Shock wave lithotripsy is not predictive of hypertension among community stone formers at long-term followup

Consensus statement addressing controversies and guidelines on pediatric urolithiasis

PURPOSE

We aimed to investigate controversial pediatric urolithiasis issues systematically, integrating expert consensus and comprehensive guidelines reviews.

METHODS

Two semi-structured online focus group meetings were conducted to discuss the study's need and content, review current literature, and prepare the initial survey. Data were collected through surveys and focus group discussions. Existing guidelines were reviewed, and a second survey was conducted using the Delphi method to validate findings and facilitate consensus. The primary outcome measures investigated controversial issues, integrating expert consensus and guideline reviews.

RESULTS

Experts from 15 countries participated, including 20 with 16+ years of experience, 2 with 11-15 years, and 4 with 6-10 years. The initial survey identified nine main themes, emphasizing the need for standardized diagnostic and treatment protocols and tailored treatments. Inter-rater reliability was high, with controversies in treatment approaches (score 4.6, 92% agreement), follow-up protocols (score 4.8, 100% agreement), and diagnostic criteria (score 4.6, 92% agreement). The second survey underscored the critical need for consensus on identification, diagnostic criteria (score 4.6, 92% agreement), and standardized follow-up protocols (score 4.8, 100% agreement).

CONCLUSION

The importance of personalized treatment in pediatric urolithiasis is clear. Prioritizing low-radiation diagnostic tools, effectively managing residual stone fragments, and standardized follow-up protocols are crucial for improving patient outcomes. Integrating new technologies while ensuring safety and reliability is also essential. Harmonizing guidelines across regions can provide consistent and effective management. Future efforts should focus on collaborative research, specialized training, and the integration of new technologies in treatment protocols.

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.

Association between renal urolithiasis after extracorporeal shock wave lithotripsy therapy and new-onset hypertension: an updated meta-analysis

OBJECTIVE

The long-term effect of extracorporeal shock wave lithotripsy (SWL) is still controversial. A previous meta-analysis showed no association between new-onset hypertension and entire upper urinary urolithiasis after SWL. Recently, there have been some reports on this topic. Therefore, we aimed to examine the association between new-onset hypertension and nephrolithiasis after SWL therapy.

METHODS

Embase, the Cochrane Central Search Library, and PubMed were used to search for reports on new-onset hypertension and patients with nephrolithiasis after SWL. A meta-analysis of the association between new-onset hypertension and nephrolithiasis after SWL was carried out. The data of relevant research were synthesized and the relative risk was computed.

RESULTS

Seven eligible studies were included in our meta-analysis. There was a significant association between nephrolithiasis after SWL and new-onset hypertension. The overall relative risk with a 95% confidence interval was 1.21 (1.11-1.31) in a fixed-effects model.

CONCLUSION

Our meta-analysis suggests an association between new-onset hypertension and patients with nephrolithiasis after SWL, which is in contrast with the finding of a previous meta-analysis.

How to maximize the efficacy of shockwave lithotripsy

Since its introduction in the early 1980s, extracorporeal shockwave lithotripsy (ESWL) has proven to be a minimally invasive and efficient procedure for the management of renal calculi. It is currently one of the most recommended treatments for small- and medium-sized stones (<20 mm) in most guidelines internationally. The recent coronavirus disease 2019 (COVID-19) outbreak could lead to a further increase in ESWL use as it avoids a general anesthetic and its potential complications in patients with COVID-19 infection. Most publications exhibit ESWL stone-free rates (SFRs) of 70%-80%; however, this is often not the case in many centers, with multiple factors affecting the efficacy of the intervention. Various stone and patient factors have been shown to influence the ESWL success. Stone position, density and size, skin-to-stone distance, and body-mass index contribute to SFRs. Modifications in the lithotripter design and revisions in the technique have also improved the SFRs over the years, with slower shock rates, power-ramping protocols, combined real-time ultrasound, and fluoroscopy imaging technology, all enhancing the efficacy. The adjuvant use of pharmacological agents, such as alpha-blockers, potassium citrate, and the emerging microbubble technology, has also been investigated and shown promising results. Arguably, the most significant determinant of the success of ESWL in a particular unit is how the lithotripsy service is set up and monitored. Careful patient selection, dedicated personnel, and post-treatment imaging review are essential for the optimization of ESWL. Through an analysis of the published studies, this review aimed to explore the measures that contribute to an effectual lithotripsy service in depth.

