Wednesday, May 24, 2006
Stone Disease: SWL & Invasive Therapy Including Ureteroscopy (II)
Antony Devasia and his coworkers from Vellore, India, studied the effects of tamsulosin after ESWL for renal and ureteral stones. In this randomized, placebo controlled and double-blind study, daily administration of 0.4 mg of tamsulosin resulted in a higher stone clearance rate, lower requirement of analgesia and reduced need of secondary intervention, as compared to placebo. Although tamsulosin has been found to facilitate spontaneous passage of distal ureteral stones in prior studies, the current study seems to be the first evidence for a similarly beneficial effect after ESWL.
Flexible ureteroscopy with holmium: YAG laser intracorporeal lithotripsy is currently the most versatile endoscopic treatment modality for stones, irrespective of location and composition. During stone fragmentation, there is some risk of damage to ancillary equipment if the laser is accidentally aimed at it. Patrick Honeck from Peter Alken's group in Mannheim, Germany, presented the results of an in vitro study to evaluate the effect of laser energy on guide wires and stone baskets. A 0.035 in Bentson guide wire, a 0.025 in Terumo glidewire, a 3 French Dormia basket and a 2.2 French tipless nitinol basket were tested with different laser fiber diameters (230 microns) and power settings (800-2000 mJ). While the holmium laser was able to transect all of these devices, the time required for disruption was fairly long for all (15-103 seconds), except for the nitinol basket (1-4 seconds). Thus, while the risk of breaking a guide wire seems to be relatively low during holmium laser lithotripsy; accidental disruption of nitinol baskets appears much more likely. Design of baskets specifically for laser lithotripsy of entrapped stones is still awaiting improvement.