Effect of Escalating Versus Fixed Voltage Treatment on Stone Comminution and Renal Injury During Extracorporeal Shock Wave Lithotripsy: A Prospective Randomized Trial

Risk factors of hematoma after SWL for renal calculi: analysis from RCTs and a literature review

OBJECTIVE

To identify risk factors of perinephric hematoma following extracorporeal shockwave lithotripsy (SWL) for renal calculi through combined analysis of two randomized controlled trials.

PATIENTS AND METHODS

This post-hoc analysis included adult patients with solitary renal calculi ranging from 5 to 15 mm, treated with SWL between 2016 and 2022. All patients received cross-sectional imaging (either non-contrast computer tomography scan or magnetic resonance imaging) two days post-SWL to assess the presence and severity of perinephric hematoma.

RESULTS

Among 573 patients analyzed, 173 (30.9%) developed perinephric hematoma by Day 2 post-SWL. Multivariate logistic regression identified higher total energy delivered (odds ratio [OR] = 1.533, p = 0.003), higher mean stone density (OR = 2.603, p = 0.01), higher maximal stone density (OR = 3.578, p = 0.03), and lower pole stone location (OR = 1.545, p = 0.029) were risk factors for the development of hematoma. Conversely, the stepwise ramping protocol was a protective factor for hematoma formation. (OR = 0.572, p = 0.042).

CONCLUSIONS

This study elucidates key factors influencing the risk of perinephric hematoma post-SWL, highlighting the importance of procedural adjustments such as the stepwise ramping protocol to reduce complications. These insights call for targeted patient and treatment strategy optimization to enhance SWL safety and efficacy.

Predictors of success following extracorporeal shock-wave lithotripsy in a contemporary cohort

OBJECTIVES

The objectives of this study are to determine the predictors of success following extracorporeal shock-wave lithotripsy (ESWL) in a contemporary cohort at a high-volume stone center.

METHODS

We conducted a retrospective review all patients who underwent an elective ESWL within our institution over a 24-month period (January 2014 to December 2015). Data on patient demographics, stone variables, and inpatient treatment outcomes were evaluated.The presence of residual stone fragments larger than 4 mm on follow-up imaging was considered to be treatment failure. Using this threshold, clinically relevant variables between the treatment success and failure groups were identified. Multivariable logistic regression analyses (MVA) of clinically relevant variables were used to determine the independent factors predicting ESWL success.

RESULTS

Of 446 study eligible patients, 421 patients had complete follow-up data and were included in the analysis. Treatment was successful in 72.2% of patients in this study. Stone size, number of shocks delivered, and maximum treatment intensity were statistically different in the two groups. In a MVA where stone size, location, density, presence of ureteric stent, skin-stone distance (SSD), number of shocks, and maximum shock intensity were included, only stone size of <10 mm (odds ratio [OR] 3.4 [95% confidence interval [CI]: 1.98-5.84]) and SSD <15 cm (OR: 0.133, [95% CI: 0.027-0.65]) were the independent predictor of ESWL success.

CONCLUSION

We have demonstrated "real world" outcomes with high-volume use of ESWL. In our experience that with diligent patient selection, ESWL remains an effective tool for the management of upper tract calculi.

Automated Generation of Personalized Shock Wave Lithotripsy Protocols: Treatment Planning Using Deep Learning

Background

Though shock wave lithotripsy (SWL) has developed to be one of the most common treatment approaches for nephrolithiasis in recent decades, its treatment planning is often a trial-and-error process based on physicians’ subjective judgement. Physicians’ inexperience with this modality can lead to low-quality treatment and unnecessary risks to patients.

Objective

To improve the quality and consistency of shock wave lithotripsy treatment, we aimed to develop a deep learning model for generating the next treatment step by previous steps and preoperative patient characteristics and to produce personalized SWL treatment plans in a step-by-step protocol based on the deep learning model.

Methods

We developed a deep learning model to generate the optimal power level, shock rate, and number of shocks in the next step, given previous treatment steps encoded by long short-term memory neural networks and preoperative patient characteristics. We constructed a next-step data set (N=8583) from top practices of renal SWL treatments recorded in the International Stone Registry. Then, we trained the deep learning model and baseline models (linear regression, logistic regression, random forest, and support vector machine) with 90% of the samples and validated them with the remaining samples.

Results

The deep learning models for generating the next treatment steps outperformed the baseline models (accuracy = 98.8%, F1 = 98.0% for power levels; accuracy = 98.1%, F1 = 96.0% for shock rates; root mean squared error = 207, mean absolute error = 121 for numbers of shocks). The hypothesis testing showed no significant difference between steps generated by our model and the top practices (P=.480 for power levels; P=.782 for shock rates; P=.727 for numbers of shocks).

Conclusions

The high performance of our deep learning approach shows its treatment planning capability on par with top physicians. To the best of our knowledge, our framework is the first effort to implement automated planning of SWL treatment via deep learning. It is a promising technique in assisting treatment planning and physician training at low cost.