Stones in pregnancy and pediatrics

Urinary stone disease is a highly prevalent condition affecting approximately 10% of the population, and has increased in incidence significantly over the past 20 years. Along with this, the rate of stone disease among women and children is also on the rise. The management of stone disease in specific populations, such as in children and during pregnancy can present unique challenges to the urologist. In both populations, a multi-disciplinary approach is strongly recommended given the complexities of the patients. Prompt and accurate diagnosis requires a high degree of suspicion and judicious use of diagnostic imaging given the higher risks of radiation exposure. In general, management proceeds from conservative to more invasive approaches and must be individualized to the patient with careful consideration of the potential adverse effects. However, innovations in endourologic equipment and techniques have allowed for the wider application of surgical stone treatment in these patients, and significant advancement in the field. This review covers the history and current advances in the diagnosis and management of stone disease in pregnant and pediatric populations. It is paramount for the urologist to understand the complexities of properly managing stones in these patients in order to maximize treatment efficacy, while minimizing complications and morbidity.

Extracorporeal Shockwave Lithotripsy Could Lead to a Prolonged Increase in the Renal Fibrotic Process of Up to 2 Years

INTRODUCTION AND OBJECTIVE

This prospective study aimed to evaluate the effect of ramping and pause protocols on renal fibrosis, blood pressure control, and renal function in patients receiving extracorporeal shockwave lithotripsy (SWL).

PATIENTS AND METHODS

This study prospectively recruited 320 patients with solitary radiopaque renal stones <15 mm in size. Patients were randomized to receive one of four shockwave protocols: (1) standard protocol (no ramping or pause); (2) ramping protocol alone; (3) ramping and pause protocols; or (4) pause protocol alone. Spot urine samples were collected before and for 2 years after treatment to monitor the levels of the renal fibrosis marker procollagen III aminoterminal propeptide (PIIINP) by blinded research staffs. Blood pressure and serum creatinine levels were also monitored during follow-up.

RESULTS

The four groups had comparable baseline data and treatment parameters. Significant increases (p < 0.05) in the urinary PIIINP levels from 6 weeks until 18 months after SWL were observed among all patients and in individual groups. PIIINP levels peaked at 1 year after SWL and gradually decreased to the baseline at 2 years. At the 2-year follow-up point, the overall serum creatinine levels remained significantly elevated (76.21-80.01 μmol/L, p < 0.001). Twenty (9.95%) patients developed new-onset hypertension and another 43 (36.4%) experienced worsening blood pressure control. However, no differences were observed among the four treatment groups.

CONCLUSIONS

SWL led to significant increases in renal fibrosis marker levels for up to 18 months after treatment. However, no differences in changes in renal fibrosis marker and serum creatinine levels and worsening of blood pressure control were observed with respect to the use of either ramping or pause treatment protocols.

Increased Risk of New-Onset Hypertension After Shock Wave Lithotripsy in Urolithiasis: A Nationwide Cohort Study

Although shock wave lithotripsy is minimally invasive, earlier studies argued that it may increase patients' subsequent risk of hypertension and diabetes mellitus. This study evaluated the association between shock wave lithotripsy and new-onset hypertension or diabetes mellitus. The Taiwanese National Health Insurance Research Database was used to identify 20 219 patients aged 18 to 65 years who underwent the first stone surgical treatment (shock wave lithotripsy or ureterorenoscopic lithotripsy) between January 1999 and December 2011. A Cox proportional model was applied to evaluate associations. Time-varying Cox models were applied to evaluate the association between the number of shock wave lithotripsy sessions and the incidence of hypertension or diabetes mellitus. After a median follow-up of 74.9 and 82.6 months, 2028 and 688 patients developed hypertension in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups, respectively. Patients who underwent shock wave lithotripsy had a higher probability of developing hypertension than patients who underwent ureterorenoscopic lithotripsy, with a hazard ratio of 1.20 (95% confidence interval, 1.10-1.31) after adjusting for covariates. The risk increased as the number of shock wave lithotripsy sessions increased. However, the diabetes mellitus risk was similar in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups. Furthermore, the hazard ratio did not increase as the number of shock wave lithotripsy sessions increased. Shock wave lithotripsy consistently increased the incidence of hypertension on long-term follow-up. Therefore, alternatives to urolithiasis treatment (eg, endoscopic surgery or medical expulsion therapy) could avoid the hypertension risk. Furthermore, avoiding multiple sessions of shock wave lithotripsy could also evade the hypertension risk.

[What is the current status of shock wave lithotripsy?]

