Shock Wave Lithotripsy For Stones Research Articles

Stone decision engine accurately predicts stone removal and treatment complications for shock wave lithotripsy and laser ureterorenoscopy patients.

Kidney stones form when mineral salts crystallize in the urinary tract. While most stones exit the body in the urine stream, some can block the ureteropelvic junction or ureters, leading to severe lower back pain, blood in the urine, vomiting, and painful urination. Imaging technologies, such as X-rays or ureterorenoscopy (URS), are typically used to detect kidney stones. Subsequently, these stones are fragmented into smaller pieces using shock wave lithotripsy (SWL) or laser URS. Both treatments yield subtly different patient outcomes. To predict successful stone removal and complication outcomes, Artificial Neural Network models were trained on 15,126 SWL and 2,116 URS patient records. These records include patient metrics like Body Mass Index and age, as well as treatment outcomes obtained using various medical instruments and healthcare professionals. Due to the low number of outcome failures in the data (e.g., treatment complications), Nearest Neighbor and Synthetic Minority Oversampling Technique (SMOTE) models were implemented to improve prediction accuracies. To reduce noise in the predictions, ensemble modeling was employed. The average prediction accuracies based on Confusion Matrices for SWL stone removal and treatment complications were 84.8% and 95.0%, respectively, while those for URS were 89.0% and 92.2%, respectively. The average prediction accuracies for SWL based on Area-Under-the-Curve were 74.7% and 62.9%, respectively, while those for URS were 77.2% and 78.9%, respectively. Taken together, the approach yielded moderate to high accurate predictions, regardless of treatment or outcome. These models were incorporated into a Stone Decision Engine web application (http://peteranoble.com/webapps.html) that suggests the best interventions to healthcare providers based on individual patient metrics.

Editorial Comment to Ultraslow full-power shock wave lithotripsy versus slow power-ramping shock wave lithotripsy in stones with high attenuation value: A randomized comparative study.

Editorial Comment to Ultraslow full-power shock wave lithotripsy versus slow power-ramping shock wave lithotripsy in stones with high attenuation value: A randomized comparative study.

Ultraslow full-power shock wave lithotripsy versus slow power-ramping shock wave lithotripsy in stones with high attenuation value: A randomized comparative study.

To compare the efficacy and safety of ultraslow full-power versus slow rate, power-ramping shock wave lithotripsy in the management of stones with a high attenuation value. This was a randomized comparative study enrolling patients with single high attenuation value (≥1000Hounsfield unit) stones (≤3cm) between September 2015 and May 2018. Patients with skin-to-stone distance >11cm or body mass index >30kg/m2 were excluded. Electrohydraulic shock wave lithotripsy was carried out at rate of 30shock waves/min for groupA versus 60shock waves/min for groupB. In groupA, power ramping was from 6 to 18kV for 100shock waves, then a safety pause for 2min, followed by ramping 18-22kV for 100shock waves, then a safety pause for 2min. This full power (22kV) was maintained until the end of the session. In groupB, power ramping was carried out with an increase of 4kV each 500shock waves, then maintained on 22kV in the last 1000-1500shock waves. Follow up was carried out up to 3months after the last session. Perioperative data were compared, including the stone free rate (as a primary outcome) and complications (secondary outcome). Predicting factors for success were analyzed using logistic regression. A total of 100 patients in groupA and 96 patients in groupB were included. The stone-free rate was significantly higher in groupA (76% vs 38.5%; P<0.001). Both groups were comparable in complication rates (20% vs 19.8%; P=0.971). The stone-free rate remained significantly higher in groupA in logistic regression analysis (odds ratio 24.011, 95% confidence interval 8.29-69.54; P<0.001). Ultraslow full-power shock wave lithotripsy for high attenuation value stones is associated with an improved stone-free rate without affecting safety. Further validation studies are required using other shock wave lithotripsy machines.

