IS NEWER ALWAYS BETTER? A COMPARATIVE STUDY OF 3 LITHOTRIPTOR GENERATIONS

Effect of Focal Zone Size on Treatment Outcomes and Renal Injury Following Extracorporeal Shockwave Lithotripsy of Renal Calculi: A Prospective Randomized Study

Background: The narrower focal zone (FZ) size of modern lithotripter was considered as one of the factors that resulted in suboptimal treatment result of extracorporeal shockwave lithotripsy (SWL). Therefore, we investigate the efficacy and safety of standard narrow or extended (FZ) sizes in SWL for patients with renal stones. Materials and Methods: In this prospective study conducted between April 2018 and October 2022, patients with renal stones were randomized to receive SWL with either standard or extended FZ. Treatment was delivered using a Modulith SLX-F2 lithotripter with a maximum of 3000 shocks at 1.5 Hz. The primary outcome was treatment success 12 weeks after a single SWL session, defined as the absence of a stone or stone fragment <4 mm on computed tomography. Secondary outcomes included the incidence of perinephric hematoma, stone-free rate (SFR), and changes in the urinary levels of acute renal injury markers. Results: A total of 320 patients were recruited, and 276 patients were randomized into the two groups. The two groups had similar baseline parameters. The treatment success rate was significantly better for standard FZ (74.3%) than the extended FZ group (59.3%) (p = 0.009). Standard FZ also had a significantly better SFR (Grade-A, 36.8% vs 23.0%, p = 0.013) and less pain after treatment. Both groups had similar perinephric hematoma formation rates, unplanned hospital admission rates, and changes in urinary acute renal injury markers. Conclusions: The standard narrow FZ has better treatment efficacy and similar safety compared with the extended FZ during SWL for renal stones. This clinical trial has been registered in the public domain (CCRBCTR) under trial number CUHK_CCRB00510.

Shock Wave Lithotripsy in Pediatric Stone Disease: A 15-Year Single-Center Experience with 2 Types of Lithotripters

INTRODUCTION AND OBJECTIVES

We report our experience with pediatric shock wave lithotripsy (SWL) using two types of lithotripters: Dornier HM3 (HM3) and Dornier Lithotripter SII (DLS).

STUDY DESIGN

We retrospectively reviewed the charts of children who underwent SWL between 2002 and 2016. Patients were divided into two groups based on the type of the lithotripter: during 2002-2009, we used the electrohydraulic HM3 lithotripter which was replaced in 2009 with the DLS electromagnetic lithotripter. Clinical and perioperative parameters were compared.

RESULTS

Our cohort included 107 children who underwent SWL. Average age was 11.5 ± 5.1 years. Average stone size was 10.6 ± 4.9 mm. HM3 was used in 38% of children and DLS2 in 62% (n = 41 and 66, respectively). There were no significant differences in age, gender, stone size, or location between the groups. The total SFR did not differ statistically between HM3 and DLS (83% vs. 74%, p = 0.35). SFR after one SWL was higher with the HM3 (78% vs. 62%, p = 0.093). Re-treatment rate was 22% and 17% (HM3 vs. DLS, p = 0.61). Complication rates were low, with renal colic being the most common (HM3 10%, DLS 20%, NS).

CONCLUSIONS

SWL in the pediatric population using the DLS showed good results with low complication rates that are equivalent to the gold standard HM3.

Extracorporeal shock wave lithotripsy for urinary tract stones in pediatric patients: Our 11 years of experience

Background/Aim: Urinary system stone disease creates a significant burden on the health system. Many treatment methods are available, including extracorporeal shock wave lithotripsy (ESWL), endourological procedures, and open and laparoscopic procedures. In recent years, in parallel with technological developments, endourological devices have become more usable in the renal system. For this reason, urologists are opting for endourological procedures more frequently. ESWL is the least invasive procedure for urinary system stone disease, and it has a higher success rate in pediatric patients than in adults. In this retrospective cohort study, we analyzed the data from the pediatric cases in which we used ESWL treatment in our clinic. We aimed to reveal the effectiveness of ESWL and the factors that will increase the success rate of this procedure in light of the current literature. Methods: The files of patients aged 16 years and under who underwent ESWL at the Urology Clinic of University of Health Sciences Sanliurfa Mehmet Akif Inan Training and Research Hospital between January 2010 and December 2021 were retrospectively reviewed. Age, gender, stone area, stone localization, number of sessions, energy and frequency used, complete stone-free status, and secondary intervention requirement were recorded. The absence of stone fragments or the presence of fragments smaller than 3 mm only in imaging after ESWL was considered a success. Results: This study included 433 pediatric patients. The mean age of the patients was calculated as 12.02 (4.67) (range: 1–16) years. The most important factors affecting the number of residual stones were stone localization (P = 0.045) and size (P < 0.001). When stone localization was compared according to patient age, the older patients were found to have a significantly higher rate of stones in the proximal ureter than in the lower calyx of the kidney (P = 0.045) and renal pelvis (P = 0.048). Conclusion: Although there are continual advances in other minimally invasive surgical methods today, ESWL is a treatment method that can be safely applied in pediatric patients. Stone size and stone localization are the two most important factors affecting its success rate.

A clinical observational study of effectiveness of a solid coupling medium in extracorporeal shock wave lithotripsy

This study aimed to investigate clinical effectiveness of stone disintegration by using isolation coupling pad (“icPad”) as coupling medium to reduce trapped air pockets during extracorporeal shock wave lithotripsy (ESWL). Patients underwent ESWL between Oct. 2017 and May 2018 were enrolled in this clinical observational study. An electromagnetic lithotripter (Dornier MedTech Europe GmbH Co., Germany) was used in this study. Patients were divided into icPad group P1, P2 and semi-gel group C by different coupling medium. The energy level and total number of shock wave (SW) for group P1 and C was set at level 2 and 3000 and group P2 at level 3 and 2500. The successful stone disintegration rate (SSDR) was determined to evaluate the treatment outcome. All patients were evaluated by KUB film and ultrasonography after 90 days. Complications during ESWL were recorded. A total of 300 patients satisfied the inclusion criteria. There were no significant differences in characteristics of patients and stone among three groups. The corresponding SSDRs for patients in group P1, P2 and C was 73.0%, 73.2% and 55.3%, respectively. The SSDR in group P1 was statistically higher than Group C. Comparing to semi-liquid gel, coupling medium using by icPad could achieve better treatment outcome of stone disintegration in ESWL.

Analgesia for patients undergoing shockwave lithotripsy for urinary stones - a systematic review and meta-analysis

Background

Shock wave lithotripsy (SWL) is the first line treatment modality for a significant proportion of patients with upper urinary tracts stones. Simple analgesics, opioids and non-steroidal anti-inflammatory drugs (NSAIDs) are all suitable agents but the relative efficacy and tolerability of these agents is uncertain.

