Shock Wave Lithotripsy Success Research Articles

Internal Structure of Kidney Calculi as a Predictor for Shockwave Lithotripsy Success.

The internal structure of renal calculi can be determined on CT using bone windows and may be classified as homogeneous or inhomogeneous with void regions. In vitro studies have shown homogeneous stones to be less responsive to extracorporeal shockwave lithotripsy (SWL). The objective was to evaluate whether the internal morphology of calculi defined by CT bone window influences SWL outcome in vivo. One hundred eleven patients with solitary renal calculi treated with SWL were included. Treatment data were registered prospectively and follow-up data were collected retrospectively. All patients had noncontrast computed tomography (NCCT) performed before SWL and at 3-month follow-up. The stones were categorized as homogeneous or inhomogeneous. At follow-up, the patient's stone status was registered. Stone-free status was defined as no evidence of calculi on NCCT. Treatment was considered successful if the patient was either stone free or had clinically insignificant residual fragments. Using simple logistic regression, the odds for being stone free 3 months post-SWL were significantly reduced in the patients with inhomogeneous stones compared with patients with homogeneous stones (odds ratio 0.43 [95% confidence interval 0.20, 0.92; p < 0.05]). However, when adjusting for stone size by multiple logistic regression, including stone size (area) as a covariate, this difference became insignificant. The internal structure of kidney stones did not predict the outcome of SWL in vivo.

Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.

This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6±3mm) were scanned using a dual-source CT machine with single- (120kVp) and dual-energy settings (80/150, 100/150SnkVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P<0.01) for the number of required shock waves with the best prediction at 80kVp (β estimate 0.576) (P<0.05). Correlation coefficients between attenuation/DEI and the number of required shock waves ranged between ρ=0.31 and 0.68 showing the best correlation at 80kVp (P<0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.

The combination of furosemide and intravenous hydration does not affect the success of shock wave lithotripsy in renal stone treatment: a prospective randomised single blinded trial

ObjectivesTo investigate the effect of furosemide given before shock wave lithotripsy (SWL) in patients with renal stones.MethodsTwo-hundred patients with renal stones measuring 6–20 mm in diameter were prospectively included in...

917 A Meta-Analysis and Systematic Review: Success of Extracorporeal Shock Wave Lithotripsy in Chronic Calcific Pancreatitis Management

917 A Meta-Analysis and Systematic Review: Success of Extracorporeal Shock Wave Lithotripsy in Chronic Calcific Pancreatitis Management

97 Factors predicting success of second shock wave lithotripsy for upper urinary tract calculi

97 Factors predicting success of second shock wave lithotripsy for upper urinary tract calculi

The effect of renal cortical thickness on the treatment outcomes of kidney stones treated with shockwave lithotripsy.

PurposeBecause the shock wave passes through various body tissues before reaching the stone, stone composition may affect the treatment efficacy of shock wave lithotripsy (SWL). We investigated the effect of various tissue components along the shock wave path on the success of SWL.Materials and MethodsFrom October 2008 to August 2010, a total of 206 patients with kidney stones sized 5 to 20 mm were prospectively recruited for a study of the factors that affect the outcome of treatment with a Sonolith Vision lithotripter. Successful SWL was defined as either stone-free status or residual fragments <4 mm at 12 weeks. Logistic regression analysis was performed to assess the factors that predicted treatment outcomes. Potential predictors included the patient's age, shock wave delivery rate, stone volume (SV), mean stone density (MSD), skin-to-stone distance (SSD), and the mean thickness of the three main components along the shock wave path: renal cortical thickness (KT), muscle thickness (MT), and soft-tissue thickness (ST).ResultsThe mean age of the patients was 53.8 years (range, 25-82 years). The overall treatment success rate after one session of SWL was 43.2%. The mean KT, MT, and ST were 26.9, 16.6, and 40.8 mm, respectively. The logistic regression results showed that a slower shock wave delivery rate, smaller SV, a lower MSD, and a thicker KT were found to be significant predictors for successful SWL. SSD, MT, and ST were not predictors of successful treatment.ConclusionsAmong the main tissue components along the shock wave path, a thicker KT was a favorable factor for successful SWL after adjustment for SV, MSD, and the shock wave delivery rate.