Renal Protection Phenomenon Observed in a Porcine Model After Electromagnetic Lithotripsy Using a Treatment Pause

Purpose: Pretreating the kidney with 100 low-energy shock waves (SWs) with a time pause before delivering a clinical dose of SWs (Dornier HM-3, 2000 SWs, 24 kV, and 120 SWs/min) has been shown to significantly reduce the size of the hemorrhagic lesion produced in that treated kidney, compared to a protocol without pretreatment. It has been assumed that a similar reduction in injury will occur with lithotripters other than the HM-3, but experiments to confirm this assumption are lacking. In this study, we sought to verify that the lesion protection phenomenon also occurs in a lithotripter using an electromagnetic shock source and dry-head coupling. Materials and Methods: Eleven female pigs were placed in a Dornier Compact S lithotripter where the left kidney of each animal was targeted for lithotripsy treatment. Some kidneys received 2500 SWs at power level (PL) = 5 (120 SWs/min) while some kidneys were pretreated with 100 SWs at PL = 1, with a 3-minute time pause, followed immediately by 2500 SWs at PL = 5 (120 SWs/min). Lesion size analysis was performed to assess the volume of hemorrhagic tissue injury created by each treatment regimen (% functional renal volume). Results: Lesion size fell by 85% (p = 0.01) in the 100 SW pretreatment group compared to the injury produced by a regimen without pretreatment. Conclusions: The results suggest that the treatment pause protection phenomenon occurs with a Dornier Compact S, a machine distinctly different from the Dornier HM-3. This result also suggests that this phenomenon may be observed generally in SW lithotripters.

Energy output modalities of shockwave lithotripsy in the treatment of urinary stones: escalating or fixed voltage? A systematic review and meta-analysis

PURPOSE

To compare the effectiveness and safety of escalating and fixed energy output modalities of shockwave lithotripsy (SWL) in the treatment of urinary stones.

METHODS

A systematic literature search using PubMed, Embase, Cochrane Library and Web of Science was performed to obtain relevant studies up to December 2018. Summarized mean differences (MDs) and risk differences (RDs) with 95% confidence intervals (CIs) were used for comparing continuous and dichotomous variables, respectively.

RESULTS

Six RCTs including 775 patients were identified. In the overall pooled outcomes, no significant difference was detected between escalating and fixed voltage group regarding initial and final success rate (SR) and stone-free status (SFS), auxiliary procedure and complication (hematoma, febrile episode, and pain) rate. However, when shockwave frequency ≥ 90 shocks/min, total shocks per session ≤ 3000, or 1-3 SWL sessions were performed, escalating group was associated with significantly higher SR1 (defined as SFS + fragments ≤ 4 mm); in addition, escalating group brought significantly less hematoma when total shocks per session ≤ 3000.

CONCLUSIONS

Escalating voltage SWL offered comparable safety and effectiveness to that of fixed voltage SWL. However, escalating voltage SWL could be recommended in following conditions: (1) shockwave frequency ≥ 90 shocks/min, total shocks per session ≤ 3000, or 1-3 SWL sessions, for better stone removal; (2) total shocks per session ≤ 3000, for less hematoma formation.

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.

Optimisation of shock wave lithotripsy: a systematic review of technical aspects to improve outcomes

Shock wave lithotripsy (SWL) remains an important treatment option for the management of upper urinary tract stones. The optimisation of certain technical principles can help to improve the results of SWL. We performed a systematic review based on preferred reporting items for systematic review and meta-analysis (PRISMA) standards for studies reporting on technical aspects of SWL. A literature search was conducted on the PubMed database between January 1984 and November 2018 using 'shockwave lithotripsy' and 'stone' as keywords. Summaries and manuscripts of relevant articles were reviewed in order to select studies with the best level of evidence in each theme covered during the review. From 4,135 titles, 165 abstracts and full-text articles were reviewed. Overall, SWL has good outcomes in the treatment of upper urinary tract stones. It remains the only truly non-invasive stone treatment. While stone-free rate (SFR) might not be equivalent to ureteroscopy or percutaneous nephrolithotomy outcomes, SWL can be optimised by changing several technical factors, including type of machine, patient position, number, rate and energy of shocks, stone targeting, and patient analgesia. For each of these included SWL themes, relevant and selected studies with the highest level of evidence were described and discussed. Paired with these improved technical factors and appropriate patient selection, SWL, with its low complication rates, remains an excellent treatment option in 2019.

Indications and contraindications for shock wave lithotripsy and how to improve outcomes

For over 35 years shock wave lithotripsy has proven to be an effective, safe and truly minimally invasive option for the treatment of nephrolithiasis. Various technical factors as well as patient selection can impact the success of the procedure. We used published work focusing on outcomes of shock wave lithotripsy, risk of complications, and strategies for improving stone fragmentation to create this review. Multiple patient and technical factors have been found to impact success of treatment. Skin to stone distance, stone density and composition, size and location of the stone within the urinary system all influence stone free rates. A slower rate with a gradual increasing voltage, precise targeting, proper coupling will improve stone fragmentation and decrease risk of complications. The selection of appropriate patients through a shared decision making process and attention to the technical factors that improve stone free rates is key to providing an effective treatment and patient satisfaction.

Electromagnetic and Electrohydraulic Shock Wave Lithotripsy-Induced Urothelial Damage: Is There a Difference?

PURPOSE

To evaluate and compare the acute effect of electromagnetic and electrohydraulic extracorporeal shockwave lithotripsy (SWL) on the urothelial layers of kidney and ureter.

