A Study On Influencing Factors For Flexible Ureteroscopy In The Treatment Of Lower Pole Calculi And The Establishment Of A Predictive Model

Objective:The flexible ureteroscopic lithotripsy(f-URL)has the advantages of less invasiveness,satisfactory surgical results and low complication rate.It has become one of the preferred options for the treatment of kidney stones < 2cm,but there are still some limitations in clinical application.Lower pole calculi is one of the most important treatment difficulties.Studies have shown that f-URL can achieve a stone free rate up to 95% in the treatment of middle and upper calculi in the kidney,and the stone free rate of lower pole calculi is only 50 to 92%.Based on the above reasons,the influencing factors affecting the curative effect of lower calculus surgery are gradually becoming a hot spot.However,there are several shortcomings in the current research on lower pole renal calculi.First,although several factors have been found that affect the efficacy of surgery,little is known about the comparison of renal collecting systems in normal people and lower pole renal calculi patients,especially the applied anatomy and structure variation.Secondly,for the treatment of lower pole calculi,the curvature of the flexible ureteroscope is often extreme.However,there is no existing research about whether the energy output of the laser fiber decreases or not and whether it affects fragmentation efficiency.In addition,the ureteroscope involved in the existing research are relatively old and have poor performance,and those researches are all retrospective with small sample sizes.The reliability of the conclusions needs further research to confirm.Based on the above reasons,this study intends to explore the influencing factors of the efficacy of f-URL in the treatment of lower pole calculi through retrospective and prospective clinical studies along with in vitro experiments and establish a predictive model.Methods:Part 1To analyze the normal imaging data of physical examination in our hospital retrospectively,based on intravenous pyelography(IVP).Study the anatomical features of lower pole kidney in normal population and summarize the features.Part 2To detect the energy output changes of different laser fibers under different full radius,different angles and energy settings,to find the core influencing factors affecting the energy output of laser fiber.Part3To explore the influencing factors of f-URL in the treatment of lower pole kidney calculi through a prospective multicenter study and establish a predictive model of lower pole calculi surgery.Results:Part 1Analyzing 203 cases of unilateral IVP retrospectively in our center,151 males and 52 females,with an average age of(49.30±12.60)years,79 cases on the left side and 124 cases on the right side.The average infundibulopelvic angle(IPA),infundibular length(IL),(infundibular width)IW,and Caliceal pelvic height(CPH)were(41.18±15.46)°,(23.17±4.30)mm,(4.78±2.49)mm,(19.80±4.30)mm.Analyzing age(20-40 years old,41-60 years old,over 60 years old),gender,and location(left and right)showed that there was no significant difference in IPA,IW,and IL at different ages,genders,and locations.Only the average CPH value of males was significantly higher than that of females(p=0.024).Part 2OLYMPUS-V ureteroscope bending radius measurement results: upper bending 180° is 16 mm,lower bending 180° is 36 mm,and lower bending 275° is 24 mm.Through statistical analysis,the 200?m Lumenis and the 200?m Moses laser fiber have more energy loss when the bending angle is larger,the bending radius is smaller,and the energy setting is higher.Through the observation of the thermal imager,there are obvious temperature changes occur at the curved surface of the fiber when adjusts the energy setting,the bending radius or the bending angle.Part3Prospective analysis of 12 centers of f-URL treatment of 172 patients with lower pole calculi,the results showed that the success rate of intraoperative lithotripsy was 89%,and the postoperative stone free rate was 75%.Univariate statistics and two-class logistic regression analysis showed that basketing,stone volume,and IPA(including mIPA)were independent predictors of the efficacy of f-URL,and stone volume,average CT value,IL,the minimum ratio of lower pole neck width with lower pole width,stone uretero pelvic junction distance(SUD)were independent predictors of stone free after f-URL.Based on the above results,a nomogram prediction model was established and prediction efficiency is good.A comparative analysis of the anatomical parameters of the normal population and the calculus found that IL,IW,and CPH are anatomical predictors of the occurrence of lower pole calculi.Conclusion:The results of this study indicate that there are certain variability in the anatomical parameters of IPA,IW,IL,CPH in the renal pelvis in the normal population.In order to better carry out minimally invasive treatment of the lower pole calculi,the surgeon needs to fully recognize the variation of the anatomy of the lower pole kidney.During f-URL in treating lower pole calculi,the curvature of laser fiber is large and the bending radius is small,which cause temperature of the curved surface of the fiber increases,and extra attention needs to be paid to appropriately reduce the energy setting and avoid damaging the flexible ureteroscope caused by the fiber fuse.Our prospective study shows that multiple factors in the flexible ureteroscopic lithotripsy have an effect on intraoperative lithotripsy and postoperative lithotripsy.It is necessary to evaluate the features of the stone and the anatomy of the lower pole kidney before surgery.