Objectives

To determine the efficacy of the different types of analgesics used for the control of pain during SWL for urinary stones.

Materials and Methods

We searched the Cochrane Renal Group’s Specialised Register, MEDLINE, EMBASE and also hand-searched reference lists of relevant articles (Figure-1). Randomised controlled trials (RCT’s) comparing the use of any opioid, simple analgesic or NSAID during SWL were included. These were compared with themselves, each-other or placebo. We included any route or form of administration (bolus, PCA). We excluded agents that were used for their sedative qualities. Data were extracted and assessed for quality independently by three reviewers. Meta-analyses have been performed where possible. When not possible, descriptive analyses of variables were performed. Dichotomous outcomes are reported as relative risk (RR) and measurements on continuous scales are reported as weighted mean differences (WMD) with 95% confidence intervals.

Results

Overall, we included 9 RCTs (539 participants from 6 countries). Trial agents included 7 types of NSAIDs, 1 simple analgesic and 4 types of opioids. There were no significant differences in clinical efficacy or tolerability between a simple analgesic (paracetamol) and an NSAID (lornoxicam). When comparing the same simple analgesic with an opioid (tramadol), both agents provided safe and effective analgesia for the purpose of SWL with no significant differences. There were no significant differences in pain scores between NSAIDs or opioids in three studies. Adequate analgesia could be achieved more often for opioids than for NSAIDs (RR 0.358; 95% CI 043 to 0.77, P=0.0002) but consumed doses of rescue analgesia were similar between NSAIDs and opioids in two studies (P=0.58, >0.05). In terms of tolerability, there is no difference in post-operative nausea and vomiting (PONV) between the groups (RR 0.72, 95% CI 0.24 to 2.17, P=0.55). One study compared outcomes between two types of NSAIDs (diclofenac versus dexketoprofen). There were no significant differences in any of our pre-defined outcomes measures.

Conclusion

Simple analgesics, NSAIDs and opioids can all reduce the pain associated with shock wave lithotripsy to a level where the procedure is tolerated. Whilst there are no compelling differences in safety or efficacy of simple analgesics and NSAIDs, analgesia is described as adequate more often for opioids than NSAIDs.

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.

Efficacy of commercialised extracorporeal shock wave lithotripsy service: a review of 589 renal stones

BACKGROUND

Extracorporeal shockwave lithotripsy (ESWL) is the management of choice for renal stones 20 mm or smaller, with a stone clearance rate of up to 89%. The purpose of the present is to investigate the efficacy of a commercialised ESWL service, being performed as an outsourced treatment using a mobile lithotripsy system on an outpatient basis. Furthermore, the study aims to evaluate the risk of needing treatment with an internal ureteral double-J stent (JJ) after ESWL treatment.

METHODS

During an eight-year period, 461 patients with a total of 589 renal stones were treated using a mobile lithotripsy system at a single Danish institution. A commercial company performed all treatments using a Storz Modulith SLK® system. Each stone was prospectively registered according to size, intra renal location and the presence of a JJ at the time of treatment. The number of required ESWL treatments and auxiliary procedures were retrospectively evaluated.

RESULTS

The success rate after the initial ESWL procedure was 69%, which increased to an overall success rate of 93% after repeated treatment. A negative correlation was found between stone size and the overall success rate (r = -0.2, p < 0.01). The upper calyx was associated with a significantly better success rate, but otherwise intra renal stone location was not predictive for treatment success. A total of 17 patients (2.9%) required treatment with a JJ after the ESWL procedure. No significant difference was observed between the stone size or intra renal location and the risk of needing treatment with JJ after ESWL.

CONCLUSIONS

Commercialised ESWL treatment can achieve an overall success rate of more than 90% using a mobile lithotripsy system. As expected, an inverse relation between stone size and success rate was found. Patients who do not require treatment with a JJ prior to ESWL will only rarely need treatment with a JJ after ESWL, irrespective of stone size and intra renal stone location.

Comparison of Broad vs Narrow Focal Width Lithotripter Fields

OBJECTIVE

To investigate the impact of lithotripter focal width on stone fragmentation.

MATERIALS AND METHODS

A modified reflector was used to reduce -6 dB beam size of the HM3 lithotripter, while increasing concomitantly peak pressure. Fragmentation in vitro was assessed with modified and original reflectors using BegoStone phantoms. A membrane holder was used to mimic lithotripsy in vivo, and a matrix holder was used to assess variations of fragmentation power in the focal plane of the lithotripter field. Stone fragmentation in vivo produced by the two reflectors was further compared in a swine model.

RESULTS

Stone fragmentation in vitro after 500 (or 2000) shocks was ∼60% (or ∼82%) vs ∼40% (or ∼75%) with original and modified reflector, respectively (p ≤ 0.0016). Fragmentation power with the modified reflector was the highest on the lithotripter axis, but dropped rapidly in the lateral direction and became insignificant at radial distances >6.0 mm. Stone fragmentation with the original reflector was lower along the lithotripter axis, but fragmentation power decayed slowly in lateral direction, with appreciable fragmentation produced at 6.0 mm. Stone fragmentation efficiency in vivo after 500 (or 2000) shocks was ∼70% (or ∼90%) vs ∼45% (or ∼80%) with original and modified reflector, respectively (p ≤ 0.04).

CONCLUSIONS

A lithotripter field with broad beam size yields superior stone comminution when compared with narrow beam size under comparable effective acoustic pulse energy both in vivo and in vitro. These findings may facilitate future improvements in lithotripter design to maximize comminution efficiency while minimizing tissue injury.

Ultrasonic propulsion of kidney stones

PURPOSE OF REVIEW

Ultrasonic propulsion is a novel technique that uses short bursts of focused ultrasonic pulses to reposition stones transcutaneously within the renal collecting system and ureter. The purpose of this review is to discuss the initial testing of effectiveness and safety, directions for refinement of technique and technology, and opinions on clinical application.

RECENT FINDINGS

Preclinical studies with a range of probes, interfaces, and outputs have demonstrated feasibility and consistent safety of ultrasonic propulsion with room for increased outputs and refinement toward specific applications. Ultrasonic propulsion was used painlessly and without adverse events to reposition stones in 14 of 15 human study participants without restrictions on patient size, stone size, or stone location. The initial feasibility study showed applicability in a range of clinically relevant situations, including facilitating passage of residual fragments following ureteroscopy or shock wave lithotripsy, moving a large stone at the ureteropelvic junction with relief of pain, and differentiating large stones from a collection of small fragments.

SUMMARY

Ultrasonic propulsion shows promise as an office-based system for transcutaneously repositioning kidney stones. Potential applications include facilitating expulsion of residual fragments following ureteroscopy or shock wave lithotripsy, repositioning stones prior to treatment, and repositioning obstructing ureteropelvic junction stones into the kidney to alleviate acute renal colic.

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.