BACKGROUND

Shock wave lithotripsy (SWL) became the therapy of choice for the majority of patients with urolithiasis early after its introduction in the early 1980s. Since then, SWL remains the only noninvasive therapy modality for the treatment of urinary stones. Although lithotripters became more versatile and affordable-making them available worldwide-indications for SWL have shifted as well. In most western countries, endoscopic techniques took the lead in stone therapy due to high (early) stone-free and better reimbursement rates. Notwithstanding SWL remains the first-line therapy for most intrarenal and many ureteral stones.

PURPOSE

This contemporary review illuminates technical aspects and improvements of lithotripsy over recent years in context with the current guideline recommendations.

RESULTS

Technical advances in lithotripsy such as shock wave generation, focusing, coupling, stone localization and modifications in therapy regimens are reviewed and presented.

CONCLUSIONS

Urologists are recommended to carefully select the appropriate therapy modality for a patient with urolithiasis. A more comprehensive understanding of the physics of shock waves could lead to much better results, thus, endorsing SWL as first-line therapy for urolithiasis instead of contemporary endourology treatment options.

Assessing the risk of incident hypertension and chronic kidney disease after exposure to shock wave lithotripsy and ureteroscopy

In this study we sought to determine if among individuals with urolithiasis, extracorporeal shock wave lithotripsy (SWL) and ureteroscopy are associated with a higher risk of incident arterial hypertension (HTN) and/or chronic kidney disease (CKD). This was measured in a population-based retrospective study of 11,570 participants with incident urolithiasis and 127,464 without urolithiasis in The Health Improvement Network. Patients with pre-existing HTN and CKD were excluded. The study included 1319 and 919 urolithiasis patients with at least one SWL or URS procedure, respectively. Multivariable Cox regression was used to estimate the hazard ratio for incident CKD stage 3-5 and HTN in separate analyses. Over a median of 3.7 and 4.1 years, 1423 and 595 of urolithiasis participants developed HTN and CKD, respectively. Urolithiasis was associated with a significant hazard ratio each for HTN of 1.42 (95% CI: 1.35, 1.51) and for CKD of 1.82 (1.67, 1.98). SWL was associated with a significant increased risk of HTN 1.34 (1.15, 1.57), while ureteroscopy was not. When further stratified as SWL to the kidney or ureter, only SWL to the kidney was significantly and independently associated with HTN 1.40 (1.19, 1.66). Neither SWL nor ureteroscopy was associated with incident CKD. Since urolithiasis itself was associated with a hazard ratio of 1.42 for HTN, an individual who undergoes SWL to the kidney can be expected to have a significantly increased hazard ratio for HTN of 1.96 (1.67, 2.29) compared with an individual without urolithiasis.

Effect of urinary stone disease and its treatment on renal function

Urolithiasis is a common disease that affects urinary tract in all age groups. Both in adults and in children, stone size, location, renal anatomy, and other factors, can influence the success of treatment modalities. Recently, there has been a great advancement in technology for minimally invasive management of urinary stones. The epoch of open treatment modalities has passed and currently there are much less invasive treatment approaches, such as percutaneous nephrolithotomy, ureteroscopy, shockwave lithotripsy, and retrograde internal Surgery. Furthermore, advancement in imaging technics ensures substantial knowledge that permit physician to decide the most convenient treatment method for the patient. Thus, effective and rapid treatment of urinary tract stones is substantial for the preservation of the renal function. In this review, the effects of the treatment options for urinary stones on renal function have been reviewed.

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.

Effect of renal shock wave lithotripsy on the development of metabolic syndrome in a juvenile swine model: a pilot study

PURPOSE

We performed a pilot study to assess whether renal shock wave lithotripsy influences metabolic syndrome onset and severity.

MATERIALS AND METHODS

Three-month-old juvenile female Ossabaw miniature pigs were treated with shock wave lithotripsy (2,000 shock waves at 24 kV with 120 shock waves per minute in 2) or sham shock wave lithotripsy (no shock waves in 2). Shock waves were targeted to the upper pole of the left kidney to model treatment that would also expose the pancreatic tail to shock waves. Pigs were then instrumented to directly measure arterial blood pressure via an implanted radiotelemetry device. They later received a hypercaloric atherogenic diet for about 7 months. Metabolic syndrome development was assessed by the intravenous glucose tolerance test.

RESULTS

Metabolic syndrome progression and severity were similar in the sham treated and lithotripsy groups. The only exception arterial blood pressure, which remained relatively constant in sham treated pigs but began to increase at about 2 months towards hypertensive levels in lithotripsy treated pigs. Metabolic data on the 2 groups were pooled to provide a more complete assessment of metabolic syndrome development and progression in this juvenile pig model. The intravenous glucose tolerance test revealed substantial insulin resistance with impaired glucose tolerance within 2 months on the hypercaloric atherogenic diet with signs of further metabolic impairment at 7 months.

