The effect and safety assessment of monitoring ethanol concentration in exhaled breath combined with intelligent control of renal pelvic pressure on the absorption of perfusion fluid during flexible ureteroscopic lithotripsy.

Purpose: Previously, we designed a ureteral access sheath with the capability of renal pelvic pressure (RPP) measurement and a medical perfusion and aspiration platform, allowing for the intelligent control of RPP. However, the effect of different RPP levels on perfusion fluid absorption remains unclear. This randomized controlled trial aimed to investigate the effects of exhaled ethanol concentration monitoring and intelligent pressure control on perfusion fluid absorption during flexible ureteroscopic lithotripsy.

Methods: Eighty patients scheduled for flexible ureteroscopic lithotripsy were randomly divided into four groups. In groups A, B, and C, the RPPs were set at 0, - 5, and - 10 mmHg, respectively. Group D was regarded as the controls with unfixed RPP. Isotonic saline containing 1% ethanol was used as the irrigation fluid, with an average irrigation flow rate of 100 mL/min. The primary outcome of this study was the absorption of perfusion fluid that was calculated based on the exhaled ethanol concentration. The secondary outcomes included duration of operation and amounts of perfusion fluid used. Postoperative complications, pre- and postoperative renal function, infection markers, and blood gas analysis were also recorded for safety assessment.

Results: In all, 76 patients were involved in this study, whose demographic characteristics and preoperative conditions were comparable among groups. Under the same perfusion flow rate, the groups with fixed RPP exhibited reduced absorption of perfusion fluid, duration of operation, and perfusion volume. In particular, the lowest values were observed in group C (RPP =  - 10 mmHg). In contrast to the unfixed RPP group, no considerable difference were observed in levels of BUN, Scr, WBC, CRP, and blood gas values among the fixed RPP groups. Moreover, postoperative complications showed no significant difference among groups.

Conclusion: In flexible ureteroscopic lithotripsy, the groups with fixed RPP had less absorption of perfusion fluid and perfusion volume, shorter duration of surgery, and higher safety than the unfixed group.