Effects of flow rate on pressure and nephrons during flexible ureteroscopy with intelligent control of renal pelvic pressure: an in-vivo pig model

To investigate the effects of flow rate on pressure and nephron injury during flexible ureteroscopy with intelligent renal pelvic pressure (RPP) control in an in vivo pig model. Twelve kidneys from six female pigs were randomly divided into six groups. Pressure-controlled (PC) and non-pressure-controlled (NPC) groups were continuously perfused at a flow rate of 50 mL/min (group A), 100 mL/min (group B), and 150 mL/min (group C) for 30 min. Color Doppler ultrasound detected exosmosis of the perirenal fluid. Nephron biopsies were performed in the upper, middle, and lower regions. Pressure changes and pathological conditions of the tissue at different flow rates and pressure control values were compared. RPP values for groups A, B, and C were 8.70 ± 1.02, 20.50 ± 3.03, and 45.97 ± 9.57 mmHg, respectively, and the difference was statistically significant in NPC groups (P < 0.05). RPP values with 10 mmHg control value were 9.43 ± 1.50, 9.97 ± 1.69, and 8.77 ± 1.77 mmHg, respectively. With 0 mm Hg control value, they were 0.40 ± 0.67, -0.40 ± 1.35, and 0.33 ± 1.03 mmHg, respectively, and with - 10 mmHg control value, -9.00 ± 1.34, -11.30 ± 1.15, and - 9.27 ± 1.62 mmHg, respectively. Values fluctuated around the set value, with clinically non-significant differences within 2 mmHg. Pathological examination showed that the nephron structure changed in the NPC group, with more marked changes associated with increasing flow rate. No changes were observed in the nephron morphology in the PC group regardless of perfusion flow rate. Flexible ureteroscopy with intelligent RPP control can effectively monitor and control pressure under different perfusion flow conditions and prevent nephron injury.