1 Department of Mechanical Engineering, University of Washington, Seattle, Washington.
2 Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, Washington.
J Endourol. 2019 May;33(5):400-406. doi: 10.1089/end.2018.0516. Epub 2019 Feb 1.
The goal was to test whether stone composition and kidney phantom configuration affected comminution in extracorporeal shockwave lithotripsy (SWL) laboratory tests. Confinement may enhance the accumulation of dust and associated cavitation bubbles in the fluid surrounding the stone. It is known that high shockwave delivery rates in SWL are less effective because bubbles generated by one shockwave do not have sufficient time to dissolve, thereby shielding the next shockwave. Experiments were conducted with a lithotripter coupled to a water bath. The rate of comminution was measured by weighing fragments over 2 mm at 5-minute time points. First, plaster and crystal stones were broken in four phantoms: a nylon wire mesh, an open polyvinyl chloride (PVC) cup, a closed PVC cup, and an anatomical kidney model-the phantoms have decreasing fluid volumes around the stone. Second, the fluid volume in the kidney model was flushed with water at different rates (0, 7, and 86 mL/min) to remove dust. The efficiency of breakage of stones decreases for the dust emitting plaster stones (percentage of breakage in 5 minutes decreased from 92% ± 2% [ = 3] in wire mesh to 19% ± 3% [ = 3] in model calix) with increasing confinement, but not for the calcite crystal stones that produced little dust (percentage of breakage changed from 87% ± 3% [ = 3] in wire mesh to 81% ± 3% [ = 3] in kidney model). Flushing the kidney phantom at the fastest rate improved comminution of smaller plaster stones by 27%. Phantoms restricting dispersion of dust were found to affect stone breakage in SWL and experiments should replicate kidney environments. The dust around the stone and potential cavitation may shield the stone from shockwaves and reduce efficacy of SWL. Understanding of stone composition and degree of hydronephrosis could be used to adapt patient-specific protocols.
目的是测试结石成分和肾模拟体构型是否会影响体外冲击波碎石术 (SWL) 实验室测试中的粉碎效果。限制条件可能会增强结石周围流体中粉尘的积累和相关空化气泡。已知 SWL 中的高冲击波输送率效果较差，因为一个冲击波产生的气泡没有足够的时间溶解，从而屏蔽了下一个冲击波。实验是在与水浴耦合的碎石机上进行的。通过在 5 分钟的时间点称重超过 2mm 的碎片来测量粉碎率。首先，将石膏和水晶石在四个模拟体中破碎：尼龙金属丝网格、开放聚氯乙烯 (PVC) 杯、封闭 PVC 杯和解剖肾脏模型——模拟体中结石周围的流体体积逐渐减小。其次，以不同的速度（0、7 和 86mL/min）用水流冲洗肾脏模型中的流体，以去除粉尘。随着限制条件的增加，产生粉尘的石膏结石的破碎效率降低（在金属丝网格中的破碎百分比从 92%±2%[=3]降低至模型肾盏中的 19%±3%[=3]），但对产生粉尘较少的方解石晶体结石则没有影响（在金属丝网格中的破碎百分比从 87%±3%[=3]变为模型肾脏中的 81%±3%[=3]）。以最快的速度冲洗肾脏模拟体可将较小的石膏结石的粉碎率提高 27%。发现限制粉尘分散的模拟体影响 SWL 中的结石破碎，实验应复制肾脏环境。结石周围的粉尘和潜在的空化可能会使结石免受冲击波的影响，从而降低 SWL 的效果。对结石成分和肾积水程度的了解可用于适应特定患者的方案。
