Commentary

This is an interesting report on the use of high intensity ultrasound to achieve hemostasis within a section of the renal parenchyma. Toperform this procedure, a total of 12 kidneys were treated with an ultrasound device to create a hemostatic boundary across the lower renalpole. A knife was then used to remove the lower pole. Despite removing 21% of the kidney by mass and frequently entering the collectingsystem, there was negligible blood loss in 9 kidneys. In the remaining 3 kidneys, a second ultrasound treatment was necessary, but the bloodloss was only 25 ml. No additional hemostatic maneuvers were needed to control bleeding, but the ultrasound was not effective in closingthe collecting system because 25% of the kidneys had urinomas.

This technology is in an early stage of development, and, thus, the investigators made concessions in their experimental methods (i.e.,use of an open incision for device placement and hilar clamping during ultrasound treatment) that would not be optimal clinically. Inaddition, no effort, such as increasing the blood pressure, was made to better mimic human renal physiology. Regardless, this technique doeshave a number of appealing aspects that make it potentially useful for laparoscopic partial nephrectomy if further engineering improvementscan occur. First, the use of ultrasound energy may allow switching between treatment and imaging of the kidney on a rapid time scale. Thisimaging would conceivably allow better targeting of coagulation and possibly confirm the effectiveness of the coagulation. Next, the abilityto coagulate blood flow to the region of a tumor followed by removal of the tumor with cold knife or scissors (as was performed in thisstudy) should allow comparable visualization of tumor margins to current partial nephrectomy techniques. Finally, the ability to retreat easilytissue if bleeding occurs during resection is appealing.

As discussed in the previous article, the sutured bolster remains the king of the hill for hemostatic control after a large resection. However,it is likely just a matter of time before an energy based technology such as this one provides comparable hemostasis to sutured bolsters afterlaparoscopic partial nephrectomy.

doi:10.1016/j.urolonc.2006.08.025Kyle Anderson, M.D.

Second prize: Simple method for achieving renal parenchymal hypothermia for pure laparoscopic partial nephrectomy. WebsterTM, Moeckel GW, Herrell SD, Department of Urology, Vanderbilt University Medical Center, Nashville, TN.

J Endourol 2005;19:1075–81

Purpose: We describe the development of an innovative device and simple technique for achieving renal parenchymal hypothermiaduring temporary renal-vascular occlusion for pure laparoscopic partial nephrectomy.

Materials and Methods: The experiment was conceived in four phases: phase 1: design, manufacture, and testing of the cooling coil;phase 2: proof of concept in nonsurvival porcine surgery; phase 3: experimental porcine survival surgery; and phase 4: human trials.

Results: Phase 1 testing confirmed that the coil cooled adequately. During phase 2, the average time required for the renal parenchymato cool to 15°C was 10.7 minutes, providing an average hypothermic window (15°–24°C) of 30.3 minutes. When recooling was required(parenchymal temperature 24°C), temperatures returned to below 15°C in 3 minutes. The core body temperature dropped an average of1.48°C. Phase 3 demonstrated an average parenchymal temperature of 11.7°C after a mean cooling time of 9.3 minutes. Temperaturesremained below 24°C for an average of 26.7 minutes. Recooling took 3 minutes, and in no procedure did the renal parenchyma temperaturesever return to �24°C prior to reperfusion. The core body temperature dropped an average of 2.20°C. At 48 hours after reperfusion, selectiverenal-vein blood was obtained for creatinine assay, and the kidneys were harvested. Creatinine results were not statistically different in thetreated and control groups. Blinded pathologic analysis confirmed a protective effect using our cooling system.

Conclusion: Our method is simple, effective, and reproducible.

Commentary

During laparoscopic partial nephrectomy, the maximal duration of warm ischemia allowable before the onset of significant renal damagecontinues to be a topic of debate. To add more complexity to the problem, there probably is variation among patients in the time to ischemicdamage, and no method exists for predicting preoperatively or actively monitoring intraoperatively for renal injury. The time-tested wayaround this time limit, regardless of what the time limit is, has been renal hypothermia. However, in the laparoscopic setting, establishingrenal hypothermia has been technically difficult and is not widely used.

Here, Webster et al. describe a simple and effective method of obtaining renal hypothermia during laparoscopic partial nephrectomy usingcooled saline. The technique was effective in cooling the porcine kidney, with a minimal decrease in systemic temperature. In addition, therequisite device would fit well with the current laparoscopic technique, and could be easily set up and treated by surgical nursing staff.

Further work will be required to determine if these results can be reproduced in the larger human kidney and if active temperaturemonitoring of the kidney is required during cooling. However, based on the available animal work, success in human beings seems likely.If this is truly the case, this technique is simple enough that renal hypothermia during laparoscopic partial nephrectomy will become anattractive possibility.

doi:10.1016/j.urolonc.2006.08.026Kyle Anderson, M.D.

95K. Anderson / Urologic Oncology: Seminars and Original Investigations 25 (2007) 87–95