| PURPOSE: To compare 'wide focus and low pressure' shockwave-induced renal injury with that induced by 'sharp focus and high pressure' one. METHOD: (1) Standard artificial stones of 15mm diameter were exposed to wide focus and sharp focus shock waves respectively, until all the fragments slipped down through a basket of 3mm mesh size. Peak pressure was varied from 30.5 to 110 MPa. The relationship between peak pressure and number of shots required for model stone disintegration was shown in a plot. (2) 20 male adult New Zealand white rabbits were randomly divided into 2 groups as follows: Group A. were exposed to sharp focus shock waves directly to the lower pole of left kidney (impulses: 122, pressure: 68MPa, rate: 1 shot/sec.). Group B were exposed to wide focus shock waves directly to the lower pole of left kidney (impulses. 150, pressure: 35.3MPa, rate: 1 shot/sec.). With such parameters, the dose 2 groups received had the same fragmentation effect onstone. The renal injury was evaluated by rcnin in scrum, P 2-MG in urine, ERPF of the left kidney, light and electron microscopic examination at different time(l day before and immediately, 1,4,7,30 day after ESWL). RESULT: The rcnin in scrum, P 2 MG in urine,ERPF of the left kidney were not significantly different between Group A and Group B (P>0.05). Neither was there any remarkable difference on light microscopic specimen during acute phase. But the thickened parietal layer of Bowman's capsule was observed occasionally in Group A one month later. The electron microscopic examination showed that the renal damage in Group B was lighter than that in Group A. CONCLUSION: The renal trauma induced by 'wide focus and low pressure' extracorporeal shock waves was less than that by 'sharp focus and high pressure' one. |
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