Renal ischemia time in laparoscopic surgery: an experimental study in a porcine model

Laparoscopic nephron sparing surgery is becoming more common, only limited by experience of the surgeon and the renal ischemia time. It is currently unknown if laparoscopic surgery alters the accepted 30 min threshold for renal ischemia. The purpose of this study was to define the normothermic ischemic threshold in the laparoscopic setting. Twenty-four domestic female pigs underwent a laparoscopic transperitoneal procedure after randomization to one of five treatment groups: 30, 60, 75, 90, and 120 min of unilateral renal ischemia. One animal was used as a control specimen and was not exposed to any surgery or pneumoperitoneum. The contralateral kidney in each animal was used as an individual control for the corresponding time of pneumoperitoneum. The animals were euthanized after 3 weeks, when both renal units were harvested and data were analyzed. Three animals died secondary to complications from their procedure and were replaced. There was no association between urine volume and ischemic time, but urine creatinine and creatinine clearance decreased significantly as ischemic time increased. The control animal and 30 min ischemic group had similar results. Functional renal parameters decreased in those animals exposed to greater than 75 min of ischemia. The histologic analysis did not show any significant differences among the experimental groups. Renal function begins to deteriorate between 75 and 90 min of renal vascular occlusion in this two-renal unit laparoscopic porcine model.