Robotic-assisted partial nephrectomy with sequential clamping of segmental renal arteries for multiple ipsilateral renal tumors: initial outcomes

From April 2016 to February 2018, consecutive twelve MIRT cases, preoperatively diagnosed as renal cell carcinoma (RCC) or renal angiomyolipomas (AMLs) by computed tomography (CT) (Additional file 1: Figure S1), underwent RPN with sequential SRA clamping in our center. Under the guidance of preoperative DSCT, all cases had at least two SRAs feeding different lesions (Additional file 1: Figure S1C). All cases had normal contralateral renal function, evaluated by Gate’s method before operation [16]. No case had bilateral or hilar lesions or metastatic foci, and no case had unacceptable anesthetic/operative risk based on the primary operator’s judgment.

All RPNs with sequential SRA clamping were performed by an experienced surgeon (Z.W.) independently through a transperitoneal approach [17, 18]. The standard SRA clamping technique was described in our previous studies on LPN [11‐15]. Before operation, an additional DSCT was taken out to establish three-dimensional (3D) dynamic renal vascular models for every case (Fig. 1a). Thus, the anatomic relationship of SRAs with lesions was obtained and the feeding SRAs of every lesion could be precisely identified before operation (Fig. 1a).

Patients under general anesthesia were placed in the modified flank position at 60 degrees (Additional file 2: Figure S2A). The placement of five ports in the abdomen region (Additional file 2: Figure S2B) and subsequently docking with the DaVinci robot arms (Intuitive Surgical, Sunnyvale, CA, USA) were same as previously reported by other centers [17, 18]. When the MRA was identified at the renal hilum, further dissection was performed to isolate target SRAs for precisely clamping with neurosurgical bulldogs [11‐15] (Fig. 1b). Following an easy-to-difficult procedure to expose each tumor (Fig. 2a, c), we first handled the renal tumor with a lower R.E.N.A.L score. With precisely clamping of the feeding SRA, a satisfying local ischemic area around the low-score lesion was achieved, and then we excised the tumor closely around its capsule with a margin of 1–2 mm normal parenchyma (Fig. 2a, b). If the ischemic area could not encompass the whole lesion after single branch was clamped, multiple SRAs would be done. When the excision was completed, renorrhaphy was performed to achieve haemostasis and the closure of incised calices using 2–0/3–0 barbed sutures (QUILL SRS, PA, USA) and hem-o-lok clips (Sanlian Xinghai Medical Innovation Co. Ltd., Jiangsu, China) before the feeding SRA was unclamped [17, 18]. It was also necessary to clamp additional SRAs when there was arterial bleeding from lesion beds. If there was excessive bleeding in the surgical field of vision, or clamping multiple SRAs could not obtain satisfactory ischemic area, conversion to MRA clamping or open procedure was required. Then, another high-score lesion with its feeding SRA was dealt with following the above procedure (Fig. 2c, d) (Additional file 3: Video S1).

We reviewed and recorded demographics, lesion characteristics, laboratory results, operative outcomes, and pathology reports. Serum creatinine (Scr) and estimated glomerular filtration rate (eGFR) at baseline and on the postoperative 30th day were applied to assess the function outcomes. All patients underwent a preoperative radiologic evaluation with contrast-enhanced CT to delineate the renal lesions and its size, as well as invasion depth. In addition, to delineate the renal vascular segmentation and indicate the target artery, CT angiography (CTA) with 3D reconstruction model was imaged before operation.

Complications were recorded according to the modified Clavien-Dindo classification [19]. eGFR was calculated using the Modification of Diet in Renal Disease equation: GFR in mL/min/1.73 m² = 186 × Scr^− 1.154 × age^− 0.203× (0.742 if female) [20]. The highest one of R.E.N.A.L nephrometry scores was considered for each patient [21]. Descriptive continuous variables were expressed with mean ± standard deviation. Descriptive categorical variable were summarized using frequencies and percentages. All statistical calculations were performed with the SPSS Statistics software v.19 (IBM, Armonk, NC, USA).