Introduction

The impact of ischemic damage on kidney function residual to partial nephrectomy (PN) remains a controversial issue. The clamping of the artery is more frequent during minimally invasive PN compared with the open counterpart._x000D_ The CLOCK study (CLamp vs Off Clamp the Kidney during partial nephrectomy, clinicaltrial.gov registration n° NCT02287987) is a perspective, randomized, multicentre trial, started in September 2014, still recruiting, with the goal of 200 patients, to compare renal function preservation after robotic partial nephrectomy (RAPN). Local ethical committee approval was obtained by every center. Here an &[Prime]ad interim&[Prime] intention-to-treat analysis of the perioperative morbidity of the two procedures is reported.

Methods

Up to September 2016, 137 patients were centrally randomized to be submitted to clamp vs off-clamp RAPN at 6 institutions. Inclusion criteria were normal coagulative function, healthy contralateral kidney, estimated GFR ≥ 60 ml/min, R.E.N.A.L score ≤10 and previous surgeon experience >50 RAPN and center surgical volume >100 renal tumors/year. Split renal function was evaluated preoperatively and after 6 months by DTPA renal scan. Data were collected in an e-crf, centrally managed.

Results

No significant differences were observed for baseline features, duration of surgery, oncological outcomes and complications, whereas there was a difference in the severity of bleeding as perceived by the surgeon and in estimated blood loss (table no.1). A shift from an off-clamp to clamp technique was observed in 29/67 patients (43.3%), established preoperatively (3 cases, 10.3%), intraoperatively before starting the resection (10, 34.5%) or during the resection because of bleeding (16, 55.2%). A shift from clamp to off-clamp procedure was observed in 10/70 cases (14.3%), always pre-operatively.

Conclusions

Off-clamp and clamped RAPN are equally safe in terms of oncological outcomes and complications. However, even for tumors with a low/intermediate complexity, at high-volume centers and for skilled surgeons, despite the setting of a RCT, in a relevant rate of cases off-clamp PN is not feasible due to bleeding while only in a few cases clamping the artery is deemed as redundant.

Funding

None