Role of Tamsulosin Therapy after Extracorporeal Shockwave Lithotripsy for Renal Stones: Randomized Controlled Trial

INTRODUCTION

To evaluate the efficacy of adjunctive tamsulosin therapy after extracorporeal shockwave lithotripsy (SWL) for renal stones.

MATERIALS AND METHODS

This prospective study was conducted on patients who underwent single-session SWL for solitary renal stone less than 20 mm. Post-SWL, patients were randomly divided into 2 groups; the tamsulosin group (TG), received a daily dose of tamsulosin 0.4 mg, for a maximum of 12 weeks, with post-SWL traditional analgesia and control group (CG), received the traditional analgesia alone.

RESULTS

The study enrolled 271 patients and eventually only 249 (123 in TG and 126 in CG) completed the study. The overall stone free rate was 73.5%: 78.0% in TG and 69.0% in CG (p = 0.108). In TG, 8.1% of patients experienced at least one episode of acute renal/ureteral colic compared with 19.8% of controls (p = 0.008). The mean cumulative analgesia dosage per subject was 313 mg in TG and 346 mg in CG (p < 0.001). Overall, 14 patients developed steinstrasse and 6 of them (all in CG) needed urgent intervention (p = 0.031).

CONCLUSIONS

Daily tamsulosin therapy does not enhance the clearance of stone fragments but decreases the pain episodes, analgesia dosage and need for adjuvant intervention after SWL for renal stones.

Extracorporeal shockwave lithotripsy without radiation: Ultrasound localization is as effective as fluoroscopy

CONTEXT

Extracorporeal shockwave lithotripsy (SWL) is the first-line treatment for renal calculi in most cases. Recent technology has allowed lithotriptor machines to localize stones using fluoroscopy or ultrasound (US).

AIM

The aim of this study is to compare stone free rates (SFR) using two techniques.

METHODS

This is a single center retrospective cohort study. We have studied 95 patients with renal calculi undergoing first SWL treatment with localization using US (48 pts) and fluoroscopy (47 pts). SFR was defined as fragments ≤2 m at 4 weeks post procedure on x-ray or US. Patient records were reviewed.

RESULTS

Stone size and location, age and body mass index were comparable between groups. Stones ≤7 mm had better SFR with US 86% (18/21) compared to fluoroscopy 59% (10/17) P= 0.08. Overall the US group had similar SFR to the fluoroscopy group for stones of all sizes and locations with 60% (29/48) compared to 45% (21/47)P= 0.18. Radiation exposure was the biggest difference between techniques with a mean radiation dose (mGy/cm²) in the US group of 103 (0-233) and 2113 (241-7821) in the fluoroscopy group. Radiation use in the US group was due to the use of a single shot pre- and post-procedure, this could be reduced to zero.

CONCLUSIONS

Our data show equivalent outcomes using US compared to the traditional fluoroscopy localization technique. We would encourage departments to develop the use of US localization to reduce radiation exposure to patients.

Changes in Urolithiasis Referral Patterns for Shock Wave Lithotripsy over a Decade: Was There Adherence to AUA/EAU Guidelines?

OBJECTIVE

The primary objective was to assess changes in referral patterns of urolithiasis for shock wave lithotripsy (SWL) over a decade. The secondary objective was to evaluate the effect of the number of years of practice of referring physicians on these referral patterns.

METHODS

A retrospective review of SWL database was performed for consecutive referrals for SWL at a tertiary stone center between December 1999 and December 2013. Patient demographics and stone characteristics were assessed. The stone location at the time of referral was used as the reference. Retreatments were excluded. In addition, years of practice of the referring physicians were calculated. The 2007 AUA/EAU guidelines on urolithiasis were considered as a reference.

RESULTS

A total of 8,992 SWL treatments were included. After December 2007, there was a significant increase in the percentage of renal pelvic stones referred for SWL (23.0 vs. 27.1%, p < 0.001). Conversely, proximal ureteral stones significantly decreased after 2007 (24 vs. 18.2%, p < 0.001) including stones > 10 mm (5.1 vs. 2.9%, p < 0.001). Otherwise, there were no changes in the referral patterns for SWL of other stone locations before and after December 2007 (p > 0.05). Furthermore, percentage of stones referred for SWL by urologists practicing for less than 10 years significantly decreased after December 2007 (29.5 vs. 22.8%, p < 0.001).

CONCLUSIONS

The significant reduction in the referral of proximal ureteral stones after December 2007 corresponds to the latest AUA/EAU guidelines on management of ureteral stones.

Combined short and long-delay tandem shock waves to improve shock wave lithotripsy according to the Gilmore-Akulichev theory

Extracorporeal shock wave lithotripsy is a common non-invasive treatment for urinary stones whose fragmentation is achieved mainly by acoustic cavitation and mechanical stress. A few years ago, in vitro and in vivo experimentation demonstrated that such fragmentation can be improved, without increasing tissue damage, by sending a second shock wave hundreds of microseconds after the previous wave. Later, numerical simulations revealed that if the second pulse had a longer full width at half maximum than a standard shock wave, cavitation could be enhanced significantly. On the other side, a theoretical study showed that stress inside the stone can be increased if two lithotripter shock waves hit the stone with a delay of only 20 μs. We used the Gilmore-Akulichev formulation to show that, in principle, both effects can be combined, that is, stress and cavitation could be increased using a pressure pulse with long full width at half maximum, which reaches the stone within hundreds of microseconds after two 20 μs-delayed initial shock waves. Implementing the suggested pressure profile into clinical devices could be feasible, especially with piezoelectric shock wave sources.

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

PURPOSE

Management of ureteral stones remains controversial. To determine whether optimizing the extracorporeal shock wave lithotripsy delivery rate would improve the treatment of solitary ureteral stones we compared the outcomes of 2 delivery rates in a prospective randomized trial.

MATERIALS AND METHODS

From July 2010 to October 2012, 254 consecutive patients were randomized to extracorporeal shock wave lithotripsy at a shock wave delivery rate of 60 and 90 pulses per minute in 130 and 124, respectively. The primary study end point was the stone-free rate at 3-month followup. Secondary end points were stone disintegration, treatment time, complications and the rate of secondary treatments. Descriptive statistics were used to compare end points between the 2 groups. The adjusted OR and 95% CI were calculated to assess predictors of success.

RESULTS

The stone-free rate at 3 months was significantly higher in patients who underwent extracorporeal shock wave lithotripsy at a shock wave delivery rate of 90 pulses per minute than in those who received 60 pulses per minute (91% vs 80%, p = 0.01). Patients with proximal (100% vs 83%, p = 0.005) and mid ureteral stones (96% vs 73%, p = 0.03) accounted for the observed difference but not those with distal ureteral stones (81% vs 80%, p = 0.9, respectively). Treatment time, complications and the rate of secondary treatments were comparable between the 2 groups. On multivariable analysis the shock wave delivery rate of 90 pulses per minute, proximal stone location, stone density, stone size and an absent indwelling Double-J® stent were independent predictors of success.

