A heuristic model of stone comminution in shock wave lithotripsy.
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ABSTRACT:
SUBMITTER: Smith NB
PROVIDER: S-EPMC3745501 | biostudies-other | 2013 Aug
REPOSITORIES: biostudies-other
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Project description:Background and Objectives: This systematic review and meta-analysis was conducted to analyze the treatment outcomes of shock wave lithotripsy (SWL) and ureteroscopic lithotripsy (URSL) according to the ureteral stone size. Materials and Methods: In this systematic review, relevant articles that compared SWL and URSL for treatment of ureteral stones were identified. Articles were selected from four English databases including Ovid-Medline, Ovid-EMBASE, the Cochrane Central Register of controlled Trials (Central), and Google Scholar. A quality assessment was carried out by our researchers independently using the Scottish Intercollegiate Guidelines Network (SIGN). A total of 1325 studies were identified, but after removing duplicates, there remained 733 studies. Of these studies, 439 were excluded, 294 were screened, and 18 met the study eligibility criteria. Results: In randomized control trial (RCT) studies, URSL showed significantly higher SFR than SWL (p < 0.01, OR= 0.40, 95% CI 0.30-0.55, I² = 29%). The same results were shown in sub-group analysis according to the size of the stone (<1 cm: p < 0.01, OR = 0.40, 95% CI 0.25-0.63; >1 cm: p < 0.01, OR = 0.38, 95% CI 0.19-0.74, I² = 55%; not specified: p < 0.01, OR = 0.43, 95% CI 0.25-0.72, I² = 70%). In the non-RCT studies, the effectiveness of the URSL was significantly superior to that of SWL (p < 0.01, OR = 0.33, 95% CI 0.21-0.52, I² = 83%). Retreatment rate was significantly lower in URSL than in SWL regardless of stone size (p < 0.01, OR = 10.22, 95% CI 6.76-15.43, I² = 54%). Conclusions: Meta-analysis results show that SFR was higher than SWL in URSL and that URSL was superior to SWL in retreatment rate. However, more randomized trials are required to identify definitive conclusions.
| S-EPMC8703529 | biostudies-literature
Project description:Early shock wave lithotripsy is associated with higher stone-free rate compared to delayed treatment of ureteral stones, but may constitute overtreatment because ureteral stones can pass spontaneously. We studied the association between time to treatment and stone-free rate in patients with ureteral stones to determine optimal shock wave lithotripsy timing. We retrospectively analyzed 537 patients undergoing shock wave lithotripsy for ureteral stones. Patients were divided into five groups according to time from onset of symptoms to lithotripsy-urgent (0-3 days), early (4-30 days), late (31-60 days), long-delayed lithotripsy (≥ 61 days), and asymptomatic. Stone-free rates were compared among groups. Mean age and stone size were 55.6 ± 13.1 years and 7.48 ± 3.29 mm, respectively. Mean number of shock wave lithotripsy sessions and stone-free rate were 1.37 and 91.6%, respectively, in the overall population. Stone-free rates were 95.2%, 96.8%, 91.3%, 86.3%, and 82.7% in urgent, early, late, long-delayed lithotripsy, and asymptomatic groups, respectively. Long-delayed lithotripsy and asymptomatic groups had significantly more lithotripsy sessions and lower stone-free rate, compared to urgent and early lithotripsy groups. In multivariate analysis, time to lithotripsy [long-delayed lithotripsy (odds ratio: 0.273, p = 0.004) and asymptomatic nature (odds ratio: 0.236, p = 0.002)] and age (odds ratio: 0.959, p = 0.003) independently affected stone-free rate. In conclusion, time to lithotripsy is a strong predictive factor for stone-free status following shock wave lithotripsy. Urgent shock wave lithotripsy did not improve stone-free rate if performed within 1 month. However, time to shock wave lithotripsy > 2 months reduced likelihood of stone-free status.
