Renal damage caused by warm ischaemia during laparoscopic and robot-assisted partial nephrectomy: an assessment using Tc 99m-DTPA glomerular filtration rate.

BACKGROUND

Few studies assessing the functional change of each kidney following warm ischaemia after partial nephrectomy are available.

OBJECTIVES

Our aim was to identify the effects of the warm ischaemic time (WIT) on renal function after partial nephrectomy under the pneumoperitoneum.

DESIGN, SETTING, AND PARTICIPANTS: Forty-four consecutive patients who underwent laparoscopic partial nephrectomy (LPN) or robot-assisted partial nephrectomy (RAPN) from June 2008 to May 2009 for a single cT1 renal tumour were included in this prospective protocol.

MEASUREMENTS

Technetium Tc 99m-diethylenetriaminepentaacetic acid (Tc 99m-DTPA) renal scintigraphy was used to determine the glomerular filtration rate (GFR) of both kidneys and each kidney individually. Tc 99m-DTPA GFR was performed preoperatively and 3 mo postoperatively. In addition, we analysed Tc 99m-DTPA scintigraphy GFR regionally in the healthy areas of the affected kidney.

RESULTS AND LIMITATIONS

Patients with WIT > 28 min had a significantly greater decrease in the GFR of the affected kidney (p = 0.031). The GFR of the affected kidney showed a significant decrease perioperatively (46.4 ± 14.3 to 37.9 ± 11.9 ml/min per 1.73 m²; p = 0.003). The functional change of the nonaffected kidney showed an increasing trend (47.5 ± 13.8 to 51.4 ± 14.3 ml/min per 1.73 m²), although it was not statistically significant (p=0.103). Regional Tc 99m-DTPA GFR of both affected kidney and nonaffected kidney showed no significant differences perioperatively (6.3 ± 1.8 to 6.1 ± 1.9 ml/min per 1.73 m²; p = 0.641; 6.6 ± 1.9 to 7.1 ± 2.0 ml/min per 1.73 m² ; p = 0.200). On multivariate analysis, preoperative GFR, resected volume of marginal healthy tissue, and WIT were independent predictors for functional reduction of the affected kidney (p < 0.05). The study was limited by small numbers and short follow-up periods.

CONCLUSIONS

Stationary overall renal function after LPN or RAPN is masked possibly by functional compensation of the contralateral healthy kidney. The damage of the affected kidney estimated by scintigraphy occurs when WIT exceeds 28 min during partial nephrectomy under the pneumoperitoneum.