Laparoscopic renal cooling device.

A new medical device has been designed for inducing hypothermia in kidneys, via laparoscopic deployment, without leaving residual fluid in the abdomen. It was tested in laboratory and animal trials to ascertain its suitability for achieving a target renal temperature of 15 degrees C for tissue preservation within a 30-min period. A simple theoretical model was developed to calculate cooling rates under ideal circumstances. In the laboratory, a potato was used as the model for the kidney and an average minimum temperature of 15.8 degrees C was reached in 30 min. The theoretical model calculated this as 9.9 degrees C. In the animal trials, an average minimum temperature of 11.4 degrees C was reached in 30 min, compared to the calculated temperature of 9.8 degrees C from the theoretical model. In conclusion, the new device can cool as affectively as other techniques trialled, with the added advantage that it does not release cold fluid or ice into the abdomen.

Evaluation of the ischemic protection efficacy of a laparoscopic renal cooling device using renal transplantation viability assessment criteria in a porcine model.

PURPOSE: We assessed the efficacy of a prototype laparoscopic topical cooling device. The aim of regional renal hypothermia in laparoscopic surgery is to limit ischemic injury and extend safe operative time. A reliable model for assessing renal ischemic injury exists in the field of nonheart beating donor renal transplantation. Hypothermic machine perfusion allows calculation of the pressure flow index and measurement of glutathione S-transferase in the perfusate. These parameters allow accurate assessment of the extent of renal damage. MATERIALS AND METHODS: The device incorporates a 2-layer cooling bag and coolant circuit. The system achieves hypothermia by circulating coolant across the surface of the kidney. Using 10 pigs individual kidneys were subjected to periods of renal ischemia with or without device in situ cooling. Each kidney was then machine perfused and assessed using nonheart beating donor viability criteria. RESULTS: The best performance of the device achieved a renal parenchymal temperature of 15C in 11.2 minutes (mean +/- SD 21.4 +/- 8.42). In the warm ischemia groups significant deterioration of pressure flow index compared to controls occurred by 60 minutes (p = 0.0001). In cooled kidneys at 60 minutes the mean pressure flow index was not significantly different from that in controls. Greater mean glutathione S-transferase measurements were associated with the warm ischemia groups. CONCLUSIONS: Our study reinforces the efficacy of topical renal cooling in the laparoscopic setting. We report the use of assessment techniques capable of accurate quantitative measurement of renal injury in an animal model. Our cooling device is currently undergoing further development to enhance its efficiency.