Retrograde Intrarenal Surgery Monotherapy Versus Shock Wave Lithotripsy for Stones 10 to 20 mm in Preschool Children: A Prospective, Randomized Study

We compared the outcome of retrograde intrarenal surgery monotherapy vs shock wave lithotripsy for stones 10 to 20 mm in preschool children. This prospective study included 60 children with a mean ± SD age of 2.4 ± 1.3 years. Patients were randomly divided into 2 groups. Group 1 underwent shock wave lithotripsy and group 2 underwent retrograde intrarenal surgery as monotherapy. Retrograde intrarenal surgery was started using a 7.5Fr semirigid ureteroscope (Storz®) and the holmium laser, and completed by the Flex X™2 flexible ureterorenoscope. A ureteral access sheath was not used and only hydrodilatation was performed. Patients were evaluated preoperatively by ultrasound and plain abdominopelvic x-ray. Followup was 3 months. The stone-free rate after a single session treatment was 70% and 86.6% in groups 1 and 2, respectively. Mean operative time was 27.9 ± 3.5 and 40 ± 7.8 minutes, mean fluoroscopy exposure time was 60 ± 42 and 50 ± 35 seconds, and mean hospital stay was 6 ± 2 and 12 ± 8 hours, respectively. No major complication occurred in either group and no child in either group received blood transfusion. Nine group 1 patients needed a second shock wave lithotripsy session, of whom 2 required a third session. At 3 months the overall stone-free rate was 93.3% and 96.6% in groups 1 and 2, respectively. Retrograde intrarenal surgery is an option for treating medium sized renal stones in preschool children with results comparable to those of shock wave lithotripsy and a safe short-term outcome.

Controlled cavitation to augment SWL stone comminution: mechanistic insights in vitro

Stone comminution in shock wave lithotripsy (SWL) has been documented to result from mechanical stresses conferred directly to the stone, as well as the activity of cavitational microbubbles. Studies have demonstrated that the presence of this cavitation activity is crucial for stone subdivision; however, its exact role in the comminution process remains somewhat weakly defined, in part because it is difficult to isolate the cavitational component from the shock waves themselves. In this study, we further explored the importance of cavitation in SWL stone comminution through the use of histotripsy ultrasound therapy. Histotripsy was used to target model stones designed to mimic the mid-range tensile fracture strength of naturally occurring cystine calculi with controlled cavitation at strategic time points in the SWL comminution process. All SWL was applied at a peak positive pressure (p+) of 34 MPa and a peak negative pressure (p-) of 8 MPa; a shock rate of 1 Hz was used. Histotripsy pulses had a p- of 33 MPa and were applied at a pulse repetition frequency (PRF) of 100 Hz. Ten model stones were sonicated in vitro with each of five different treatment schemes: A) 10 min of SWL (600 shocks) with 0.7 s of histotripsy interleaved between successive shocks (totaling to 42 000 pulses); B) 10 min of SWL (600 shocks) followed by 10 min of histotripsy applied in 0.7-s bursts (1 burst per second, totaling to 42 000 pulses); C) 10 min of histotripsy applied in 0.7-s bursts (42 000 pulses) followed by 10 min of SWL (600 shocks); D) 10 min of SWL only (600 shocks); E) 10 min of histotripsy only, applied in 0.7-s bursts (42 000 pulses). Following sonication, debris was collected and sieved through 8-, 6-, 4-, and 2-mm filters. It was found that scheme D, SWL only, generated a broad range of fragment sizes, with an average of 14.9 ± 24.1% of the original stone mass remaining > 8 mm. Scheme E, histotripsy only, eroded the surface of stones to tiny particulate debris that was small enough to pass through the finest filter used in this study (<2 mm), leaving behind a single primary stone piece (>8 mm) with mass 85.1 ± 1.6% of the original following truncated sonication. The combination of SWL and histotripsy (schemes A, B, and C) resulted in a shift in the size distribution toward smaller fragments and complete elimination of debris > 8 mm. When histotripsy-controlled cavitation was applied following SWL (B), the increase in exposed stone surface area afforded by shock wave stone subdivision led to enhanced cavitation erosion. When histotripsy-controlled cavitation was applied before SWL (C), it is likely that stone surface defects induced by cavitation erosion provided sites for crack nucleation and accelerated shock wave stone subdivision. Both of these effects are likely at play in the interleaved therapy (A), although shielding of shock waves by remnant histotripsy microbubble nuclei may have limited the efficacy of this scheme. Nevertheless, these results demonstrate the important role played by cavitation in the stone comminution process, and suggest that the application of controlled cavitation at strategic time points can provide an adjunct to traditional SWL therapy.

Treating lower pole renal stones: in defence of shock wave lithotripsy

I have been invited to participate in this written debate, with Reem Al-Bareeq and John Denstedt, on the preferred treatment option for lower pole renal stones.

