In vitro calcium oxalate lithotripsy: comparison of Dornier HM3 and Siemens Lithostar

Operator experience and adequate anesthesia improve treatment outcome with third-generation lithotripters

PURPOSE

To characterize the effect of operator experience and type of anesthesia on treatment outcome when switching from the Dornier HM3 to the third-generation Dornier U/50 lithotripter.

PATIENTS AND METHODS

A population of 370 consecutive patients treated by 15 urologists was divided into two groups. Group I (N = 225) included patients treated during the initial 3 months with our new lithotripter. Group II (N = 145) included patients treated during the last 3 months. Changes were made during the intervening 6 months in focusing technique, anesthesia type, coupling technique, and shockwave delivery. Information was collected regarding success of stone treatment (defined as complete clearance of stone or fragments < 3 mm at 1 month).

RESULTS

There were no differences between the two groups with regard to age, sex, fluoroscopic time or maximal shockwave intensity used. Group I had a slightly higher percentage of upper ureteral stones (20% v 13%); however, the difference was not significant. Upper ureteral stones in Group II were on average significantly larger (9.4 mm v 7.3 mm; P = 0.003). Intravenous sedation was used frequently in Group I (111 patients; 49%) and not at all in Group II. General anesthesia was used more frequently in Group II than in group I (34% v 24%; P < 0.02). Spinal anesthesia also was utilized more frequently in Group II patients (66% v 28%; P < 0.0001). Overall, general or regional anesthesia was received by 100% of the patients in Group II but only 52% of the patients in group I. The success rate of stone treatment was much better for Group II than for Group I (78% v 51%; P < 0.0001).

CONCLUSION

The transition from a Dornier HM3 lithotripter to a third-generation lithotripter can be difficult, but if adequate anesthesia is given to minimize patient movement and balloon pressures are optimized, stone targeting can be accurate and similar stone clearance rates can be obtained.

Applicability of Iceland spar as a stone model standard for lithotripsy devices

The identification of a universal stone model standard would enable reproducible fragmentation data useful for the design, evaluation, and comparison of various lithotripsy devices. The clinical benefits of such a stone model include the elucidation of setting parameters that would optimize fragmentation strategies. Iceland spar is a pure form of calcite (CaCO3) that was subjected to experimental disintegration by electrohydraulic lithotripsy and extracorporeal shockwave lithotripsy. Iceland spar was fragmented with both lithotripsy methods in a reproducible fashion. The degree of fragmentation was directly related to alterations in either power or shock frequency. Iceland spar is radiopaque, inexpensive, easily obtained, homogenous in composition, and sizable. Iceland spar meets a variety of stone model criteria, warranting its continued investigation as a potential stone model standard.