Evaluation of a bifocal reflector on a clinical lithotripter

PURPOSE: To perform in vitro and in vivo tests using a clinical lithotripter in order to determine whether a bifocal reflector is more efficient and produces the same or less tissue damage than a conventional ellipsoidal reflector for electrohydraulic lithotripters. MATERIALS AND METHODS: A standard ellipsoidal and a novel bifocal reflector were tested on a Tripter Compact lithotripter (Direx Medical Systems, Petach Tikva, Israel). The bifocal reflector was constructed by joining two sectors of two rotationally symmetrical ellipsoidal reflectors having different distances between their foci. The F1 foci of the sectors coincided, creating a separation between the F2 foci. The fragmentation efficiency of the reflectors was compared using kidney-stone models. Shockwave-induced trauma was evaluated in vivo by treating both kidneys of six healthy dogs. One kidney was exposed to shockwaves generated with the conventional reflector, and the other kidney was treated using the bifocal reflector. Pressure measurements were obtained for both reflectors using needle hydrophones. RESULTS: The new design appeared to be more efficient than the conventional reflector in breaking up kidney-stone models. Tissue damage did not increase when using the bifocal reflector. CONCLUSION: The use of bifocal, instead of standard ellipsoidal, reflectors should be considered as an alternative to improve extracorporeal shockwave lithotripsy.     

Pressure-release versus rigid reflector for extracorporeal shockwave lithotripsy

PURPOSE: To evaluate the advantages and disadvantages of using a pressure-release reflector instead of a rigid reflector to concentrate shockwaves for extracorporeal shockwave lithotripsy (SWL). MATERIALS AND METHODS: As in all electrohydraulic lithotripters, shockwaves were generated by electrical breakdown of water between two electrodes, located at the focus (F1) closest to a paraellipsoidal reflector. A pressure-release reflector, made out of polyurethane foam, was constructed and tested on a research lithotripter using kidney stone models. Fragmentation data and pressure measurements were compared with those of a conventional rigid reflector tested on the same device. RESULTS: The weight of stone model fragments remaining after shockwave exposure was less with the pressure-release reflector after screening through a 3.0 x 3.0-mm mesh. The residual fragment weight was less with the rigid reflector using 1.0 x 1.0- and 0.6 x 0.6-mm meshes. CONCLUSION: Pressure-release reflectors may maintain acceptable stone fragmentation while offering improved patient safety and should be considered for SWL.     

Synchronous twin-pulse technique to improve efficacy of SWL: preliminary results of an experimental study.

BACKGROUND AND PURPOSE: Extracorporeal shockwave lithotripsy (SWL) is the treatment of choice for the majority of renal and ureteral stones. The Dornier HM3 lithotripter has good results but with some limitations and complications. A number of second- and third-generation machines have been developed employing different energy sources, focusing devices, and coupling media. These devices overcome some of the limitations and lessen the complications but at the expense of the success rate. Use of the consecutive double-pulse technique (as in the MFL 5000) and of combined under-table and over-table modules consecutively (as in the Siemens Lithostar Plus) improves the efficacy of fragmentation. The aim of this study was to study the effects of the use of synchronous twin pulses generated by under-table and over-table identical shockwave reflectors for stone fragmentation. MATERIALS AND METHODS: We designed a lithotripter with two identical shockwave generators and identical reflectors (twin heads). One reflector was under the table and fixed, while the second reflector was over the table and hangs on a C-arm so that the angle between the axes of the two reflectors could be changed. The second focal points (F2) of the two reflectors lay in the same position. A lucent lightweight acrylic water tank with one side sealed by a silicon rubber membrane was fixed to the SWL table so that the membrane coupled with the water cushions of both reflectors. The tank was filled with degassed water and the targeted material was fixed on a holder and immersed in the water so as to be at F2. Comparison of the use of one shockwave source and two shockwave sources simultaneously was done relative to: (1) cavitation effect on aluminum foil; (2) quality of disintegration, shape of the focal zone, and ideal position of F2 using ceramic blocks; and (3) disintegrative efficacy using dental bone cement. RESULTS: The cavitation effect became more localized with the use of two reflectors. Also, the volume and rate of stone disintegration increased with the use of the two reflectors, with production of fine (<2-mm) fragments. The focal zone became smaller and conical with no propagation of shockwaves beyond F2. These results were more evident if the angle between the axes of the reflectors was 90 degrees. CONCLUSION: This new technique of SWL may improve the efficacy of treatment of urinary tract stones. It also may be less harmful to the renal tissues, but animal experiments must be carried out to prove this.     

