A comparative study of nerve stimulator versus ultrasound-guided supraclavicular brachial plexus block

Anesth Essays Res. Sep-Dec 2013;7(3):359-64. doi: 10.4103/0259-1162.123235.


Introduction: With the advent of ultrasound (US) guidance, this technique saw resurgence in the late 1990s. As US guidance provides real-time view of the block needle, the brachial plexus, and its spatial relationship to the surrounding vital structures; it not only increased the success rates, but also brought down the complication rates. Most of the studies show use of US guidance for performing brachial plexus block, results in near 100% success with or without complications. This study has been designed to examine the technique and usefulness of state-of-the-art US technology-guided supraclavicular brachial plexus block and compare it with routine nerve stimulator (NS)-guided technique.

Aim: To note block execution time, time of onset of sensory and motor block, quality of block and success rates.

Settings and design: Randomized controlled trial.

Materials and methods: A total of 60 patients were enrolled in this prospective randomized study and were randomly divided into two groups: US (Group US) and NS (Group NS). Both groups received 1:1 mixture of 0.5% bupivacaine and 2% lignocaine with 1:200000 adrenaline. The amount of local anaesthetic injected calculated according to the body weight and not crossing the toxic dosage (Inj. bupivacaine 2 mg/kg, Inj. lignocaine with adrenaline 7 mg/kg). The parameters compared between the two groups are block execution time, time of onset of sensory and motor block, quality of sensory and motor block, success rates are noted. The failed blocks are supplemented with general anesthesia.

Statistical analysis: The data were analyzed using the SPSS (version 19) software. The parametric data were analyzed with student "t" test and the nonparametric data were analyzed with Chi-square test A P < 0.05 was considered significant.

Results: There was no significant difference between patient groups with regard to demographic data, the time of onset of sensory and motor block. Comparing the two groups, we found that the difference in the block execution time and success rates is not statistically significant. A failure rate of 10% in US and 20% in NS group observed and is statistically insignificant (P = 0.278). No complication observed in either group.

Conclusions: US and NS group guidance for performing supraclavicular brachial plexus blocks ensures a high success rate and a decreased incidence of complications that are associated with the blind technique. However, our study did not prove the superiority of one technique over the other. The US-guided technique seemed to have an edge over the NS-guided technique. A larger study may be required to analyze the advantages of using US in performing supraclavicular brachial plexus blocks, which could help justify the cost of purchase of the US machine.

Keywords: Brachial plexus block; nerve stimulator; supraclavicular; ultrasound.