Study of Ultrasound-guided Thoracic Paravertebral Block Using Ropivacaine With/Without Dexamethasone in Elective Thoracotomy

The procedures of thoracotomy are among the most painful operations. In addition to post-thoracotomy pain, the outcomes of surgery are affected adversely by postoperative discomfort. Therefore, post-thoracotomy pain control can improve the satisfaction of patient and prevent postoperative complications such as pneumonia, atelectasis, or respiratory failure. Thoracic epidural analgesia (TEA) used to be widely considered as a standard technique for providing analgesia after a thoracotomy. However, TEA carries side-effects such as incomplete or failed block, epidural hematoma, abscess, hypotension, respiratory depression, or bradycardia, etc. Recently, thoracic paravertebral block (TPVB) is an alternative technique for TEA that may offer a comparable analgesic effect and a better side -effect profile for post-thoracotomy analgesia. When local anesthetic agents are used as single injection, they can provide analgesia for limited period. Various adjuvants have been tried in the past in order to enhance the duration and quality of postoperative analgesia. Previous studies with perineural dexamethasone demonstrated that it enhanced the duration of local anesthetic block. The mechanism of its action is blocking the nociceptive impulse transmission along the myelinated C fibers. Patient-controlled analgesia (PCA) devices have been shown to provide superior analgesia and greater patient satisfaction compared with intermittent administration. System of wire-less PCA provides remote monitoring, information management and PCA devices with high precision. The purpose of this research is to determine whether dexamethasone might prolong the duration of analgesia and improve the short-time outcomes when administered for TPVB along with local anesthetic agents in elective thoracotomy.