Evaluation of Synchronous Twin Pulse Technique for Shock Wave Lithotripsy: Determination of Optimal Parameters for In Vitro Stone Fragmentation

PurposeThe Twinheads extracorporeal shock wave lithotriptor (THSWL) is composed of 2 identical shock wave generators and reflectors. One reflector is under the table and the other is over the table with a variable angle between the axes of the 2 reflectors. The 2 reflectors share a common second focal point, making it possible to deliver an almost synchronous twin pulse to the targeted stone. We studied the optimal parameters for in vitro stone fragmentation.Materials and MethodsTwo types of 1 cm artificial stones were used, namely Bon(n)-stones of 3 compositions (75% calcium oxalate monohydrate [COM] plus 25% uric acid, struvite and cystine) and plaster of Paris. The parameters tested were shock wave number (100, 500 and 1,000), shock wave power (8, 11 and 14 kV) and angle between the reflector axes (67, 90 and 105 degrees). After the optimal parameters were determined we studied the disintegrative efficacy of THSWL for 3 types of human urinary calculi, including COM, calcium hydrogen phosphate (brushite) and cystine. Each stone received 1,000 twin shock waves at 14 kV with an angle of 90 degrees between the reflectors. All experiments were done using a rate of 60 twin shock waves per minute. Following lithotripsy stone fragments were processed and sized. The ratio of the weight of fragments greater than 2 mm-to-total weight of all fragments was calculated.ResultsOptimal stone fragmentation results for THSWL were obtained with the maximum number of shock waves (1,000) and full power (14 kV). There was no significant statistical difference in fragment size or the ratio of fragments greater than 2 mm with the use of different angles except for cystine and plaster of Paris calculi, for which the right angle was most effective. At application of the optimal parameters to human stones THSWL produced small fragment size for COM and cystine stones, while brushite stones were not fragmented to the same extent.ConclusionsThe efficacy of synchronous twin pulse technology improves as the number of shock waves and power increase. A 90-degree angle between the shock wave reflectors is advantageous for certain stones (that is cystine and plaster of Paris) but it is not a factor for other stone compositions. THSWL has satisfactory disintegrative efficacy for human stones, especially COM and cysteine calculi.     

A new integrated ultrasound system for shockwave lithotripsy

BACKGROUND AND PURPOSE: Inline ultrasound monitoring requires good image quality for accurate stone localization, as well as low shockwave shadowing and a robust transducer. In general, conventional transducers designed for another purpose, such as abdominal scanning, are employed. The distance between the transducer and the SWL focus can be varied by a mechanical drive. The drawback is reduced fragmentation at short distances and poor imaging at long distances. This paper introduces a new approach using a specially designed transducer without a mechanical drive. MATERIALS AND METHODS: A transducer prototype with optimized beam focusing (B-K Medical, Herlev, Denmark) was integrated into a modified Compact Delta II therapy head (Dornier MedTech, Wessling, Germany). Image quality was tested at two clinical sites, where 40 kidney and 14 ureteral stones were treated. The shockwave was characterized by model stone tests and fiberoptic hydrophone measurements. RESULTS: Both kidney and ureteral stone treatments could be monitored reliably. Despite the long distance to the SWL focus, the transducer could be operated with relatively high frequencies (3.5-6 MHz), so that high image resolution was obtained. Model stone tests yielded the same fragmentation as the standard Compact Delta II without a transducer. CONCLUSIONS: This study shows that the concept of an integrated transducer distant from the shockwave focus is feasible. Transducer elevation, which is accompanied by shockwave shadowing and early transducer failure, is avoided by employing a dedicated transducer design.     

