A randomised controlled comparison between stimulating and standard catheters for lumbar plexus block.

The aim of this randomised, prospective, blinded study was to evaluate if stimulating catheters can decrease the minimum effective anaesthetic volume in 50% of patients during lumbar plexus block using mepivacaine 1.5% compared with standard catheters. Fifty-eight patients of ASA physical status 1-3 were randomly allocated to receive a lumbar plexus block via a stimulating or standard catheter, with 29 in each group. The first dose was 30 ml and subsequent doses were determined using the up-and-down staircase method. The minimum effective anaesthetic volume50 was 12.2 ml (95% CI 7.3-17.1 ml) using the stimulating catheter and 24.8 ml (95% CI 23.2-27.5 ml) with the standard catheter (p < 0.0001). Complete lumbar plexus block was achieved with the initial dose of mepivacaine in 29 (100%) patients in the stimulating catheter group and 20 (69%) patients in the standard catheter group (p = 0.002). This study showed that use of a stimulating catheter halves the minimum effective anaesthetic volume50 of mepivacaine 1.5% while increasing the success rate in patients receiving continuous lumbar plexus block.