Article

Optimising an escalating shockwave amplitude treatment strategy to protect the kidney from injury during shockwave lithotripsy

Departments of Anatomy and Cell Biology Biostatistics, Indiana University School of Medicine Methodist Hospital Institute for Kidney Stone Disease, Indianapolis, IN, USA.
BJU International (Impact Factor: 3.53). 05/2012; 110(11C). DOI: 10.1111/j.1464-410X.2012.11207.x
Source: PubMed

ABSTRACT

Study Type – Therapy (case series)
Level of Evidence 4
What's known on the subject? and What does the study add?
Animal studies have shown that one approach to reduce SWL-induced renal injury is to pause treatment for 3–4 min early in the SWL-treatment protocol. However, there is typically no pause in treatment during clinical lithotripsy.
We show in a porcine model that a pause in SWL treatment is unnecessary to achieve a reduction in renal injury if treatment is begun at a low power setting that generates low-amplitude SWs, and given continuously for ≈4 min before applying higher-amplitude SWs.

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    ABSTRACT: The treatment of kidney stone disease has changed dramatically over the past 30 years. This change is due in large part to the arrival of extracorporeal shock wave lithotripsy (ESWL). ESWL along with the advances in ureteroscopic and percutaneous techniques has led to the virtual extinction of open surgical treatments for kidney stone disease. Much research has gone into understanding how ESWL can be made more efficient and safe. This article discusses the parameters that can be used to optimize ESWL outcomes as well as the new concepts that are affecting the efficacy and efficiency of ESWL.
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    ABSTRACT: Background and purpose: It is known that pretreating one renal pole with shockwaves generated at the minimum energy setting of an HM3 lithotripter reduces renal damage in pigs during shockwave lithotripsy; however, the minimum energy level to induce this effect is unknown. The purpose of this study was to analyze if exposing the whole kidney to low-energy-pressure pulses by positioning it out of focus protects the tissue from a clinical dose of shock waves. Materials and methods: Seven rabbits were exposed to 250 shockwaves focused on the renal pelvis of the left kidney using a Piezolith 2300 lithotripter. A second group of seven rabbits received 50 prophylactic pressure pulses to the whole kidney at an out-of-focus position, followed by 250 shockwaves focused on the renal pelvis of the same kidney. The animals were sacrificed 1 week after shockwave treatment, and a bilateral nephrectomy was performed to compare tissue damage in both groups. Results: All shockwave-treated kidneys showed macro- and microhistologic changes. Capsular fibrosis, subcapsular hematoma, inflammation, and necrotic areas in the renal capsule were significantly less in kidneys that received the prophylactic treatment. No differences between both groups were observed for tissue damage in the renal cortex and the renal medulla. Conclusions: Our preliminary experiment reveals that an out-of-focus pretreatment to the whole kidney reduces the damage to the renal capsule of rabbit kidneys during shockwave application. This protective effect may be extended to areas inside the kidney by adjusting the dose of the prophylactic pressure pulses.
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