LA CONSULTA SEMANAL

 

AGOSTO 2000

 

 

CONSULTA

Litiasis renal

 

Hosp Pract (Off Ed) 2000 Mar 15;35(3):49-50, 53-6, 62-3 passim [Texto completo] 

New insights into causes and treatments of kidney stones. 

Scheinman SJ 

Division of Nephrology, State University of New York Health Science Center at Syracuse College of Medicine, USA. 

Recent findings have provided insight into the molecular basis of kidney stone formation and entirely changed our approach to management of calcium stones. Understanding the role of genetic factors and the various promotors and inhibitors of stone formation should lead to more effective prophylaxis and treatment of other types of stones as well. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):355-65 

Chemolysis of urinary calculi. 

Bernardo NO, Smith AD 

Department of Urology, Long Island Jewish Medical Center, New Hyde Park, New York, USA. 

Irrigant chemolysis was developed to collaborate with open surgery, removing the residual fragments. With the worldwide diffusion of the procedures performed by the endourologist in the early 1980s and the present availability of ESWL, however, direct irrigation of stones has a reduced field of influence even as an adjunctive measure. Urologists have applied economic analysis to their clinical practices, and the findings related to irrigant chemolysis made this technique an unusual procedure. The cost to the providers of medical care, the burden on the patient in terms of suffering and loss of productivity, and the amount of time required to liberate the patient even partially from the stones make irrigant chemolysis an inauspicious scenario. In this era of cost containment and decreasing length of stay, it is increasingly difficult to justify hospital admissions for this form of therapy. Being simultaneously more expensive and less effective than the existing alternatives, local chemolysis should be discarded, except for special situations, such as patients at high risk for any surgical procedure. Oral chemolysis preserves reduced indications, for example as an adjuvant to an endourologic operation or ESWL in special situations. As long as urinary stones continue to afflict humans, chemolysis is likely to retain a limited but important role in their management. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):347-54 

Management of residual stones. 

Delvecchio FC, Preminger GM 

Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA. 

Stone-free status is highly dependent on selection of the appropriate surgical technique, which should be tailored according to the individual stone and patient parameters. Although a stone-free state is the desired outcome of surgical intervention of urolithiasis, the authors believe that the presence of noninfection, nonobstructive, asymptomatic postprocedural residual fragments can be managed metabolically in order to prevent stone growth adequately. Further surgical intervention in the case of residual fragments is warranted if the clinical indications that prompted the original surgery persist. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):333-46 

The vesical calculus. 

Schwartz BF, Stoller ML 

Department of Urology, MCHK-DSU, Honolulu, Hawaii. 

Bladder calculi account for 5% of urinary calculi and usually occur because of foreign bodies, obstruction, or infection. Males with prostate disease or previous prostate surgery and women who undergo anti-incontinence surgery are at higher risk for developing bladder calculi. Patients with SCI with indwelling Foley catheters are at high risk for developing stones. There appears to be a significant association between bladder calculi and the formation of malignant bladder tumors in these patients. Transplant recipients are not at increased risk for developing vesical calculi in the absence of intravesical suture fragments and other foreign bodies. Patients who undergo bladder-augmentation procedures using a vascularized gastric patch appear to be protected from vesicolithiasis, perhaps by the acidic environment. Ileum and colon tissues, however, are colonized by urease-producing organisms, producing an alkaline pH that promotes stone formation. Children remain at high risk for bladder-stone development in endemic areas. Diet, voiding dysfunction, and uncorrected anatomic abnormalities, such as posterior urethral valves and vesicoureteral reflux, predispose them to bladder-calculus formation. Finally, there are a number of techniques and modalities available to remove bladder stones. Relieving obstruction, eliminating infection, meticulous surgical technique, and accurate diagnosis are essential in their treatment. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):323-31 

Is there a role for open stone surgery? 

Paik ML, Resnick MI 

Department of Urology, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Ohio, USA. 

Modern day urinary-stone treatment involves procedures and techniques that were not even available 20 years ago. The relatively rapid and sometimes explosive development of ESWL, percutaneous techniques, and ureteroscopy and intracorporeal lithotripsy has ushered in the era of minimally invasive stone management. In many regards, open surgery has such a limited role that its performance often is regarded as a sign of failure. To think of open stone surgery in this manner is likely to do a disservice to a small but important segment of the urinary-stone patient population. The critical responsibility of the urologist treating stone disease is to be able to recognize those clinical situations in which open stone surgery may represent at least a viable and reasonable alternative to less-invasive modalities. The duty of the surgeon is then to be able to present this option to the patient in an unbiased fashion and to effectively perform and implement this form of treatment if chosen. It is only with this approach that open surgery will continue to be correctly applied on those rare occasions and will not become a lost surgical art in the era of minimally invasive surgery. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):315-22 

Extracorporeal lithotripsy. Update on technology. 

Chow GK, Streem SB 

Department of Urology, Cleveland Clinic Foundation, Ohio, USA. 

