To what extent can local anesthetics be reduced for infraclavicular block with ultrasound guidance?

Objectives: To assess the adequacy of different amounts of local anesthetics (LA) in infraclavicular blockade (ICB) under ultrasonographic (US) guidance and neurostimulation and compare them to the conventional doses under neurostimulation (NS).
Material and Methods: In this study 100 patients scheduled for upper limb surgery and suitable for ICB were randomly allocated to 1 of 5 groups: group NS (NS alone group 0.5 ml/kg LA), group FD (full-dose US group 0.5 ml/kg LA), group 30 (30% reduced dose LA 0.35 ml/kg), group 50 (0.25 ml/kg LA) and group 70 (0.15 ml/kg LA). The ICB was performed under US in conjunction with NS in all groups except group NS in which neurostimulation was used alone. When necessary local anesthetic supplementation to the operation site was administered during surgery and propofol infusion for sedation ensued. Evaluation of sensory and motor block was performed for each terminal nerve (i.e. radial, ulnar, median and musculocutaneous nerves). Block quality (assessing the need for rescue LA and propofol sedation) and duration of the block were documented.
Results: None of the patients in the FD and 30 groups required any supplementation or sedation, whereas LA supplementation rates were 5% in group 50 and 10% in groups 70 and NS. The propofol sedation rates were 20% in group NS, 25% in group 50 and 40% in group 70. Sensory block was significantly better in groups FD, 30 and NS at 30 min. A complete block was achieved more rapidly in all nerve territories in the full-dose group (p = 0.0001). Block duration was longest in group FD and was significantly longer in group 30 than in the other two groups (p = 0.0001).
Conclusion: The results show that US guidance is more effective in maintenance of successful ICB than neurostimulation guidance alone and a reduction of LA doses even to 70% of conventionally used doses seems possible with US guidance. This article is published in English.