Impact of parenchymal loss on renal function after laparoscopic partial nephrectomy under warm ischemia

To elucidate the impact of renal parenchymal loss and the ischemic reperfusion injury (RI) on the renal function after laparoscopic partial nephrectomy (LPN) under warm ischemia (WI).

Thirty-five patients with a single polar renal mass ≤4 cm and normal contralateral kidney underwent LPN. Transperitoneal LPN with WI using en bloc hilar occlusion was performed. The total differential renal function (T-DRF) using ^99mTc-dimercaptosuccinic acid was evaluated preoperatively and postoperatively over a period of 1 year. A special region of interest (ROI) was selected on the non-tumorous pole of the involved kidney, and was compared with the same ROI in the contralateral kidney. The latter comparison was defined as partial differential renal function (P-DRF). Any postoperative decline in the P-DRF of the operated kidney was attributed to the RI. Subtraction of the P-DRF decline from the T-DRF decline was attributed to the parenchymal loss caused by the resection of the tumor and suturing of the normal parenchyma.

The mean WI time was 22 min, and the mean weight of resected specimen was 18 g. The mean postoperative eGFR declined to 87 ml/min/1.73 m² from its baseline mean value of 97 ml/min/1.73 m² (p value = 0.075). Mean postoperative T-DRF and P-DRF of the operated kidney declined by 7 and 3 %, respectively.

After LPN of small renal mass, decline in renal function is primarily attributed to parenchymal loss caused by tumor resection and suturing of the normal parenchyma rather than the RI.