Optimization of Extracorporeal Shock Wave Lithotripsy Delivery Rates Achieves Excellent Outcomes for Ureteral Stones: Results of a Prospective Randomized Trial

2022 Recommendations of the AFU Lithiasis Committee: Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy (ESWL) is a minimally invasive technique for the fragmentation of urinary tract stones using shock waves under fluoroscopic and/or ultrasound guidance. ESWL results depend on the indication (stone size/composition, clinical context) and also on how it is performed. The stone structure, nature and density (Hounsfield units; evaluated by CT without contrast agent) influence the fragmentation achieved by ESWL. The upper size limit of kidney stones has been lowered to 15mm (1.68cm3) due to the increased risk of steinstrasse with larger sizes and the potential need of anesthesia and ureteral stenting. Conversely, the development of endourological technologies allows a finer stone fragmentation and/or better elimination, thus reducing the risk of steinstrasse and decreasing the potential number of sessions or additional interventions. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendations method (CPR) and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis [EAU 2022]) and their adaptability to the French context.

Shockwave Lithotripsy Complications According to Modified Clavien-Dindo Grading System. A Systematic Review and Meta-regression Analysis in a Sample of 115 Randomized Controlled Trials

CONTEXT

Shockwave lithotripsy (SWL) shows clear associated benefits for urolithiasis patients.

OBJECTIVE

To identify and classify SWL complications according to modified Clavien-Dindo grading system while assessing the effect of different patient characteristics, stone parameters, types of lithotripters, and lithotripsy techniques.

EVIDENCE ACQUISITION

Literature was reviewed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement.

EVIDENCE SYNTHESIS

We analyzed the results of 115 randomized trials including 17827 patients, of whom 16.06%, 2.07%, 2.23%, 1.32%, 0.85%, 0.16%, and 0% suffered from Clavien I, II, III, IIIa, IIIb, IV, and V complications, respectively. In total, 18.43% of patients suffered from Clavien I-II and 2.48% from Clavien III-IV complications. In studies with >100 treated patients, Clavien I, III, and IV complication rates and need for auxiliary procedure rates were lower than in studies with smaller sample size. Electrohydraulic lithotripters led to a higher rate of Clavien IIIb and IV complications than electromagnetic lithotripters. Clavien I-II complications were increased by 14.3% in patients with multiple and complicated stones. Hematuria was increased by 8.29% in patients who underwent intravenous urography preoperatively and had longer duration of SWL. Pain occurrence was increased by 14.79% in patients with more than one stone at the time of SWL and by 3.21% in those who were managed with a piezoelectric lithotripter.

CONCLUSIONS

SWL should not be considered an uneventful procedure, as in 2.5% of cases an intervention or Clavien III-V complication will be observed. Low-volume centers, treatment of multiple or complex stones, a long-lasting SWL session, and electrohydraulic lithotripters are associated with higher rates of complications.

PATIENT SUMMARY

We analyze the occurrence of shockwave lithotripsy (SWL) complications in 17000 patients. In centers with larger caseloads, complications were less common. The type of lithotripter is associated with complications. An increased number of treated stones, complex stones, and increased SWL duration were associated with a higher incidence of pain and hematuria.

A novel model using computed tomography parameters to predict shock wave lithotripsy success in ureteral stones at different locations

OBJECTIVE

To combine non-contrast computerized tomography (NCCT)-based parameters with stone and patient characteristics that are already known to affect shock wave lithotripsy (SWL) success and assess this novel model's effectiveness in predicting SWL success for single ureteral stones in different locations.

MATERIALS AND METHODS

Data of patients treated by SWL for a single ureteral stone between January 2017 and January 2019 were retrospectively reviewed. Demographic parameters of patients and stone characteristics were combined with NCCT-based parameters. NCCT-based parameters included the presence or absence of hydronephrosis, perinephric stranding, periureteral edema, diameter of the proximal ureter, ureteral wall thickness (UWT) at ureteral stone site. The logistic regression method was used for the development of a useful predictive model. Subsequently, the receiver operating curve was used to determine cut-off levels, and a scoring system was developed for prediction of SWL success.

RESULTS

Stone-free rate was 77,1% (267/346) in the entire cohort. Univariate analysis revealed that age, stone volume, density, perinephric stranding, diameter of proximal ureter, and UWT, were associated with SWL success. In multivariate analysis, proximal ureteral stone location, stone volume, density, and UWT were independent predictors of SWL success. The formula used during logistic regression analysis was: 1/[1 + exp {-8.856 + 0.008 (stone volume) + 0.002 (stone density) + 0.673 (UWT) + 1026 (proximal ureteral stone)}]. The scores of 0, 1, 2, 3 and 4 were associated with 97,8%, 83,4%, 60,8%, 33,2% and 11,1% success rates, respectively, in the prediction model based on these parameters.

