Different methods of hilar clamping during partial nephrectomy: Impact on renal function

Objectives: To evaluate the impact of different hilar clamping methods on changes in renal function after partial nephrectomy. Methods: We analyzed the clinical data of 369 patients who underwent partial nephrectomy for a single renal tumor of size ≤4.0cm and a normal contralateral kidney. Patients were separated into three groups depending on hilar clamping method: non-clamping, cold ischemia and warm ischemia. Estimated glomerular filtration rate was examined at preoperative, nadir and 1 year postoperatively. Percent change in estimated glomerular filtration rate was used as the parameter to assess the renal functional outcome. Results: Percent change in nadir estimated glomerular filtration rate in the non-clamping group was significantly less compared with the cold ischemia and warm ischemia groups (P<0.001). However, no significant differences among the groups were noted in percent change of estimated glomerular filtration rate at 1 year (P=0.348). The cold ischemia group had a similar serial change of postoperative renal function compared with the warm ischemia group. Percent change in 1-year estimated glomerular filtration rate increased with increasing ischemia time in the cold ischemia (P for trend=0.073) and warm ischemia groups (P for trend=0.010). On multivariate analysis, hilar clamping (both warm ischemia and cold ischemia) were significantly associated with percent change in nadir estimated glomerular filtration rate, but not in 1-year estimated glomerular filtration rate. Conclusions: Non-clamping partial nephrectomy results in a lower percent change in nadir estimated glomerular filtration rate, whereas it carries an estimated glomerular filtration rate change at 1 year that is similar to partial nephrectomy with cold ischemia and warm ischemia. Cold ischemia and warm ischemia provide a similar effect on renal function. Therefore, when hilar clamping is required, minimization of ischemia time is necessary.