Local Anesthetic Concentration and Rebound Pain

Evaluation of the Effect of Local Anesthetic Concentration on Rebound Pain After Interscalene Block for Shoulder Surgery

The rebound pain after nerve block could interfere with patient's recovery and rehabilitation. It is not known how local anesthetic concentrations affect rebound pain. The aim of this study is evaluation of the effect of local anesthetic concentration on rebound pain after interscalene block for shoulder surgery.

Shoulder surgery is related to more than moderate pain after surgery. Interscalene nerve block could reduce the postoperative pain effectively. When the effect of nerve block ends, however, rebound pain could appear. The rebound pain could interfere with patient's recovery and rehabilitation.

The mechanism of rebound pain is not well known. One of possible mechanism is that the pain stimulus that was blocked suddenly comes out, and it is perceived as more severe pain. The strength of the block may vary depending on the concentration of the local anesthetic. Therefore, the concentration of local anesthetics could affect rebound pain. The aim of this study is evaluation of the effect of local anesthetic concentration on rebound pain after interscalene block for shoulder surgery.

Inclusion Criteria:

• Elective shoulder surgery under general anesthesia and interscalene block for postoperative pain

Exclusion Criteria:

• Contraindication of interscalene block: pulmonary disease, lung resection history, brachial nerve injury
• Diabetic neuropathy
• Adverse drug reaction history to ropivacaine, fentanyl
• Impaired coagulation