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LA
CONSULTA SEMANAL
AGOSTO
2000
CONSULTA
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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