CONCLUSIONS

Optimizing the extracorporeal shock wave lithotripsy delivery rate can achieve excellent results for ureteral stones.

Efficacy of extracorporeal shockwave lithotripsy using Dornier SII in different levels of ureteral stones

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of the Dornier lithotripter S II system in the treatment of ureteral calculi.

PATIENTS AND METHODS

A total of 97 cases which consists of 54 males and 43 females with ureteral stones were treated by extracorporeal shock wave lithotripsy (ESWL). Mean age was 42.6 years. Inclusion criteria were solitary radiopaque ureteral stones of radiological stone size of ≤1 cm. The stones were not impacted, with normal kidney functions. Procedure time, number of shocks, energy used, number of sessions and complications were reported. The outcome of ESWL was also recorded.

RESULTS

Stones were in the abdominal (upper ureter) in 50% of patients, in pelvic (middle ureter) in 47% of patients. All patients had unilateral stones and the mean stone size in maximum length was) 10 mm). Good dye excretion passing the stone was noted in all patients. Mild hydronephrosis was found in 85% of cases. A total of 49 cases were treated by a single session, while in 35% of cases two sessions were enough and 16% received three sessions. The average number of shocks per session was 3125. The average number of shocks per patient was 5962.5 shocks and average energy was 204.3 Joules. The overall stone-free rate 3 months after lithotripsy was 94%. After a single session of lithotripsy, 49 patients (49%) became stone-free. Stone free rates after ESWL for upper, middle ureteral stones were 94%, 95.7% respectively. Additional procedures were needed in only 6 cases (6%) to render patients stone-free after lithotripsy. No serious complications occurred.

CONCLUSION

The Dornier lithotripter S II is very effective in the treatment of ureteral calculi with no major complications.

Fragmentation of urinary calculi in vitro by burst wave lithotripsy

PURPOSE

We developed a new method of lithotripsy that uses short, broadly focused bursts of ultrasound rather than shock waves to fragment stones. We investigated the characteristics of stone comminution by burst wave lithotripsy in vitro.

MATERIALS AND METHODS

Artificial and natural stones (mean ± SD size 8.2 ± 3.0 mm, range 5 to 15) were treated with ultrasound bursts using a focused transducer in a water bath. Stones were exposed to bursts with focal pressure amplitude of 6.5 MPa or less at a 200 Hz burst repetition rate until completely fragmented. Ultrasound frequencies of 170, 285 and 800 kHz were applied using 3 transducers, respectively. Time to fragmentation for each stone type was recorded and fragment size distribution was measured by sieving.

RESULTS

Stones exposed to ultrasound bursts were fragmented at focal pressure amplitudes of 2.8 MPa or greater at 170 kHz. Fractures appeared along the stone surface, resulting in fragments that separated at the surface nearest to the transducer until the stone was disintegrated. All natural and artificial stones were fragmented at the highest focal pressure of 6.5 MPa with a mean treatment duration of 36 seconds for uric acid stones to 14.7 minutes for cystine stones. At a frequency of 170 kHz the largest artificial stone fragments were less than 4 mm. Exposure at 285 and 800 kHz produced only fragments less than 2 mm and less than 1 mm, respectively.

CONCLUSIONS

Stone comminution with burst wave lithotripsy is feasible as a potential noninvasive treatment method for nephrolithiasis. Adjusting the fundamental ultrasound frequency allows for stone fragment size to be controlled.

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter

The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently acquired knowledge of the key lithotripter field characteristics that correlate with efficient and safe SWL. The new lens design addresses concomitantly three fundamental drawbacks in EM lithotripters, namely, narrow focal width, nonidealized pulse profile, and significant misalignment in acoustic focus and cavitation activities with the target stone at high output settings. Key design features and performance of the new lens were evaluated using model calculations and experimental measurements against the original lens under comparable acoustic pulse energy (E+) of 40 mJ. The -6-dB focal width of the new lens was enhanced from 7.4 to 11 mm at this energy level, and peak pressure (41 MPa) and maximum cavitation activity were both realigned to be within 5 mm of the lithotripter focus. Stone comminution produced by the new lens was either statistically improved or similar to that of the original lens under various in vitro test conditions and was significantly improved in vivo in a swine model (89% vs. 54%, P = 0.01), and tissue injury was minimal using a clinical treatment protocol. The general principle and associated techniques described in this work can be applied to design improvement of all EM lithotripters.

Treatment efficacy and outcomes using a third generation shockwave lithotripter

OBJECTIVES

To evaluate the clinical efficiency of a third generation electromagnetic shock wave lithotripter, the Lithoskop(®) (Siemens, Erlangen, Germany), regarding outcomes, stone disintegration, retreatment and complication rates. To compare the results of the Lithoskop with other currently available systems and the reference standard lithotripter, the HM-3 (Dornier MedTech Europe GmbH, Wessling, Germany).

PATIENTS AND METHODS

We analysed the data from 183 patients, including 13 children, undergoing extracorporeal shock wave lithotripsy (ESWL) for renal and ureteric calculi collected from a prospectively populated database. Outcomes were assessed by plain abdominal film of kidney, ureter and bladder and renal ultrasonography for radiopaque and computerized tomography for radiolucent stones 1 day after treatment and after 3 months. We analysed stone size and location before and after treatment, stone disintegration rate, retreatment rate, stone-free and residual fragment rates after 3 months, along with auxiliary procedures and complications.

RESULTS

The mean (range) patient age was 48.6 (1.3-81.4) years, including 13 children with a mean (range) age of 8.4 (1.3-16.7) years, and 77% of the patients were male. In all, 46% of the calculi were localized in the kidney and 54% in the ureter. Renal stones were localized in the upper, middle and lower calyx and in the renal pelvis in 9, 29, 30 and 32% of patients, respectively. Ureteric stones were localized in the upper, mid- and distal ureter in 29, 19 and 52% of patients, respectively. The median (range) stone size before ESWL was 10 (4-25) mm in the kidney and 8 (4-28) mm in the ureteric calculi. The overall stone-free rate after 3 months was 91% (88% for renal and 93% for ureteric calculi); the mean number of sessions to achieve these rates was 1.3. Stone-free rates and the required number of sessions were determined only by stone size. In 7.1% of the patients (n = 13) post-interventional auxiliary procedures were necessary. We observed one perirenal haematoma as a major complication (0.5%), but this did not require any further therapy.

CONCLUSIONS

Clinical stone-free rates with the Lithoskop are high and similar to those of other available systems, including the reference standard HM-3 lithotripter. Retreatment and complication rates are low, supporting the use of ESWL as first-line therapy for urinary calculi <10 mm, independent of stone location.

