Ex vivo training model for percutaneous renal surgery

Percutaneous endourological procedures require an advanced level of skills. To facilitate training in the proper technique, simulators are helpful. Non-biological models, useful for learning the basic steps, do not represent the clinical situation in an ideal way. Recently, we developed a porcine urinary tract model for ureteroscopy. Proceeding from this experience, we developed a further ex vivo model for training percutaneous endourological procedures. The kidney with the ureter is dissected off of the retroperitoneal organ package of freshly slaughtered pigs. It is embedded in silicon. The renal pelvis can be filled with saline to simulate hydronephrosis, stones can be implanted for percutaneous nephrolithotomy. This ex vivo model allows training of all percutaneous endourological procedures (e.g. percutaneous nephrostomy, percutaneous lithotomy, endopyelotomy). It is an ideal way to train these techniques, being superior to non-biological models in terms of tissue feeling for anatomic relations, and the great variety of procedures that can be trained. Nevertheless, it is readily available and inexpensive.     

Extracorporeal Shock Wave Lithotripsy of Renal Pelvis Stones with PCK Stonelith Lithotripter

Shock wave lithotripsy (SWL) has made a revolution in the treatment of urolithiasis. It is a safe procedure with a lower morbidity than open surgery or percutaneous nefrolithotomy (PCN) [Brannen GE, Bush WH, Correa RJ et al., J Urol 1985; 133: 6 and Lingeman JE, Newman D, Mertz JHO et al., J UROL 1986; 135: 1134]. In this article, we analyze our results of SWL with PCK Stonelith-V5 Lithotripter for the renal pelvis localized stones. About 97 patients with radiopaque stone localized in the renal pelvis were treated with PCK lithotripter from January 2001 to March 2003. The study group was divided into two groups according to their stone size. The stone size was ≤ 10 mm in the first group and 11–20 mm in the second group. 56(57) patients were male and 41 (43) were female. Age range was 7–68 (mean 44) years. The overall success rates of SWL for the treatment of renal pelvic stones in our study group was 35 and 62.2 for stones 10 mm or less and 11–20 mm, respectively. Since the focal zone is 7.7 × 30 mm, the stones can easily get out of the focal zone area with respiration and as a result, the success rate is decreased. So, general anesthesia can be preferred for the treatment of stones ≤10 mm with the PCK Stonelith Lithotripter.     

The paradox of inhibition and enhancement of the formation of urinary stones

Summary Nucleation (B^o) and linear crystal growth (G) rates, average particle size (L_1,0) and total mass (M_T) of calcium oxalate dihydrate crystals were measured in artificial urine with and without polylysine, polyglutamic acid or heparin. The purpose of the study was to see if any of these polymers had effects on crystallisation similar to those created by addition of 5% natural urine to artificial urine, wherein B^o had increased but G, L_1,0 and M_T decreased. Polylysine addition had insignificant effects. Heparin increased B^o and decreased G, L_1,0 and M_T significantly, and polyglutamate had similar but more marked effects than did heparin. It is concluded that properly structured organic polymers can significantly inhibit calcium oxalate dihydrate crystallisation by paradoxical enhancement of nucleation. It is possible that such polymers may act as nucleation substrates.     

The impact of dietary oxalate on kidney stone formation

The role of dietary oxalate in calcium oxalate kidney stone formation remains unclear. However, due to the risk for stone disease that is associated with a low calcium intake, dietary oxalate is believed to be an important contributing factor. In this review, we have examined the available evidence related to the ingestion of dietary oxalate, its intestinal absorption, and its handling by the kidney. The only difference identified to date between normal individuals and those who form stones is in the intestinal absorption of oxalate. Differences in dietary oxalate intake and in renal oxalate excretion are two other parameters that are likely to receive close scrutiny in the near future, because the research tools required for these investigations are now available. Such research, together with more extensive examinations of intestinal oxalate absorption, should help clarify the role of dietary oxalate in stone formation.     

