OFF‐CLAMP ROBOT‐ASSISTED PARTIAL NEPHRECTOMY: HOW FAR SHALL WE PROCEED?: MP49‐18

BACKGROUND Off-clamp robot-assisted partial nephrectomy (RAPN) is associated with increased intraoperative blood loss compared with on-clamp technique. Our aim was to demonstrate our surgical technique and to determine which tumors are ideally suited for this technique. METHODS Sixty-two patients who underwent off-clamp RAPN for renal tumor between 2006 and 2016 were retrospectively analyzed. Increased estimated blood loss (EBL) volume was defined as more than 75 percentile. receiver operating characteristic (ROC) analysis was used to determine exact cut-off tumor size and the preoperative aspects and dimensions used for an anatomical (PADUA) score that are associated with increased EBL. Risk factors for increased EBL >400 mL and chronic kidney disease (CKD) upstaging were evaluated using logistic regression analysis. RESULTS The median follow-up period was 20 months (interquartile range [IQR]: 12-84). Patient's mean age, mean tumor size, and mean body mass index were 53.5 ± 12.2 years, 2.6 ± 1.5 cm, and 25 ± 4.1 kg/m2, respectively. Median EBL volume was 200 mL (IQR: 100-400). ROC analysis showed that tumor size of 3.2 cm (area under the curve [AUC] = 0.82, P < .001) and PADUA score of 9 (AUC = 0.79, P = .001) were cut-off values for increased EBL >400 mL. Patients with tumor size >3.2 cm had longer operative time (116 versus 163 minutes, P = .002), more EBL (150 versus 575 mL, P < .001), and higher blood transfusion rate (0% versus 18.8%, P = .015), with increased tendency of conversion to radical nephrectomy (0% versus 12.5%, P = .063) compared with tumor size ≤3.2 cm. Overall CKD upstaging was present in 22 patients (35.4%). Multivariable logistic regression analysis showed that EBL >400 mL was the only predictor of CKD upstaging (odds ratio: 6.704, P = .009). CONCLUSIONS Our study showed that the risk of intraoperative bleeding and transfusion rate during off-clamp RAPN is increased if tumor size >3.2 cm and/or PADUA complexity score ≥9. Moreover, EBL >400 mL was a risk factor of CKD upstaging, despite zero ischemia. Further larger prospective studies are warranted to validate our results.