Strategies to optimize shock wave lithotripsy outcome: Patient selection and treatment parameters

Shock wave lithotripsy (SWL) was introduced in 1980, modernizing the treatment of upper urinary tract stones, and quickly became the most commonly utilized technique to treat kidney stones. Over the past 5-10 years, however, use of SWL has been declining because it is not as reliably effective as more modern technology. SWL success rates vary considerably and there is abundant literature predicting outcome based on patient- and stone-specific parameters. Herein we discuss the ways to optimize SWL outcomes by reviewing proper patient selection utilizing stone characteristics and patient features. Stone size, number, location, density, composition, and patient body habitus and renal anatomy are all discussed. We also review the technical parameters during SWL that can be controlled to improve results further, including type of anesthesia, coupling, shock wave rate, focal zones, pressures, and active monitoring. Following these basic principles and selection criteria will help maximize success rate.

Ureteral wall thickness at the impacted ureteral stone site: a critical predictor for success rates after SWL.

The aim of the study was to determine the possible predictive value of certain patient- and stone-related factors on the stone-free rates and auxiliary procedures after extracorporeal shock wave lithotripsy in patients with impacted proximal ureteral calculi. A total of 111 patients (86 male, 25 females M/F: 3.44/1) with impacted proximal ureteral stones treated with shock wave lithotripsy were evaluated. Cases were retrieved from a departmental shock wave lithotripsy database. Variables analyzed included BMI of the case, diameter of proximal ureter and renal pelvis, stone size and Hounsfield unit, ureteral wall thickness at the impacted stone site. Stone-free status on follow-up imaging at 3 months was considered a successful outcome. All patients had a single impacted proximal ureteral stone. While the mean age of the cases was 46 ± 13 years (range 26-79 years), mean stone size was 8.95 mm (5.3-15.1 mm). Following shock wave lithotripsy although 87 patients (78.4%) were completely stone-free at 3-month follow-up visit, 24 (21.6%) cases had residual fragments requiring further repeat procedures. Prediction of the final outcome of SWL in patients with impacted proximal ureteral stones is a challenging issue and our data did clearly indicate a highly significant relationship between ureteral wall thickness and the success rates of shock wave lithotripsy particularly in cases requiring additional procedures. Of all the evaluated stone- and patient-related factors, only ureteral wall thickness at the impacted stone site independently predicted shock wave lithotripsy success.

Evaluation of computed tomography findings for success prediction after extracorporeal shock wave lithotripsy for urinary tract stone disease.

Currently, the most widely used method of treatment of urinary tract stones is extracorporeal shock wave lithotripsy (SWL). Patient and stone characteristics are important for SWL success. We evaluated noncontrast computed tomography (NCCT) characteristics of urinary tract stones for the prediction of SWL success. Records of patients who underwent NCCT before SWL treatment between January 2008 and June 2012 were retrospectively evaluated. Demographic data were recruited from patient files. Hounsfield units (HU), stone size and skin-to-stone distance (SSD) were measured on NCCT. After serial measurements of the highest HU value (HUmax) and lowest HU value (HUmin), HU value was calculated as the average of these two values (HUave). These parameters were compared between successful [stone-free (SF) group] and unsuccessful [residual fragment (RF) group] cases after SWL. A total of 254 patients, 113 kidney stones and 141 ureteral stones, were evaluated. Mean age was 51.0±14.6 (18-87) years, and mean stone size was 10.9±3.7 mm. Stone diameter, HUmax, HUmin and HUave were significantly lower in SF group when compared with RF group for both kidney and ureteral stones (p<0.05). We also found that SSD for kidney stones was predictive for SWL success. We suggest that HUmax, HUmin and HUave values are significant predictors of SWL success for both kidney and ureteral stones. They might be used in daily clinical practice for patient counselling.

What have we learned about shock wave lithotripsy in the past thirty years?

