Austin Health, Monash Health, Peter McCallum Cancer Centre
Introduction: Holmium lasers are an effective endoscopic treatment for renal stones, with both high- and low-power lasers commonly in use in Australia. Laser settings for stone destruction are relatively limited when using 10-20W lasers. Basket extraction of fragments is often required. This can be time consuming and associated with ureteric injury. High-power lasers can deliver more energy (up to 120W) at higher frequencies. This allows more variation in laser settings, including the ability to dust stones with low-power high-frequency settings. Dusted stones may result in fewer large fragments and increase the likelihood of spontaneous passage of residual stone. In addition, laboratory studies have demonstrated reduced destruction times for high-power lasers, although clinical evidence is lacking. Clinical evidence for superior stone destruction based on operative times was the focus of this study – theatre times for URS were investigated comparing high and low power lasers in a general hospital setting.
Methods: An audited review was conducted of 354 patients who underwent URS over a two-year period at two hospital sites utilising high or low power laser. Operative time, stone characteristics, disposables equipment, use of dusting, complications and stone free rates were recorded. Linear regression was used to model the relationship between laser type and theatre time. Univariate analysis was performed to determine other factors associated with increased operative time.
Results: Mean operative time was 61.9 minutes. No significant difference between sites (0.40, p=0.88, CI -4.9-5.8) was found, including following exclusion of large stones (>20mm). Stone size categories analysed separately showed reduced operative times for larger stones when using high-power laser. Basket use (8.4, p=0.002, CI 3.06-13.65) and increasing stone size (6.9, p<0.005, CI 3.4-10.4) were associated with increased operative time. Complication and stone free rates did not vary between sites.
Conclusions: High-power laser was not associated with reduced total operative time in this cohort, although there was a trend towards this for larger renal calculi. Further delineation by surgeon expertise would be useful to determine if high power laser is advantageous in the clinical setting generally. In training hospitals, any difference may be obscured by other factors.
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