ESWL and the future of stone management

Summary Based on optimal efficacy regarding disintegration and stone clearance, combined with minimal invasiveness, extracorporeal shockwave lithotripsy (ESWL) represents the first choice therapy for urolithiasis. Further developments in ESWL have related more to economic aspects than to improvement of disintegration efficacy or reduction of side effects. Routine indications for ESWL are well known and widely accepted. Its limitations are also well established: silent calyceal stones, calyceal diverticula stones, nephrolithiasis in horse-shoe kidneys, medullary sponge kidney, and residual fragments after ESWL. Although endourology provides new, less invasive and traumatic means of stone retrieval or disintegration, including laser lithotripsy, small ureteroscopes and actively deflectable uretero- and pyeloscopes, indications for an aggressive approach in such cases are limited to those who are symptomatic. In the case of distal ureteral calculi ureteroscopy in traureteral laser-induced shockwave lithotripsy open up new and interesting possibilities for the future.     

布洛芬联合体外冲击波治疗膝骨关节炎的随机对照研究

目的探讨布洛芬缓释胶囊联合体外冲击波对膝关节骨关节炎的治疗效应。 方法2018年9月至2019年9月，从重庆市人民医院纳入膝关节骨关节炎患者作为前瞻性随机对照临床研究。纳入标准：初治单侧膝关节骨关节炎；依从性良好者。排除标准：既往有其他膝关节疾患；膝关节强(僵)直；Kellgren-Lawrence分级为Ⅳ级的患者；对非甾体类抗炎药(NSAIDs)类药物禁忌或过敏的患者；合并其他内科系统疾病等。共198例患者通过随机数字表法分别分入联合组、布洛芬组、冲击波组。联合组给予布洛芬缓释胶囊联合体外冲击波治疗；布洛芬组给予单纯布洛芬缓释胶囊治疗；冲击波组给予单纯体外冲击波治疗，疗程5周。于治疗开始后8周时采用膝关节损伤和骨关节炎评分(KOOS)、加拿大西安大略和麦克玛斯特大学骨关节炎指数(WOMAC)及SF-12生活质量评分对三组患者进行评价，并记录三组患者并发症发生率。结果用单因素方差分析、LSD-t检验、配对t检验和卡方检验进行分析。 结果布洛芬缓释胶囊联合体外冲击波治疗可显著改善骨关节炎患者膝关节KOOS、WOMAC及SF-12生活质量评分。联合组患者的疼痛(F＝174.5，P<0.001)、症状(F＝12.991，P<0.001)及功能评分(F＝6.009，P＝0.003)等显著改善，效应较单纯给予布洛芬缓释胶囊或体外冲击波治疗更佳。同时，并不明显增加治疗相关并发症的发生率(χ²＝2.479，P>0.05)。 结论布洛芬缓释胶囊联合体外冲击波对骨关节炎具有良好的治疗效应，效果优于单用布洛芬缓释胶囊或冲击波治疗。     

Management of urolithiasis in the congenitally abnormal kidney (horseshoe and ectopic)

PURPOSE OF REVIEW: Urolithiasis in horseshoe and ectopic kidneys presents unique challenges in the decision-making and technical aspects of stone treatment. Specific renal anatomy, stone size and associated conditions such as ureteropelvic junction obstruction are factors that may influence treatment. Detailed review of imaging is important to ensure efficient stone treatment and minimize complications. RECENT FINDINGS: Widespread use of extracorporeal shockwave lithotripsy for calculi in congenitally abnormal kidneys is now giving way to stone-size and anatomy-appropriate therapeutic decision making. Multiple modalities including shockwave lithotripsy, ureteroscopy, percutaneous nephrolithotomy and laparoscopy are being employed in this group of patients. SUMMARY: Treatment decisions for stones in horseshoe and ectopic kidneys can be challenging, and must be made on an individual basis taking into account multiple variables.     