MATERIALS AND METHODS

Fifty patients, 29 males (58%) and 21 females (42%), with an average age of 51.68 years (range: 37-70) who underwent SWL application in two different centers were included. Twenty-eight patients (56%) were treated with electrohydraulic and 22 (44%) were treated with electromagnetic lithotripsy. Urinary cytologic examinations were done immediately before and after SWL therapy and 10 days later. The average numbers of epithelial cells, red blood cells (RBC), and myocytes were counted under 40 × magnification.

RESULTS

There were significant differences in the number of epithelial cells and RBC before and after immediate application of SWL: 1.66 and 14.9 cells/field, (p = 0.001), 5.44 and 113.45 cells/field, respectively (p = 0.001). The number of RBC was significantly higher in patients treated with electromagnetic lithotripsy than those treated with electrohydraulic: 141.9 and 93.4 cells/field, respectively (p = 0.02). No myocyte or basement membrane elements were detected in any of the cytologic examinations. Cytologic examinations done after 10 days of SWL therapy revealed recovery of all abnormal cytologic findings.

CONCLUSIONS

The acute increments in the number of epithelial cells and RBC after SWL were statistically significant but it was not permanent. SWL-induced urinary urothelial lesion is limited to the mucosal layer and there was no evidence of damage to the basal membrane or muscle layer. Electromagnetic lithotripsy caused high numbers of RBC than the electrohydraulic device on the postimmediate urine cytologic examination.

A Prospective Randomized Study Comparing the Effect of Different Kidney Protection Treatment Protocols on Acute Renal Injury After Extracorporeal Shockwave Lithotripsy

OBJECTIVES

To perform a prospective study to evaluate the renal protective effects of ramping protocol and pause protocol for extracorporeal shockwave lithotripsy (SWL) in human subjects.

PATIENTS AND METHODS

Three hundred twenty patients with solitary renal stone <15 mm were randomized to receive one of four protocols: (1) 80% power from beginning until the end of treatment; (2) the first 100 shockwaves (SWs) at 40% power, and then 80% power until the end of treatment; (3) the first 100 shocks at 40% power, followed by a 3-minute pause, and then further SWs at 80% power until the end of treatment; and (4) the first 100 shocks at 80% power, followed by a 3-minute pause, and then further SWs at 80% power until the end of treatment. The primary endpoint was the incidence of renal hematoma assessed by imaging on day 2. Spot urine samples were also collected before and after treatment for acute renal injury marker measurement.

RESULTS

The baseline information and treatment parameters of the four groups were comparable. The overall incidence of hematoma formation was 7.69% (24 patients). The number of patients developing hematoma in the four groups was 8 (10.26%), 7 (8.97%), 6 (7.59%), and 3 (3.90%), respectively, and the incidence of hematoma among the four groups was not significantly different. Only patient's body mass index and mean blood pressure during treatment were predictors for hematoma formation. There was also no significant difference in changes in the levels of all markers and complication and hospitalization rates between the four groups.

CONCLUSION

Comprehensive assessment of clinical parameters, imaging results, and urinary markers showed no obvious improvement in post-SWL renal insult by either protocol.

Recent advances in lithotripsy technology and treatment strategies: A systematic review update

INTRODUCTION

Shock wave lithotripsy (SWL) is a well - established treatment option for urolithiasis. The technology of SWL has undergone significant changes in an attempt to better optimize the results while reducing failure rates. There are some important limitations that restrict the use of SWL. In this review, we aim to place these advantages and limitations in perspective, assess the current role of SWL, and discuss recent advances in lithotripsy technology and treatment strategies.

METHODS

A comprehensive review was conducted to identify studies reporting outcomes on ESWL. We searched for literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. Relevant articles in English published since 1980 were selected for inclusion.

RESULTS

Efficacy has been shown to vary between lithotripters. To maximize stone fragmentation and reduce failure rates, many factors can be optimized. Factors to consider in proper patient selection include skin - to - stone distance and stone size. Careful attention to the rate of shock wave administration, proper coupling of the treatment head to the patient have important influences on the success of lithotripsy.

CONCLUSION

Proper selection of patients who are expected to respond well to SWL, as well as attention to the technical aspects of the procedure are the keys to SWL success. Studies aiming to determine the mechanisms of shock wave action in stone breakage have begun to suggest new treatment strategies to improve success rates and safety.

Comparison of escalating, constant, and reduction energy output in ESWL for renal stones: multi-arm prospective randomized study

This study was designed to find out the optimized energy delivery strategy in Shock Wave Lithotripsy (SWL) that yield to the best stone-free rate (SFR). In this clinical trial, 150 consecutive patients were randomized into three groups: (a) Dose escalation, 1500 SW at 18 kV, followed by 1500 SW at 20 kV then 1500 SW at 22 kV. (b) Constant dose, 4500 SW at 20 kV. All patients undergo plain X-ray film of the urinary tract at day 1, 14, and 90 to assess stone-free rate (SFR) which was defined as no stones or painless fragments less than 4 mm. (c) Dose reduction, 1500 SW at 22 kV, followed by 1500 SW at 20 kV and then 1500 SW at 18 kV. The three treatment groups were comparable in terms of age, sex, stone size and distribution of the kidneys, and the need for Double J stent use. On day 90, the SFR achieved was 82, 90, and 84 % in the escalating, constant, and reduction energy groups, respectively. However, this rate was not statistically significant (x ² = 1.38, p level = 0.28). At a slow rate of 60 shocks, there was no difference in stone-free rate between different voltages at 1, 14, and 90 days. Our randomized clinical trial showed no statistically significant difference in SFR between the three groups while using the slow SWL rate. Our trial is the first randomized trial comparing the three strategies. As such, a dose adjustment strategy while delivering SWL in slow rate was not recommended.