| S-EPMC7778408 | biostudies-literature
Project description:PurposeShock-wave lithotripsy (SWL) is accepted as the first line treatment modality for uncomplicated upper urinary tract stones; however, validated prediction models with regards to stone-free rates (SFRs) are still needed. We aimed to develop nomograms predicting SFRs after the first and within the third session of SWL. Computed tomography (CT) information was also modeled for constructing nomograms.Materials and methodsFrom March 2006 to December 2013, 3028 patients were treated with SWL for ureter and renal stones at our three tertiary institutions. Four cohorts were constructed: Total-development, Total-validation, CT-development, and CT-validation cohorts. The nomograms were developed using multivariate logistic regression models with selected significant variables in a univariate logistic regression model. A C-index was used to assess the discrimination accuracy of nomograms and calibration plots were used to analyze the consistency of prediction.ResultsThe SFR, after the first and within the third session, was 48.3% and 68.8%, respectively. Significant variables were sex, stone location, stone number, and maximal stone diameter in the Total-development cohort, and mean Hounsfield unit (HU) and grade of hydronephrosis (HN) were additional parameters in the CT-development cohort. The C-indices were 0.712 and 0.723 for after the first and within the third session of SWL in the Total-development cohort, and 0.755 and 0.756, in the CT-development cohort, respectively. The calibration plots showed good correspondences.ConclusionsWe constructed and validated nomograms to predict SFR after SWL. To the best of our knowledge, these are the first graphical nomograms to be modeled with CT information. These may be useful for patient counseling and treatment decision-making.
| S-EPMC4758663 | biostudies-literature
Project description:Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93). If cavitation nuclei remain in the propagation path of successive lithotripter pulses, especially in the acoustic coupling cushion of the shock wave source, they will consume part of the incident wave energy, leading to reduced tensile pressure in the focal region and thus lower stone comminution efficiency. We introduce a method to remove cavitation nuclei from the coupling cushion between successive shock exposures using a jet of degassed water. As a result, pre-focal bubble nuclei lifetime quantified by B-mode ultrasound imaging was reduced from 7 to 0.3 s by a jet with an exit velocity of 62 cm s(-1). Stone fragmentation (percent mass <2 mm) after 250 shocks delivered at 1 Hz was enhanced from 22 ± 6% to 33 ± 5% (p = 0.007) in water without interposing tissue mimicking materials. Stone fragmentation after 500 shocks delivered at 2 Hz was increased from 18 ± 6% to 28 ± 8% (p = 0.04) with an interposing tissue phantom of 8 cm thick. These results demonstrate the critical influence of cavitation bubbles in the coupling cushion on stone comminution and suggest a potential strategy to improve the efficacy of contemporary shock wave lithotripters.
| S-EPMC3693448 | biostudies-literature
Project description:Introduction: Burst wave lithotripsy is an experimental technology to noninvasively fragment kidney stones with focused bursts of ultrasound (US). This study evaluated the safety and effectiveness of specific lithotripsy parameters in a porcine model of nephrolithiasis. Methods: A 6- to 7-mm human kidney stone was surgically implanted in each kidney of three pigs. A burst wave lithotripsy US transducer with an inline US imager was coupled to the flank and the lithotripter focus was aligned with the stone. Each stone was exposed to burst wave lithotripsy at 6.5 to 7 MPa focal pressure for 30 minutes under real-time image guidance. After treatment, the kidneys were removed for gross, histologic, and MRI assessment. Stone fragments were retrieved from the kidney to determine the mass comminuted to pieces <2 mm. Results: On average, 87% of the stone mass was reduced to fragments <2 mm. In three of five treatments, stones were completely comminuted to <2-mm fragments. In two of five treatments, stones were partially disintegrated, but larger fragments remained. One stone was not treated because no suitable acoustic window was identified. No injury was detected through gross, histologic, or MRI examination in the parenchymal tissue, although petechial damage and surface erosion were identified on the urothelium of the collecting system limited to the area around the stone. Conclusion: Burst wave lithotripsy can consistently produce stone fragments small enough to spontaneously pass by transcutaneous administration of US pulses. The data suggest that such exposures produce minimal injury to the kidney and urinary tract.
