Bifunctional irrigation liquid as an ideal energy converter for laser lithotripsy with nanosecond laser pulses

摘要

Abstract: The intracorporal lithotripsy of ureter stones using laser pulses with a duration of 8 to 20 ns is carried out by means of energy converters. These devices have the purpose to transform the optical energy of the laserlight into mechanical energy of shockwaves, which cause the intended stone fragmentation. Therefore this method is independent of any optical property of the stone. For the endoscopic lithotripsy a continuous flow of irrigation liquid must be supplied to ensure a clear field of view and to transport the small stone fragments out of the body. In the case of the method developed by us, a second function is appointed to this liquid: the energy conversion. In transparent liquids, conversion of the optical energy is done by the laser-induced breakdown (LIB), which produces mechanical shockwaves. To release such a LIB, the laserpulse intensity must exceed a certain threshold. To achieve a LIB in the liquid at the fiber exit there are two possibilities. First, the fiber exit is spherically shaped, which leads to a kind of focus between fiber and stone. Second, the threshold intensity of the liquid is lowered. This is performed by addition of minimal amounts of Fe$+$PLU$PLU$PLU$/-ions. To obtain a stable and physiologically applicable irrigation solution the Fe$+$PLU$PLU$PLU$/-ions were added to isotonic saline solution in form of a dextran complex.!