The Journal of lithotripsy & stone disease最新文献

Initial clinical trials using a new overhead piezoelectric extracorporeal lithotripter is presented. The advantages of this machine are the installation of an anti-misshot control device (AMCD) to prevent misshots to renal tissue, simplicity for ultrasound stone localization by the overhead type applicator, and elimination of necessity for anesthesia. Thirty patients with upper urinary tract calculi were treated by this machine with a success rate of 77% and stone destruction rate of 93%. No serious complication was observed. The AMCD functioned in such a manner that shock waves were generated only when the stone was in the focal region. Although there were AMCD nonfunctioning cases (small and deeply located stones), it is indicated that this machine is favorable for safe, extracorporeal lithotripsy.

Between 1985 and 1988, 2,200 patients were treated at our institution by extracorporeal shock wave lithotripsy. Forty-two children were included in this group and ranged in age from 3-8 years. Weight and height range was 13-28 kg and 82-126 cm, respectively. In order to treat children in this height and weight range some technical changes had to be made to the gantry chair of the Dornier HM-3 lithotripter. All children had upper urinary tract calculi with stone size ranging from 0.8-2.5 cm. The total number of treatments in these 42 children was 51, and the number of shock waves did not exceed 900 per session at 18 kV. A stone-free rate of 85% was achieved at 3-month follow-up.

Electric sparks are used as the sources for both intra- and extracorporeal shock wave lithotripters. Upon ignition, a pressure pulse, headed by a shock, is generated that propagates as a spherically diverging wave. Simultaneously, a bubble is created that, in the case of the Wolf Model 2137.50 Electrohydraulic Lithotripter, expands to a radius of approximately 5 mm and collapses spontaneously after approximately 1 msec. Upon rebound, the bubble generates a second pressure pulse that is almost equal in amplitude and acoustic energy to the first shock wave. Measured pressures are almost entirely positive and decrease in amplitude with the reciprocal of the distance from the source. For the Wolf lithotripter at its maximum output setting, the pressure amplitude at a distance of 3 cm from the spark is typically 3 MPa.

Among 78 patients with hemiacidrin soluble staghorn renal stones, 23 were treated with a combination of one session of percutaneous debulking and high-energy extracorporeal shock wave lithotripsy (ESWL) (Group A); 17 were treated with high-energy ESWL only (Group B); and 38 were treated with low-energy only ESWL (Group C). In all patients percutaneous nephrostomies were inserted and the ESWL procedure was followed by hemiacidrin irrigation. ESWL was performed with anesthesia in Groups A and B, but without anesthesia in Group C. Groups A and B did not differ in number of ESWL sessions or length of hospital stay, and the therapeutic results at discharge and at 6-month follow-up were comparable, whereby 59% of the patients in both groups were either stone-free or had only small ( less than or equal to 3 mm) residual fragments. In Group C more ESWL sessions were performed, and the hospital stay as well as the hemiacidrin irrigation periods were longer. The fraction of stone-free renal units at discharge was significantly higher in Group C than in Group A (p less than 0.05) and after 4 weeks higher than in both Groups A (p less than 0.025) and B (p < 0.05). At 6 month follow-up, 92% of the patients in Group C were either stone-free or had only small ( less than or equal to 3 mm) residual fragments. Combined low-energy ESWL and hemiacidrin irrigation can successfully be used for treatment of even very large infection staghorn stones.

Three hundred and sixteen patients with ureteral stones were treated in situ (without retrograde stone manipulation) with and without stent bypass (DJ stent, ureteral catheter). Results were generally better with stent bypass, but only marginally so for stones larger than 10 mm in diameter. Regardless of whether or not the ureter was stented, lower ureteral stones were more difficult to fragment than upper ureteral stones and pre-sacral stones did not respond well to in situ treatment. We observed that evaluation of stone disintegration and fragment evacuation could only be properly assessed after approximately 3 weeks post-ESWL.

In the last 9 years, extracorporeal shock wave lithotripsy has become one of the preferred procedures for the treatment of urinary and gallbladder calculi. While there is still uncertainty as to the mechanisms of stone fragmentation, current hypotheses suggest that acoustical shock wave parameters such as rise time, peak compressional and rarefactional pressure, and frequency content may all influence the treatment's efficiency. Thus, optimization of lithotripsy treatment needs pressure sensors that can adequately characterize the shock wave field. This article presents and discusses the design of reliable, wideband, quantitative shock wave sensors made of piezoelectric material. The development, design, and performance characteristics of the sensors are presented. Sensor construction details are described, as are the methods used to characterize the sensor's acoustical performance. The key acoustical parameters of the sensor, its frequency response, and directivity pattern are presented; theory indicates that the probes feature uniform sensitivity over the frequency range up to 100 MHz. Preliminary experimental results indicate that piezoelectric polymer sensors made of polyvinylidene fluoride (PVDF) with a low acoustical impedance backing are suitable for lithotripter field measurements. The applicability of sensors based on fiber optics to shock wave measurements is also briefly discussed. In a companion article, shock wave measurement techniques are outlined and selected lithotripter test data are presented.

Extracorporeal shock wave lithotripsy has become the treatment of choice for upper urinary tract stones. We evaluated the impact of a new lithotripter on the kidneys of 14 nonobstructed patients treated for renal stones, using several physiological parameters and renal ultrasonography. Glomerular filtration rates (GFR) were estimated from the renal scan. Complete disintegration of the stone was accomplished in all but one patient. Treatment did not alter the serum parameters or the renal ultrasonography. Also, no changes were found in the GFR on the follow-up renal scans in both kidneys. The implications of these findings are discussed.

Within 26 months a total of 4,126 procedures were performed on the ESWL multipurpose table. Forty percent of the procedures were comprised of endourology, 25% functional urinary tract radiology, and 37% ESWL therapy. Biplane fluoroscopy is an extraordinary help for percutaneous interventions. A further advantage is the possibility to perform endourology and ESWL in one session without having to transport the patient. This has facilitated pre- and post-operative ancillary measures in a total of 35.3%. Seventy-six percent of stones greater than 15 mm were managed via indwelling stents. In situ ESWL for ureteral stones has become the therapy of choice in more than 80% of patients due to the availability of radiological localization systems and a complication and failure rate of 20% for the push-and-smash procedure. The multipurpose table is equally successful as the piezoelectric system for ESWL therapy. Drawbacks include operational inconvenience with percutaneous interventions and the necessity to change patient position during ureterorenoscopy and retrograde pyelography. The multipurpose unit used is a valid compromise for ESWL and percutaneous endourology. For purely diagnostic interventions, a standard x-ray table is preferred.