Relation between renal pelvic pressure and ratio of endoscope-sheath diameter during percutaneous nephrolithotomy

Abstract

Objective To observe the influence of ratio of endoscope-sheath diameter on renal pelvic pressure during PCNL. Methods The model of 24 isolated adult porcine kidneys were used to imitate percutaneous nephrolithotomy from September 2016 to June 2017. Each tract was established ( F12, F14 and F16). Three kinds of endoscopes (F8 all-seeing needle percutaneous nephroscope, F6/7.5 and F8/9.8 rigid ureteroscope), input a 200μm laser, were adopted. There were 8 combinations, and 3 kidneys were used for each one. Renal pelvic pressure was measured 3 times repeatedly in every combination with steady irrigation (50, 100, 150, 200, 250, 300, 350, 400, 450, 500 cmH2O). Results The linear equations, ratios of endoscope-sheath diameter and highest renal pelvic pressures for each combination were: F8-F12, Pr=0.026P0-1.533, 0.67, 12.2±0.54; F6/7.5-F12, Pr=0.112P0-5.001, 0.92, 51.2±0.93; F8-F14, Pr=0.010P0+ 1.067, 0.58, 6.2±0.48; F6/7.5-F14, Pr=0.020P0+ 1.000, 0.79, 10.8±0.46; F8/9.8-F14, Pr=0.144P0+ 20.933, 0.87, 84.7±1.17; F8-F16, Pr=0.005P0+ 1.067, 0.50, 2.8±0.34; F6/7.5-F16, Pr=0.009P0+ 0.533, 0.68, 5.1±0.32; F8/9.8-F16, Pr=0.020P0+ 2.200, 0.75, 12.6±0.56. The combinations of F6/7.5-F12 and F8/9.8-F14 might lead to a high renal pelvic pressure without proper irrigation (<401.7 cmH2O for F6/7.5-F12; <132.4 cmH2O for F8/9.8-F14). Conclusion In order to keep a safe pressure, a proper ratio of endoscope-sheath diameter (<0.80) and appropriate irrigation must be considered. Key words: Percutaneous nephrolithotomy; Renal pelvic pressure; nephrostomy tract size; Ratio of endoscope-sheath diameter