| S-EPMC6798804 | biostudies-literature
Project description:IntroductionWe determine the effect of patient characteristics (age, sex, and body mass index BMI) and stone characteristics (density, location, and size) by non-contrast computed tomography of the kidneys, ureters, and bladder (CT-KUB) in predicting the success of extracorporeal shock wave lithotripsy (ESWL) in the treatment of kidney and ureteric stones. We present this study to further enrich the knowledge of physicians towards the effect of different patient characteristics upon predicting extra-corporal shock wave lithotripsy success rates.MethodsWe evaluated 155 patients who received ESWL for renal and ureteric stone measuring 3-20 mm (mm), over a 3-month period. The stone size in millimeters, density in Hounsfield units (HU) and its location was determined on pre-treatment CT-KUB. ESWL was successful if post-treatment residual renal stone fragments were ≤3 mm and for ureteric stones should be totally cleared.ResultsThe overall success of ESWL treatment was observed in 65.8% of the 155 patients. There was no significant difference seen when the effect of patients age, sex and BMI were studied with ESWL outcome with P values were 0.155, 0.101 and 0.415 respectively. Also, stone location either in the kidney or ureter has no statistically significant effect on ESWL response rate. while stone density and size determined on CT KUB have statistically significant effect on the success rate of ESWL with a P-value of 0.002 and 0.000 respectively.ConclusionsThis study shows that determination of stone density and stone size on CT KUB pre ESWL can help to predict the outcome of ESWL. We propose that stone density <500 HU and stone size < 5 mm are highly likely to result in successful ESWL.
| S-EPMC8441084 | biostudies-literature
Project description:ObjectivesTo perform a systematic review and network meta-analysis of randomized controlled trials (RCTs) to determine the optimal shock wave lithotripsy (SWL) frequency range for treating urinary stones, i.e., high-frequency (100-120 waves/minute), intermediate-frequency (80-90 waves/minute), and low-frequency (60-70 waves/minute) lithotripsy.Materials and methodsRelevant RCTs were identified from electronic databases for meta-analysis of SWL success and complication rates. Using pairwise and network meta-analyses, comparisons were made by qualitative and quantitative syntheses. Outcome variables are provided as odds ratios (ORs) with 95% confidence intervals (CIs).ResultsThirteen articles were included in the qualitative and quantitative synthesis using pairwise and network meta-analyses. On pairwise meta-analyses, comparable inter-study heterogeneity was observed for the success rate. On network meta-analyses, the success rates of low- (OR 2.2; 95% CI 1.5-2.6) and intermediate-frequency SWL (OR 2.5; 95% CI 1.3-4.6) were higher than high-frequency SWL. Forest plots from the network meta-analysis showed no significant differences in the success rate between low-frequency SWL versus intermediate-frequency SWL (OR 0.87; 95% CI 0.51-1.7). There were no differences in complication rate across different SWL frequency ranges. By rank-probability testing, intermediate-frequency SWL was ranked highest for success rate, followed by low-frequency and high-frequency SWL. Low-frequency SWL was also ranked highest for low complication rate, with high- and intermediate-frequency SWL ranked lower.ConclusionsIntermediate- and low-frequency SWL have better treatment outcomes than high-frequency SWL when considering both efficacy and complication.
| S-EPMC4936716 | biostudies-literature
Project description:IntroductionExtracorporeal shock wave lithotripsy (ESWL) is an effective treatment for urolithiasis. Tamsulosin is capable of causing dilation and facilitating the migration of stones. The aim of this study is to evaluate the efficacy of adjuvant treatment with tamsulosin for improving the stone-free rate after a single session of ESWL in the treatment of kidney stones.MethodsThis is a randomized, nonplacebo-controlled study with a sample of 60 adults with a single radiopaque kidney stone of 5-20 mm in diameter. After the ESWL session, the patients were divided into two groups. The control group received standard treatment for analgesia consisting of oral diclofenac (75 mg/12 h) as needed. The tamsulosin group received standard treatment for analgesia plus oral tamsulosin (0.4 mg/day) for eight weeks. In both groups, stone-free status was determined using a CT scan eight weeks after ESWL. The protocol of this study was registered with ClinicalTrials.gov, identifier: NCT04819828.ResultsOnly 57 patients completed the study (28 tamsulosin and 29 control). Overall, the average stone diameter was 11.42 ± 4.52 mm. The stone-free rate was 50.88% (29 of 57) overall, 53.57% (15 of 28) for the tamsulosin group, and 48.27% (14 of 29) for the control group (p = 0.680). The estimated relative risk in favor of the tamsulosin group to achieve a stone-free status was 1.11 (95% CI 0.67-1.9). The estimated number needed to treat to achieve a single patient with renal stone-free status after eight weeks of ESWL adjuvant treatment with tamsulosin was 19.ConclusionOur findings suggest that tamsulosin as adjuvant treatment after a single ESWL session is well tolerated and safe, but it does not increase the stone-free rate in patients with a single radiopaque renal stone of 5-20 mm in diameter. Our results may support the use of tamsulosin with ESWL in the case of patients with a single radiopaque renal stone of 11-20 mm in diameter based on an apparent higher stone-free rate and a low rate of complications.
