success rate was 43.2%. It was significantly better in group 1 than in group 2 (50.5% vs 35.9%, p = 0.035). There was no between group difference in the success rate for stones 10 mm or less but the success rate was statistically better for group 1 patients with stones greater than 10 mm (p = 0.002). Immediately after shock wave lithotripsy there was a statistically significant greater increase in urinary NAG (p = 0.003) and interleukin-18 (p = 0.022) in group 1. There was no between group difference in pain scores, analgesic consumption during shock wave lithotripsy or unplanned hospital visits.
CONCLUSIONS: Slower shock wave delivery yielded better treatment outcomes, particularly for stones greater than 10 mm, without increasing patient pain or analgesic demand. However, slower shock wave delivery also appeared to cause a statistically significant increase in acute renal injury markers, although the clinical implication was uncertain.
Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
J Urol. 2012 Sep;188(3):837-42. doi: 10.1016/j.juro.2012.05.009. Epub 2012 Jul 20
PMID: 22819406 [PubMed - indexed for MEDLINE]
This paper contributes to the conflicting data of animal experiments and clinical experience but raises a lot of questions. The treatment was done in two different time periods.
Where the cases equally distributed in 2008 and 2010? Was the quality of the operators identical? Were the treatment protocols identical? Was ramping used? How did the higher fluoroscopy time in group 1add to the better results? What do increased urinary marker levels signal? Are similar results to be expected with other lithotripters?
Some results of the study may turn out to be important if the questions are answered by other studies. But at present the conclusion is difficult to justify: “ slower shock wave delivery should be considered in patients with greater than 10 mm stones but not in patients with smaller stones.”