CONCLUSIONS

These preliminary results suggest that renal shock wave lithotripsy is not a risk factor for worsening glucose tolerance or diabetes mellitus onset. However, it appears to be a risk factor for early onset hypertension in metabolic syndrome.

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.

Acute and chronic kidney injury in nephrolithiasis

PURPOSE OF REVIEW

Nephrolithiasis is a common systemic disease associated with both acute kidney injury (AKI) and chronic kidney disease (CKD). The purpose of this review is to discuss recent publications regarding nephrolithiasis-associated kidney damage, with an emphasis on AKI.

RECENT FINDINGS

Nephrolithiasis is not a common cause of adult AKI (1-2% of cases), although it may be a more important factor in young children (up to 30%). The primary mechanism of nephrolithiasis-associated AKI is obstructive nephropathy, and factors on presentation with obstructive uropathy predict the likelihood of long-term renal recovery. Crystalline nephropathy is another potential pathway in certain circumstances that is often associated with a worse outcome. Recent studies have elucidated additional pathways whereby calcium oxalate crystals can cause acute injury, implicating innate immunity and intracellular inflammasome pathways. Several large cohort studies have demonstrated an independent association of nephrolithiasis with CKD and end-stage renal disease, although the effect size is modest. Urologic comorbidities, urinary infection, and shared underlying risk factors (e.g., diabetes, hypertension) all impact nephrolithiasis-associated CKD risk.

SUMMARY

Obstructive nephropathy and crystalline nephropathy both contribute to nephrolithiasis-associated AKI, although the latter appears to have a worse prognosis. Nephrolithiasis is an independent, albeit small, risk factor for CKD. Further study is needed to clarify the incidence and mechanisms of nephrolithiasis-associated AKI, and the relationship between nephrolithiasis-associated AKI and CKD.

Long-term effects of pediatric extracorporeal shockwave lithotripsy on renal function

Introduction

Extracorporeal shock wave lithotripsy (ESWL) is a well-known and successful treatment modality. In addition, it can be used in premature infants. ESWL is used to treat kidney and ureter stones in children. However, although it is a preferred noninvasive treatment in that setting, there is debate about its long-term effects on growing kidneys in children.

Objectives

To investigate the long-term effects of pediatric ESWL on renal function in light of updated literature.

Methods

PubMed and Medline were searched for studies on ESWL in a pediatric population with keywords including efficacy, child, kidney calculi, ureter calculi, lithotripsy, injury, vascular trauma, and shock waves. The research was limited to the English literature during a period from 1980 to 2014. In total, 3,000 articles were evaluated, but only 151 papers were considered. Only the manuscripts directly related to the reviewed subjects were included in the current study.

Results

However, the acute effects of ESWL in kidney are well-described. Although there are limited studies on the long-term effects of ESWL in children, there is a widespread opinion that ESWL is not affecting renal functions in the long-term.

Conclusion

ESWL is a safe, effective, and noninvasive treatment option in children. Although ESWL can cause some acute effects in the kidney, there is no long-term effect on the growing kidneys of children.

A systematic review and meta-analysis of new onset hypertension after extracorporeal shock wave lithotripsy

OBJECTIVE

Previous studies on the association between extracorporeal shock wave lithotripsy (SWL) and new onset hypertension have only illustrated contradictory results. In order to illustrate the association between SWL and new onset hypertension, a meta-analysis of case-control and cohort studies was conducted.

METHODS

Relevant literature was searched using PubMed, EMBASE, and the Cochrane Central Search Library. A meta-analysis of the association between SWL and new onset hypertension was performed. Studies were pooled, and summary relative risk was calculated. Subgroup analyses were also conducted.

RESULTS

Eleven studies were eligible for our analysis. No statistical significance was detected between SWL and new onset hypertension (RR = 1.06, 95 % CI 0.83-1.35). No association was observed when stratified analyses were performed on age, gender, study design, bilateral SWL, and different machines.

CONCLUSION

Our analysis indicated that no association was found between SWL and the development of hypertension.

Extracorporeal Shock-wave Lithotripsy Success Rate and Complications: Initial Experience at Sultan Qaboos University Hospital

OBJECTIVE

To assess the efficacy and safety of extracorporeal shock wave lithotripsy with Modularis Vario Siemens in the management of patients with renal and ureteral stones.

METHODS

Between 2007 and 2009, 225 outpatients were treated with Siemens Modularis Vario lithotripter at Sultan Qaboos University Hospital. Stone size, location, total number of shockwaves, stone-free rate, complications and adjunctive interventions were investigated. Chi-Square and Logistic Regression analyses were used, with p<0.05 set as the level of significance.