CONCLUSION

We conclude that our model can facilitate decision-making for SWL treatment of ureteral stones in different locations.

Clinical application of the therapeutic ultrasound in urologic disease: Part II of the therapeutic ultrasound in urology

This article aimed to review the clinical application and evidence of the therapeutic ultrasound in detail for urological diseases such as prostate cancer, kidney tumor, erectile dysfunction, and urolithiasis. We searched for articles about high-intensity focused ultrasound (HIFU), extracorporeal shock wave therapy, ultrasound lithotripsy, and extracorporeal shockwave lithotripsy (ESWL) in the MEDLINE and Embase. HIFU may be indicated as a primary treatment for low- or intermediate-risk prostate cancer, and salvage therapy for local recurrence as a promising way to address the limitations of current standard therapies. The application of HIFU in treating kidney tumors has scarcely been reported with unsatisfactory results. Evidence indicates that low-intensity shockwave therapy improves subjective and objective erectile function in patients with erectile dysfunction. Regarding the application of ultrasound in stone management, the novel combination of ultrasound lithotripsy and other energy sources in a single probe promises to be a game-changer in efficiently disintegrating large kidney stones in percutaneous nephrolithotomy. ESWL is losing its role in managing upper urinary tract calculi worldwide. The burst-wave lithotripsy and ultrasound propulsion could be the new hope to regain its position in the lithotripsy field. According to our investigations and reviews, cavitation bubbles of the therapeutic ultrasound are actively being used in the field of urology. Although clinical evidence has been accumulated in urological diseases such as prostate cancer, kidney tumor, erectile dysfunction, and lithotripsy, further development is needed to be a game-changer in treating these diseases.

Which frequency is better for pediatric shock wave lithotripsy? Intermediate or low: a prospective randomized study

PURPOSE

Shock wave lithotripsy (SWL) is the first option in the treatment of pediatric kidney stones; however, optimal frequency is still uncertain. The aim of this study was to compare low frequency [60 shocks per minute (SWs/min)] and intermediate frequency [90 SWs/min] in terms of lithotripsy success, complications, cardiac arrhythmia, anesthesia time, secondary procedures, and efficiency quotient (EQ) in children.

METHODS

Seventy-eight consecutive children who received SWL for radiopaque renal stones between July 2016 and January 2020 were randomly divided into two groups: Group 60 (SWL frequency: 60 SWs/min) and Group 90 (SWL frequency: 90 SWs/min). After exclusion (remaining 71 children), Group 60 (n = 38) and Group 90 (n = 33) were compared using univariate analysis.

RESULTS

The median age of children (37 girls, 34 boys) was 5 (1-16) years. Patient demographics and stone features were similar between the groups. Success rate after the last SWL session was 81.6% (n = 31) for Group 60 and 87.9% (n = 29) for Group 90 (p = 0.527). Stone-free rate after the first, second, and third sessions was 42.1%, 18.4%, and 21.1% for Group 60 and 48.5%, 27.3%, and 12.1% for Group 90, respectively. Additional treatment rate was similar between the groups. In Group 60, the EQ was 57.83, and it was 64.07 in Group 90. Median total anesthesia time was significantly longer in Group 60 (74.5 min) than in Group 90 (32 min; p < 0.001).

CONCLUSION

Intermediate frequency and low-frequency pediatric SWL have similar success rates; however, intermediate-frequency SWL has a shorter anesthesia time.

The role of extracorporeal shock wave lithotripsy in the future of stone management

PURPOSE OF REVIEW

The most relevant recent findings on the use of extracorporeal shock wave lithotripsy (ESWL) in adult population to provide an insight of its role in the current and future of stone treatment. Comparing ESWL with other modalities is not in the scope of this review.

RECENT FINDINGS

We conducted a PubMed/Embase search and reviewed recent publications that include relevant information on the development of ESWL. Low-rate shock waves improve stone breakage, ramping energy modalities improve stone fragmentation and have lower incidence of hematoma and kidney injury. Transgluteal approach is suggested to improve stone-free rates for distal ureteral stones in a single session. Proper coupling is the most important technical aspect of the treatment and coupling improvement can be achieved by optical monitorization. Triple D score is a promising tool in proper patient selection, but external validation is needed. Predictive information arising from computed tomography scans has been refined by the variant coefficient of stone density and 3D texture analysis that might improve outcomes in the future.

