Amount of Ipsilateral Parenchymal Volume Preserved Is a Key Determinant of Split Renal Function after Robot-Assisted Partial Nephrectomy.

Abstract

Objective: To identify factors associated with preserved split renal function (SRF) after robot-assisted partial nephrectomy (RAPN). Patients and Methods: The study included patients who underwent RAPN at Nagasaki University Hospital between November 2016 and December 2023. SRF was determined by 99mTc-dimercaptosuccinic acid renal imaging and the estimated glomerular filtration rate, with measurements obtained before and 6 months after surgery. The ipsilateral parenchymal volume (IPV) was measured at the same time. More than 90% SRF after surgery was considered to indicate successful preservation of renal function (the successful group), and ≤90% SRF was considered failure to preserve renal function (the unsuccessful group). The factors most relevant to SRF were sought in univariate and multivariate analyses. Results: Data for a total of 169 patients were analyzed. The median SRF was 32.04 mL/min/1.73 m² (interquartile range [IQR] 25.95, 38.06) before surgery and 27.33 mL/min/1.73 m² (IQR 21.64, 34.32) after surgery. The median SRF preservation rate was 88% (IQR 78.4, 97.0), with 94 cases (55.6%) having SRF >90% and 75 cases (44%) having SRF ≤90%. The median IPV on the surgical side was calculated by the software to be 152.2 cm³ (IQR 126.9, 186.6) preoperatively and 127.3 cm³ (IQR 102.9, 161.3) postoperatively, with a median preservation rate of 84.6% (IQR 72.2, 89.7). Univariate analysis showed significant between-group differences in diabetes status, RENAL Nephrometry score, operation time, warm ischemia time, whether or not parenchymal sutures were needed, and the amount of IPV preserved. Only percentage of IPV preserved remained significant in multivariate analysis. Conclusion: The findings of this study suggest that the residual IPV is an important determinant of SRF after RAPN.