THE ABILITY OF THE ACOUSTIC ENERGY STONE BURDEN RATIO TO PREDICT GALLSTONE CLEARANCE IN BILIARY LITHOTRIPSY

The relationship between acoustic energy, stone burden, and stone clea rance in biliary extracorporeal shock wave lithotripsy (ESWL) is uncle ar. We hypothesized that there is a consistent relationship between th ese parameters that enables gallstone clearance to be predicted. Using a porcine model and various gallstone burdens, we performed biliary E SWL with varying energy levels and number of shock waves. The acoustic energy/stone burden ratio (AE/SB) was calculated that incorporated th ese variables. Stone clearance increased with higher energy settings a nd fewer stones present (p < 0.005). The relationship between AE/SB ra tio and stone clearance was logarithmic (r2 = 0.82). The plateau of th is curve showed optimal stone clearance at approximately 20 joules/g, beyond which point the benefit of further ESWL may not outweigh the ri sks. This relationship between AE/SB ratio and stone clearance may be able to predict the optimal energy required and probable outcome of bi liary ESWL prior to the procedure.