Evaluation of thermal injury to liver, pancreas and kidney during irreversible electroporation in an in vivo experimental model.

BACKGROUND: Irreversible electroporation (IRE) is a new technique for tumour cell ablation that is reported to involve non-thermal-based energy using high voltage at short microsecond pulse lengths. In vivo assessment of the thermal energy generated during IRE has not been performed. Thermal injury can be predicted using a critical temperature model. The aim of this study was to assess the potential for thermal injury during IRE in an in vivo porcine model. METHODS: In vivo continuous temperature assessments of 86 different IRE procedures were performed on porcine liver, pancreas, kidney and retroperitoneal tissue. Tissue temperature was measured continuously throughout IRE by means of two thermocouples placed at set distances (0·5 cm or less, and 1 cm) from the IRE probes within the treatment field. Thermal injury was defined as a tissue temperature of 54°C lasting at least 10 s. Tissue type, pulse length, probe exposure length, number of probes and retreatment were evaluated for associations with thermal injury. In addition, IRE ablation was performed with metal clips or metal stents within the ablation field to determine their effect on thermal injury. RESULTS: An increase in tissue temperature above the animals' baseline temperature (median 36·0°C) was generated during IRE in all tissues studied, with the greatest increase found at the thermocouple placed within 0·5 cm in all instances. On univariable and multivariable analysis, ablation in kidney tissue (maximum temperature 62·8°C), ablation with a pulse length setting of 100 µs (maximum 54·7°C), probe exposure of at least 3·0 cm (maximum 52·0°C) and ablation with metal within the ablation field (maximum 65·3°C) were all associated with a significant risk of thermal injury. CONCLUSION: IRE can generate thermal energy, and even thermal injury, based on tissue type, probe exposure lengths, pulse lengths and proximity to metal. Awareness of probe placement regarding proximity to critical structures as well as probe exposure length and pulse length are necessary to ensure safety and prevent thermal injury. A probe exposure of 2·5 cm or less for liver IRE, and 1·5 cm or less for pancreas, with maximum pulse length of 90 µs will result in safe and non-thermal energy delivery with spacing of 1·5-2·3 cm between probe pairs.

A cost analysis of somatostatin use in the prevention of pancreatic fistula after pancreatectomy.

BACKGROUND: Studies have shown that somatostatin reduces the occurrence of postoperative pancreatic fistula. However, no study to date has analyzed the cost effectiveness of this treatment. The purpose of this study was to analyze the cost effectiveness of prophylactic somatostatin use with respect to pancreatectomy. METHODS: Review of prospectively collected 2002 patient hepato-pancreatico-biliary database from January 2007 to May 2012. Patients received somatostatin prophylactically at the discretion of their surgeon. Data were analyzed using univariate analysis to determine if somatostatin had an effect on imaging costs, lab costs, "other" costs, PT/OT costs, surgery costs, room and board costs, and total hospital costs. RESULTS: A total of 179 patients underwent pancreatectomy at a single teaching institution. Median total hospital costs were 90,673.50 (59,979-743,667) for patients who developed a postoperative pancreatic fistula versus 86,563 (39,190-463,601) for those who did not (p = 0.004). Median total hospital costs were 89,369 (39,190-743,667) for patients who were administered somatostatin versus 85,291 (40,092-463,601) for patients who did not (p = 0.821). CONCLUSIONS: Pancreatic fistulas significantly increase hospital costs, and somatostatin has been shown to decrease the rate of pancreatic fistula formation. Somatostatin has no significant effect on hospital costs.