Second-generation lithotripsy: a safe, noninvasive, ambulatory procedure

A total of 600 patients underwent 696 treatments of extracorporeal shockwave lithotripsy (ESWL) during the period between June and November 1987. Our progressively increasing experience with the second-generation device shows that this new unit is as effective as the conventional one, and reveals several advantages. The focusing of the stone is easier; therapy time is shorter; general or regional anesthesia is no longer necessary; distal ureteral stones can be disintegrated, and adjuvant procedures are easily performed during the ESWL session. Of the last 400 patients of our series, 76% were treated on an outpatient basis without any major complications.     

Effect of vibration massage therapy after extracorporeal shockwave lithotripsy in patients with lower caliceal stones

PURPOSE: To determine whether vibration massage influences the results of extracorporeal shockwave lithotripsy (SWL) in patients with lower caliceal stones. PATIENTS AND METHODS: One hundred three patients with lower caliceal stones were entered in the study. Patients were divided into two groups that received either SWL alone (Group A, N = 52) or with vibration massage (Group B, N = 51). There was no statistically significant difference between the two groups in stone size, duration of follow-up, or patient age. The complication, stone-free, and stone recurrence rates of the groups were compared. RESULTS: There was no statistically significant difference between the groups in the number of shockwaves, number of SWL sessions, or shockwave energy. The renal colic rate was higher in Group B than in Group A (P = 0.03). The stone-free rates in Group A and Group B were 60% and 80%, respectively (P = 0.003). The stone recurrence rate was higher in Group A than in Group B (P = 0.0006). CONCLUSIONS: This retrospective study demonstrates that SWL with vibration massage appears to have a beneficial effect on the passage of fragments in patients with lower caliceal stones.     

Extracorporeal shockwave lithotripsy in sedation-analgesia

The aim of the present study was to examine the effects of combined sedation and analgesia during extracorporeal shockwave lithotripsy using the Dornier lithotriptor HM III. We used a combination of a benzodiazepin derivatives with an opioid. We tested the dosage of drugs needed in relation to the length of treatment, the size of the stone and the overall energy output of the lithotriptor. In addition, continuous records were made of the patient's blood pressure and the oxygen saturation in the blood, with and without oxygen insufflation. Our results show that sedation combined with analgesia is a reasonable and useable alternative to general or regional anaesthesia for extracorporeal lithotripsy.     

Aspects on how extracorporeal shockwave lithotripsy should be carried out in order to be maximally effective

The present review summarizes the most important considerations and steps for an optimal result of extracorporeal shockwave lithotripsy. The relationship between shockwave path, geometry and anatomical conditions is of utmost importance. Selection of appropriate treatment variables in terms of shockwave number, power and frequency, is an important prerequisite for proper disintegration and prevention of complications. Several supportive measures such as inversion therapy, citrate therapy, high diuresis, α-receptor antagonists, chemolysis and recurrence preventive measures are important parts of the management of this group of patients in order to avoid problems with residual fragments and new stone formation. Proper understanding of these factors as well as of the physics of shockwaves is necessary for a successful application of this non-invasive technology treatment concept.     

Lower pole ratio: A new and accurate predictor of lower pole stone clearance after shockwave lithotripsy?