The efficacy of tamsulosin therapy after extracorporeal shock-wave lithotripsy for ureteric calculi: A prospective randomised, controlled study

OBJECTIVE

To evaluate whether tamsulosin hydrochloride is effective as an adjunctive medical therapy to increase the effectiveness of extracorporeal shock-wave lithotripsy (ESWL) for treating ureteric stones, and minimises the use of analgesic drugs after the procedure.

PATIENTS AND METHODS

To treat single ureteric stones of 5-15 mm in diameter, 130 patients were treated with ESWL. After treatment, equal numbers of patients were randomly assigned to receive either the standard medical therapy alone (controls) or combined with 0.4 mg tamsulosin daily for ⩽12 weeks. All patients were followed up for 3 months or until an alternative treatment was offered.

RESULTS

At 3 months the treatment was considered to be clinically successful in 55/65 (85%) of those receiving tamsulosin and in 58/65 (89%) of the controls (P = 0.34). When patients were classified according to stone size the success rate was similar in both groups (P = 0.22) for those with a stone of >10 mm. However, ureteric colic was reported in 12% of patients treated with standard therapy but in only 5% of those treated with tamsulosin (P = 0.006). The mean cumulative diclofenac dose was 380 mg/patient in the tamsulosin group and 750 mg/patient in the control group (P = 0.004).

CONCLUSIONS

This study showed the effectiveness of tamsulosin as an adjunctive medical therapy after ESWL for ureteric stones, but it did not improve stone clearance when treating ureteric stones. However, it decreased the use of analgesics and reduced the complication rate, especially for steinstrasse.

Comparison of tissue injury from focused ultrasonic propulsion of kidney stones versus extracorporeal shock wave lithotripsy

PURPOSE

Focused ultrasonic propulsion is a new noninvasive technique designed to move kidney stones and stone fragments out of the urinary collecting system. However, to our knowledge the extent of tissue injury associated with this technique is not known. We quantitated the amount of tissue injury produced by focused ultrasonic propulsion under simulated clinical treatment conditions and under conditions of higher power or continuous duty cycles. We compared those results to extracorporeal shock wave lithotripsy injury.

MATERIALS AND METHODS

A human calcium oxalate monohydrate stone and/or nickel beads were implanted by ureteroscopy in 3 kidneys of live pigs weighing 45 to 55 kg and repositioned using focused ultrasonic propulsion. Additional pig kidneys were exposed to extracorporeal shock wave lithotripsy level pulse intensity or continuous ultrasound exposure 10 minutes in duration using an ultrasound probe transcutaneously or on the kidney. These kidneys were compared to 6 treated with an unmodified Dornier HM3 lithotripter (Dornier Medical Systems, Kennesaw, Georgia) using 2,400 shocks at 120 shock waves per minute and 24 kV. Histological analysis was performed to assess the volume of hemorrhagic tissue injury created by each technique according to the percent of functional renal volume.

RESULTS

Extracorporeal shock wave lithotripsy produced a mean ± SEM lesion of 1.56% ± 0.45% of functional renal volume. Ultrasonic propulsion produced no detectable lesion with simulated clinical treatment. A lesion of 0.46% ± 0.37% or 1.15% ± 0.49% of functional renal volume was produced when excessive treatment parameters were used with the ultrasound probe placed on the kidney.

CONCLUSIONS

Focused ultrasonic propulsion produced no detectable morphological injury to the renal parenchyma when using clinical treatment parameters but produced injury comparable in size to that of extracorporeal shock wave lithotripsy when using excessive treatment parameters.

A heuristic model of stone comminution in shock wave lithotripsy

A heuristic model is presented to describe the overall progression of stone comminution in shock wave lithotripsy (SWL), accounting for the effects of shock wave dose and the average peak pressure, P+(avg), incident on the stone during the treatment. The model is developed through adaptation of the Weibull theory for brittle fracture, incorporating threshold values in dose and P+(avg) that are required to initiate fragmentation. The model is validated against experimental data of stone comminution from two stone types (hard and soft BegoStone) obtained at various positions in lithotripter fields produced by two shock wave sources of different beam width and pulse profile both in water and in 1,3-butanediol (which suppresses cavitation). Subsequently, the model is used to assess the performance of a newly developed acoustic lens for electromagnetic lithotripters in comparison with its original counterpart both under static and simulated respiratory motion. The results have demonstrated the predictive value of this heuristic model in elucidating the physical basis for improved performance of the new lens. The model also provides a rationale for the selection of SWL treatment protocols to achieve effective stone comminution without elevating the risk of tissue injury.

Single-shot measurements of the acoustic field of an electrohydraulic lithotripter using a hydrophone array

Piezopolymer-based hydrophone arrays consisting of 20 elements were fabricated and tested for use in measuring the acoustic field from a shock-wave lithotripter. The arrays were fabricated from piezopolymer films and were mounted in a housing to allow submersion into water. The motivation was to use the array to determine how the shot-to-shot variability of the spark discharge in an electrohydraulic lithotripter affects the resulting focused acoustic field. It was found that the dominant effect of shot-to-shot variability was to laterally shift the location of the focus by up to 5 mm from the nominal acoustic axis of the lithotripter. The effect was more pronounced when the spark discharge was initiated with higher voltages. The lateral beamwidth of individual, instantaneous shock waves were observed to range from 1.5 mm to 24 mm. Due to the spatial variation of the acoustic field, the average of instantaneous beamwidths were observed to be 1 to 2 mm narrower than beamwidths determined from traditional single-point measurements that average the pressure measured at each location before computing beamwidth.

Assessment of a modified acoustic lens for electromagnetic shock wave lithotripters in a swine model

PURPOSE

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model.

MATERIALS AND METHODS

Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave treated kidneys were perfused, dehydrated, cast in paraffin wax and sectioned. Digital images were captured every 120 μm and processed to determine functional renal volume damage.

RESULTS

After 500 shocks, the mean ± SD stone fragmentation efficiency produced by the original and modified lenses was 48% ± 12% and 52% ± 17%, respectively (p = 0.60). However, after 2,000 shocks, the modified lens showed significantly improved stone fragmentation compared to the original lens (mean 86% ± 10% vs 72% ± 12%, p = 0.02). Tissue injury caused by the original and modified lenses was minimal at a mean of 0.57% ± 0.44% and 0.25% ± 0.25%, respectively (p = 0.27).

CONCLUSIONS

With lens modification the Modularis lithotripter demonstrates significantly improved stone fragmentation with minimal tissue injury at a clinically relevant acoustic pulse energy. This new lens design could potentially be retrofitted to existing lithotripters, improving the effectiveness of electromagnetic lithotripters.

Evaluation of the LithoGold LG-380 lithotripter: in vitro acoustic characterization and assessment of renal injury in the pig model

PURPOSE

Conduct a laboratory evaluation of a novel low-pressure, broad focal zone electrohydraulic lithotripter (TRT LG-380).

