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Introduction and Objectives: Warm ischemia time (WIT) during partial nephrectomy (PN) is the strongest modifiable surgical risk factor for decreased postoperative renal function. Zero ischemia techniques during PN, including unclamped PN and super-selective segmental arterial clamping, have been reported but are exceedingly difficult. Minimally invasive PN using an early unclamping (EU) technique consists of renal artery bulldog clamping, tumor resection, and placement of one layer of running suture at the base of the resection defect. The bulldog clamp is then removed, and completion of hemostasis, reconstruction, and renorrhaphy are done “off clamp”, with the intention of decreasing warm ischemia time and decreasing bleeding complications by visualizing arterial bleeding prior to renorrhaphy. Our objective was to report a prospective multi-institutional experience using the EU technique during robot-assisted partial nephrectomy (RAPN).
Materials & Methods: Prospectively maintained databases from two academic kidney cancer centers were combined and analyzed. We report the demographic, perioperative, and postoperative data.
Results: Between 2009 and 2013, 156 patients underwent RAPN; the EU technique was used in 135 cases (Table 1). The majority of tumors were clinical stage T1 (mean tumor size 3.1 cm) and of moderate to high complexity (nephrometry scores ≥ 7 in 67% of tumors). Mean WIT was 16.1 minutes (range 5-31 minutes), and mean estimated blood loss was 266 mL. 3 (2.2%) patients required a blood transfusion, 2 (1.5%) required open conversion, and 1 (0.7%) required radical nephrectomy. Positive surgical margin rate was 5.2%. 32 patients (23.7%) had a postoperative complication, of which 16 (50%) were Clavien grade I and 14 (44%) were grade II. Only one of these complications concerned post-operative bleeding. Mean length of stay was 2.4 days.
Conclusion: RAPN with early unclamping is safe and reproducible, providing a reliably short WIT with acceptable perioperative complication risks. In our experience, EU may be a more straightforward method of limiting WIT than unclamped and segmental occlusion techniques, and can be feasibly utilized by all urologic surgeons that perform nephron sparing surgery.

Table 1 Demographics characteristics and perioperative outcomes
N	135
Mean age (range)	57.4 (19-88)
Mean kg/m2 body mass index (range)	29.4 (19.8-53.7)
Mean ASA score (range)	2.3 (1-3)
Mean Charlson comorbidity index (range)	3.0 (0-11)
Mean cm preoperative tumor size (range)	3.1 (1.1-10.0)
Tumor Pole Upper Mid Lower	36.5% 29.8% 33.7%
Mean total nephrometry score Percent Low (4-6) Percent Medium (7-9) Percent High (10-12)	7.14 33% 61% 6%
Mean ml/min per 1.73m2 preoperative eGFR (range)	84.9 (32.7-132.6)
Mean operative minutes (range)	199 (71-353)
Mean mL EBL (range)	266 (25-2000)
Mean minutes WIT (range)	16.1 (5-31)
Transfusion (N, %)	3, 2.2%
Mean days LOS (range)	2.4 (1-15)
Intraoperative Complications (N, %)	1, 0.7%
Conversion: Lap to Open (N, %)	2, 1.5%
Conversion: Partial to Radical (N, %)	1, 0.7%
PSM (N, %)	7, 5.2%
Postoperative Complications (N, %)	32, 23.7% Clavien Grade: I: 16 (50%) II: 14 (44%) IIIa: 2 (6%) ≥ IIIb: 0
Mean postoperative eGFR change ≤ 3 months (%, range)	-8.46% (-40.0 - 33.8)
ASA American Society of Anesthesia eGFR estimated glomerular filtration rate, EBL estimated blood loss, WIT warm ischemia time, LOS length of stay, PSM positive surgical margin