Are We Banging Our Heads Against the Wall? The Effect of Treatment Head Wear on the Outcomes of Extracorporeal Shockwave Lithotripsy

INTRODUCTION AND OBJECTIVE

The manufacturer for the Storz Modulith SLX-F2 lithotripter recommends treatment head exchange after 1.65 million shocks. However, there is no documentation describing longevity of the treatment head with continued usage. The objective of this study is to determine whether there is a difference in stone fragmentation effectiveness with the treatment head at the beginning versus the end of its treatment life.

METHODS

We conducted a retrospective chart review of 200 patients-50 consecutive patients treated immediately preceding, and following, two separate treatment head exchanges. Primary outcome measures were stone-free rate (no stone), total stone fragmentation (any decrease in size), and fragmentation rate ≤4 mm (decrease in size with largest residual fragment ≤4 mm), based on most recent follow-up imaging post shockwave.

RESULTS

There were no baseline characteristic differences between the pre-exchange and postexchange groups with respect to first time lithotripsy for the stone (85% vs. 77%), stone location, preoperative stenting (3% vs. 4%), mean stone density (912 hounsfield units [HU] vs. 840 HU), mean stone size (9.0 mm vs. 8.1 mm), stone location, and mean number of shocks delivered (3105 vs. 3089). Mean time to follow-up was 2.7 weeks in both groups, with most follow-up imaging consisting of a kidney ureter bladder X-ray (87% pre-exchange vs. 85% postexchange). Stone free (34% vs. 27%), total stone fragmentation (76% vs. 76%), fragmentation ≤4 mm (48% vs. 42%), re-treatment rates (38% vs. 51%), and complication rates (6% vs. 7%), were not statistically different between the pre and postexchange groups, respectively.

CONCLUSIONS

Exchanging the Storz Modulith F2 lithotripter head at the manufacturer recommended 1.65 million shocks does not affect the stone-free or fragmentation rate. If the manufacturer's recommendation for treatment head longevity is based on clinical outcomes, then there is likely room to extend this number without affecting treatment efficacy.

Using 300 Pretreatment Shock Waves in a Voltage Ramping Protocol Can Significantly Reduce Tissue Injury During Extracorporeal Shock Wave Lithotripsy

PURPOSE

Pretreating a pig kidney with 500 low-energy shock waves (SWs) before delivering a clinical dose of SWs (2000 SWs, 24 kV, 120 SWs/min) has been shown to significantly reduce the size of the hemorrhagic lesion produced in that treated kidney, compared with a protocol without pretreatment. However, since the time available for patient care is limited, we wanted to determine if fewer pretreatment SWs could be used in this protocol. As such, we tested if pretreating with 300 SWs can initiate the same reduction in renal lesion size as has been observed with 500 SWs.

MATERIALS AND METHODS

Fifteen female farm pigs were placed in an unmodified Dornier HM-3 lithotripter, where the left kidney of each animal was targeted for lithotripsy treatment. The kidneys received 300 SWs at 12 kV (120 SWs/min) followed immediately by 2000 SWs at 24 kV (120 SWs/min) focused on the lower pole. These kidneys were compared with kidneys given a clinical dose of SWs with 500 SW pretreatment, and without pretreatment. Renal function was measured both before and after SW exposure, and lesion size analysis was performed to assess the volume of hemorrhagic tissue injury (% functional renal volume, FRV) created by the 300 SW pretreatment regimen.

RESULTS

Glomerular filtration rate fell significantly in the 300 SW pretreatment group by 1 hour after lithotripsy treatment. For most animals, low-energy pretreatment with 300 SWs significantly reduced the size of the hemorrhagic injury (to 0.8% ± 0.4%FRV) compared with the injury produced by a typical clinical dose of SWs.

CONCLUSIONS

The results suggest that 300 pretreatment SWs in a voltage ramping treatment regimen can initiate a protective response in the majority of treated kidneys and significantly reduce tissue injury in our model of lithotripsy injury.

Review on Lithotripsy and Cavitation in Urinary Stone Therapy

Cavitation is the sudden formation of vapor bubbles or voids in liquid media and occurs after rapid changes in pressure as a consequence of mechanical forces. It is mostly an undesirable phenomenon. Although the elimination of cavitation is a major topic in the study of fluid dynamics, its destructive nature could be exploited for therapeutic applications. Ultrasonic and hydrodynamic sources are two main origins for generating cavitation. The purpose of this review is to give the reader a general idea about the formation of cavitation phenomenon and existing biomedical applications of ultrasonic and hydrodynamic cavitation. Because of the high number of the studies on ultrasound cavitation in the literature, the main focus of this review is placed on the lithotripsy techniques, which have been widely used for the treatment of urinary stones. Accordingly, cavitation phenomenon and its basic concepts are presented in Section II. The significance of the ultrasound cavitation in the urinary stone treatment is discussed in Section III in detail and hydrodynamic cavitation as an important alternative for the ultrasound cavitation is included in Section IV. Finally, side effects of using both ultrasound and hydrodynamic cavitation in biomedical applications are presented in Section V.