Shock wave lithotripsy (SWL) has revolutionized the treatment of kidney stone disease since its introduction in the early 1980s. Considering the paucity of knowledge about the bioeffects of shockwaves in various tissues and renal concretions 30 years ago, the success of SWL is a truly remarkable fest on its own. We have learned a lot since then. New technologies have been introduced for shock wave generation, focusing, and measurement, among others. In parallel, new knowledge has been acquired progressively about the mechanisms of stone comminution and tissue injury. Yet there are still outstanding issues that are constantly debated, waiting for resolution. In this talk, the quest for a better understanding of the shockwave interaction with stones and renal tissue in the field of SWL will be reviewed in chronological order. Focus will be on stress waves and cavitation for their distinctly different (for their origin), yet often synergistically combined (in their action), roles in the critical processes of SWL. This historical review will be followed by a discussion of the recent development and future prospects of SWL technologies that may ultimately help to improve the clinical performance and safety of contemporary shock wave lithotripters. [Work supported by NIH through 5R37DK052985-18.]

The usefulness of stone density and patient stoutness in predicting extracorporeal shock wave efficiency: Results in a North African ethnic group.

We determine the role of stone density and skin-to-stone distance (SSD) by non-contrast computed tomography of the kidneys, ureters and bladder (CT-KUB) in predicting the success of extracorporeal shock wave lithotripsy (ESWL). We evaluated 89 patients who received ESWL for renal and upper ureteric calculi measuring 5 to 20 mm, over a 12-month period. The mean stone density in Hounsfield units (HU) and mean SSD in mm was determined on pre-treatment CT-KUB at the CT workstation. ESWL was successful if post-treatment residual stone fragments were ≤3 mm. ESWL success was observed in 68.5% of patients. Mean stone densities were 505 ± 153 and 803 ± 93 HU in the ESWL successful and failure groups, respectively (p < 0.001, student's t-test). The mean SSD were 10.6 ± 2.0 and 11.2 ± 2.6 cm in ESWL successful and failure groups, respectively; this was not statistically significant. This study shows that stone density can help to predict the outcome of ESWL. We propose that stone density <500 HU are highly likely to result in successful ESWL. Conversely, stone densities >800 HU are less likely to be successful.

The Role of Plain Radiography in Predicting Renal Stone Fragmentation by Shockwave Lithotripsy in the Era of Noncontrast Multidetector Computed Tomography

The objective of this study is to determine if plain radiography has a role in prediction of stone fragmentation by shockwave lithotripsy (SWL). Our study included 106 patients undergoing SWL for renal stones. Based on plain radiography criteria, stones were classified according to density, homogeneity, and outline. We compared the success of SWL in fragmentation of stones with a density equal to or less than bone, nonhomogeneous stones, and stones with irregular outline to its success in stones with a density more than bone, homogeneous stones, and stones with smooth outline. In plain radiography, stone density equal to or less than bone, nonhomogeneous stones, and stones with irregular outline showed successful SWL fragmentation in 88.8%, 91.2%, and 90.6%, respectively. Stones with a density more than bone, homogeneous stones, and stones with smooth outline showed successful SWL fragmentation in 52.9%, 52.6%, and 57.1%, respectively. CT attenuation value was significantly less in stones successfully fragmented by SWL compared with nonfragmented stone (649±169 and 1465±256, respectively). In homogeneous stones with smooth outline having a density more than bone, we found a significantly lower CT attenuation in patients with successful stone fragmentation by SWL compared with those with failed stone fragmentation (690.9±171 and 1462±212, respectively). In relatively large solitary renal pelvic stones, plain radiography can predict the success of stone fragmentation by SWL. Nonhomogeneous stones with irregular outline and a density equal to or less than bone are expected to be successfully fragmented by SWL. Noncontrast CT is only needed, to predict success of SWL, in cases of homogeneous stones with smooth outline and density more than bone.

