SWL literature
SWL Literature

Yoon JH. et al., 2021: Outcomes of extracorporeal shock wave lithotripsy for ureteral stones according to ESWL intensity

Yoon JH, Park S, Kim SC, Park S, Moon KH, Cheon SH, Kwon T.
Department of Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.

Abstract

Background: We evaluated the treatment outcomes of ureteral stones according to energy intensity generated by extracorporeal shock wave lithotripsy (ESWL).

Methods: We retrospectively analyzed 150 patients who underwent ESWL for treatment of ureteral stones between September 2018 and February 2020. All stones were confirmed by a computed tomography examination, and the size, location, skin-to-stone distance, and Hounsfield units (HU) of the stones were assessed. In addition, patient characteristics including body mass index and estimated glomerular filtration rate, which can affect treatment outcome, were also evaluated. The success or failure of ESWL was confirmed according to the session, and the factors affecting the treatment outcome were analyzed using a logistic regression model.

Results: Of the 150 patients, 82 (54.7%) had stones in the proximal ureter, 5 (3.3%) in the mid, and 63 (42.0%) in the distal ureter. Patients underwent ESWL an average of 1.5 times, and the success rate according to session was 65.3% for the first, 83.3% for the second, and 90.0% for the third session. A multivariate analysis revealed that stone size [odds ratio (OR) 0.81, 95% confidence interval (CI), 0.66-0.99, P=0.049] and HU (OR 0.99, 95% CI, 0.98-0.99, P=0.001) were significant factors affecting the success rate after the first ESWL session; ESWL intensity was not related to success rate. Stone size (OR 0.78, 95% CI, 0.62-0.96, P=0.022) was the only significant factor affecting the success rate in the third session.

Conclusions: Stone size and HU affected the ESWL success rate. ESWL intensity was not significantly related to the success rate, so it should be adjusted according to patient pain and the degree of stone fragmentation.
Transl Androl Urol. 2021 Apr;10(4):1588-1595. doi: 10.21037/tau-20-1397. PMID: 33968647. FREE ARTICLE

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Comments 1

Hans-Göran Tiselius on Monday, September 06 2021 08:30

The authors of this article studied and discussed the influence of SWL intensity on stone disintegration. Their conclusion was that stone size and HU were determinants for successful stone treatment, but shockwave intensity was not.

It is of note that experimental studies clearly have shown that with high energy levels, stone fragments are larger than when low energy levels are applied, provided a certain energy threshold is passed. Most patients were treated with an average energy flux density of 0.28 mJ/mm2. It is surprising that all treatments were carried out without analgesics.

It is problematic to draw definite conclusions from this report regarding the importance of energy intensity because energy levels were determined by the patients’ pain experience and with a better analgesic regimen the result might have been different.
The mean number of sessions was 1.48 and it is not known how many of the re-treated patients that had benefitted from shockwaves with higher energy density.

Hans-Göran Tiselius

The authors of this article studied and discussed the influence of SWL intensity on stone disintegration. Their conclusion was that stone size and HU were determinants for successful stone treatment, but shockwave intensity was not. It is of note that experimental studies clearly have shown that with high energy levels, stone fragments are larger than when low energy levels are applied, provided a certain energy threshold is passed. Most patients were treated with an average energy flux density of 0.28 mJ/mm2. It is surprising that all treatments were carried out without analgesics. It is problematic to draw definite conclusions from this report regarding the importance of energy intensity because energy levels were determined by the patients’ pain experience and with a better analgesic regimen the result might have been different. The mean number of sessions was 1.48 and it is not known how many of the re-treated patients that had benefitted from shockwaves with higher energy density. Hans-Göran Tiselius
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Sunday, December 05 2021

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