V11-12: HOLMIUM LASER SETTINGS DURING LITHOTRIPSY OF DIFFERENT TYPES OF KIDNEY STONES
Currently, holmium laser is the most versatile energy source for the treatment of intrarenal stones by intracorporeal lithotripsy since it may be used with both flexible and rigid endoscopes, permitting access to all parts of the kidney. High-power laser enables the destruction of all kinds of stones, but the settings most suitable for the treatment of individual types remain to be defined.
In the operation theatre we used a pelvic trainer into which we introduced six different types of urinary stones from our stone library: uric acid, cystine, struvite, brushite, calcium oxalate monohydrate, and calcium oxalate dihydrate._x000D_ Ex vivo lithotripsy was performed by means of continuous serum irrigation with the Lumenis VersaPulse 120 W high-power laser, with a 550-micron fibre. Power, frequency, and potency parameters, as well as the short-pulse/long-pulse variable, were varied among the six different types of stones.
In all cases lithotripsy was commenced using low power and frequency: 0.2 J and 10 Hz. Power and frequency were raised up to a maximum of 3 J and 40 Hz, according to the type of stone, and until maximum potencies close to 120 W were obtained._x000D_ The difference in hardness of the investigated types of stones required differing power settings according to whether fragmentation into large pieces or pulverisation was desired. The different power settings used for the various types of stones are described, and the fragmentation ability and speed of the holmium laser are appraised.
High-power laser is useful for destruction of any type of urinary stone. The harder the stone, the greater is the potency needed; however, the frequency is not so important. Low power is able to yield good results on soft stones, and excellent pulverisation can be obtained by increasing the pulse frequency. The long pulse is very useful for lowering the stone retropulsion and increasing pulverisation, particularly in the case of softer stones.