A Comparison of Single Versus Multiple Injections on the Extent of Anesthesia with Coracoid Infraclavicular Brachial Plexus Block

Abstract

Single-injection coracoid infraclavicular brachial plexus block produces inconsistent anesthesia of the upper limb. In this study, we sought to determine the number of injections needed to provide a reasonably complete anesthesia of the upper limb with this approach. Seventy-five patients were randomly assigned to receive a coracoid block guided by nerve stimulator with 42 mL of 1.5% mepivacaine with a single-injection (Group 1), dual-injection (Group 2), or triple-injection (Group 3) technique. No search for a specific motor response was performed in any group. Sensory and motor block was assessed 5 and 20 min after the end of the injection of local anesthetic. Significantly less complete anesthesia to pinprick in the distributions of the axillary, musculocutaneous, radial, ulnar, and medial cutaneous forearm nerves was found in Group 1 at 20 min. Significantly less complete paralysis for arm, wrist, and hand movements was found in Group 1 at 20 min. No significant difference was found between Groups 2 and 3. We conclude that dual and triple injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single-injection technique.

Case series: Septa can influence local anesthetic spread during infraclavicular brachial plexus blocks

“…Although this does not fully support the observed lower success rates with single injection techniques, further study is warranted to examine the outcome of unilateral local anesthetic spread. [3][4][5] Furthermore, because we used only 33 mL instead of the traditional 40 to 50 mL of local anesthetic in performing the infraclavicular brachial plexus blocks, it is unclear if the smaller volume may have contributed to the observed unilateral spread of local anesthetic in our study. According to Sandhu et al, 13 however, a volume as low as 14 mL of carefully injected local anesthetic under ultrasound guidance is sufficient to produce adequate nerve blocks.…”

“…Secondly, because failed and partial blocks occurred more frequently when the injection was made after stimulating only the lateral cord, we thought that this location would provide us with better opportunity to examine the relationship between the septae and the distribution of local anesthetic. [3][4][5][6]11 Klaastad et al 12 reported uneven local anesthetic spread on magnetic resonance imaging examination after single injection axillary brachial plexus blocks. In our study, approximately 20% (six of 28) of patients had unilateral spread of the local anesthetic after one injection when the infraclavicular brachial plexus was approached from the lateral direction.…”

“…Because all observed septae were located in posterolateral aspect of the axillary artery, local anesthetic was not seen to reach the posterior cord in cases of suspected septal presence, as has been shown to provide the most effective anesthesia. [3][4][5][6] This may explain the high failure rate of the single lateral injection technique. This finding also agrees with a recent study that examined the relationship between the local anesthetic spread and the infraclavicular block success.…”

“…11 It is generally accepted that multiple injections improve the success of infraclavicular brachial plexus blocks. 4,5 However, one of the criticisms of the multiple injection technique is its potential to increase complications. 5 By selectively performing multiple injections only when the local anesthetic spread is unilateral, our blocks were 100% successful without any complication.…”

“…1,2 With the use of nerve stimulators, the success rate of the single injection technique was as low as 44%, especially when only the lateral cord was stimulated. [3][4][5][6] We hypothesized that ultrasonographic identification of septae may be beneficial in performing infraclavicular brachial plexus blocks. The purpose of this study was to ultrasonically identify the presence of septae within the neurovascular sheath and to assess their possible effect on local anesthetic spread.…”