Impact of warm versus cold ischemia on renal function following partial nephrectomy

Introduction: We evaluated renal function following partial nephrectomy with cold ischemia (CI) versus warm ischemia (WI).

Methods: Data were collected from 1,396 patients at six institutions who underwent partial nephrectomy for a renal mass with normal contralateral kidney to evaluate percent change in glomerular filtration rate (GFR) at 3–18 months. A multivariate linear regression model tested the association of percent change GFR with clinical, operative, and pathologic factors.

Results: A total of 874 patients (63 %) underwent PN with CI and 522 (37 %) with WI. All patients undergoing laparoscopic and robotic-assisted partial nephrectomy (n = 443) had WI, whereas 92 % of open partial nephrectomy patients (n = 953) had CI. The CI group had a lower mean baseline GFR (72 vs. 80 ml/min/1.73 m²), longer median ischemia time (33 vs. 29 min), and larger mean tumor size (3.2 vs. 2.9 cm) with more advanced pathologic stage (T1b-T3: 25 vs. 16 %) (all p values <0.001). Patients with CI and WI demonstrated 12.3 and 10.1 % reductions in renal function from baseline, respectively (p = 0.067). Increasing age, female gender, and increasing tumor size were associated with reduction in renal function (all p values <0.001). Neither renal hypothermia nor operative technique independently predicted reduced renal function. Sensitivity analyses limited to ischemia time >30 min, baseline estimated glomerular filtration rate <60 ml/min/1.73 m², or tumors >4 cm did not significantly alter the findings.

Conclusions: Increasing age, female gender, and larger tumor size independently predict a decrease in renal function following partial nephrectomy with a normal contralateral kidney. Within the limitations of a non-randomized comparison, including lack of parenchymal preservation percentage, neither surgical approach (open or laparoscopic) nor presence of hypothermia appears to be associated with long-term renal function.