METHODS

Mapping of the acoustic field of the LG-380, along with a Dornier HM3, a Storz Modulith SLX, and a XiXin CS2012 (XX-ES) lithotripter was performed using a fiberoptic hydrophone. A pig model was used to assess renal response to 3000 shockwaves (SW) administered by a multistep power ramping protocol at 60 SW/min, and when animals were treated at the maximum power setting at 120 SW/min. Injury to the kidney was assessed by quantitation of lesion size and routine measures of renal function.

RESULTS

SW amplitudes for the LG-380 ranged from (P(+)/P(-)) 7/-1.8 MPa at PL-1 to 21/-4 MPa at PL-11 while focal width measured ~20 mm, wider than the HM3 (8 mm), SLX (2.6 mm), or XX-ES (18 mm). For the LG-380, there was gradual narrowing of the focal width to ~10 mm after 5000 SWs, but this had negligible effect on breakage of model stones, because stones positioned at the periphery of the focal volume (10 mm off-axis) broke nearly as well as stones at the target point. Kidney injury measured less than 0.1% FRV (functional renal volume) for pigs treated using a gradual power ramping protocol at 60 SW/min and when SWs were delivered at maximum power at 120 SW/min.

CONCLUSIONS

The LG-380 exhibits the acoustic characteristics of a low-pressure, wide focal zone lithotripter and has the broadest focal width of any lithotripter yet reported. Although there was a gradual narrowing of focal width as the electrode aged, the efficiency of stone breakage was not affected. Because injury to the kidney was minimal when treatment followed either the recommended slow SW-rate multistep ramping protocol or when all SWs were delivered at fast SW-rate using maximum power, this appears to be a relatively safe lithotripter.

Size and location of defects at the coupling interface affect lithotripter performance

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? In shock wave lithotripsy air pockets tend to get caught between the therapy head of the lithotripter and the skin of the patient. Defects at the coupling interface hinder the transmission of shock wave energy into the body, reducing the effectiveness of treatment. This in vitro study shows that ineffective coupling not only blocks the transmission of acoustic pulses but also alters the properties of shock waves involved in the mechanisms of stone breakage, with the effect dependent on the size and location of defects at the coupling interface.

OBJECTIVE

• To determine how the size and location of coupling defects caught between the therapy head of a lithotripter and the skin of a surrogate patient (i.e. the acoustic window of a test chamber) affect the features of shock waves responsible for stone breakage.

MATERIALS AND METHODS

• Model defects were placed in the coupling gel between the therapy head of a Dornier Compact-S electromagnetic lithotripter (Dornier MedTech, Kennesaw, GA, USA) and the Mylar (biaxially oriented polyethylene terephthalate) (DuPont Teijin Films, Chester, VA, USA) window of a water-filled coupling test system. • A fibre-optic probe hydrophone was used to measure acoustic pressures and map the lateral dimensions of the focal zone of the lithotripter. • The effect of coupling conditions on stone breakage was assessed using gypsum model stones.

RESULTS

• Stone breakage decreased in proportion to the area of the coupling defect; a centrally located defect blocking only 18% of the transmission area reduced stone breakage by an average of almost 30%. • The effect on stone breakage was greater for defects located on-axis and decreased as the defect was moved laterally; an 18% defect located near the periphery of the coupling window (2.0 cm off-axis) reduced stone breakage by only ~15% compared to when coupling was completely unobstructed. • Defects centred within the coupling window acted to narrow the focal width of the lithotripter; an 8.2% defect reduced the focal width ~30% compared to no obstruction (4.4 mm vs 6.5 mm). • Coupling defects located slightly off centre disrupted the symmetry of the acoustic field; an 18% defect positioned 1.0 cm off-axis shifted the focus of maximum positive pressure ~1.0 mm laterally. • Defects on and off-axis imposed a significant reduction in the energy density of shock waves across the focal zone.

CONCLUSIONS

• In addition to blocking the transmission of shock-wave energy, coupling defects also disrupt the properties of shock waves that play a role in stone breakage, including the focal width of the lithotripter and the symmetry of the acoustic field • The effect is dependent on the size and location of defects, with defects near the centre of the coupling window having the greatest effect. • These data emphasize the importance of eliminating air pockets from the coupling interface, particularly defects located near the centre of the coupling window.

Stone comminution correlates with the average peak pressure incident on a stone during shock wave lithotripsy

To investigate the roles of lithotripter shock wave (LSW) parameters and cavitation in stone comminution, a series of in vitro fragmentation experiments have been conducted in water and 1,3-butanediol (a cavitation-suppressive fluid) at a variety of acoustic field positions of an electromagnetic shock wave lithotripter. Using field mapping data and integrated parameters averaged over a circular stone holder area (R(h)=7 mm), close logarithmic correlations between the average peak pressure (P(+(avg))) incident on the stone (D=10 mm BegoStone) and comminution efficiency after 500 and 1000 shocks have been identified. Moreover, the correlations have demonstrated distinctive thresholds in P(+(avg)) (5.3 MPa and 7.6 MPa for soft and hard stones, respectively), that are required to initiate stone fragmentation independent of surrounding fluid medium and LSW dose. These observations, should they be confirmed using other shock wave lithotripters, may provide an important field parameter (i.e., P(+(avg))) to guide appropriate application of SWL in clinics, and facilitate device comparison and design improvements in future lithotripters.

Extracorporeal shock wave lithotripsy (ESWL) versus ureteroscopic management for ureteric calculi

BACKGROUND

Ureteral stones frequently cause renal colic, and if left untreated, can lead to obstructive uropathy. Extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy, with or without intracorporeal lithotripsy, are the most common interventions used to treat ureteral stones. ESWL treatment is less invasive than ureteroscopy, but has some limitations such as a high retreatment rate, and is not available in all centres. Recent advances in ureteroscopy have increased success rates and reduced complication rates.

OBJECTIVES

To examine evidence from randomised controlled trials (RCTs) on the outcomes of ESWL or ureteroscopy in the treatment of ureteric calculi.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library Issue 2, 2011), MEDLINE (1966 to March 2011), EMBASE (1980 to March 2011), CINAHL, Clinicaltrials.gov, Google Scholar, reference lists of articles and abstracts from conference proceedings, all without language restriction.

SELECTION CRITERIA

RCTs that compared ESWL with ureteroscopic retrieval of ureteric stones were included in this review. Study participants were adults with ureteric stones requiring intervention. Published and unpublished sources were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed study quality, risk of bias, and extracted data. Statistical analyses were performed using the random-effects model. Results were expressed as risk ratios (RR) for dichotomous outcomes or mean differences (MD) for continuous data, both with 95% confidence intervals (CI).