BACKGROUND: Lower pole spatial anatomy is an important determinant of success after extracorporeal shockwave lithotripsy. In the present study, we determine whether there is a significant relationship between lower pole ratio (infundibular length : infundibular width) on preoperative intravenous urograms and stone fragment clearances after shockwave lithotripsy. METHODS: A total of 42 patients with isolated lower pole stones were retrospectively reviewed. Anatomical factors, such as infundibular length, width and infundibulopelvic angle were measured and the lower pole ratio was calculated on pretreatment intravenous urogram. Stone fragment clearance was assessed at three months with a plain abdominal X-ray. RESULTS: The overall three-month stone-free rate was 62%. Mean stone size +/- SD was 10 +/- 4.8 mm, mean infundibular length was 21.7 +/- 6.9 mm, mean infundibular width was 6.1 +/- 2.3 mm, mean infundibulopelvic angle was 62.1 +/- 30.1 degrees and mean lower pole ratio was 4.3 +/- 2.8. Stone-free status after shockwave lithotripsy was significantly related to infundibular length and width as well as to lower pole ratio, but not to infundibulo-pelvic angle. Infundibular length less than 30 mm, width greater than 5 mm and lower pole ratio less than 3.5 were noted to have an improved three-month stone-free rate (P = 0.049, 0.01 and <0.01, respectively). CONCLUSION: Caliceal anatomy is an important consideration for lower pole stone clearance after shockwave lithotripsy. The present study suggests that a lower pole ratio of less than 3.5, which considers both infundibular length and width, is a promising predictor for stone-free status.     

The recurrence rate of stones following ESWL

Summary With extracorporeal shockwave lithotripsy (ESWL) stone fragmentation and the potential creation of residual stones has become an integral part of the treatment strategy. Therefore true recurrence, regrowth and pseudo-recurrence determine the rate of new stone formation. In unselected series the overall recurrence rate after ESWL varies between 6% after 1 year and 20% after 4 years. The comparison between the recurrence rate after ESWL and the natural recurrence rate reveals that the results of ESWL are better than expected. Lithotripsy has no special effect on true stone recurrence, and even pseudo-recurrence is of minor clinical significance.     

In-Vivo relation between CT attenuation value and shockwave fragmentation

PURPOSE: To use CT attenuation numbers as a means of determining the susceptibility of an artificial stone to in-vivo fragmentation with extracorporeal shockwave lithotripsy (SWL). MATERIALS AND METHODS: Four types of artificial kidney stones having different CT attenuation values were used. One randomly selected stone was implanted in the renal pelvis of a kidney of 12 young pigs and exposed in vivo to 2500 shockwaves (21 kV) using an electrohydraulic lithotripter. Bilateral nephrectomy was performed after SWL. Fragments were strained through a mesh with a 3.1-mm grid, and the debris left on the mesh was dried and weighed. Fragmentation coefficients (FCs) were associated with CT attenuation values using a statistical model. RESULTS: The relation between FC and CT number was significant, indicating that as CT attenuation increases, FC is reduced. Larger stone fragments were obtained from stones with higher CT numbers. Initial stone weight was not a significant explanation for variations in FC. CONCLUSION: The CT values could be helpful in selecting patients for SWL in the future. However, other parameters such as stone porosity, shape, and roughness also will have to be considered.     

Comparison of methods for transcatheter fragmentation of gallstones

Summary Alternative methods have been considered for treating cholelithiasis. Compared to extracorporeal shockwave lithotripsy (ESWL), a percutaneous endoscopic approach would be more invasive, but would offer the advantage of immediate stone removal without the need for subsequent drug therapy. We performed an in vitro comparison of three methods of transcatheter cholecystolithotripsy with regard to effectiveness of stone fragmentation, damage to the gallbladder mucosa, and compatibility with percutaneous delivery systems. The three devices used for cholecystolithotripsy were the ultrasonic lithotriptor (UL), the electrohydraulic lithotriptor (EHL), and the thulium-holmium-chromium: YAG laser (THC:YAG). The UL effectively fragmented all types of stones studied, although it is necessary to hold the stone against the tip of the probe. The EHL quickly fragmented noncalcified and pigment stones simply by placing the tip in the vicinity of the stone, but calcified stones had to be held in position near the electrode. The THC:YAG was effective at fragmenting each type of stone, but the number of pulses required was quite large, corresponding to 7 min for some stones. The EHL had the most capacity for mucosal damage, followed by the THC:YAG laser. The UL produced no mucosal damage at the exposure times tested. The UL is not compatible with flexible endoscopes while the EHL and the THC:YAG are. Because of the specific advantages and disadvantages of each device, a combination of devices may be required for successful clinical cholecystolithotripsy.     