The development of shock-wave lithotripsy was a serendipitous event. Fortunately, the significance of this accidental discovery was not overlooked by the engineers at Dornier and their medical counterparts. There are many components that make up a lithotripter, but the heart of the lithotripter is its energy source. These machines often are categorized by the type of shock-wave generator used, and each type of generator has its own advantages and disadvantages. Unfortunately, no quantitative value of a shock-wave generator can be correlated to its qualitative effect. Interestingly, each type of energy source delivers its shock-wave energy with such distinctiveness that even the crater pattern it leaves in a stone is unique. New technology and ideas have transformed lithotripters in form and function so that they bear little resemblance to the original HM-1 prototype. Ongoing research is attempting to improve ESWL in several different ways, and advances in shock-wave generation, shock-wave measurement, and stone localization should result in even more efficient lithotripsy. The application of the time-reversal process to 
lithotripsy ultimately may enable lithotripters to track stones and electronically steer shock waves toward the target. Advances like these herald a time when ESWL, fortunately or unfortunately, will become automated completely. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):301-13 

Intracorporeal lithotripsy. Update on technology. 

Zheng W, Denstedt JD 

Division of Urology, University of Western Ontario, London, Canada. 

The number and variety of devices currently available for endoscopic lithotripsy reflect the reality that no single device is ideal in all situations. Although the search for the universal lithotriptor continues, the urologist must consider several factors if faced with the decision of which device to purchase. Perhaps foremost among these factors is the clinical situation with which one commonly deals. For example, although the smaller, flexible probes such as EHL or laser demonstrate considerable utility if used ureteroscopically, the larger stone burden associated with today's percutaneous nephrolithotripsy population often is treated more efficiently with one of the mechanical devices employing a larger, rigid probe, such as ultrasound or the Lithoclast. Similarly, the type and size of endoscopic equipment at one's disposal have a significant impact on which device to purchase or use. There are physical constraints affecting which device may or may not be used, rigid versus flexible endoscope, working channel caliber, and offset versus end-on-port. The skill and experience of the surgeon is also a factor of obvious importance, particularly if one is using a modality with a relatively narrow margin of safety such as EHL. Likewise, the training and experience of nursing personnel is a factor, especially regarding the use of lasers, which require certified personnel who are well versed in laser safety. Finally, in today's environment one must carefully evaluate cost in terms of not only initial capital outlay but also ongoing charges for disposable and maintenance items. Thus, the decision of which device to purchase is complex and requires careful evaluation of all of the previously noted variables. Likewise, if one is fortunate enough to have more than one device available, the decision of which lithotriptor to employ requires a similar decision based on sound surgical judgment. 

Publication Types: 

Review 

Review, tutorial 

 

Urol Clin North Am 2000 May;27(2):255-68 

Role of diet in the therapy of urolithiasis. 

Assimos DG, Holmes RP 

Department of Urology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA. 

The data reviewed in this paper indicate that there is compelling direct and indirect evidence that certain dietary modifications can limit the risk for stone formation. Fluid therapy should be a front-line approach for all stone formers, because it is safe, cheap, and effective. Restricting sodium and animal-protein consumption produces changes in the urinary environment that should benefit the majority of stone formers, including a decrease in calcium and increase in citrate excretion. Minimizing the intake of processed goods limits sodium gluttony. These dietary modifications also reduce cardiovascular risks. Indiscriminant calcium restriction should be avoided, because it could accelerate stone formation and violate skeletal integrity. Oxalate restriction should be considered for calcium oxalate stone formers, especially those with hyperoxaluria. Specific recommendations for modifying the consumption of other nutrients cannot be made at this time because of the limited available information about the resultant effects. The aforementioned goals can be achieved within the context of a nutritionally balanced diet providing adequate sources of fruits and vegetables. There is a definite need for better designed studies of the nutritional effects on stone disease. This would promote a better understanding of the interplay between the genetic and environmental components of this disorder. 

Publication Types: 

Review 

Review, tutorial 

 

Am Fam Physician 1999 Nov 15;60(8):2269-76 [Texto completo] 

Prevention of recurrent nephrolithiasis. 

Goldfarb DS, Coe FL 

New York Department of Veterans Affairs Medical Center, New York City 10010, USA. 

The first episode of nephrolithiasis provides an opportunity to advise patients about measures for preventing future stones. Low fluid intake and excessive intake of protein, salt and oxalate are important modifiable risk factors for kidney stones. Calcium restriction is not useful and may potentiate osteoporosis. Diseases such as hyperparathyroidism, sarcoidosis and renal tubular acidosis should be considered in patients with nephrolithiasis. A 24-hour urine collection with measurement of the important analytes is usually reserved for use in patients with recurrent stone formation. In these patients, the major urinary risk factors include hypercalciuria, hyperoxaluria, hypocitraturia and hyperuricosuria. Effective preventive and treatment measures include thiazide therapy to lower the urinary calcium level, citrate supplementation to increase the urinary citrate level and, sometimes, allopurinol therapy to lower uric acid excretion. Uric acid stones are most often treated with citrate supplementation. Data now support the cost-effectiveness of evaluation and treatment of patients with recurrent stones. 

Publication Types: 

Review 

Review, tutorial 

 

Lancet 1998 Jun 13;351(9118):1797-801 

Kidney stones. 

Pak CY 

University of Texas Southwestern Medical Center, Center for Mineral Metabolism and Clinical Research, Dallas 75235-8885, USA. 

Publication Types: 

Review 

Review, tutorial

 

 

 

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