The Clinical Application Of The Posterior Approach For Brachial Plexus Block

Objective: Brachial plexus block by the posterior approach described by Pippa is not widely used in contrast to the lateral approach of Winnie. We compared the clinical efficacy of both approaches in a randomized prospective study.Methods: Eighty patients, American Society of Anesthesiologists physical status I or II, scheduled for surgery of the shoulder or upper arm were randomized in 2 groups: lateral(Winnie, n = 40) or posterior approach(Pippa, n =40). With the aid of nerve stimulator, a single injection of 0.5% ropivacaine 0.5ml/kg was made after obtaining a motor response in the distribution of the axillary nerve at a current below 0.5 m A(2 Hz, 0.1 ms). Onset and distribution of analgesia and motor block were assessed at 5, 10, 15, 20, 30, and 60 minutes after the local anesthetic injection. Complete block was defined as anesthesia in all dermatomes C3-C6 at 60 minutes after injection. Record the block procedure time(min); needle depth; electrostimulation block(m A); second attempt needle introduction; side effects and clinical satisfaction.Results: The posterior approach provided complete block in 37 patients(92.5%) and the lateral approach in 32 patients(80%). Corresponding motor block was similar in both approaches, but the block procedure time was faster in the posterior approach(7.0 minutes v 8.9minutes; P<0.01). The needle depth is deeper(6.1cm v 2.9cm;P<0.01)and the second attempt needle introduction is less(P<0.01) in the posterior approach. The side effects were also less in the posterior approaches. In 1 patient in the lateral group, the block was insufficient for surgery. The clinical satisfaction of the 2 approaches shows no significant difference except the only one failure case in the lateral approach.Conclusions: The posterior approach for brachial plexus block is safe and acceptable regarding clinical efficacy for anesthesia of the shoulder and upper arm.