Pediatric Ureteroscopic Management of Intrarenal Calculi

Data addressing ureteroscopic management of intrarenal calculi in prepubertal children are limited. We reviewed our experience from January 2002 through December 2007. We retrospectively reviewed ureteroscopic procedures for intrarenal calculi in children younger than 14 years. Stone-free status was determined with postoperative imaging. Multiple logistic regression analysis was used to assess the influence of preoperative factors on initial stone-free status and the need for additional procedures. Intrarenal calculi were managed ureteroscopically in 52 kidneys in 50 children with a mean age of 7.9 years (range 1.2 to 13.6). Mean stone size was 8 mm (range 1 to 16). Stone-free rate after a single ureteroscopic procedure was 50% (25 of 50 patients) on initial postoperative imaging and 58% (29 of 50) with extended followup. Initial stone-free status was dependent on preoperative stone size (p = 0.005) but not stone location. Additional stone procedures were required in 18 upper tracts. Younger patient age (p = 0.04) and larger preoperative stone size (p = 0.002) were associated with the need for additional procedures. Additional procedures were required in more than half of the stones 6 mm or larger but in no stone smaller than 6 mm. Ureteroscopy is a safe method for the treatment of intrarenal calculi in the prepubertal population. Our ureteroscopic stone-free rate for intrarenal stones is lower than that reported for ureteral stones. Parents should be informed that additional procedures will likely be required, especially in younger patients and those with stones larger than 6 mm.

When is Prior Ureteral Stent Placement Necessary to Access the Upper Urinary Tract in Prepubertal Children?

We studied the possibility that age, height, weight and body mass index could be used to predict the likelihood of successful ureteroscopic access to the upper urinary tract without previous stent placement in prepubertal children. We retrospectively reviewed all ureteroscopic procedures for upper tract calculi in prepubertal children from 2003 to 2007. We compared age, height, weight and body mass index in patients who underwent successful primary flexible ureteroscopic access and in those who required initial stent placement to perform ureteroscopy. Successful primary ureteroscopic access to the upper tract was achieved in 18 of 30 patients (60%). There was no difference in mean age (9.9 vs 9.5 years, p = 0.8), height (132 vs 128 cm, p = 0.6), weight (37 vs 36 kg, p = 0.86) or body mass index (19.3 vs 20.5 kg/m(2), p = 0.55) between patients with successful vs unsuccessful upper tract access. Locations that prevented access to the upper urinary tract were evenly distributed among the ureteral orifice, iliac vessels and ureteropelvic junction. Age, height, weight and body mass index could not predict the likelihood of successful ureteroscopic access to the upper tract. Placement of a ureteral stent for passive ureteral dilation is not necessary for successful ureteroscopic access to the renal pelvis in prepubertal children. An initial attempt at ureteroscopy, with placement of a ureteral stent if upper tract access is unsuccessful, decreases the number of procedures while maintaining a low complication rate.

Pediatric Shockwave Lithotripsy: Size Matters!

Shockwave lithotripsy (SWL) is a safe and efficacious modality for pediatric urolithiasis. Recent reports claim good results even with larger stone burdens, irrespective of stone location. We reviewed the outcomes of SWL in the pediatric population at our center to assess the impact of stone burden and location and the age of the child on the stone-free rate. Records of 106 patients <or=16 years of age (mean age 10.9 years) treated with SWL for stones with a surface area of 20 to 600 mm2 (mean 124.17 mm2) from July 1989 to June 2004 were reviewed. Metabolic abnormalities were present in 20.7% of the patients. All procedures were performed using the Siemens Lithostar, and stone clearance was assessed 3 months after SWL. Complications and the need for re-treatment and ancillary procedures were noted, and the impacts of stone size and location and the age of the child on stone clearance were assessed. The overall stone-free rate was 87% (complete clearance 72%; insignificant [<3-mm] residual fragments 15%). The re-treatment rate was 58%, and the efficiency quotient was 47. Whereas stone size correlated strongly with the stone-free rate (Mann-Whitney U test x = 0.004; chi-square test P = 0.02), patient age and stone location did not have a significant impact. Extracorporeal shockwave lithotripsy is an effective modality to treat pediatric upper urinary-tract calculi, especially when the stone burden is <200 mm2. Larger stone burdens are associated with poorer results, necessitate more ancillary procedures, and have a higher complication rate.

