Low volume, high concentration block of the sciatic nerve.

Sciatic nerve block was performed in two groups of patients using a low power peripheral nerve stimulator to aid nerve location. In group A 1% prilocaine with felypressin was used as the local anaesthetic agent in a volume of 0.25 ml/kg body weight. In group B 3% prilocaine with felypressin was used in a volume of 0.08 ml/kg body weight (i.e. equal total drug dosages). Use of the 3% solution resulted in highly significant reductions in the mean latency for analgesia of the nerve block and in the latency and degree of motor block achieved (p less than 0.005 in each case). The clinical value of high concentration, low volume nerve block is discussed.