Background and Objectives To investigate the use of interscalene block by posterior approach in upper extremity surgery and its effects on routine pulmonary function tests.

Methods Interscalene block by posterior approach was performed with a peripheral nerve stimulator localization in 29 ASA Physical Status I and II patients undergoing upper extremity surgery. All patients were given 20 mL of 1% lidocaine and 20 mL of 0.5% bupivacaine. Modified Bromage Scale for motor block and pinprick test for sensory anesthesia was used. Pulmonary function, measurements [forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and VC (vital capacity)] were done in all patients just before and 2, 5, 10, 15, and 30 minutes after the block.

Results Surgery location was the arm in four cases, and the forearm in 25 cases. General anesthesia was added in nine patients. Intravenous analgesics or sedatives were needed in four cases. Ulnar nerve was missed in 13 patients. FEV₁ decreased 11.5% in 2 minutes (P > .05), 19.7% in 5 minutes (P = .0525), and FVC decreased 16.6% in 2 minutes (P > .05), 24.5% in 5 minutes after block (P < .05).

Conclusions Interscalene block by posterior approach did not provide a satisfactory anesthesia for forearm and hand surgery. This method also caused hemidiaphragmetic paresis and a reduction in pulmonary function tests as in the lateral approach of Winnie. We believe limitations and relative contraindications for interscalene block by lateral approach are the same for posterior approach.