The lithotripsy table height: a novel predictor of outcome in shockwave lithotripsy
BACKGROUND: Outcome of Extracorporeal Shockwave Lithotripsy (SWL) is determined by physical factors that affect stone fragmentation and clearance. PURPOSE: To evaluate the predictive value of the Lithotripsy Table Height (LTH) in SWL outcome. Lithotripsy Table Height (LTH) is a variable that represe...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Sociedade Brasileira de Urologia
2011-06-01
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| Series: | International Brazilian Journal of Urology |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-55382011000300009 |
| Summary: | BACKGROUND: Outcome of Extracorporeal Shockwave Lithotripsy (SWL) is determined by physical factors that affect stone fragmentation and clearance. PURPOSE: To evaluate the predictive value of the Lithotripsy Table Height (LTH) in SWL outcome. Lithotripsy Table Height (LTH) is a variable that represents skin to therapy head distance, and it is proportional to the energy that reaches the stone. MATERIALS AND METHODS: A prospective study enrolled patients undergoing SWL for radiopaque urinary stones. All procedures were performed using a Modulith SLX (Karl Storz, Germany) Lithotripter. Patient weight, height and age; stone location and size; number of shock waves delivered, and LTH were recorded. One month post-procedure a KUB was obtained. Logistic regression analysis was used to evaluate the effects of these variables on stone-free outcome. A ROC curve was plotted. RESULTS: Fifty-six patients were enrolled. After one month follow-up, overall success rate (Stone Free) was 83.9% (n = 47). LTH was the only independent predictor of outcome in both univariate and multivariate analysis (p = 0.029). Stone size (p = 0.45) and BMI (p = 0.32) were not significant. In the ROC curve, LTH showed an Area under the Curve = 0.791. Patients with LTH < 218 (n = 8) had relative risk of residual stones = 7.5, odds Ratio: 6.6 (Stone free rate 37.5% vs. 91.5%). CONCLUSION: LTH appears to be an independent predictor of SWL outcome. High success rates can be expected if LTH > 218. Patients with lower LTH had a less effective therapy, therefore, worse stone fragmentation and clearance. These findings may help improve patient selection for SWL therapy. |
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| ISSN: | 1677-5538 1677-6119 |