Radiofrequency ablation of renal tumors in patients unfi t for surgery. Our experience.

PURPOSE: To evaluate the feasibility and safety of the minimally invasive percutaneous technique radiofrequency ablation (RFA) in patients with small renal cell carcinomas (RCCs) who are unfit for surgery. METHODS: From January 2008 to November 2009, 7 patients (5 males and 2 females, median age 78 years) with small RCCs were treated with RFA. The indications for RFA were either inoperability due to high cardiovascular and pulmonary risk or a high probability of complete renal failure after nephrectomy. Exclusion criteria were tumor size larger than 6 cm and the localization of the tumor within the renal pelvis. RESULTS: All RFAs were technically successful in terms of complete tumor ablation and all procedures could be done under conscious sedation. Complications after RFA included transient rise in plasma creatinine in 2 patients and hydrocalyx at 18 months in one. The mean hospital stay was 3.14 days (range 2-5). CONCLUSION: RFA has limitations such as an uncertain long-term oncological result and need for strict follow up. Physicians must be aware of these limitations and present them clearly to the patients. It is a safe treatment modality that, with longer follow-up, could play a more important role in the care of patients with renal masses due to its potential for decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population.

Factors affecting accuracy of producing time intervals.

The present study assessed the accuracy of producing time intervals. 92 subjects were asked to produce three different time intervals (15, 30, and 60 sec.) under six experimental conditions during which they performed concurrent tasks of different cognitive difficulty and requiring different cognitive functions. Real-life working situations guided the design of the experiment. Accuracy of time estimation was significantly affected by the length of the intervals to be produced and the concurrent tasks performed. 15-sec. intervals were more accurately estimated. Accuracy decreased as the cognitive demands of the concurrent tasks increased; subjects systematically overestimated the duration of the intervals. Having an activity requiring time estimation seems to have a positive effect on the accuracy of time estimation. The same was found for certain strategies aiding time estimation which were used spontaneously by certain subjects. No significant difference in the accuracy of estimation between women and men was found.