Efficacy and outcome of surgical intervention in patients with nephrolithiasis and chronic renal failure

Aim: To prospectively evaluate the efficacy and outcome of surgical intervention in patients with renal stones and chronic renal insufficiency.Methods: The study was carried out from January 1999 till January 2001. Only patients with chronic renal failure without medical renal disease were taken up for study. All patients were subjected to an ultrasound assessment of the kidney, ureter and bladder. In case of obstructed and infected systems a preliminary percutaneous nephrostomy was carried out. After correction of dyselectrolytemia, acid base imbalanceand dialysis (if indicated)patients were subjected to surgical intervention (open surgery or percutaneous nephrolithotomy). ESWL was offered for stones persisting after surgery. The stone burden, composition, therapeutic procedures required to render patients stone free were assessed. The outcome of stone removal on renal function was also evaluated by serial renal dynamic scans and creatinine clearance estimations.Results: Out of 90 patients operated for staghorn or calyceal calculi, complete follow up data was available in 70.Pyelo-nephrolithotomy and percutaneous nephrolithotomy was carried out in 63 and 7 patients respectively. Out of 15 patients with residual stones ESWL was successfully performed in 9 cases. Mixed, calcium oxalate monohydrate, calcium oxalate dihydrate, and struvite stones were encountered in48%, 14%, 17% and 21% respectively. The average pre operative serum creatinine was 4.76 (1.9–16) mg%.The maximum duration of follow up was 9 months. By the 9th post operative month the average fall in serum creatinine values was 1.53 mg/dl (32%)and the average functional improvement by renal dynamic scans stood at 20.665%. 41 patients were saved from further dialysis.Conclusion: Patients with mild to moderate renal failure showed maximal improvement in renal function forestalling or reducing the need for dialysis/renal replacement therapy.     

Effects of different doses of alkaline citrate on urine composition and crystallization of calcium oxalate

Summary Prophylactic treatment with alkaline citrate in patients with recurrent calcium oxalate (CaOx) stone disease results in reduced CaOx supersaturation and increased urinary citrate. The effects of a single evening dose were compared with those of two and three daily doses in six recurrent CaOx stone formers with hypercalciuria, hypocitraturia or raised calcium/citrate quotients. While on a standardized hospital diet the patients were given 7.5 g (28 mmol) of sodium potassium citrate (URALYT-U) in one, two, and three doses. Fractional urine collections during 24 hours were analyzed for pH, composition, and crystallization risk (CR). All dosage regimens had favourable effects on urinary calcium, citrate, calcium/citrate quotients, and CaOx-CR. The most sustained effect was recorded with three divided doses. Single evening doses resulted in the most pronounced effects between 22.00–06.00 h, thereby counteracting the increased risk of CaOx crystallization during that period. In terms of 24 h urine composition the best effect was recorded with alkaline citrate administered three times daily, but because of the favourable response by a single evening dose between 22.00–06.00 h the assumption was made that this dosage regimen might be sufficient to reduce the risk of CaOx crystallization and stone formation. However, the validity of such an assumption can only be established by long-term clinical studies.     

The etiology of urolithiasis in udaipur (Western Part of India)

Summary Fifty-two cases of urinary tract calculus disease were investigated for dietary habits, routine chemical and microscopic urinalysis, bacterial culture, quantitative analysis of 24 h urine sample and qualitative analysis of the stones. 54 out of the 56 stones analysed were of mixed type. Magnesium ammonium phosphate was present in 78.2% stones. Dietary habits revealed principal dependence on cereals, lack of animal proteins, consumption of oxalate rich vegetables and widespread consumption of tea. Urinary tract infection was present in 63.7% of the cases. Significant calcium oxalate crystalluria (2+ to 4+) was present in 34.6% of the cases. Hyperoxaluria, hypercalciuria associated with hyperoxaluria-lower excretion of magnesium and citric acid were important urinary risk factors in the local population. These observations strongly suggest the multifactorial etiology of stone disease in this region. Imbalanced nutrition and urinary tract infection were the principal risk factors for urolithiasis in this study.This paper was presented by Dr. A. K. Pendse at the 24th Biennial Congress of the International College of Surgeons at Manila (Philippines)     

Effect of antiepileptic drug polytherapy on urinary pH in children and young adults

Objects  The relationship between antiepileptic drugs (AEDs) polytherapy and urinary pH was studied to demonstrate the effect and difference of AED polytherapy compared to monotherapy. Materials and methods  A total of 271 urine samples from patients receiving AED polytherapy aged from 7 months to 35 years were enrolled. Two AEDs were co-administered to 215 patients, three AEDs to 45 patients, four AEDs to ten patients, and five AEDs to one patient. Results  The distribution of urinary pH shifted to the alkaline range with increasing numbers of co-administered AEDs (p < 0.0001). The distribution of urinary pH shifted to the alkaline side with AED polytherapy that included valproate (p < 0.05) or acetazolamide (p < 0.03). The distribution of urinary pH did not change with or without zonisamide, carbamazepine, phenobarbital, phenytoin, or clonazepam. Conclusions  Urinary pH should be monitored in patients receiving AED polytherapy, particularly those receiving valproate, acetazolamide, or various AEDs in combination.