SUMMARY

Recent evidence suggests that modifying techniques and protocols, and better patient selection are the current trends for improving ESWL outcomes. EWSL will keep its role as the single noninvasive treatment in stone management with room for outcome improvement in the future.

Dual-frequency setting for urinary stone fragmentation during shock wave lithotripsy: an in vitro study

Extracorporeal shock wave lithotripsy (SWL) is less invasive compared to the other invasive modalities of stone treatment that are gaining popularity. Hence, methods to improve the efficacy of SWL are desirable. We studied the effectiveness of dual frequency on the efficacy of stone fragmentation, but minimizing treatment time. A phantom 10 mm spherical BegoStone was fragmented in vitro in a kidney model using an electromagnetic lithotripter (Storz MODULITH^®SLX-F2). A total of 78 stones were fragmented each with 3000 shocks at 60 Hz or 120 Hz or a dual frequency (DF) of 60-120 Hz. For the DF setting, the first 1000 shocks were delivered at 60 Hz and the next 2000 at 120 Hz. Total weight and number of significant fragments of > 3 mm (TWSF and TNSF, respectively) and also > 2 mm was measured. Results: The mean TWSF was 0.1, 0.16, and 0.08 g for 60 Hz, 120 Hz, and DF 60-120 Hz, respectively. The TWSF of DF 60-120 Hz was significantly lower than that of 120 Hz (p = 0.02), but same as the 60 Hz (p = 0.32). The mean TNSF of > 3 mm was 2.6, 3.0, and 2.0 for 60 Hz, 120 Hz, and DF 60-120 Hz, respectively, without significant differences between each setting. However, increasing trend of TWSF, TW2 mm and TN2 mm was seen in the order of DF, 60 Hz and 120 Hz (p = 0.019, p = 0.004 and 0.017, respectively). Treatment time for 60 Hz, 120 Hz, and DF 60-120 Hz was 50, 25, and 34 min, respectively. Dual-frequency setting produced effective stone fragmentation compared to the recommended 60 Hz, while decreasing treatment time. DF variation is one other factor that may be tailored for effective stone comminution and needs clinical evaluation.

Clinical use of renal point-of-care ultrasound after extracorporeal shock wave lithotripsy

Background

Extracorporeal shock wave lithotripsy is widely used to treat symptomatic nephrolithiasis. Complications of this procedure can occur and point-of-care ultrasound can help to diagnose and manage some of these cases.

Case presentation

A 61-year-old man was admitted to the hospital with intense right lumbar pain 24 h after being submitted to a extracorporeal shock wave lithotripsy. Bedside ultrasound showed a hyperechoic subcapsular lesion along the right kidney. This finding, along with the clinical examination, suggested the diagnosis of subcapsular renal hematoma. The patient was managed conservatively with clinical and ultrasound reassessments.

Conclusions

This case shows the use of bedside ultrasound to diagnose a subcapsular renal hematoma as a complication of extracorporeal shock wave lithotripsy. However, the sensitivity is low and other image methods can be necessary to make the diagnosis.

Can intervals in extracorporeal shock wave lithotripsy sessions affect success in the treatment of upper ureteral stones?

Introduction

Managing upper ureteral stones with shock wave lithotripsy (SWL) has been done for many years. However, no conclusive data have been found on the intervals required between repeated SWL sessions.

Aim

To identify the most optimal intervals between SWL sessions.

Material and methods

Between September 2015 and December 2016, 80 patients undergoing elective outpatient lithotripsy who required repeated SWL sessions for ureteral stones were evaluated. These patients were categorised into two groups according to different SWL session intervals. The intervals between SWL sessions (n = 40) for the first group lasted one day, whereas those for the second group (n = 40) lasted 1 week. The data recorded during SWL included visual analogue scale (VAS) scores, total number of shocks, total energy used and number of sessions. The stone clearance rates, number of urinary tract infections, complication rates and VAS scores were compared between the two groups.

Results

All patients’ clinical outcomes after SWL therapy are shown in Table I. The stone clearance rate for group 1 was 70%, whereas that for group 2 was 72.5% (p = 0.805). Additionally, the number of urinary tract infections, complications and VAS scores were similar for both groups. In group 1, 3 patients had steinstrasse, two suffered from severe renal colic, and one had a urinary tract infection. In group 2, 3 patients endured steinstrasse, and 2 patients experienced severe renal colic during the study.

