Popliteal blocks for foot and ankle surgery: success rate and contributing factors.

The purpose of the present study was to evaluate the factors contributing to the success of popliteal nerve blocks performed by podiatric surgical residents in various stages of training. A retrospective review was conducted of 143 consecutively performed blocks during a 2-year period. A total of 29 blocks using a lateral approach and 114 blocks using a modified posterior approach were performed. The intrinsic and extrinsic variables contributing to block outcome were analyzed. A total of 109 successful blocks were performed, for an overall success rate of 76.2%. Significant differences (p < .002) were found between the success and failure groups with respect to the patients body mass index and age. No differences were observed between the success and failure groups with respect to the block approach or months of resident training. In conclusion, podiatric surgical residents in all stages of training can safely and effectively perform popliteal nerve blocks for peri- and postoperative analgesia. Surgeons should be aware of the potential influence of patients body mass index and age on the overall block success rates.

The adaptive value of tool-aided defense against wild animal attacks.

Throughout history humans have faced the persistent threat of attacks by wild animals, and how humans respond to this problem can make the difference between survival and death. In theory, the use of tools to fend off animal attacks would be more effective than resisting bare-handed, yet evidence for the advantage of tool-aided defense is scarce and equivocal. Two studies of news accounts of wild animal attacks against humans were conducted to test the hypothesis that tool-aided defense is indeed associated with reductions in injuries and deaths. Results of both Study 1 (N=172) and Study 2 (N=370) supported the hypothesis. The observed survival advantage of tool-aided defense for modern humans suggests that this tactic also would have worked for human ancestors who lived more closely to dangerous wild animals.