Renal function after partial nephrectomy: effect of warm ischemia relative to quantity and quality of preserved kidney.

OBJECTIVE

To evaluate the effects of warm ischemia time (WIT) and quantity and quality of kidney preserved on renal functional recovery after partial nephrectomy (PN). The effect of WIT relative to these other parameters has recently been challenged.

METHODS

We identified 362 consecutive patients with a solitary kidney who had undergone PN using warm ischemia. Multivariate models with multiple imputations were used to evaluate the associations with acute renal failure and new-onset stage IV chronic kidney disease (CKD).

RESULTS

The median WIT was 21 minutes (range 4-55), the median percentage of kidney preserved was 80% (range 25%-98%), and the median preoperative glomerular filtration rate (GFR) was 61 mL/min/1.73 m2 (range 11-133). Postoperative acute renal failure occurred in 70 patients (19%). Of the 226 patients with a preoperative GFR>30 mL/min/1.73 m2, 38 (17%) developed new-onset stage IV CKD during follow-up. On multivariate analysis, the WIT (P=.021), percentage of kidney preserved (P=.009), and preoperative GFR (P<.001) were significantly associated with acute renal failure, and only the percentage of kidney preserved (P<.001) and preoperative GFR (P<.001) were significantly associated with new-onset stage IV CKD during follow-up. Using our previously published cutpoint of 25 minutes, a WIT of >25 minutes remained significantly associated with new-onset stage IV CKD in a multivariate analysis adjusting for the quantity and quality factors (hazard ratio 2.27, P=.049).

CONCLUSION

Our results have validated that the quality and quantity of kidney are the most important determinants of renal function after PN. In addition, we have also demonstrated that the WIT remains an important modifiable feature associated with short- and long-term renal function. The precision of surgery, maximizing the amount of preserved, vascularized parenchyma, should be a focus of study for optimizing the PN procedure.