Simultaneous percutaneous implantation of a microdialysis probe for monitoring perineural concentrations of local anaesthetics during peripheral nerve block in rabbits

Objective To develop a technique that allows simultaneous percutaneous implantation of both a microdialysis probe and injection catheter in order to monitor the perineural pharmacokinetics of local anaesthetics (LA) after a femoral block. Study design Prospective experimental study. Animals Five anaesthetized male New Zealand rabbits with a mean ± SD weight of 3.2 ± 0.2 kg. Methods After femoral nerve localization by electrostimulation, an injection catheter and a microdialysis probe were slowly and simultaneously inserted into a cannula left into place in the perineural region. Both were then secured into place, after removal of the cannula. At the end of the experiment, methylene blue was injected to confirm the distance from the femoral nerve during subsequent postmortem anatomical dissection of the injection site. Results Staining was adequate and the catheter found to be located within 4 mm of the femoral nerve in three out of five rabbits. Conclusions and clinical relevance This procedure allows direct implantation of a microdialysis probe near the injection site of LA during a femoral nerve block without loosing nerve localization accuracy. This procedure has been used successfully to monitor the regional pharmacokinetics of LA after a peripheral nerve block.