Editorial comment on “Efficacy of a mobile lithotripsy service: A one-year review of 222 patients”

This is an interesting and important article that clearly reflects some of the problems of shockwave lithotripsy (SWL) today. The clearly presented results show that successful SWL requires a considerable input that most certainly is difficult to achieve in a mobile lithotripter organization and with treatments carried out entirely by technicians. With full respect to the skill of qualified SWL technicians, there are several treatment variables that need consideration and modification in order to achieve acceptable results. When the responsibility of this technique more or less completely is handed over to technicians and nurses, it stands to reason that the procedure in most or at least in several cases will be carried out it a stereotyped way. When the responsible urologist accordingly has very limited experience of the technique the results will be inferior. It is, for instance, my own experience that effective SWL requires adequate pain relief, and just a small dose of paracetamol and tramadol (if needed!) is probably insufficient. I strongly agree with the authors that the lithotripter service needs to be stationary. But it is also necessary to make certain that the lithotripters are run by operators who can modify the procedure according to the course of the disintegration progress. Moreover, there is a need for strict follow-up routines with the possibility of repeating the SWL if necessary, rather than immediately switching to an invasive solution. If we continue to ignore the many basic principles of SWL an increasing number of patients will be treated with anaesthesiarequiring endoscopic and more expensive procedures.

Skin-to-Stone Distance Has No Impact on Outcomes of Percutaneous Nephrolithotomy

Objective: Skin-to-stone distance (SSD) is a stronger factor than body mass index in predicting the success of shock wave lithotripsy. We aimed to evaluate the impact of SSD on outcomes of percutaneous nephrolithotomy (PCNL). Materials and Methods: The medical records of 1,280 patients who had undergone PCNL between April 2007 and February 2012 were evaluated retrospectively. 192 patients who had had preoperative non-contrasted computed tomography and single renal access were included the study. According to this median SSD value, patients were divided into two groups: group 1 (SSD ≤94 mm) (n = 92) and group 2 (SSD >94 mm) (n = 90). The groups were compared according to operative and postoperative parameters. Results: We found no significant differences between the two groups with regard to stone-free rate, operation time, fluoroscopy time, hospitalization time, visual analog score of pain, stone burden, transfusion rates and complication rates. On the other hand, the mean body mass index of group 1 was significantly lower than that of group 2 (p < 0.05). Conclusions: In this retrospective review of patients undergoing PCNL, we found that SSD has no impact on operative and postoperative outcomes. These results were in accordance with the safety of PCNL in obese patients.

Efficacy of shock wave lithotripsy in management of kidney stones in infants

Introduction and objectivesDespite being uncommon, infantile kidney stone remains a major health problem due to its higher recurrence rate and morbidity. The parents usually notice that their infants have recurrent fever and failure to thrive of unknown origin. Those patients comprise a big challenge for the urologist in management. Therefore, this study aimed to evaluate the outcome of shockwave lithotripsy (SWL) in management of renal stones in infants. Subjects and methodsA retrospective analysis of prospectively collected data performed between January 2009 and December 2012 for infants underwent SWL for single radio-opaque renal stones ≤15mm at a single stone center. SWL was performed with Dorneir S lithotripter with a maximum of 1500 shocks per session. A single session was indicated for each infant, but a second session was performed when satisfactory disintegration was not achieved. Follow-up based on urinalysis, urine culture and sensitivity, plain X-ray kidney ureter bladder (KUB) and abdominal ultrasonography (US) was carried out 2 weeks post SWL and monthly for 3 successive months. Multislice Computed tomography (MSCT) was performed 3-months post-SWL to confirm the stone-free status. ResultsA total of 87 infants, less than 24 months of age were enrolled in this research. SWL success was defined as absence of any residual fragments on MSCT 3-months after the last session. Stone free rate was 93.1% after the first SWL session and reached 100% after the second session. Rate of retreatment with second session of SWL was 6.9%. Urinary tract infection (UTI) was detected in 10.3%, transient renal obstruction with low grade fever in 4.6% of infants and no major complication had been recorded. ConclusionThe new generation of SWL technology with a precise focal area seems to be safe and effective in management of kidney calculi in infants.