Spontaneous knotting of a pigtail ureteric stent in the ureter requiring percutaneous removal.

Insertion of a ureteric stent is a common procedure in urologic practice. Ureteric stenting may be performed for: ureteric obstruction, benign or malignant: to prevent ureteric obstruction from stone fragments after extracorporeal shockwave lithotripsy (ESWL); or to prevent leakage from the upper urinary tract. A case of spontaneous knotting of a ureteric stent in situ is reported. Although this complication has been reported previously it is rare.     

Extracorporeal shockwave lithotripsy in the management of salivary calculi

BACKGROUND: The aim was to investigate the results of extracorporeal shockwave lithotripsy in the management of salivary calculi using a dedicated sialolithotriptor. METHODS: Some 122 salivary calculi (84 submandibular and 38 parotid) were treated in an experimental study using a sialolithotriptor. RESULTS: Complete success was achieved in 40 procedures (33 per cent), 27 of 84 submandibular and 13 of 38 parotid calculi. A further 43 patients (35 per cent) were rendered asymptomatic although some stone debris remained in the duct (26 submandibular and 17 parotid). Failure (retention of stone debris and continued symptoms) occurred in 39 patients (32 per cent), 30 submandibular and eight parotid glands. The chance of failure increased with the size of the calculus and increasing duration of symptoms. CONCLUSION: Extracorporeal shockwave lithotripsy provides a useful option for the management of salivary calculi, particularly for stones less than 7 mm in diameter.     

Percutaneous stone implantation in the pig kidney: a new animal model for lithotripsy research

PURPOSE: This report describes a new animal model for research on the parameters of shockwave delivery and the mechanisms of shockwave action in SWL. MATERIALS AND METHODS: Female pigs (approximately 45 kg) were anesthetized for creation of an upper pole peripheral caliceal access. The tract was dilated with a 30F Nephromax balloon and Amplatz sheath, and a 24F rigid nephroscope was used to guide a gypsum artificial stone into a lower pole calix. An internal ureteral stent was then placed. After a 2-hour recovery period, lithotripsy was performed using an unmodified Dornier HM3 lithotripter. Following SWL, en bloc excision of the urinary tract was performed, and the stone fragments were collected. RESULTS: As observed by nephroscopy, most stones were surrounded by urine that was free of clot or debris. Urine output was >1 mL/kg per minute by the time the animal was positioned for SWL after a 2-hour observation period. When the conditions of shockwave (SW) exposure were 400 SWs, 20 kV, and 120 SW/min, the efficiency of stone fragment recovery was 85% +/- 2% (N = 6 stones). CONCLUSIONS: This procedure provides a minimally invasive method for placement of model stones of clinically relevant size within the pig kidney. Stone implantation is efficient and permits experiments to be conducted in 1 day. Stone fragmentation can be quantitated, and the animal can serve as its own control. Long-term experiments are also feasible. Overall, this new animal model is appropriate for experimentation on the parameters of SW delivery in SWL.     

SPONTANEOUS KNOTTING OF A PIGTAIL URETERIC STENT IN THE URETER REQUIRING PERCUTANEOUS REMOVAL

Insertion of a ureteric stent is a common procedure in urologic practice. Ureteric stenting may be performed for: ureteric obstruction, benign or malignant: to prevent ureteric obstruction from stone fragments after extracorporeal shockwave lithotripsy (ESWL); or to prevent leakage from the upper urinary tract. A case of spontaneous knotting of a ureteric stent in siru is reported. Although this complication has been reported previously it is rare.