Variables Entire Cohort Pre-existing CKD De novo CKD P Patient specific factors Mean (median, range) or n (%) Estimated blood loss (ml) 222 (100, 5-3280) 212 (105, 10-2200) 239 (95, 5-3280) 0.7324 Clamping time (min) 46 (45, 0-100) 47 (47, 0-100) 45 (43, 18-84) 0.5952 Operative time (min) 235 (227, 126-379) 242 (241, 126-379) 224 (216, 137-377) 0.0955 Surgery type Open 109 (86) 69 (88) 40 (82) 0.3055 Laparoscopic 18 (14) 9 (12) 9 (18) Ischemia Cold 116 (91) 70 (90) 46 (94) 0.3782 Warm 8 (6) 5 (6) 3 (6) Zero 3 (2) 3 (4) 0 Tumor factors Tumor size (mm) 32 (29, 10-94) 30.1 (28, 10-94) 33.6 (29, 12-72) 0.3039 RENAL-NS 4-6 42 (33) 27 (35) 15 (32) 0.5731 7-9 68 (54) 43 (55) 25 (52) 10-12 8 (13) 8 (10) 8 (17) Radius component 1 94 (75) 60 (77) 34 (71) 0.5318 2 28 (22) 15 (19) 13 (27) 3 4 (3) 3 (4) 1 (2) Exophytic/endophytic component 1 51 (40) 33 (42) 18 (38) 0.6233 2 59 (47) 34 (44) 25 (52) 3 16 (13) 11 (14) 5 (10) Nearness component 1 31 (25) 21 (27) 10 (21) 0.6622 2 25 (20) 14 (18) 11 (23) 3 70 (56) 43 (55) 27 (56) Location component 1 51 (40) 35 (45) 16 (33) 0.3948 2 28 (22) 17 (22) 11 (23) 3 47 (37) 26 (33) 21 (44) Postoperative eGFR 3m 47.8 (51.7, 11.4-74.2) 43.5 (44.9, 11.4-74.2) 54.5 (56.4, 22.7-59.8) 6m 47.8 (50.2, 8.28-70.2) 43.4 (45.0, 8.28-70.2) 54.8 (55.6, 27.4-65.6) 12m 48.9 (51.4, 6.99-72.0) 43.5 (46.3, 6.99-72.0) 57.6 (57.8, 31.1-70.9) % change between 3m-6m 0.27 (0, -27.3-23.2) 0.06 (0.22, -27.3- 23.2) 0.60 (0, -18.5-20.6) 0.7639 % change between 3m-12m 1.82 (1.16, -53-40.8) -0.54 (0, -53.1-32.7) 5.56 (6.18, -13.7- 40.8) 0.0063 CKD: chronic kidney disease eGFR: estimated glomerular filtration rate BMI: body mass index RENAL-NS: R.E.N.A.L nephrometry score Source of Funding: None 1191 RESIDUAL FUNCTIONAL PARENCHYMAL VOLUME, NOT WARM ISCHEMIA TIME, PREDICTS FUNCTIONAL OUTCOMES FOLLOWING NEPHRON-SPARING RENAL SURGERY Serge Ginzburg*, Robert Uzzo, Christopher Miller, David Kurz, Tianyu Li, John Walton, Awad Ahmed, Anthony Corcoran, Jeffrey Tomaszevski, Reza Mehrazin, Marc Smaldone, Rosalia Viterbo, David Chen, Richard Greenberg, Alexaner Kutikov, Philadelphia, PA INTRODUCTION AND OBJECTIVES: Importance of curtailing ischemia time is coming under increasing scrutiny, while residual functional parenchymal volume (FPV) has been proposed as the key factor in predicting functional outcomes following nephron-sparing sur- gery (NSS). We reexamined the relative contribution of functional parenchymal preservation and renal ischemia following NSS. METHODS: Our prospectively maintained kidney cancer data- base was queried for patients who underwent NSS with warm ischemia (WIT). Patients with available cross-sectional imaging were included (n=188). Cylindrical volume approximation methodology was em- ployed to calculate FPV pre- and post-operatively, accounting for the volume of tumor’s endophytic component. Percent eGFR preservation, as estimated by the CKD-EPI formula at approximately 6 months following surgery was used as the outcome metric. Spearman correla- tion was used to evaluate associations of WIT and percent FPV preservation with renal function preservation. Linear regression analy- sis was performed to control for age, BMI, weighted Charlson comor- bidity index (CCI), tumor size and pre-operative eGFR. RESULTS: Of the 188 eligible patients, 36% had open and 64% minimally-invasive NSS employing WIT. Median age was 60 years with 66% of patients being male and 89% Caucasian. Median pre-operative eGFR was 88.4 (10% CKD-III or IV). Median tumor size was 2.7cm [0.9 - 10.7] with tumor complexity as captured by RENAL NS being low in 34%, intermediate in 57% and high in 9%. Median WIT was 30 minutes [10-67min], resulting in a 97.4 % FPV preservation. Median post- operative eGFR at 6.5 months was 80.4 (19% CKD-III or IV), a median 93.3% eGFR preservation. FPV demonstrated significant association with eGFR preservation (spearman correlation = 0.26, p=0.001), while WIT showed no statistically significant correlation (p=0.53). Results of the multivariable analysis are shown in Table 1. CONCLUSIONS: Residual FPV, and not WIT, appears to be the main predictor of functional outcomes following NSS. Table 1: Multivariable analysis controlling for age, BMI, weighted CCI, tumor size, pre-operative eGFR, WIT, and FPV preservation, assessing association with % eGFR outcome. Variable Linear Regression Coefficient p value Age -0.161 0.268 BMI -0.030 0.862 Tumor Size (mm) 0.008 0.919 Weighted CCI -0.534 0.556 Pre-Operative eGFR -0.217 0.006* Warm Ischemia Time (min) -0.039 0.735 % Functional Parenchymal Volume Preservation 0.527  0.001* Source of Funding: Fox Chase Cancer Center Kidney Cancer Keystone Grant 1192 ZERO-ISCHEMIA VERSUS CLAMPED ROBOTIC PARTIAL NEPHRECTOMY: INITIAL RESULTS OF 121 PATIENTS Andre Luis de Castro Abreu, Scott Leslie, Andre Berger*, Dennis Lee, Raed Azhar, Arjuna Dharmaraja, Anmol Amin, Osamu Ukimura, Monish Aron, Inderbir Gill, Mihir Desai, Los Angeles, CA INTRODUCTION AND OBJECTIVES: The objective of this study is to compare peri-operative outcomes of zero-ischemia versus clamped robotic partial nephrectomy (PN). METHODS: Prospective data on 121 patients undergoing zero- ischemia (n=58) and clamped (n=63) robotic PN were retrospectively analyzed. The clamped cohort underwent hilar cross-clamping of the main renal artery. The zero-ischemia cohort underwent tumor-specific devascularization maintaining perfusion of the remnant at all times. Both groups were compared for peri-operative factors and post-oper- ative renal function. RESULTS: Compared to the clamped group, tumors in the zero-ischemia group were more commonly hilar (24% vs 6%, p=0.009), larger (3.4 vs 2.6 cm, p=0.04) and more complex (PADUA score 10 vs 8, p=0.009). All 121 robotic procedures were successful, Vol. 189, No. 4S, Supplement, Monday, May 6, 2013 THE JOURNAL OF UROLOGY e487