Endoscopic vs. Surgical Drainage for Chronic Pancreatitis

Pancreatic-duct (PD) obstruction is an important etiologic factor for pain in chronic pancreatitis (CP) patients; thus, PD decompression is an appropriate treatment for symptomatic patients with markedly dilated PDs. To compare outcomes of endoscopic and surgical drainage, researchers from Amsterdam enrolled 39 patients with CP, obstruction of the PD (due to strictures, stones, or both), dilation of the PD (≥5 mm proximal to stenosis), and severe recurrent pancreatic pain (not relieved by non-narcotic analgesics). Patients were randomized to endoscopic therapy, consisting of sphincterotomy, pancreatic stone removal (extracorporeal shockwave lithotripsy for stones …

PEDIATRIC STONE DISEASE: AN EVOLVING EXPERIENCE

The presentation and management of pediatric stone disease have changed due to early identification and treatment of congenital urological conditions, as well as technological advances. Therefore, we reviewed our 12-year experience. A total of 123 patients with 158 stones presented from 1991 to 2003. The 46 boys and 77 girls were 8 months to 25 years old, including 5 boys (4%) younger than 3 years, 46 (37%) 4 to 12 years old and 72 (59%) older than 13 years. A 24-hour urine collection was done in 50 patients (41%) and serum chemistry studies were performed in 66 (54%). The seasons of presentation were fall in 41% of cases, summer in 24%, spring in 22% and winter in 13%. Of the patients 94 (76%) had loin pain, 10 (8%) had urinary tract infections, 13 (11%) had a history urinary tract infection, 18 (15%) had gross hematuria, 14 (11%) had structural urological abnormalities and 7 (6%) had neurogenic bladder. Metabolic abnormalities were uncommon and included hypercalciuria in 12%, hyperoxaluria in 2% and cystinuria in 2%. A total of 57 patients (46%) passed the stones and 34 (28%) underwent extracorporeal shock wave lithotripsy, of whom 24 (71%) became stone-free. Ureteroscopy was performed in 10 patients (8%) 6 to 19 years old, percutaneous nephrostolithotomy was done in 4 (3%) and 4 (3%) underwent open surgery. Stone analysis showed calcium based in 88% of the cases, struvite in 7% and cystine in 5%. The majority of patients had no congenital abnormalities. Early diagnosis of urological abnormalities and urinary infection, and appropriate management of neurogenic bladder may have reduced the incidence in those groups. Most stones are calcium based but occur in the absence of metabolic disturbances. More patients presented in the fall, perhaps reflecting the increased concentration of urine in the summer. Half of the patients passed the stones and shock wave lithotripsy was curative in most others. Ureteroscopy, percutaneous nephrostolithotomy and open surgery were rarely required.

1117: Shock Wave Lithotripsy of Stones Implanted in the Proximal Ureter of the Pig

1117: Shock Wave Lithotripsy of Stones Implanted in the Proximal Ureter of the Pig

Extracorporeal Shock Wave Lithotripsy in Children

Extracorporeal Shock Wave Lithotripsy in Children

Management Of Ureteral Calculi: A Cost Comparison And Decision Making Analysis

We compared the cost of treatment strategies for ureteral calculi using a decision tree model. A comprehensive literature review was performed to determine the average success rate of each of 3 treatment modalities, namely observation, ureteroscopy and shock wave lithotripsy. Using these success rates decision analysis models were constructed using Data 3.5 software (TreeAge Software, Inc., Williamstown, Massachusetts) to estimate the cost of treatment and followup for each of the 3 treatments. One-way sensitivity analysis was performed to evaluate the effect of varying individual probabilities of success and costs, and 2-way sensitivity analysis was done to evaluate the model for a wide range of potential costs and success rates of ureteroscopy and shock wave lithotripsy. In addition, a table was constructed to enable individual surgeons and institutions to determine the cost impact of ureteroscopy and shock wave lithotripsy in their unique clinical scenarios. Observation was the least costly pathway if no financial cost, such as emergency room visits, was incurred by failed observation. Ureteroscopy was less costly than shock wave lithotripsy for stones at all ureteral locations. A cost difference between the 2 modalities of approximately $1,440, $1,670 and $1,750 was noted for proximal, mid and distal ureteral calculi, respectively. One-way sensitivity analysis showed that the cost of ureteroscopy would have to increase by more than $1,400, $1,700 and $1,850, and the success rate would have to decrease by 28%, 36% and 39% for proximal, mid and distal stones, respectively, before reaching cost equivalence with shock wave lithotripsy. Likewise, the cost of shock wave lithotripsy would have to decrease by more than $1,489 to achieve cost equivalence with ureteroscopy. Overall ureteroscopy was more cost-effective at all stone sites regardless of the success rate of shock wave lithotripsy. Ureteroscopy is the most cost-effective treatment strategy for ureteral stones at all locations after observation fails. The high cost of purchasing and maintaining a lithotriptor is responsible for the high treatment cost associated with shock wave lithotripsy. However, cost is only one of a number of important factors that are considered when determining an appropriate treatment strategy.

