Limited Warm Ischemia During Elective Partial Nephrectomy has Only a Marginal Impact on Renal Functional Outcomes

Purpose: Ischemic damage during partial nephrectomy increases with each minute of warm ischemia, leading some groups to advocate hypothermia in all cases or partial nephrectomy without vascular occlusion as a primary technique. The renal functional implications of these approaches have not been well studied in patients who undergo elective partial nephrectomy. Materials and Methods: We evaluated early and late renal functional outcomes in 1,132 patients with 2 functioning kidneys and normal preoperative serum creatinine who underwent partial nephrectomy without regional ischemia (58), with less than 30-minute warm ischemia (809) or with cold ischemia (265). Results: The preoperative, postoperative and latest glomerular filtration rates were not significantly different in the 3 groups. At latest followup the relative decrease in renal function was less in cases without regional ischemia than in those with less than 30-minute warm ischemia and those with cold ischemia (0.5% vs 13% and 11%, respectively, p < 0.001). In part this reflected selection bias since tumor size and the amount of parenchyma removed were lowest in that group (p < 0.001). On multivariate analysis the percent of parenchyma preserved and the baseline glomerular filtration rate were strongly associated with the postoperative and latest glomerular filtration rates (p < 0.001) but the partial nephrectomy approach was not (p > 0.05). Adverse short or long-term renal functional outcomes were marginally increased in patients with 20 to 30-minute warm ischemia. However, such events were uncommon and renal failure developed in only 4 of 1,132 patients (less than 0.4%). Conclusions: During elective partial nephrectomy a warm ischemia time of less than 20 minutes is not associated with clinically relevant functional loss compared to that of alternative techniques. However, longer warm ischemia time may correlate with ischemic injury and should be avoided.