ENDOUROLOGY & LAPAROSCOPY

Laparoscopic Ice Slurry Coolant for Renal Hypothermia
Orvieto MA, Zorn KC, Lyon MB, Tohurst SR, Rapp DE, Mikhail AA, Oras JJ, Son H, Kasza KE, Brendler CB, Shalhav AL
Section of Urology, University of Chicago, Chicago and Argonne National Laboratory, Energy Technology Division, Argonne, Illinois
J Urol. 2007; 177: 382-5

• Purpose: We assessed the safety and efficacy of microparticulate ice slurry for laparoscopic hypothermia during renal ischemia in a single kidney porcine model.
• Materials and Methods: A total of 18 farm pigs were randomized to 3 groups of 6 each. All groups underwent initial right laparoscopic nephrectomy, followed by 1 of 3 procedures on the left kidney. Group 1 underwent 90 minutes hilar clamping under warm ischemia, group 2 underwent 90 minutes hilar clamping under cold ischemia using laparoscopically delivered microparticulate ice slurry and control group 3 underwent hilar dissection, no clamping and no microparticulate ice slurry. Body and renal cortical temperatures were measured. Serum creatinine and the glomerular filtration rate were assessed preoperatively, and on postoperative days 1,3,8 and 15.
• Results: Average time to achieve a renal temperature of 20ºC or less was 9.7 minutes and it remained constant during the 90 minutes cold ischemia time. Mean serum creatinine was significantly higher in the warm ischemia group than in the cold ischemia and control groups on postoperative days 1 and 3. Additionally, mean serum creatinine in the cold ischemia and control groups was similar at all time points. The mean glomerular filtration rate was significantly lower in the warm ischemia group than in the cold ischemia and control groups on postoperative days 1,3 and 8. The mean glomerular filtration rate in the cold ischemia group was lower than in the control group on postoperative day 1, while it was similar on postoperative days 3,8 and 15.
• Conclusions: In the porcine model laparoscopic renal hypothermia achieved with microparticulate ice slurry was safe and efficient. It significantly decreased renal dysfunction secondary to an ischemic insult with no adverse effects or complications associated with microparticulate ice slurry use.
  
  
• Editorial Comment
  Prevention of renal ischemia-reperfusion injury remains a challenge, particularly in laparoscopic partial nephrectomy. Gill et al. first reported the use of ice slush laparoscopically to achieve cold ischemia in laparoscopic partial nephrectomy, but the delivery system was somewhat cumbersome. Conversely, this animal study used microparticulate ice slurry (MPS) for laparoscopic hypothermia during renal ischemia in a single kidney porcine model. MPS contains smooth globular ice particles (< 100 mm in diameter) suspended in saline carrier medium. MPS may be pumped through a 4 mm catheter without plugging, in contrast to the standard ice slush which is composed of dendritic ice crystals that do not flow through narrow tubes, making it not applicable for laparoscopic surgery but it is used for regional hypothermia during open procedures. Survival studies comparing 3 different groups (Group 1 - 90 minutes warm ischemia, group 2 - 90 minutes cold ischemia using laparoscopically delivered MPS, and control group 3 - hilar dissection, no clamping and no microparticulate ice slurry), demonstrated significant difference in renal function in group 1 when compared to other groups. The authors concluded that MPS was safe and efficient to achieve renal hypothermia and to decrease renal dysfunction due to ischemia-reperfusion injury.

Dr. Fernando J. Kim
Chief of Urology, Denver Health Med Ctr
Assistant Professor, Univ Colorado Health Sci Ctr
Denver, Colorado, USA