MAIN RESULTS

Seven RCTs (1205 patients) were included in the review. Stone-free rates were lower in patients who underwent ESWL (7 studies, 1205 participants: RR 0.84, 95% CI 0.73 to 0.96) but re-treatment rates were lower in ureteroscopy patients (6 studies, 1049 participants: RR 6.18, 95% CI 3.68 to 10.38. ESWL-treated patients had less need for auxiliary treatment (5 studies, 751 participants: RR 0.43, 95% CI 0.25 to 0.74; fewer complications (7 studies, 1205 participants: RR 0.54, 95% CI 0.33 to 0.88); and shorter length of hospital stay (2 studies, 198 participants: MD -2.55 days, 95% CI -3.24 to -1.86).Three studies adequately described the randomisation sequence, three studies were unclear on how they randomised, while one study had a high risk of selection bias. All the studies had an unclear risk of performance bias and detection bias, while all had a low risk of attrition bias, reporting bias, or other sources of bias identified.

AUTHORS' CONCLUSIONS

Compared with ESWL, ureteroscopic removal of ureteral stones achieves a greater stone-free state, but with a higher complication rate and longer hospital stay.

Evaluation of shock wave lithotripsy injury in the pig using a narrow focal zone lithotriptor

What's known on the subject? and What does the study add? Of all the SW lithotriptors manufactured to date, more research studies have been conducted on and more is known about the injury (both description of injury and how to manipulate injury size) produced by the Dornier HM-3 than any other machine. From this information have come suggestions for treatment protocols to reduce shock wave (SW)-induced injury for use in stone clinics. By contrast, much less is known about the injury produced by narrow-focus and high-pressure lithotriptors like the Storz Modulith SLX. In fact, a careful study looking at the morphology of the injury produced by the SLX itself is lacking, as is any study exploring ways to reduce renal injury by manipulating SW delivery variables of this lithotriptor. The present study quantitates the lesion size and describes the morphology of the injury produced by the SLX. In addition, we report that reducing the SW delivery rate, a manoeuvre known to lower injury in the HM-3, does not reduce lesion size in the SLX.

OBJECTIVE

• To assess renal injury in a pig model after treatment with a clinical dose of shock waves using a narrow focal zone (≈3 mm) lithotriptor (Modulith SLX, Karl Storz Lithotripsy).

MATERIALS AND METHODS

• The left kidney of anaesthetized female pigs were treated with 2000 or 4000 shock waves (SWs) at 120 SWs/min, or 2000 SWs at 60 SWs/min using the Storz SLX. • Measures of renal function (glomerular filtration rate and renal plasma flow) were collected before and 1 h after shock wave lithotripsy (SWL) and the kidneys were harvested for histological analysis and morphometric quantitation of haemorrhage in the renal parenchyma with lesion size expressed as a percentage of functional renal volume (FRV). • A fibre-optic probe hydrophone was used to determine acoustic output and map the focal width of the lithotriptor. • Data for the SLX were compared with data from a previously published study in which pigs of the same age (7-8 weeks) were treated (2000 SWs at 120 or 60 SWs/min) using an unmodified Dornier HM3 lithotriptor.

RESULTS

• Treatment with the SLX produced a highly focused lesion running from cortex to medulla and often spanning the full thickness of the kidney. Unlike the diffuse interstitial haemorrhage observed with the HM3, the SLX lesion bore a blood-filled core of near-complete tissue disruption devoid of histologically recognizable kidney structure. • Despite the intensity of tissue destruction at the core of the lesion, measures of lesion size based on macroscopic determination of haemorrhage in the parenchyma were not significantly different from kidneys treated using the HM3 (2000 SWs, 120 SWs/min: SLX, 1.86 ± 0.52% FRV; HM3, 3.93 ± 1.29% FRV). • Doubling the SW dose of the SLX from 2000 to 4000 SWs did not significantly increase lesion size. In addition, slowing the firing rate of the SLX to 60 SWs/min did not reduce the size of the lesion (2.16 ± 0.96% FRV) compared with treatment at 120 SWs/min, as was the case with the HM3 (0.42 ± 0.23% FRV vs 3.93 ± 1.29% FRV). • Renal function fell significantly below baseline in all treated groups but was similar for both lithotriptors. • Focal width of the SLX (≈2.6 mm) was about one-third that of the HM3 (≈8 mm) while peak pressures were higher (SLX at power level 9: P+≈90 MPa, P-≈-12 MPa; HM3 at 24 kV: P+≈46 MPa, P-≈-8 MPa).

CONCLUSIONS

• The lesion produced by the SLX (narrow focal width, high acoustic pressure) was a more focused, more intense form of tissue damage than occurs with the HM3. • Slowing the SW rate to 60 SWs/min, a strategy shown to be effective in reducing injury with the HM3, was not protective with the SLX. • These findings suggest that the focal width and acoustic output of a lithotriptor affect the renal response to SWL.

Extracorporeal shock wave lithotripsy (ESWL) versus ureteroscopic management for ureteric calculi

BACKGROUND

Ureteral stones frequently cause renal colic, and if left untreated, can lead to obstructive uropathy. Extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy, with or without intracorporeal lithotripsy, are the most common interventions used to treat ureteral stones. ESWL treatment is less invasive than ureteroscopy, but has some limitations such as a high retreatment rate, and is not available in all centres. Recent advances in ureteroscopy have increased success rates and reduced complication rates.

OBJECTIVES

To examine evidence from randomised controlled trials (RCTs) on the outcomes of ESWL or ureteroscopy in the treatment of ureteric calculi.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library Issue 2, 2011), MEDLINE (1966 to March 2011), EMBASE (1980 to March 2011), CINAHL, Clinicaltrials.gov, Google Scholar, reference lists of articles and abstracts from conference proceedings, all without language restriction.

SELECTION CRITERIA

RCTs that compared ESWL with ureteroscopic retrieval of ureteric stones were included in this review. Study participants were adults with ureteric stones requiring intervention. Published and unpublished sources were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed study quality, risk of bias, and extracted data. Statistical analyses were performed using the random-effects model. Results were expressed as risk ratios (RR) for dichotomous outcomes or mean differences (MD) for continuous data, both with 95% confidence intervals (CI).

MAIN RESULTS

Seven RCTs (1205 patients) were included in the review. Stone-free rates were lower in patients who underwent ESWL (7 studies, 1205 participants: RR 0.84, 95% CI 0.73 to 0.96) but re-treatment rates were lower in ureteroscopy patients (6 studies, 1049 participants: RR 6.18, 95% CI 3.68 to 10.38. ESWL-treated patients had less need for auxiliary treatment (5 studies, 751 participants: RR 0.43, 95% CI 0.25 to 0.74; fewer complications (7 studies, 1205 participants: RR 0.54, 95% CI 0.33 to 0.88); and shorter length of hospital stay (2 studies, 198 participants: MD -2.55 days, 95% CI -3.24 to -1.86).Three studies adequately described the randomisation sequence, three studies were unclear on how they randomised, while one study had a high risk of selection bias. All the studies had an unclear risk of performance bias and detection bias, while all had a low risk of attrition bias, reporting bias, or other sources of bias identified.