| S-EPMC9159172 | biostudies-literature
Project description:We investigated whether stone heterogeneity index (SHI), which a proxy of such variations, was defined as the standard deviation of a Hounsfield unit (HU) on non-contrast computed tomography (NCCT), can be a novel predictor for shock-wave lithotripsy (SWL) outcomes in patients with ureteral stones. Medical records were obtained from the consecutive database of 1,519 patients who underwent the first session of SWL for urinary stones between 2005 and 2013. Ultimately, 604 patients with radiopaque ureteral stones were eligible for this study. Stone related variables including stone size, mean stone density (MSD), skin-to-stone distance, and SHI were obtained on NCCT. Patients were classified into the low and high SHI groups using mean SHI and compared. One-session success rate in the high SHI group was better than in the low SHI group (74.3% vs. 63.9%, P = 0.008). Multivariate logistic regression analyses revealed that smaller stone size (OR 0.889, 95% CI: 0.841-0.937, P < 0.001), lower MSD (OR 0.995, 95% CI: 0.994-0.996, P < 0.001), and higher SHI (OR 1.011, 95% CI: 1.008-1.014, P < 0.001) were independent predictors of one-session success. The radiologic heterogeneity of urinary stones or SHI was an independent predictor for SWL success in patients with ureteral calculi and a useful clinical parameter for stone fragility.
| S-EPMC4817509 | biostudies-other
Project description:Shock wave lithotripsy has been commonly used to treat children with renal and ureteral calculi but recently ureteroscopy has been used more frequently. We examined postoperative outcomes from these 2 modalities in children.We reviewed linked inpatient, ambulatory surgery and emergency department data from 2007 to 2010 for 5 states to identify pediatric admissions for renal/ureteral calculi treated with shock wave lithotripsy or ureteroscopy. Unplanned readmissions, additional procedures and emergency room visits were extracted. Multivariate logistic regression using generalized estimating equations to adjust for hospital level clustering was performed.We identified 2,281 admissions (1,087 for shock wave lithotripsy and 1,194 for ureteroscopy). Ages of patients undergoing ureteroscopy and those undergoing shock wave lithotripsy were similar (median 17.0 years for both cohorts, p = 0.001) but patients were more likely to be female (63.4% vs 54.7%, p <0.0001), to be privately insured (69.8% vs 62.2%, p <0.0005) and to have a ureteral stone (81.0% vs 34.8%, p <0.0001). Patients undergoing ureteroscopy demonstrated a lower rate of additional stone related procedures within 12 months (13.6% vs 18.8%, p <0.0007) but a higher rate of readmissions (10.8% vs 6.3%, p <0.0002) and emergency room visits (7.9% vs 4.9%, p <0.0036) within 30 days postoperatively. On multivariable analysis patients undergoing ureteroscopy were nearly twice as likely to visit an emergency room within 30 days of the procedure (OR 1.97, p <0.001) and to be readmitted to inpatient services (OR 1.71, p <0.01).Ureteroscopy is now used more commonly than shock wave lithotripsy for initial pediatric stone intervention. Although repeat treatment rates did not differ between procedures, ureteroscopy patients were more likely to be seen at an emergency room or hospitalized within 30 days of the initial procedure.
| S-EPMC6103480 | biostudies-literature