CUA Guideline: Management of ureteral calculi

The focus of this guideline is the management of ureteral stones. Specifically, the topics covered include: conservative management, medical expulsive therapy, active intervention with either shockwave lithotripsy (SWL) or ureteroscopy (URS), factors affecting SWL treatment success, optimizing success, and special considerations (e.g., pregnancy, urinary diversion). By performing extensive literature reviews for each topic evaluated, we have generated an evidence-based consensus on the management of ureteral stones. The objective of this guideline is to help standardize the treatment of ureteral stones to optimize treatment outcomes.

Non-compliance with randomised allocation and missing outcome data in randomised controlled trials evaluating surgical interventions: a systematic review

Background

Randomised controlled trials are widely acknowledged as the gold standard in medical research although their validity can be undermined by non-compliance with the randomly allocated treatment and missing data. Due to the nature of the intervention, surgical trials face particular threat to compliance and data collection. For example, ineligibility for the intervention may only become apparent once the operation has commenced. It is unclear how such cases are reported and handled.

Objective

The objective was to assess non-compliance and missing data in reports of trials of surgical interventions.

Methods

Searches for reports of trials involving at least one surgical procedure and published in 2010 were carried out in the Medical Literature Analysis and Retrieval System Online (MEDLINE^®). Data on missing data, non-compliance and methods of handling missing data were extracted from full texts. Descriptive data analyses were carried out on the data.

Results

Forty-five (55 %) studies reported non-compliance with treatment allocation and 52 (63 %) reported primary outcome missing data. The median levels of non-compliance and missing data were 2 % [IQR (0, 5), range (0–29)] and 6 % [IQR (0, 15), range (0–57)], respectively. Fifty-two (63 %) studies analysed as randomised, 17 (21 %) analysed per protocol and 3 (4 %) analysed as treated. Complete case analysis was the most common method used to deal with missing data, 35/52 (67 %).

Conclusions

The reporting of non-compliance to allocation and the handling of missing data were typically suboptimal. There is still room for improvement on the use of the CONSORT statement particularly in accounting for study participants. Transparency in reporting would facilitate evidence synthesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1364-9) contains supplementary material, which is available to authorized users.

Does Stepwise Voltage Ramping Protect the Kidney from Injury During Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial

BACKGROUND

Renal damage is more frequent with new-generation lithotripters. However, animal studies suggest that voltage ramping minimizes the risk of complications following extracorporeal shock wave lithotripsy (SWL). In the clinical setting, the optimal voltage strategy remains unclear.

OBJECTIVE

To evaluate whether stepwise voltage ramping can protect the kidney from damage during SWL.

DESIGN, SETTING, AND PARTICIPANTS

A total of 418 patients with solitary or multiple unilateral kidney stones were randomized to receive SWL using a Modulith SLX-F2 lithotripter with either stepwise voltage ramping (n=213) or a fixed maximal voltage (n=205).

INTERVENTION

SWL.

OUTCOMES MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was sonographic evidence of renal hematomas. Secondary outcomes included levels of urinary markers of renal damage, stone disintegration, stone-free rate, and rates of secondary interventions within 3 mo of SWL. Descriptive statistics were used to compare clinical outcomes between the two groups. A logistic regression model was generated to assess predictors of hematomas.

RESULTS AND LIMITATIONS

Significantly fewer hematomas occurred in the ramping group(12/213, 5.6%) than in the fixed group (27/205, 13%; p=0.008). There was some evidence that the fixed group had higher urinary β2-microglobulin levels after SWL compared to the ramping group (p=0.06). Urinary microalbumin levels, stone disintegration, stone-free rate, and rates of secondary interventions did not significantly differ between the groups. The logistic regression model showed a significantly higher risk of renal hematomas in older patients (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00-1.05; p=0.04). Stepwise voltage ramping was associated with a lower risk of hematomas (OR 0.39, 95% CI 0.19-0.80; p=0.01). The study was limited by the use of ultrasound to detect hematomas.

CONCLUSIONS

In this prospective randomized study, stepwise voltage ramping during SWL was associated with a lower risk of renal damage compared to a fixed maximal voltage without compromising treatment effectiveness.

PATIENT SUMMARY

Lithotripsy is a noninvasive technique for urinary stone disintegration using ultrasonic energy. In this study, two voltage strategies are compared. The results show that a progressive increase in voltage during lithotripsy decreases the risk of renal hematomas while maintaining excellent outcomes.

TRIAL REGISTRATION

ISRCTN95762080.

Analysis of the safety profile of treatment with a large number of shock waves per session in extracorporeal lithotripsy

OBJECTIVE

To assess the safety of increasing the number of waves per session in the treatment of urolithiasis using extracorporeal lithotripsy.

