Re: Risk factors for the formation of a steinstrasse after extracorporeal shock wave lithotripsy: a statistical model.
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Confidence Intervals↗
Biomedical subjects
K Z Sheir
Publications and source records attributed to K Z Sheir.
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.
Equipment Design↗
Impact of lower pole renal anatomy on stone clearance after shock wave lithotripsy: fact or fiction?
PURPOSE: We determined whether there is a significant relationship between the spatial anatomy of the lower pole on preoperative excretory urography and stone fragment clearance after shock wave lithotripsy. MATERIALS AND METHODS: The anatomical factors affecting lower pole stone clearance after shock wave lithotripsy were evaluated retrospectively in 108 patients. Stone-free status was assessed by renal computerized tomography with or without renal ultrasound. The stone-free rate at 3 months was correlated with lower pole infundibular length and width in mm. as well as with the lower pole infundibulopelvic angle in degrees. The statistical significance of each lower pole anatomical factor as well as other stone, renal and treatment factors were correlated with the stone-free rate using the Mann-Whitney and chi-square tests. RESULTS: Three months after shock wave lithotripsy 79 patients (73.1%) were free of stones. Mean lower infundibular length plus or minus standard deviation was 20.9 +/- 6.56 mm., mean infundibular width was 5.65 +/- 2.34 mm. and the mean lower pole infundibulopelvic angle was 48.33 +/- 14.84 degrees. In 49 (45.4%) and 59 (54.6%) patients infundibular length was greater than 3 cm. and 3 cm. or less, respectively. Infundibular width was greater than 5 mm. and 5 mm. or less in 45 (41.7%) and 63 (58.3%) patients, respectively. No obtuse infundibulopelvic angles were noted. None of the 3 lower pole anatomical factors had any significant impact on the stone-free rate at 3 months. Renal morphology was the only factor significantly affecting the stone-free rate since stone clearance was significantly less in pyelonephritic kidneys (p = 0.0009). CONCLUSIONS: Differences in the intrarenal anatomy of the lower pole have no significant impact on stone clearance after shock wave lithotripsy. Further examination of the lower pole renal anatomy with a search for other contributing factors is still warranted.
Adolescent↗
Extracorporeal shock wave lithotripsy in children: experience using two second-generation lithotripters.
OBJECTIVES: To assess the value of extracorporeal shock wave lithotripsy (ESWL) in treating paediatric urolithiasis, and to determine factors that may affect the results. PATIENTS AND METHODS: Using two types of lithotripters (MFL 5000, Dornier MedTech GmbH, Germany, and the Echolith, Toshiba Medical Systems, Japan), 148 children and adolescents (mean age 11.2 years, SD 4.7, range 1-18) were treated for urinary stones. Of these, 137 patients had renal stones and 11 had ureteric stones. The respective mean (SD) stone width and length were 10.2 (4.1) and 12.9 (5.6) mm for renal stones and 7.6 (2.7) and 9.1 (2.7) mm for ureteric stones. The patients were assessed 3 months after treatment and the results compared using the chi-square test to detect factors that might be associated with the stone-free rate. RESULTS: For those with renal stones, the overall stone-free rate was 86% and the re-treatment rate 64%. The only significant factor associated with the stone-free rate was the transverse diameter of the stone (P = 0.012); there was no significant effect of the type of lithotripter but there was a significant difference in re-treatment rate (P = 0.016) in favour of the MFL 5000. All those with ureteric stones were rendered stone-free and only four required re-treatment. Only one child among those with renal stones developed steinstrasse; this was managed by ureteroscopy and otherwise no other complications were recorded in either group. CONCLUSIONS: ESWL is a safe and effective treatment for paediatric urolithiasis. The stone-free rate is influenced significantly by stone size. The re-treatment rate differed significantly between the electrohydraulic and piezoelectric lithotripters, but the stone-free rate did not.
Adolescent↗
Posterior urethral valves with persistent high serum creatinine: the value of percutaneous nephrostomy.
PURPOSE: In patients with posterior urethral valves and persistent high serum creatinine irrespective of vesical drainage proximal urinary diversion is done for presumed concomitant ureterovesical junction obstruction. We retrospectively evaluated whether such management is justified. MATERIALS AND METHODS: Between 1982 and 1995 we reviewed the records of all patients with posterior urethral valves and serum creatinine persistently higher than 1.5 mg./dl. Patient characteristics, treatment method and eventual outcome were determined as well as the results of radiological and Whitaker pressure studies done to exclude obstruction at the ureterovesical junction. RESULTS: Of the 48 patients evaluated 28 underwent primary valve ablation, 16 high loop ureterostomy and 4 vesicostomy. After an average of 78 months (range 37 to 135) chronic renal failure developed in 31% and 25% of those treated with and without high loop ureterostomy, respectively. However, in patients who underwent ureterostomy initially there was a significantly higher rate of decreased bladder capacity, urinary incontinence and augmentation cystoplasty. Obstruction at the ureterovesical junction was noted at surgery and after an average of 2 weeks of diversion in 7 (32%) and 1 (5%) of the 22 cases of percutaneous nephrostomy, respectively. However, after an average of 18 months of ureterostomy drainage we noted evidence of obstruction in 2 of the 27 ureterovesical units (7%). Early in our series 15 of 34 patients (44%) underwent ureterostomy. Subsequently, according to a treatment algorithm including percutaneous nephrostomy, only 1 of 14 boys (7%) underwent such diversion. CONCLUSIONS: Based on our findings high loop ureterostomy does not prevent progression to renal insufficiency and is associated with more complications than primary valve ablation or vesicostomy. Unresolved ureterovesical junction obstruction is rare. Before performing formal supravesical diversion short-term percutaneous nephrostomy drainage helps to identify patients who require diversion.
Creatinine↗
The modified rectal bladder (the augmented and valved rectum) for urine diversion in children.
OBJECTIVES: Urinary diversion is usually the procedure of choice for children having complicated primary closure for bladder exstrophy. We introduce the modified rectal bladder as a low pressure and functionally isolated rectal reservoir as a bladder substitute for these cases. METHODS: Modified rectal bladder urinary diversion was done on 15 children as a low pressure and functionally isolated rectal reservoir via the adoption of sigmoid intussuscepted valve and the rectal patching with detubularized sheet of ileum. Fourteen of these children are currently evaluable, with follow-up ranging from 16 to 72 months (median 55 months). All of them are subjected to thorough history-taking, clinical examination, laboratory and radiologic investigations, and urodynamic study. RESULTS: A high rate of urinary continence was achieved and so far the upper urinary tract and the metabolic status were preserved. Reflux to the colon and kidneys was prevented. Urine samples from the renal pelvis through percutaneous needle aspiration revealed sterile cultures in 82% of the renal units (23 of 28). CONCLUSIONS: Our results demonstrate the distinct advantages of the modified rectal bladder over the conventional methods of urinary diversion to the rectum or the abdominal reservoirs coupled to the skin via continent catheterizable stomas.
Bladder Exstrophy↗
Adenocarcinoma in an isolated rectosigmoid bladder: case report.
We report a case of primary adenocarcinoma of the rectum 11 years after a radical operation and construction of an isolated rectosigmoid bladder for squamous cell carcinoma of the bladder. The isolated rectosigmoid bladder, which is not exposed to the fecal stream, may be associated with adenocarcinoma as in ureterosigmoidostomy.
Adenocarcinoma↗