Comparison of shock wave lithotripsy, flexible ureterorenoscopy and percutaneous nephrolithotripsy on moderate size renal pelvis stones

To compare success and complication rates of shock wave lithotripsy (SWL), flexible ureterorenoscopy (F-URS) and percutaneous nephrolithotripsy (PNL) according to modified clavien grading system of renal pelvis stones between 1 and 2 cm. The results of 149 patients were evaluated retrospectively. Patients were divided into three groups as 52 for SWL, 47 for F-URS and 50 for PNL. Complications were evaluated by modified Clavien grading system. In the first group, stone-free rates after a mean of 2, 6 sessions was 86 % (45/52). In Group 2, this ratio was 91.4 % (43/47), and in Group 3, it was 98 % (49/50). The success rate in Group 3 was significantly higher than other groups. Complication rates for Group 1, 2 and 3 were 7.6 % (4/52), 6.3 % (3/47) and 12 % (6/50), respectively. Although PNL was the most successful technique compared with other techniques, complications were also higher in this group. Even though PNL is the most successful, it should be performed for selected patient groups and indications should be carefully evaluated.

Success of electromagnetic shock wave lithotripter as monotherapy in large renal calculi—Our experience

ObjectivesTo evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renal stones larger than 2cm without ureteral stenting. Hence, if our study result demonstrates acceptable success and safety, we can recommend ESWL as a treatment option for patients with large renal calculi. Subjects and methodsThis is a prospective study conducted in the Department of Urology, Regional Institute of Medical Sciences, Imphal, India, from January 2011 to December 2012. A total of 104 patients aged between 20 and 70 years with solitary large (>2cm) renal stones underwent ESWL using the Dornier Compact Sigma Lithotripter. Stone size was calculated by measuring the largest dimension of the stone in KUB plain films. In each session, 3000–3500 shocks at frequency 60–90min−1 and intensity between 1 and 4 were given. A maximum number of six sessions were given. Successful treatment was defined as complete clearance or residual stones smaller than 4mm on KUB performed 3 months after the first session. ResultsTotal number of patients was 104. The M:F ratio was 1:1.4. The stone size ranged from 21 to 55mm. The overall success rate was 73%. For stones >30mm, the success rate was only 62.2% (n=28). The number of sessions required increased as the stone size increased. The most common complication encountered was haematuria. ConclusionESWL remains the cornerstone of therapy for renal calculi less than 2cm. Our study reveals that multiple sessions were required for solitary renal calculi, with higher rate of ancillary procedures. The success rate of ESWL for both non-staghorn and staghorn calculi with size above 2cm is low, so other treatment modalities like PCNL should be considered as the first treatment option. However, with appropriate patient selection, significant improvements in stone-free rates may be achieved.

S245 Shock wave lithotripsy success for renal stones based on patient and stone computed tomography characteristics

S245 Shock wave lithotripsy success for renal stones based on patient and stone computed tomography characteristics

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

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

Impact of official technical training for urologists on the efficacy of shock wave lithotripsy

To evaluate the efficacy of company-initiated training of urologists on shock wave lithotripsy (SWL) treatment results, we retrospectively assessed 602 patients who underwent SWL in Nagoya City University Hospital between January 2004 and June 2011 using Lithotripter S (Dornier MedTech, Japan). Training-provided by a training specialist of the company in June 2010-focused on the targeting of renal and proximal ureter stones with a combination of radiography and ultrasonography (US). The stretcher wedges were positioned in the semi-prone position or the semi-supine position for middle and distal ureter stones, respectively. Success rates between 519 pre-training treatments and 83 post-training treatments were compared. Patient age and stone location, burden, number, and composition did not significantly differ between pre- and post-training. Training improved the overall success rate from 66.3 to 87.2% (P<0.0001). The mean number of SWL treatments decreased from 1.8±1.8 to 1.4±1.3 (P=0.01). The first SWL treatment success rate increased from 67.1 to 83.7% (P=0.002), and the need for multiple treatments decreased. The frequency of detection of renal and proximal ureter stones by both radiography and US increased from 10.5% before training to 58.2% after training (P<0.0001). Significant factors for successful SWL were determined to be training and prone position for distal ureter stones by multivariate analysis and ultrasonic detection for renal and proximal ureter stones by univariate analysis. Skills in targeting stones using ultrasonography and selecting the proper therapeutic position are essential for improving the success rate of stone removal.