MATERIAL AND METHODS

Prospective, comparative, nonrandomized parallel study of patients with renoureteral lithiasis and an indication for extracorporeal lithotripsy who were consecutively enrolled between 2009 and 2010. We compared group I (160 patients) treated on schedule with a standard number of waves/session (mean 2858,3±302,8) using a Dornier lithotripter U/15/50 against group II (172 patients) treated with an expanded number of waves/session (mean, 6728,9±889,6) using a Siemens Modularis lithotripter. The study variables were age, sex, location, stone size, number of waves/session and total number of waves to resolution, stone-free rate (SFR) and rate of complications (Clavien-Dindo classification). Student's t-test and the chi-squared test were employed for the statistical analysis.

RESULTS

The total rate of complications was 11.9% and 10.46% for groups I and II, respectively (P=.39). All complications were minor (Clavien-Dindo grade I). The most common complications were colic pain and hematuria in groups I and II, respectively, with a similar treatment intolerance rate (P>.05). The total number of waves necessary was lower in group II than in group I (P=.001), with SFRs of 96.5% and 71.5%, respectively (P=.001).

CONCLUSION

Treatment with an expanded number of waves per session in extracorporeal lithotripsy does not increase the rate of complications or their severity. However, it could increase the overall effectiveness of the treatment.

Extracorporeal shock wave lithotripsy in the treatment of renal and ureteral stones

The use of certain technical principles and the selection of favorable cases can optimize the results of extracorporeal shock wave lithotripsy (ESWL). The aim of this study is to review how ESWL works, its indications and contraindications, predictive factors for success, and its complications. A search was conducted on the Pubmed® database between January 1984 and October 2013 using "shock wave lithotripsy" and "stone" as key-words. Only articles with a high level of evidence, in English, and conducted in humans, such as clinical trials or review/meta-analysis, were included. To optimize the search for the ESWL results, several technical factors including type of lithotripsy device, energy and frequency of pulses, coupling of the patient to the lithotriptor, location of the calculus, and type of anesthesia should be taken into consideration. Other factors related to the patient, stone size and density, skin to stone distance, anatomy of the excretory path, and kidney anomalies are also important. Antibiotic prophylaxis is not necessary, and routine double J stent placement before the procedure is not routinely recommended. Alpha-blockers, particularly tamsulosin, are useful for stones >10mm. Minor complications may occur following ESWL, which generally respond well to clinical interventions. The relationship between ESWL and hypertension/diabetes is not well established.

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

PURPOSE

To investigate the effect of fixed versus escalating voltage during SWL on treatment outcomes in patients with ureteral calculi (UC).

METHODS

A prospective, randomized, multicenter trial was conducted on 120 patients who were diagnosed with a single radiopaque UC. The patients were randomized into group C (n = 60, constant 13 kV, 3,000 shock wave, 2 Hz) or group E (n = 60, 11.4-12.0-13 kV per 1,000 shock waves, 2 Hz). They were evaluated by plain abdominal radiography and urinalysis at 1 week after a single session of SWL, and repeat SWL was performed if needed. The primary endpoint was stone-free rate at 1 week (SFR1) after SWL. Secondary endpoints were post-SWL visual pain score (VPS), oral analgesic requirements during 1 week, and cumulative SFRs after the second and third sessions of SWL.

RESULTS

Groups C and E were well balanced in terms of baseline patients and stone characteristics, including pre-SWL VPS, stone location, and stone size (6.24 ± 1.92 vs. 6.30 ± 2.13 mm). SFR1s were not significantly different between groups C and E (60.0 vs. 68.3%, p = 0.447). Analyses stratified by stone size (<6 vs. ≥6 mm) showed no difference in SFR1 (p = 0.148 vs. 0.808). In the analyses stratified by stone location, group E tended to be more effective in distal UC (81.0 vs. 50.0%, p = 0.052), whereas no difference was seen in proximal UC (p = 0.487). Secondary endpoints were also similar between the two groups.

CONCLUSIONS

Our results suggest that voltage escalation during SWL in UC may not provide superior stone fragmentation compared to fixed voltage.

Shock wave lithotripsy: the new phoenix?

INTRODUCTION

Following its introduction in 1980, shock wave lithotripsy (SWL) rapidly emerged as the first-line treatment for the majority of patients with urolithiasis. Millions of SWL therapies have since been performed worldwide, and nowadays, SWL still remains to be the least invasive therapy modality for urinary stones. During the last three decades, SWL technology has advanced in terms of shock wave generation, focusing, patient coupling and stone localization. The implementation of multifunctional lithotripters has made SWL available to urology departments worldwide. Indications for SWL have evolved as well. Although endoscopic treatment techniques have improved significantly and seem to take the lead in stone therapy in the western countries due to high stone-free rates, SWL continues to be considered as the first-line therapy for the treatment of most intra-renal stones and many ureteral stones.

METHODS

This paper reviews the fundamentals of SWL physics to facilitate a better understanding about how a lithotripter works and should be best utilized.

RESULTS

Advances in lithotripsy technology such as shock wave generation and focusing, advances in stone localization (imaging), different energy source concepts and coupling modalities are presented. Furthermore adjuncts to improve the efficacy of SWL including different treatment strategies are reviewed.

