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

Rajash K. Handa, James A. McAteer, Bret A. Connors, Ziyue Liu, James E. Lingeman, Andrew P. Evan

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

OBJECTIVE • To test the idea that a pause ( ≈ 3 min) in the delivery of shockwaves (SWs) soon after the initiation of SW lithotripsy (SWL) is unnecessary for achieving a reduction in renal injury, if treatment is begun at a low power setting that generates lowamplitude SWs. MATERIALS AND METHODS • Anaesthetised female pigs were assigned to one of three SWL treatment protocols that did not involve a pause in SW delivery of > 10 s (2000 SWs at 24 kV; 100 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV; 500 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV). • All SWs were delivered at 120 SWs/min using an unmodified Dornier HM3 lithotripter. • Renal function was measured before and after SWL. • The kidneys were then processed for quantification of the SWL-induced haemorrhagic lesion. Values for lesion size were compared to previous data collected from pigs in which treatment included a 3-min pause in SW delivery. RESULTS • All SWL treatment protocols produced a similar degree of vasoconstriction (23-41% reduction in glomerular filtration rate and effective renal plasma fl ow) in the SW-treated kidney. • The mean renal lesion in pigs treated with 100 low-amplitude SWs delivered before the main dose of 2000 highamplitude SWs (2.27% functional renal volume [ FRV ] ) was statistically similar to that measured for pigs treated with 2000 SWs all at high-amplitude (3.29% FRV). • However, pigs treated with 500 low-amplitude SWs before the main SW dose had a significantly smaller lesion (0.44% FRV) that was comparable with the lesion in pigs from a previous study in which there was a 3-min pause in treatment separating a smaller initial dose of 100 low-amplitude SWs from the main dose of 2000 high-amplitude SWs (0.46% FRV). The time between the initiation of the low-and high-amplitude SWs was ≈ 4 min for these latter two groups compared with ≈ 1 min when there was negligible pause after the initial 100 low-amplitude SWs in the protocol. CONCLUSIONS • Pig kidneys treated by SWL using a two-step low-to-high power ramping protocol were protected from injury with negligible pause between steps, provided the time between the initiation of low-amplitude SWs and switching to high-amplitude SWs was ≈ 4 min. • Comparison with results from previous studies shows that protection can be achieved using various step-wise treatment scenarios in which either the initial dose of SWs is delivered at low-amplitude for ≈ 4 min, or there is a definitive pause before resuming SW treatment at higher amplitude. • Thus, we conclude that renal protection can be achieved without instituting a pause in SWL treatment. It remains prudent to consider that renal protection depends on the acoustic and temporal properties of SWs administered at the beginning stages of a SWL ramping protocol, and that this may differ according to the lithotripter being used.

Original languageEnglish (US)
Pages (from-to)E1041-E1047
JournalBJU International
Volume110
Issue number11 C
DOIs
StatePublished - Dec 1 2012

Keywords

  • Kidney
  • Lithotripsy
  • Swine
  • Tissue injury

ASJC Scopus subject areas

  • Urology

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