Conclusions

Short-interval SWL sessions are safe and effective for treating upper ureteral stones, and such sessions do not increase complication rates.

Numerical study of a confocal ultrasonic setup for cavitation creation

Acoustic cavitation has found a wide range of applications in the last few decades. For potential applications involving cavitation, the acoustic characteristics of a confocal ultrasonic setup are studied: two high-intensity focused ultrasound transducers are mounted so that their focal points overlap. A mathematical simulator is developed that takes into account nonlinear propagation, absorption, and diffraction. Each one of these physical effects is solved in the frequency domain for successive planes. Comparing the confocal setup with equivalent single transducer setups, it is shown that, with the confocal configuration, nonlinear distortion of the waveform is reduced, resulting in a greater peak rarefactional pressure and a lower peak positive pressure. Furthermore, additional features are investigated for confocal configurations such as a greater spatial stability for the focal point, which can be maintained while increasing the pressure level, and a focal region consisting of interference acting as an acoustic trap.

Ureteral stenting can be a negative predictor for successful outcome following shock wave lithotripsy in patients with ureteral stones

Purpose

To evaluate ureteral stenting as a negative predictive factor influencing ureteral stone clearance and to estimate the probability of one-session success in shock wave lithotripsy (SWL) patients with a ureteral stone.

Materials and Methods

We retrospectively reviewed the medical records of 1,651 patients who underwent their first SWL. Among these patients, 680 had a ureteral stone measuring 4–20 mm and were thus eligible for our study. The 57 patients who underwent ureteral stenting during SWL were identified. Maximal stone length (MSL), mean stone density (MSD), skin-to-stone distance (SSD), and stone heterogeneity index (SHI) were determined by pre-SWL noncontrast computed tomography.

Results

After propensity score matching, 399 patients were extracted from the total patient cohort. There were no significant differences between stenting and stentless groups after matching, except for a higher one-session success rate in the stentless group (78.6% vs. 49.1%, p=0.026). In multivariate analysis, shorter MSL, lower MSD, higher SHI, and absence of a stent were positive predictors for one-session success in patients who underwent SWL. Using cutoff values of MSL and MSD obtained from receiver operator curve analysis, in patients with a lower MSD (≤784 HU), the success rate was lower in those with a stent (61.1%) than in those without (83.5%) (p=0.001). However, in patients with a higher MSL (>10 mm), the success rate was lower in those with a stent (23.6%) than in those without (52.2%) (p=0.002).

Conclusions

Ureteral stenting during SWL was a negative predictor of one-session success in patients with a ureteral stone.

Comparison of High, Intermediate, and Low Frequency Shock Wave Lithotripsy for Urinary Tract Stone Disease: Systematic Review and Network Meta-Analysis

OBJECTIVES

To perform a systematic review and network meta-analysis of randomized controlled trials (RCTs) to determine the optimal shock wave lithotripsy (SWL) frequency range for treating urinary stones, i.e., high-frequency (100-120 waves/minute), intermediate-frequency (80-90 waves/minute), and low-frequency (60-70 waves/minute) lithotripsy.

MATERIALS AND METHODS

Relevant RCTs were identified from electronic databases for meta-analysis of SWL success and complication rates. Using pairwise and network meta-analyses, comparisons were made by qualitative and quantitative syntheses. Outcome variables are provided as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Thirteen articles were included in the qualitative and quantitative synthesis using pairwise and network meta-analyses. On pairwise meta-analyses, comparable inter-study heterogeneity was observed for the success rate. On network meta-analyses, the success rates of low- (OR 2.2; 95% CI 1.5-2.6) and intermediate-frequency SWL (OR 2.5; 95% CI 1.3-4.6) were higher than high-frequency SWL. Forest plots from the network meta-analysis showed no significant differences in the success rate between low-frequency SWL versus intermediate-frequency SWL (OR 0.87; 95% CI 0.51-1.7). There were no differences in complication rate across different SWL frequency ranges. By rank-probability testing, intermediate-frequency SWL was ranked highest for success rate, followed by low-frequency and high-frequency SWL. Low-frequency SWL was also ranked highest for low complication rate, with high- and intermediate-frequency SWL ranked lower.

CONCLUSIONS

Intermediate- and low-frequency SWL have better treatment outcomes than high-frequency SWL when considering both efficacy and complication.