CONCLUSION

If urologists make use of a more comprehensive understanding of the pathophysiology and physics of shock waves, much better results could be achieved in the future. This may lead to a renaissance and encourage SWL as first-line therapy for urolithiasis in times of rapid progress in endoscopic treatment modalities.

The protective role of coenzyme Q10 in renal injury associated with extracorporeal shockwave lithotripsy: a randomised, placebo-controlled clinical trial

OBJECTIVE

To determine the efficacy of coenzyme Q10 (CoQ10) in preventing renal injury in patients with lithiasis undergoing extracorporeal shockwave lithotripsy (ESWL).

PATIENTS AND METHODS

Prospective, randomised, double-blind, placebo-controlled clinical trial of 100 patients with renal lithiasis who were treated with ESWL. The patients were distributed randomly into two groups receiving either placebo or CoQ10 (200 mg/day), a powerful antioxidant with vasoactive properties, orally administered during the week before ESWL and for 1 week after. Renal dysfunction markers, vasoactive hormones, oxidative stress, plasma levels of several interleukins and vascular resistance index (VRI) using Doppler ultrasound were evaluated the week before ESWL, 2 h before ESWL and at 2 h, 24 h and 7 days after ESWL.

RESULTS

There was a significant increase in glomerular filtration (P = 0.013), as well as a decrease in the albumin/creatinine ratio and the β2 -microglobulin level (P = 0.02) after 1 week of treatment in the CoQ10 group. These changes were maintained at the follow-up after ESWL. The administration of CoQ10 was associated with improvement in vasoactive hormone parameters, VRI and interleukin levels. These improvements were maintained until the end of the follow-up period. However, the administration of CoQ10 was not associated with significant changes in the oxidative stress parameters.

CONCLUSION

Our results indicate that CoQ10 administration improves renal function and vasoactive and inflammation parameter values, allowing for preconditioning before the tissue insult caused by ESWL.

Turbulent water coupling in shock wave lithotripsy

Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93). If cavitation nuclei remain in the propagation path of successive lithotripter pulses, especially in the acoustic coupling cushion of the shock wave source, they will consume part of the incident wave energy, leading to reduced tensile pressure in the focal region and thus lower stone comminution efficiency. We introduce a method to remove cavitation nuclei from the coupling cushion between successive shock exposures using a jet of degassed water. As a result, pre-focal bubble nuclei lifetime quantified by B-mode ultrasound imaging was reduced from 7 to 0.3 s by a jet with an exit velocity of 62 cm s(-1). Stone fragmentation (percent mass <2 mm) after 250 shocks delivered at 1 Hz was enhanced from 22 ± 6% to 33 ± 5% (p = 0.007) in water without interposing tissue mimicking materials. Stone fragmentation after 500 shocks delivered at 2 Hz was increased from 18 ± 6% to 28 ± 8% (p = 0.04) with an interposing tissue phantom of 8 cm thick. These results demonstrate the critical influence of cavitation bubbles in the coupling cushion on stone comminution and suggest a potential strategy to improve the efficacy of contemporary shock wave lithotripters.

Extracorporeal shock wave lithotripsy: What is new?

OBJECTIVES

Thirty years after its introduction, extracorporeal shockwave lithotripsy (ESWL) is still first-line treatment for more than half of all urinary tract stones, but machines and treatment strategies have significantly developed over time. In this review, we summarise the latest knowledge about the clinically important aspects of ESWL.

METHODS

We searched PubMed to identify relevant reports and the latest European Association of Urology guidelines, and standard urological textbooks were consulted.

RESULTS

New technical developments include: Twin-head and tandem-pulse shock-wave generators; wide-focus, low-pressure systems; optimised coupling; and automated location and acoustic tracking systems. Indications have been refined, making possible the identification of patients in whom ESWL treatment is likely to fail. By lowering the shock-wave rate, improving coupling, applying abdominal compression, power 'ramping' and postoperative medical expulsion therapy, treatment protocols have been optimised.

CONCLUSIONS

Promising new technical developments are under development, with the potential to increase the stone-free rate after ESWL. For optimal results, the refined indications need to be respected and optimised treatment protocols should be applied.

Optimising an escalating shockwave amplitude treatment strategy to protect the kidney from injury during shockwave lithotripsy

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Animal studies have shown that one approach to reduce SWL-induced renal injury is to pause treatment for 3-4 min early in the SWL-treatment protocol. However, there is typically no pause in treatment during clinical lithotripsy. We show in a porcine model that a pause in SWL treatment is unnecessary to achieve a reduction in renal injury if treatment is begun at a low power setting that generates low-amplitude SWs, and given continuously for ≈ 4 min before applying higher-amplitude SWs.

OBJECTIVE

• To test the idea that a pause (≈ 3 min) in the delivery of shockwaves (SWs) soon after the initiation of SW lithotripsy (SWL) is unnecessary for achieving a reduction in renal injury, if treatment is begun at a low power setting that generates low-amplitude SWs.

MATERIALS AND METHODS

• Anaesthetised female pigs were assigned to one of three SWL treatment protocols that did not involve a pause in SW delivery of >10 s (2000 SWs at 24 kV; 100 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV; 500 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV). • All SWs were delivered at 120 SWs/min using an unmodified Dornier HM3 lithotripter. • Renal function was measured before and after SWL. • The kidneys were then processed for quantification of the SWL-induced haemorrhagic lesion. Values for lesion size were compared to previous data collected from pigs in which treatment included a 3-min pause in SW delivery.

