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EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY EXPERIENCE AT THE UROLOGY AMBULATORY SURGICAL CENTER
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Sushil S. Lacy, M.D., Richard A. Crusinberry, M.D., Alan H. Domina,
M.D., Don L. Henslee, M.D.,
Peter E. Howe, M.D., Christopher E. Larson,
M.D., Andrew J. Lepinski,
M.D., David B. Wiltfong,
M.D.,
and John Haller, RT®, RDMS - Lincoln, Nebraska
Presentation by Dr. Lacy.
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We reviewed the experiences with ESWL from February 2001 through December 2001 at our ASC. A total of 208 kidneys were treated on the Direx Tripter Compact (Direx Systems Corp.). In the group of 183 patients, 119 were male and 64 female. Age ranged from 18 - 79 years. General anesthetic was used in each case. Stone size varied from 5 to 35mm.
Eight patients were lost to follow-up. Two patients needed hospitalization for pain control and one for observation of subcapsular hematoma.
Post ESWL procedures: Four patients had ureteroscopy with stone extraction and one needed percutaneous nephrolithotomy.
Results:
Follow-up in all patients was 4 - 6 weeks. Overall success rate was 94%. Stone free was 86%. Re-treatment was 1.4% and the post-treatment auxiliary procedure rate was 2.4%.
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Number ofKidneys Treated |
Success Rate |
Stone Free Rate |
Re-treatment Rate |
Post Aux Procedure Rate |
| Urology Surgical Center |
208 |
94% |
86% |
1% |
2% |
| Midwest Stone Management |
48,084 |
88% |
66% |
6% |
5% |
| U.S. Cooperative Study |
2,501 |
84% |
66% |
16% |
8% |
Conclusion:
ESWL done at an ASC setting is effective and it is hoped that the overall success rate will continue to improve with better technology.
UROLOGY, P.C.
5500 PINK LAKE ROAD
LINCOLN, NE 68516
FAX (402) 421-1945,
PHONE (402) 489-8888
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Excerpts from the 1st Stone Consultation meeting
Paris, July 4-5, 2001
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1st International Consultation on Stone Disease
Committee 8: Bioeffects and Physical Mechanisms of SW Effects in SWL
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Chairman:
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James E. Lingeman, M.D. |
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Committee Members:
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Michael Delius, M.D. |
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Andrew Evan, PhD |
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Mantu Gupta, M.D. |
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Kemal Sarica, M.D. |
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Walter Strohmaier, M.D. |
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Contributing Authors:
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James McAteer, PhD |
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James Williams, PhD |
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1) Introduction A
….." Unfortunately current lithotriptor designs have not been based on fundamental advances in the basic science
of SWL vis-?-vis stone comminution and tissue effects. The result has been that newer generation machines have
not improved outcomes for patients and indeed may be both less effective in breaking stones and more traumatic
to renal tissue. "
2) Page 9
…." In addition, the newer generation lithotriptors that have very small focal areas and extremely high peak
positive pressures are reporting higher clinically significant hematoma rates of 3 to 12% (Kohrmann et al, 1995;
Stefan et al, 1998; Piper et al, 2001; Ueda et al, 1993), a trend that is worrisome."
3) Page 10
…." In addition, Roessler et al (1996) determined the size of lesion induced by an electromagnetic vs. electrohydraulic
lithotriptor and found a much larger lesion with the electrohydraulic machines. However, the electromagnetic
lithotriptor produced complete cellular destruction at F2, which may explain a higher rate of subcapsular hemorrhage
for electromagnetic lithotriptors."
4) Page 69
…." Newer generation machines have not improved outcomes for patients. The introduction of new lithotriptors
that generate extremely high pressures and tight focal zones does not appear to be much of an improvement, as
the need for re-treatment and the incidence of adverse effects with these devices appears to be higher with
older machines."
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FOCAL CROSS SECTION,TRUNCATED FOCAL
AREA AND
TRUNCATED VOLUME:THREE NEW TOOLS TO COMPARE
EFFECTIVENESS OF SHOCK WAVE LITHOTRIPTERS
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THREE NEW TOOLS TO COMPARE THE EFFECTIVENESS
OF SHOCK WAVE LITHOTRIPTERS
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Introduction and Objectives:
The peak pressure at F2 and the focal area are used to compare the effectiveness of the shock wave
produced by lithotripters. New electromagnetic lithotripters feature high peak pressures. This suggests
that they are more effective than traditional electrohydraulic systems. Closer analysis reveals that
electromagnetic systems have a very thin focal area, smaller than the size of a typical stone. The
objective of the study was to determine whether the available energy was optimal for stone fragmentation,
and whether these devices require an increased number of shock waves when compared to traditional
electrohydraulic lithotripters. Analysis of the geometry of the focal volume was utilized to evaluate
each system. The Focal Volume of each lithotripter approximates an ellipsoidal shape (cigar).Three
parameters derived from the focal volume are: the focal cross section at F2, the truncated focal area
and truncated volume. These new tools were employed to accurately analyze the shock wave characteristics
and efficiency of different lithotripters
Methods:
Using geometric formulas and integral calculus, 11 currently used lithotripters were evaluated.
Truncation of the ellipsoid was determined at 15 mm.
Results:
The results identify two distinct categories of lithotripters based on the three new parameters
outlined: a) LARGE FOCUS: Dornier HM-3, Medstone STS-T , Direx Tripter Compact and Medispec Econolith.
b) SMALL FOCUS: All electromagnetic lithotripters, plus Edap Praktis and the Healthronics Lithotron.
The average focal cross section for LARGE FOCUS lithotripters is 5 times larger ( 157 mm˛ vs.30
mm˛), the average truncated area is 2.35 times larger.( 209 mm˛ vs. 89 mm˛) and the average truncated
volume is 5 times larger (2306 mm 3 vs. 435 mm 3 ) than SMALL FOCUS devices.
Source of Funding: none
Disclosures (by author):
Brian Saltzman - No Disclosure Necessary
Josef Hochman
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