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Argüelles-Salido E et al, 2014: Prediction of the energy required for extracorporeal shock wave lithotripsy of certain stones composition using simple radiology and computerized axial tomography

Argüelles-Salido E, Campoy-Martínez P, Aguilar-García J, Podio-Lora V, Medina-López R
Unidad de Gestión Clínica de Urología y Nefrología, Hospitales Universitarios Virgen del Rocío, Sevilla, España
Unidad de Gestión Clínica de Diagnóstico por la Imagen, Hospitales Universitarios Virgen del Rocío, Sevilla, España
Unidad de Gestión Clínica de Laboratorios Clínicos, Hospitales Universitarios Virgen del Rocío, Sevilla, España


Abstract

OBJECTIVE: To demonstrate that urinary lithiasis have a specific susceptibility to fracture through extracorporeal shock wave lithotripsy (ESWL), which is common for all calculi with the same composition and which can be estimated before treatment using CT or plain x-ray.

MATERIAL AND METHOD: We present an in vitro, prospective, randomized, blind and multi-centre study involving 308urinary calculi. 193 of these met the inclusion criteria: whole calculi composed purely of calcium oxalate monohydrate (COM), uric acid (UA) or carbonate apatite (CA), or a mix of oxalate (COMix) and of a size greater than 0.5cm. The samples were broken using lithotripsy until reaching a pre-established level of comminution. The variables employed were energy dose (Edose) per cm3 of lithiasis and Edose adjusted to lithiasic surface (EdAJ) per cm3.

RESULTS: COM was the hardest, requiring an Edose of 119,624mJ/cm3 and an EdAJ of 36,983mJ/cm3, followed by COMix (75,501/36,983), CA (22,734/21,186) and UA (22,580/6,837) (P<.05). Gmax y Gmda were correlated with Edose (r=0.434/r=0.420) and EdAJ (r=0.599/r=0.545) (P<.01). UH were correlated, in bone window and soft tissue window, with Edose/cm3 (r=0.478/r=0.539) y EdAJ/cm3 (r=0.745/r=0.758) (P<.01).

CONCLUSIONS: In our in vitro research lithiasis require, due to the specific nature of their composition, a given amount of energy in order to be broken by ESWL, which is inherent to all those sharing the same composition, and can be predicted using CT or plain x-ray.

Actas Urol Esp. 2014 Mar;38(2):115-121. doi: 10.1016/j.acuro.2013.07.004. Epub 2013 Oct 5.
PMID:24099824 [PubMed - as supplied by publisher]

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Comments 1

Hans-Göran Tiselius on Friday, 10 January 2014 09:50

The authors report in vitro results of stone disintegration and concluded in line with several other studies that COM stones are harder than those composed of carbonate apatite and uric acid. Specific energies for disintegration were derived from the experiments and comparison was made with stone size and radiological observations. It is not clear how important this information is from a clinical perspective. The in vivo disintegration depends not only on the composition of the stone and its size, but also on the body habitus of the patient. Attenuation of shockwave power during passage through muscle and fat has been demonstrated and the geometry of the shockwave is considered highly important. It is therefore difficult to know how the energy requirement for a specific stone in one patient can be determined. Prediction of stone composition and its hardness is absolutely important, but it is only the behaviour of the stone during SWL that should determine the treatment settings. Every attempt to set up specific rules and protocols for stones with an assumed composition is not beneficial for the SWL method.

Hans-Göran Tiselius

The authors report in vitro results of stone disintegration and concluded in line with several other studies that COM stones are harder than those composed of carbonate apatite and uric acid. Specific energies for disintegration were derived from the experiments and comparison was made with stone size and radiological observations. It is not clear how important this information is from a clinical perspective. The in vivo disintegration depends not only on the composition of the stone and its size, but also on the body habitus of the patient. Attenuation of shockwave power during passage through muscle and fat has been demonstrated and the geometry of the shockwave is considered highly important. It is therefore difficult to know how the energy requirement for a specific stone in one patient can be determined. Prediction of stone composition and its hardness is absolutely important, but it is only the behaviour of the stone during SWL that should determine the treatment settings. Every attempt to set up specific rules and protocols for stones with an assumed composition is not beneficial for the SWL method. Hans-Göran Tiselius
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