Background and Goal of Study: The ipsilateral shoulder pain (ISP) following thoracotomy is known to be unresponsive to epidural or paravertebral analgesia. Several methods have been investigated to treat ISP including interscalene block (ISB). Pulmonary function in patients undergoing thoracotomy can be further impaired due to side effects of ISB. In this prospective study, we aimed to evaluate whether ISB using lower concentration of local anesthetic reduces an incidence of post-thoracotomy ISP and affects pulmonary function in patients undergoing lung lobectomy.
Materials and Methods: Patients undergoing lung lobectomy were assigned randomly to either the control group or ISB group according to randomization. On arrival to the operating room, only for patients assigned to ISB group, single-shot ISB was performed under ultrasound guidance by one experienced anaesthesiologist. Then, all patients underwent general anesthesia using one lung ventilation. For all patients, continuous paravertebral block at the proper level was performed with the use of automated pump before closure of chest. The primary outcome was the incidence of ISP during the first 48 hours following surgery. Secondary outcomes were pulmonary function test, pain score of surgical site and the incidence of adverse events up to 48 h. 
Results and Discussion: The incidence of ISP was significant lower in ISB patients. Satisfactory sensory blockade of shoulder was achived in all ISB patients, and any diaphragm elevation was not observed at plain chest radiography taken immediately after surgery. Compared to baseline, FVC, FEV1 and PEFR significantly decreased after surgery, however, there was no difference between groups. The pain score at the surgical saite was similar at rest and coughing. No adverse events related with ISB occurred during study period.
Conclusion(s): Single-shot ISB with low concentration of local anesthetic and dexamethasone prevent post-thoracotomy ISP. It did not result in any diaphragmatic elevation and deterioration of pulmonary function in patients undergoing open-thoracotomy. 
References: Barak M, Iaroshevski D, Poppa E, et al. Low-volume interscalene brachial plexus block for post-thoracotomy shoulder pain. J Cardiothorac Vasc Anesth 2007; 21:554-557.

Single-shot Interscalene brachial plexus block reduces the incidence of post-thoracotomy shoulder pain without additional impairment of pulmonary function in patients undergoing open-thoracotomy