[Intravenous regional anesthesia of the arm and foot using 0.5, 0.75 and 1.0 percent prilocaine].

Quality of anaesthesia and risk of intoxication are competing principles in IVRA. To evaluate the optimal prilocaine concentration with injection of 40 ml, 300 patients were randomly allocated to receive either a 0.5 (PRI 0.5), 0.75 (PRI 0.5) or a 1.0 (PRI 1.0) per cent solution. Using PRI 0.5, fifteen patients required supplementary fentanyl, with PRI 0.75 one, and with PRI 1.0 two (p less than or equal to 0.05). General anaesthesia proved necessary in three patients of the PRI 0.5 and 0.75 groups, respectively, and in one patient of the PRI 1.0 group (NS). With PRI 1.0 seven patients had subjective signs of intoxication upon tourniquet release, with PRI 0.75 none, and with PRI 0.5 one (p less than or equal to 0.05). Objective symptoms of local anaesthetic toxicity were not observed. The incidence of tourniquet-related pain was 25-30% in all three groups and not related to the prilocaine concentration. In conclusion, with 40 ml injection volume the 0.75% solution of prilocaine offers the optimal relation between incidence of anaesthesia and risk of intoxication.