PROSPECTIVE RANDOMIZED TRIAL COMPARING SHOCK WAVE LITHOTRIPSY AND URETEROSCOPY FOR MANAGEMENT OF DISTAL URETERAL CALCULI

We compared the efficacy of shock wave lithotripsy and ureteroscopy for treatment of distal ureteral calculi. A total of 64 patients with solitary, radiopaque distal ureteral calculi 15 mm. or less in largest diameter were randomized to treatment with shock wave lithotripsy (32) using an HM3 lithotriptor (Dornier MedTech, Kennesaw, Georgia) or ureteroscopy (32). Patient and stone characteristics, treatment parameters, clinical outcomes, patient satisfaction and cost were assessed for each group. The 2 groups were comparable in regard to patient age, sex, body mass index, stone size, degree of hydronephrosis and time to treatment. Procedural and operating room times were statistically significantly shorter for the shock wave lithotripsy compared to the ureteroscopy group (34 and 72 versus 65 and 97 minutes, respectively). In addition, 94% of patients who underwent shock wave lithotripsy versus 75% who underwent ureteroscopy were discharged home the day of procedure. At a mean followup of 21 and 24 days for shock wave lithotripsy and ureteroscopy, respectively, 91% of patients in each group had undergone imaging with a plain abdominal radiograph, and all studies showed resolution of the target stone. Minor complications occurred in 9% and 25% of the shock wave lithotripsy and ureteroscopy groups, respectively (p value was not significant). No ureteral perforation or stricture occurred in the ureteroscopy group. Postoperative flank pain and dysuria were more severe in the ureteroscopy than shock wave lithotripsy group, although the differences were not statistically significant. Patient satisfaction was high, including 94% for shock wave lithotripsy and 87% for ureteroscopy (p value not significant). Cost favored ureteroscopy by $1,255 if outpatient treatment for both modalities was assumed. Ureteroscopy and shock wave lithotripsy were associated with high success and low complication rates. However, shock wave lithotripsy required significantly less operating time, was more often performed on an outpatient basis, and showed a trend towards less flank pain and dysuria, fewer complications and quicker convalescence. Patient satisfaction was uniformly high in both groups. Although ureteroscopy and shock wave lithotripsy are highly effective for treatment of distal ureteral stones, we believe that HM3 shock wave lithotripsy, albeit slightly more costly, is preferable to manipulation with ureteroscopy since it is equally efficacious, more efficient and less morbid.

Extracorporeal shock wave lithotripsy of stones in the ureter.

In the present paper we report on one-year experience with the application of extracorporeal shock wave lithotripsy (ESWL) in 157 patients with stones in the ureter 63 of which were in the pyeloureteral segment, 52 in the lumbar part and 42 in the distal third. The indications and contraindications for lithotripsy, the peculiarities in performing the manipulation are determined and the results analysed. They are evaluated as very good because 78.98% of the patients have passed completely disintegrated stones up to the tenth day after lithotripsy. The average hospital stay was 4.08 days. The drawback of the method is the high cost of manipulation.

Extracorporeal Shock Wave Lithotripsy of Stones in the Upper, Mid, and Lower Ureter

Extracorporeal Shock Wave Lithotripsy of Stones in the Upper, Mid, and Lower Ureter

Successful Extracorporeal Shock Wave Lithotripsy of Stones in Ectopic Pelvic Kidneys

We present two cases of calculi in ectopic pelvic kidneys that were removed by extracorporeal shock wave lithotripsy (ESWL). Gantry alterations of the HM3 Model Dornier Lithotripter and repositioning of the patient are necessary to allow adequate placement and imaging of the stone. These changes broaden the clinical usefulness of ESWL to include patients with anomalous kidneys or unusual body habitus.