RESULTS

• All SWL treatment protocols produced a similar degree of vasoconstriction (23-41% reduction in glomerular filtration rate and effective renal plasma flow) in the SW-treated kidney. • The mean renal lesion in pigs treated with 100 low-amplitude SWs delivered before the main dose of 2000 high-amplitude SWs (2.27% functional renal volume [FRV]) was statistically similar to that measured for pigs treated with 2000 SWs all at high-amplitude (3.29% FRV). • However, pigs treated with 500 low-amplitude SWs before the main SW dose had a significantly smaller lesion (0.44% FRV) that was comparable with the lesion in pigs from a previous study in which there was a 3-min pause in treatment separating a smaller initial dose of 100 low-amplitude SWs from the main dose of 2000 high-amplitude SWs (0.46% FRV). The time between the initiation of the low - and high-amplitude SWs was ≈ 4 min for these latter two groups compared with ≈ 1 min when there was negligible pause after the initial 100 low-amplitude SWs in the protocol.

CONCLUSIONS

• Pig kidneys treated by SWL using a two-step low-to-high power ramping protocol were protected from injury with negligible pause between steps, provided the time between the initiation of low-amplitude SWs and switching to high-amplitude SWs was ≈ 4 min. • Comparison with results from previous studies shows that protection can be achieved using various step-wise treatment scenarios in which either the initial dose of SWs is delivered at low-amplitude for ≈ 4 min, or there is a definitive pause before resuming SW treatment at higher amplitude. • Thus, we conclude that renal protection can be achieved without instituting a pause in SWL treatment. It remains prudent to consider that renal protection depends on the acoustic and temporal properties of SWs administered at the beginning stages of a SWL ramping protocol, and that this may differ according to the lithotripter being used.

Shock wave technology and application: an update

CONTEXT

The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems.

OBJECTIVE

To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies.

EVIDENCE ACQUISITION

We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy.

EVIDENCE SYNTHESIS

Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60-80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures.

CONCLUSIONS

New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL.

A prospective randomised trial comparing the modified HM3 with the MODULITH® SLX-F2 lithotripter

BACKGROUND

The relative efficacy of first- versus last-generation lithotripters is unknown.

OBJECTIVES

To compare the clinical effectiveness and complications of the modified Dornier HM3 lithotripter (Dornier MedTech, Wessling, Germany) to the MODULITH(®) SLX-F2 lithotripter (Storz Medical AG, Tägerwilen, Switzerland) for extracorporeal shock wave lithotripsy (ESWL).

DESIGN, SETTING AND PARTICIPANTS

We conducted a prospective, randomised, single-institution trial that included elective and emergency patients.

INTERVENTIONS

Shock wave treatments were performed under anaesthesia.

MEASUREMENTS

Stone disintegration, residual fragments, collecting system dilatation, colic pain, and possible kidney haematoma were evaluated 1 d and 3 mo after ESWL. Complications, ESWL retreatments, and adjuvant procedures were documented.

RESULTS AND LIMITATIONS

Patients treated with the HM3 lithotripter (n=405) required fewer shock waves and shorter fluoroscopy times than patients treated with the MODULITH(®) SLX-F2 lithotripter (n=415). For solitary kidney stones, the HM3 lithotripter produced a slightly higher stone-free rate (p=0.06) on day 1; stone-free rates were not significantly different at 3 mo (HM3: 74% vs MODULITH(®) SLX-F2: 67%; p=0.36). For solitary ureteral stones, the stone-free rate was higher at 3 mo with the HM3 lithotripter (HM3: 90% vs MODULITH(®) SLX-F2: 81%; p=0.05). For solitary lower calyx stones, stone-free rates were equal at 3 mo (63%). In patients with multiple stones, the HM3 lithotripter's stone-free rate was higher at 3 mo (HM3: 64% vs MODULITH(®) SLX-F2: 44%; p=0.003). Overall, HM3 lithotripter led to fewer secondary treatments (HM3: 11% vs MODULITH(®) SLX-F2: 19%; p=0.001) and fewer kidney haematomas (HM3: 1% vs. MODULITH(®) SLX-F2: 3%; p=0.02).

CONCLUSIONS

The modified HM3 lithotripter required fewer shock waves and shorter fluoroscopy times, showed higher stone-free rates for solitary ureteral stones and multiple stones, and led to fewer kidney haematomas and fewer secondary treatments than the MODULITH(®) SLX-F2 lithotripter. In patients with a solitary kidney and solitary lower calyx stones, results were comparable for both lithotripters.

Adjuncts to improve outcomes of shock wave lithotripsy

Shock wave lithotripsy (SWL) has been a major tool in the treatment of urinary stones for nearly three decades. In recent years, SWL technology has been less effective at fragmenting stones than earlier devices; thus, adjunctive maneuvers to improve stone-free rates after SWL have been required. This article summarizes several of these adjuncts, such as slower shock wave rate, the use of percussion therapy to clear fragments, medications to hasten expulsion of fragments, and appropriate selection and positioning of patients for SWL.