Using 300 Pretreatment Shock Waves in a Voltage Ramping Protocol Can Significantly Reduce Tissue Injury During Extracorporeal Shock Wave Lithotripsy

Abstract

Purpose: Pretreating a pig kidney with 500 low-energy shock waves (SWs) before delivering a clinical dose of SWs (2000 SWs, 24 kV, 120 SWs/min) has been shown to significantly reduce the size of the hemorrhagic lesion produced in that treated kidney, compared with a protocol without pretreatment. However, since the time available for patient care is limited, we wanted to determine if fewer pretreatment SWs could be used in this protocol. As such, we tested if pretreating with 300 SWs can initiate the same reduction in renal lesion size as has been observed with 500 SWs. Materials and Methods: Fifteen female farm pigs were placed in an unmodified Dornier HM-3 lithotripter, where the left kidney of each animal was targeted for lithotripsy treatment. The kidneys received 300 SWs at 12 kV (120 SWs/min) followed immediately by 2000 SWs at 24 kV (120 SWs/min) focused on the lower pole. These kidneys were compared with kidneys given a clinical dose of SWs with 500 SW pretreatment, and without pretreatment. Renal function was measured both before and after SW exposure, and lesion size analysis was performed to assess the volume of hemorrhagic tissue injury (% functional renal volume, FRV) created by the 300 SW pretreatment regimen. Results: Glomerular filtration rate fell significantly in the 300 SW pretreatment group by 1 hour after lithotripsy treatment. For most animals, low-energy pretreatment with 300 SWs significantly reduced the size of the hemorrhagic injury (to 0.8% -0.4%FRV) compared with the injury produced by a typical clinical dose of SWs. Conclusions: The results suggest that 300 pretreatment SWs in a voltage ramping treatment regimen can initiate a protective response in the majority of treated kidneys and significantly reduce tissue injury in our model of lithotripsy injury.

Ultraslow full‐power shock wave lithotripsy versus slow power‐ramping shock wave lithotripsy in stones with high attenuation value: A randomized comparative study

“…It was reported that pretreatment with 300-500 low-energy (12 kV) SWs before delivering the clinical dose of SWs (2000 SWs, 24 kV) was associated with a protective response in treated pigs. 16,17 Connors et al reported that the interval (3-4 min pause) between the initial 100 SWs and the clinical dose of SWs is more important for protecting the kidney rather than starting at low voltage. 7 This protocol of pretreatment with low-voltage 100 shocks (12 kV) with 3-min intervals before the clinical dose was also proved to significantly reduce acute oxidative stress and inflammation in the treated porcine kidney.…”

“…Other renal protective protocols were also proved in animal studies. It was reported that pretreatment with 300–500 low‐energy (12 kV) SWs before delivering the clinical dose of SWs (2000 SWs, 24 kV) was associated with a protective response in treated pigs . Connors et al .…”

Indications and contraindications for shock wave lithotripsy and how to improve outcomes

“…When compared to a fixed voltage protocol ramping improves SFR, while renal damage as measured by urinary excretion of microglobulins is decreased [71] , [72] , [73] . Recently, using a porcine model, it was shown that pretreatment (300–500 shocks) at a low voltage without a pause decreases damage to the kidney [74] , [75] . A recent clinical trial supports these in vitro results; stepwise voltage ramping was associated with a lower risk of hematoma (odds ratio 0.39) when compared to a fixed maximal voltage protocol [76] .…”

Prevalence of hypertension and diabetes after exposure to extracorporeal shock-wave lithotripsy in patients with renal calculi: a retrospective non-randomized data analysis

“…Limitations of our study are the moderate questionnaire response rate and the unavailable information regarding hypertension or diabetes at time-point of SWL. Additionally, currently used lithotripter, newer settings (e.g., ramping [ 20 , 21 ]) and co-current medications [ 22 ] have been discussed to reduce damage to the kidneys but were not used in this study. Nevertheless, in the absence of prospective data from larger cohorts with an appropriate follow-up, our study is a unique and valuable opportunity to study long-term adverse effects.…”