[Peculiarity of pulsed dye laser lithotriptor and its clinical application].

Ultrasound lithotriptors (USL) and electrohydraulic lithotriptors (EHL) are representative lithotriptors for endoscopic elimination of upper urinary tract stones. However, they have some disadvantages. For example, USL can not be used with flexible scopes and EHL can cause unexpected tissue injury. To overcome these problems, the pulsed dye laser lithotriptor (MDL-1, Candera Co.) was developed. The characteristics of this laser lithotriptor and its direct effects on tissue was investigated. This pulsed dye laser lithotriptor generates a 504 nm wavelength green light beam by using a combination of a xenon flash lamp and the greenish dye composed of coumarin solution. The maximum output energy is 60 mJ/pulse and the pulse duration is 1.5 microsecond. The pulse rate can be varied from 1 to 20 Hz. First, the intensity of the shock wave was measured by using a combination of a piezoelectric element and an oscilloscope, and then, the results were compaired with those obtained by a similar experiment with an EHL. The average intensity of the shock wave was 54.4 mW under the conditions of 40 mJ/pulse of output energy and 10 Hz of pulse duration. On the other hand, the EHL generated an average of 54.7 W under the conditions of 400 mJ/pulse output energy. Then, fragmentation of various kinds of urinary stones in saline solution was performed. The results showed that this lithotriptor could fragment almost all kinds of stones except cystine stones. Then, hen's eggs were used to observe the effect if laser bean influenced on the organism immediately behind the photoradiated object. Only the egg shell was demolished but the egg membrane below the eggshell did not undergo any change. After these experiments, skin, liver, kidney and urinary bladder of nude mice and human prostatic urethral mucosa in case of TUR-P were irradiated by this laser. The results showed that laser energy caused slight penetration and localized hemorrhage from the surface of epithelium to subcutaneous tissue. It was confirmed that these effects were generated when the tip of the quartz fiber was in direct contact with the object.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical experience of the newly developed ultrasound lithotripter].

At present, to perform percutaneous nephrolithotomy (PNL), the ultrasound lithotripter (US) is most widely used, permitting simultaneous breakup of a calculus and suction of fragments. Recently, we have used the OLYMPUS LUS (oscillation frequency 23 kHz, maximum amplitude 60 microns) in 24 cases of renal calculi (including 6 staghorn and 5 multiple), 4 cases of ureteral calculi and 2 cases of reno-ureteral calculi. Although the degree of breakability varied depending on the substance of the calculi, cystine calculi, generally deemed relatively hard, could also be fragmented. The calculi which were found in the ureter were all situated in the upper portion of the ureter. Direct access by the US probe was possible in 1 case, but in 5 other cases the electrohydraulic lithotripter (EHL) was applied first and larger fragments blasted back into the pelvis were broken up and suctioned with the US. Residual calculi were recognized in 4 cases of 6 staghorn calculi and 2 cases of 5 multiple calculi, all of which were found within calyces and were small enough to allow spontaneous passage. In all the other 24 cases, calculi were destructed and removed with the US. We consider that most renal and ureteral calculi can be broken up and suctioned with the US, virtually regardless of the kind of substance, as long as they are situated in the areas accessible by the US probe. The 60 micron amplitude hardly posed any risk of serious injury to the renal parenchyma, not to mention the pelvic mucosa.

[Clinical experience of the newly developed electrohydraulic lithotripter].

The electrohydraulic lithotripter (EHL) is a calculus-breaking device used in percutaneous nephrolithotomy (PNL). The conventional EHL has a shortcoming in that its breakability decreases in the saline irrigation environment. The newly developed EHL (Lithotron EL-21 OLYMPUS) is designed to discharge optimum sparks during saline irrigation, without having to dilute the solution, thus providing greater convenience. We used the new EHL in 17 cases of renal calculi, 11 cases of ureteral calculi and 2 cases of reno-ureteral calculi, with a breakup efficiency of 96.7%. As a direct, incidental complication, perforation of the ureter occurred in one case of ureteral calculi (uneventful spontaneous recovery detected 3 days afterward). The new EHL has a breakup capability suitable for the PNL: the EHL provides a safe procedure, provided that one takes sufficient caution to the correct positioning of the probe against the target calculus when activating it. Since the probe shaft is flexible, permitting use with the flexible endoscope, the EHL is particularly effective in treating ureteral and renal calculi in cases where access by the rigid US probe is not feasible. One disadvantage of the EHL is that it lacks the fragment-collecting capability that the ultrasound lithotripter features.