Introduction: Basket extraction of all possible stone fragments has been shown in recent studies to increase stone clearance and recurrence in patients undergoing laser lithotripsy of renal calculi. However, data are lacking on distribution of size of fragments created with different laser settings, stone density and composition that may impact the ability to basket such fragments. Dust (< 1mm) and small fragments (1-3 mm) may be too small to be efficiently basketed compared to larger fragments (> 3mm). In this study we report size distribution of fragments created with various energy settings during holmium laser lithotripsy.
Methods: 110 patients with renal calculi underwent Mini- PCNL using ClearPetra sheath( Well Lead Medical Co., China) with controllable irrigation and suction system that minimizes fragment dispersion and maximizes fragment aspiration. Moses Holmium laser (Lumenis INC, Israel) was used with various combinations of energy settings for lithotripsy. Single energy setting was used in 57 cases and multiple settings in 53 cases . All fragments were collected in strainer incorporated in aspiration system and separated, weighed into dust (<1mm), small (1-3 mm) and large (>3 mm) fragments for each energy setting. Factors influencing creation of baskettable (> 3mm) fragments was assessed using multivariable regression analysis. Sensitivity analysis according to stone composition and stone clearance was also performed.
Results: Mean stone diameter was 17.5±8.9 mm and stone density was 1198 HU±271. Laser settings ranged from various combinations of frequency (10-80 Hz) and power (0.2-2 J). Complete stone clearance at 48 hours was achieved in 76% cases. 80 % patients completed one month follow-up and had 100% stone clearance on CT KUB. Proportion of fragment size < 1mm was 45.8±17.1% (9-81%), 1-3 mm was 28.8±11.8% (3-53%), and > 3 mm was 24.9±16.4% (0-64%) for entire cohort. Using multivariable regression analysis frequency, energy and power were all predictive for proportion of creating > 3 mm fragments (P<0.05). Average efficiency of fragmentation was 5.5 mm3 /sec and was not associated with any factor on multivariable regression.
Conclusions: Despite varying laser energy settings, across various stone compositions, majority of fragments created are either < 1mm or 1-3 mm that may be difficult to basket. Only 25% fragments were >3 mm that would basket easily. These findings suggest basketing techniques alone may be insufficient to achieve complete stone clearance and may influence stone extraction strategies going forward. Source of
