Reducing shock number dramatically decreases lesion size in a juvenile kidney model.
OBJECTIVE
Adult stone patients are treated with several thousand lithotripter shockwaves (SWs) in order to pulverize a kidney stone. This typical clinical dose assures that the stone will be fractured completely. However, this same dose induces damage to the kidney, especially pediatric-size kidneys. If increasing SW number is known to increase renal injury and functional impairment, will reducing SW number below typical treatment levels significantly decrease kidney damage and hemodynamic changes?


METHODS
To address this question, one kidney in each of nine juvenile pigs (6-7 weeks old) was treated with 1000 SWs at 24 kV directed at a lower-pole calix with an unmodified HM-3 lithotripter. Parenchymal-lesion size was determined by sectioning the entire kidney and quantitating the amount of hemorrhage in each slice. Renal function was determined before and after SW treatment by inulin clearance, paraaminohippurate (PAH) extraction, and PAH clearance. The resulting morphologic and functional changes were then compared with those of kidneys that had been treated with a typical clinical dose of 2000 SWs (data previously published; J Am Soc Nephrol 2000;11:310). Eleven pigs were utilized as sham-treated controls.


RESULTS
Limiting SW number to 1000 significantly reduced the size of the lesion (by 95%) and reduced the degree of functional change (glomerular filtration rate by 38%, PAH extraction by 73%, renal plasma flow by 46%) compared with kidneys receiving 2000 SWs (an adult dose).


CONCLUSIONS
These data support the idea that SW number should be reduced to the lowest number that fractures kidney stones in order to minimize renal injury and functional impairment.
Connors
Bret A
BA
Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. connors@anatomy.iupui.edu
Evan
Andrew P
AP
Blomgren
Philip M
PM
Willis
Lynn R
LR
Handa
Rajash K
RK
Lifshitz
David A
DA
Lingeman
James E
JE
Ying
Jun
J
D000818:Animals; D005260:Female; D005630:Fructans / Q000097:blood / Q000652:urine; D005919:Glomerular Filtration Rate; D006470:Hemorrhage / Q000473:pathology*; D007444:Inulin / Q000097:blood / Q000652:urine; D007668:Kidney / Q000473:pathology*; D007669:Kidney Calculi / Q000628:therapy*; D008096:Lithotripsy / Q000379:methods*; D023421:Models, Animal; D009929:Organ Size; D012079:Renal Circulation; D013552:Swine; D010130:p-Aminohippuric Acid / Q000097:blood / Q000652:urine
D005630:Fructans; C002938:polyfructosan; D007444:Inulin; D010130:p-Aminohippuric Acid