Application Of R.E.N.A.L Nephrometry Score In Retroperitoneal Laparoscopic Partial Nephrectomy And Analysis Of The Predictive Factors Of Warm Ischemia Time

Objective:To explore the application of R.E.N.A.L Nephrometry Score in retroperitoneal laparoscopic partial nephrectomy.And to investigate the predictors of intraoperative warm ischemia time.Methods:The medical records of 147 patients with renal tumor who underwent retroperitoneal laparoscopic partial nephrectomy in our hospital from January2016 to September 2019 were retrospectively analyzed.The total RENAL score and score of each item were calculated based on preoperative imaging data(CT/MRI),and the relationship between the different grades of RENAL score and the main indicators of perioperative period(warm ischemia time,operation time,estimated blood loss,serum creatinine changes,postoperative complications,postoperative hospital stay)was analyzed.The relationship between R.E.N.A.L Nephrometry Score and other indicators(age,sex,BMI,side,proportion of clinical symptoms,proportion of hypertension,proportion of diabetes)and intraoperative warm ischemia time(>30min)was analyzed on univariate analysis,and the independent predictors were determined by multivariate logistic regression analysis.Furthermore,the ROC curve of multiple factors joint index and independent predictors was drawn.Results:A total of 147 patients with renal tumor were enrolled in this study.The mean age was 52.5±12.7 years old.According to the R.E.N.A.L Nephrometry Score,tumor complexity was low in 88(59.9%)patients,moderate in 43(29.2%)patients,and high in 16(10.9%)patients.There were statistically significant difference among the three groups in warm ischemia time,operative time and postoperative hospital stay,but no significant difference in estimated blood loss,serum creatinine changes,and postoperative complication rate.In the analysis of predictors of warm ischemia time,80 patients(54.4%)with warm ischemia time≤30min and 67 patients(45.6%)with warm ischemia time>30min,respectively.Univariate analysis results showed that BMI,maximal diameter(R)score,proportion of diabetes exophytic/endophytic properties(E)score,nearness of the tumor to the collecting system or sinus(N)score,total RENAL score were associated with intraoperative warm ischemia time(>30 min).However,patients’age,gender,side,proportion of clinical symptoms,proportion of hypertension,anterior/posterior(A),location relative to the polar lines(L)score at there were no statistically significant difference between the two groups.It showed that BMI,N score and total RENAL score were independent risk factors for>30min of warm ischemia time on multivariate logistic regression analysis.For the risk of>30min of warm ischemia time,BMI≥28kg/m~2 was 4.596 times to BMI<24kg/m~2(95%CI,1.198-17.636;P=0.026),but there was no significant difference between the 24≤BMI<28 kg/m~2 group and the BMI<24 kg/m~2 group;The risk of longer warm ischemia time(>30min)of N score(2 points)was 5.642 times to N score(1points)(95%CI,1.882-16.909;P=0.002),it was 6.255 times when N score(3points)compared to N score(1 points)(95%CI,1.290-30.335;P=0.023);The risk of longer warm ischemia time(>30min)of total RENAL score(7-9 points)was 7.222 times to total RENAL score(4-6 points)(95%CI,1.808-28.845;P=0.005),it was 16.166 times when total RENAL score(10-12 points)compared to total RENAL score(4-6 points)(95%CI,1.258-207.654;P=0.033).In the ROC curve,the area under the curve of BMI,N score,total RENAL score,multiple factors joint index were 0.590,0.812,0.783,0.858,respectively.Conclusion:Warm ischemia time,operation time and postoperative hospital stay were prolonged in patients with higher total RENAL score in retroperitoneal laparoscopic partial nephrectomy.However,its value in predicting estimated blood loss,postoperative complication rate and serum creatinine changes was limited.Further studies found that BMI(kg/m~2),N score and total RENAL score were independent risk factors for intraoperative warm ischemia time(>30min).In obese patients,the closer the tumor was to the renal collecting system or the renal sinus and the higher the total RENAL score was,the greater the risk of>30min of warm ischemia time was.This is helpful for the clinicians to choose an appropriate surgical procedure after preoperative evaluation.