AUTHORS' CONCLUSIONS

Compared with ESWL, ureteroscopic removal of ureteral stones achieves a greater stone-free state, but with a higher complication rate and longer hospital stay.

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.

Should percutaneous nephrolithotripsy be considered the primary therapy for lower pole stones?

PURPOSE

The efficacy of percutaneous nephrolithotripsy (PCNL) as a primary therapy for the treatment of lower pole caliceal lithiasis was determined.

MATERIALS AND METHODS

We reviewed 144 consecutive files of patients, over a period of 10 years, with noncomplicated lower pole calculi, who underwent PCNL after a single unsuccessful session of extracorporeal shockwave lithotripsy (SWL).

RESULTS

The stone-free rate for stones less than 10 mm was 95%. A 97% rate was accomplished for stones between 11 and 20 mm and a 98% rate for stones larger than 20 mm. PCNL achieved a mean overall stone-free rate of 96.7% after a 3-month follow-up, regardless of stone size. PCNL outclasses SWL, when stratified by stone burden and lower pole location. No significant postoperative complications were encountered.

CONCLUSION

PCNL is a safe and effective procedure for the management of lower pole caliceal calculi after a single unsuccessful SWL session. This procedure should be considered the primary method for the treatment of lower pole stones.

Effect of lithotripter focal width on stone comminution in shock wave lithotripsy

Using a reflector insert, the original HM-3 lithotripter field at 20 kV was altered significantly with the peak positive pressure (p(+)) in the focal plane increased from 49 to 87 MPa while the -6 dB focal width decreased concomitantly from 11 to 4 mm. Using the original reflector, p(+) of 33 MPa with a -6 dB focal width of 18 mm were measured in a pre-focal plane 15-mm proximal to the lithotripter focus. However, the acoustic pulse energy delivered to a 28-mm diameter area around the lithotripter axis was comparable ( approximately 120 mJ). For all three exposure conditions, similar stone comminution ( approximately 70%) was produced in a mesh holder of 15 mm after 250 shocks. In contrast, stone comminution produced by the modified reflector either in a 15-mm finger cot (45%) or in a 30-mm membrane holder (14%) was significantly reduced from the corresponding values (56% and 26%) produced by the original reflector (no statistically significant differences were observed between the focal and pre-focal planes). These observations suggest that a low-pressure/broad focal width lithotripter field will produce better stone comminution than its counterpart with high-pressure/narrow focal width under clinically relevant in vitro comminution conditions.

Shock wave lithotripsy: advances in technology and technique

Shock wave lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with shock waves carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to shock waves and to determine the mechanisms of shock wave action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower shock wave rate using a step-wise protocol. The aim is to achieve stone comminution using as few shock waves and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future.

Lithotripsy

Shock wave lithotripsy (SWL) is the process of fragmentation of renal or ureteric stones by the use of repetitive shock waves generated outside the body and focused onto the stone. Following its introduction in 1980, SWL revolutionized the treatment of kidney stones by offering patients a non-invasive procedure. It is now seen as a mature technology and its use is perceived to be routine. It is noteworthy that, at the time of its introduction, there was a great effort to discover the mechanism(s) by which it works, and the type of sound field that is optimal. Although nearly three decades of subsequent research have increased the knowledge base significantly, the mechanisms are still controversial. Furthermore there is a growing body of evidence that SWL results in injury to the kidney which may have long-term side effects, such as new onset hypertension, although again there is much controversy within the field. Currently, use of lithotripsy is waning, particularly with the advent of minimally invasive ureteroscopic approaches. The goal here is to review the state of the art in SWL and to present the barriers and challenges that need to be addressed for SWL to deliver on its initial promise of a safe, effective, non-invasive treatment for kidney stones.

Predictive factors of lower calyceal stone clearance after extracorporeal shockwave lithotripsy (ESWL): the impact of radiological anatomy

BACKGROUND

This study was carried out to determine whether or not there is a significant relationship between the radiologic anatomy of the lower calyx, as seen on preoperative intravenous urography (IVU), and the outcome of stone clearance after extracorporeal shockwave lithotripsy (ESWL) for lower renal calyceal stones.

METHODS

Between June 1998 and April 2007, 112 patients with a solitary lower renal calyceal stone measuring 20 mm or less in size were enrolled in this retrospective study. Pretreatment IVU was reviewed for measuring the anatomical predictors, such as lower pole infundibular length, infundibular width (IW) and infundibulopelvic angle, while the stone location and size were determined on plain abdominal X-ray. All patients were treated with ESWL using a Siemens Lithostar Plus lithotriptor and were followed-up for the outcome of stone clearance 3 months after ESWL with plain abdominal X-ray films and ultrasonography.

RESULTS

Three months after ESWL, only 49 (43.7%) patients were stone-free. Under multivariate analysis with logistic regression, smaller stone size (10 mm or less, p = 0.005) and greater IW (4 mm or more, p = 0.029) were significant favourable predictors for better stone clearance.

CONCLUSION

In addition to the influence of stone size, lower pole anatomy, especially IW, has a significant impact on stone clearance for lower calyceal stone after ESWL.

Effect of initial shock wave voltage on shock wave lithotripsy-induced lesion size during step-wise voltage ramping

OBJECTIVE

To determine if the starting voltage in a step-wise ramping protocol for extracorporeal shock wave lithotripsy (SWL) alters the size of the renal lesion caused by the SWs.

MATERIALS AND METHODS

To address this question, one kidney from 19 juvenile pigs (aged 7-8 weeks) was treated in an unmodified Dornier HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA) with either 2000 SWs at 24 kV (standard clinical treatment, 120 SWs/min), 100 SWs at 18 kV followed by 2000 SWs at 24 kV or 100 SWs at 24 kV followed by 2000 SWs at 24 kV. The latter protocols included a 3-4 min interval, between the 100 SWs and the 2000 SWs, used to check the targeting of the focal zone. The kidneys were removed at the end of the experiment so that lesion size could be determined by sectioning the entire kidney and quantifying the amount of haemorrhage in each slice. The average parenchymal lesion for each pig was then determined and a group mean was calculated.

RESULTS

Kidneys that received the standard clinical treatment had a mean (sem) lesion size of 3.93 (1.29)% functional renal volume (FRV). The mean lesion size for the 18 kV ramping group was 0.09 (0.01)% FRV, while lesion size for the 24 kV ramping group was 0.51 (0.14)% FRV. The lesion size for both of these groups was significantly smaller than the lesion size in the standard clinical treatment group.

CONCLUSIONS

The data suggest that initial voltage in a voltage-ramping protocol does not correlate with renal damage. While voltage ramping does reduce injury when compared with SWL with no voltage ramping, starting at low or high voltage produces lesions of the same approximate size. Our findings also suggest that the interval between the initial shocks and the clinical dose of SWs, in our one-step ramping protocol, is important for protecting the kidney against injury.