Evaluation of selected Doppler parameters of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy

Introduction Despite the risk of complications, which does not exceed several percent, extracorporeal shock wave lithotripsy (ESWL) causes morphological and functional changes in kidneys as a result of the effect of the generated shock wave energy on the renal parenchyma structure. Material and methods Forty-two patients were included in the study. The mean age in the studied group was 50.9 years (SD ±13.7). Extracorporeal lithotripsy treatments were carried out during the period from January 2014 to April 2014 using an electromagnetic shock wave generator. The spectrum of blood flow of the interlobar arteries of both the treated and the opposite kidney was investigated. On the basis of these spectrums, parameters such as: resistive index (RI), pulsatility index (PI) and acceleration time (AT) were calculated. Results The ESWL treatment causes a statistically significant increase of the RI parameter in the ipsilateral kidney (p <0.0001) as well as in the opposite kidney (p <0.0001). The RI value decreases after 92 hours after the treatment, reaching statistical significance in both kidneys (p <0.005). The PI parameter substantially increases after treatment in both kidneys (p <0.0001), and decreases after 92 hours (p <0.0001). Statistically significant correlations are shown between RI as well as the PI parameters and the patient's age. Conclusions Extracorporeal shock wave lithotripsy (ESWL) of renal stones causes temporary impairment of the renal perfusion in both ipsilateral and contralateral kidneys. The main factor that determines the value of the RI and PI parameters is the patient's age.