Clinical evaluation and related factor analysis of intrarenal pressure using a Chinese-made disposable...

The pressure fluctuations during retrograde intrarenal surgery (RIRS) can cause related complications, so precise monitoring and control of intrarenal pressure (IRP) play an important role. This study aimed to assess the clinical value of a Chinese-made disposable pressure-measuring flexible ureteroscope in monitoring IRP during RIRS for upper urinary tract stones <2 cm, and analyze factors affecting IRP.

In this prospective single-arm study, 35 patients (38 renal units) underwent RIRS. Mean age was 42.3 ± 6.1 years, body mass index (BMI) 24.2 ± 2.6 kg/m², and maximum stone diameter 1.6 ± 0.4 cm. Stones were located in the ureter (21.1%), kidney and ureter (15.8%), or kidney only (63.2%). IRP threshold was 30 mmHg; irrigation used gravity or low-pressure pump. Ureteral access sheath (UAS) size (Fr11-13 or Fr12-14) was selected based on ureteroscopy. Outcomes included safe IRP (<30 mmHg), high/maximum IRP, cumulative time above threshold, influencing factors, infection markers, fever incidence, operative time, stone-free rate, and Visual Analogue Scale (VAS) score.

All procedures succeeded. Mean safe IRP was 10.9 ± 3.4 mmHg, high IRP 63.6 ± 13.5 mmHg, and maximum IRP 181.2 ± 50.5 mmHg. Mean cumulative time above threshold was 485.2 ± 61.3 s. Low-position UAS placement led to significantly higher high IRP, maximum IRP, and longer high-pressure time compared to conventional placement (all p < 0.05). UAS size did not significantly affect IRP. Postoperative infection markers showed no difference between mean IRP subgroups (0-30 mmHg vs. 30-60 mmHg). Overweight patients had higher mean IRP than normal BMI patients (26.1 ± 4.2 vs. 15.9 ± 5.7 mmHg, p < 0.05). Postoperative fever occurred in 3 cases (8.6%), all with high IRP and prolonged high-pressure exposure. Operative time averaged 45.2 ± 8.3 min, stone-free rate was 92.1%, and mean VAS score was 2.52 ± 0.21. No major complications occurred.

The disposable pressure-measuring flexible ureteroscope enables real-time IRP monitoring during RIRS, allowing surgical strategy adjustments to improve safety. Low UAS position and high BMI are risk factors for elevated IRP.