RESULTS

Of the 225 initial consecutive patients who underwent extracorporeal shock wave lithotripsy, 192 (85%) had renal stones and 33 (15%) had ureteric stones. The mean±SD stone size was 11.3±4.5 mm, while the mean age of the patients was 39.9±12.8 years with 68.5% males. The mean renal stone size was 11.6±4.7 mm; a mean of 1.3 sessions was required. The mean ureteric stone size was 9.9±3 mm; and a mean of 1.3 sessions was required. Treatment success (defined as complete clearance of ureteric stones, stone-free or clinically insignificant residual fragments of <4 mm for renal stones) was 74% for renal stones and 88% for ureteric stones. Additional extracorporeal shock wave lithotripsy and ureteroscopy were the most adjunctive procedures used for stone clearance. Complications occurred in 74 patients (38.5%) with renal stones and 13 patients (39.4%) with uretetric stones. The most common complication was loin pain (experienced by 16.7% with renal stones and 21% with ureteric stones). Severe renal colic mandating admission occurred in 2% of patients with renal stones and 6% of patients with ureteric stones. In patients with renal stone, steinstrasse occurred in 3.6% and infection post extracorporeal shock wave lithotripsy in 0.5%. Using Multivariate Logistic Regression analysis, factors found to have significant effect on complete stone clearance were serum creatinine (p=0.004) and the number of shockwaves (p=0.021).

CONCLUSION

Siemens Modularis Vario lithotripter is a safe and effective tool for treating renal and ureteric stones.

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.

Are there long-term effects of extracorporeal shockwave lithotripsy in paediatric patients?

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Extracorporeal shockwave lithotripsy is effective for the treatment of paediatric renal stones with favourable short-term safety. Extracorporeal shockwave lithotripsy for treatment of paediatric renal stones is also safe for the kidney and the child on long-term follow-up.

OBJECTIVE

To evaluate the long-term effects of extracoporeal shockwave lithotripsy (SWL) for treatment of renal stones in paediatric patients.

PATIENTS AND METHODS

A database of paediatric patients who underwent SWL monotherapy for treatment of renal stones from September 1990 through to January 2009 was compiled. This study included only patients with follow-up for more than 2 years. The long-term effects of SWL were evaluated at the last follow-up with measurement of patients' arterial blood pressure, estimation of random blood sugar and urine analysis. The results of diastolic blood pressure were plotted against a standardized age reference curve. The treated kidney was examined by ultrasonography for measurement of renal length and detection of stones. The measured renal lengths were plotted against age-calculated normal renal lengths in healthy individuals.

RESULTS

The study included 70 patients (44 boys (63%) and 26 girls) with mean age at the time of SWL 6.5 ± 3.6 years (range 1-14). The mean follow-up period was 5.2 ± 3.6 years (range 2.1-17.5). The mean age at last follow-up was 11.7 ± 5.3 years (range 4.4-27.5). No patients developed hypertension or diabetes. Only one treated kidney was smaller than one standard deviation of the calculated length. The cause of this was obstruction by a stone in the pelvic ureter 3 years after SWL.

CONCLUSION

The long-term follow-up after SWL for treatment of renal stones in paediatric patients showed no effect on renal growth and no development of hypertension or diabetes.

Chronic kidney disease in kidney stone formers

Recent population studies have found symptomatic kidney stone formers to be at increased risk for chronic kidney disease (CKD). Although kidney stones are not commonly identified as the primary cause of ESRD, they still may be important contributing factors. Paradoxically, CKD can be protective against forming kidney stones because of the substantial reduction in urine calcium excretion. Among stone formers, those with rare hereditary diseases (cystinuria, primary hyperoxaluria, Dent disease, and 2,8 dihydroxyadenine stones), recurrent urinary tract infections, struvite stones, hypertension, and diabetes seem to be at highest risk for CKD. The primary mechanism for CKD from kidney stones is usually attributed to an obstructive uropathy or pyelonephritis, but crystal plugs at the ducts of Bellini and parenchymal injury from shockwave lithotripsy may also contribute. The historical shift to less invasive surgical management of kidney stones has likely had a beneficial impact on the risk for CKD. Among potential kidney donors, past symptomatic kidney stones but not radiographic stones found on computed tomography scans were associated with albuminuria. Kidney stones detected by ultrasound screening have also been associated with CKD in the general population. Further studies that better classify CKD, better characterize stone formers, more thoroughly address potential confounding by comorbidities, and have active instead of passive follow-up to avoid detection bias are needed.

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.