The Effect of Dexamedetomidine for Interscalene Brachial Plexus Block on Plasma Cortisol and IL-6 After Rotator Cuff Repair: a Prospective Randomized Study

Background The incidence of severe postoperative pain after shoulder surgery is 30% to 70%.The postoperative pain should be relieved for early rehabilitation and recovery. Patient-controlled analgesia (PCA) with opiate therapy may control some of the postoperative pain, but it has several side effects such as nausea, vomiting, and dizziness, which can prevent early discharge. Conversely, there are several regional blocks to control postoperative pain. Interscalene brachial plexus block (ISB) is known as one of the most effective regional blocks for shoulder surgery, but it has relatively short duration of effect.

Dexmedetomidine (DEX), a selective agonist of α2-adrenergic receptors, can be an effective adjuvant to local anesthetics for peripheral nerve block. Preclinical and clinical studies have described prolonged duration of analgesia when dexmedetomidine was added to bupivacaine, levobupivacaine, or ropivacaine for peripheral perineural blocks.

Pro-inflammatory cytokines, such as interleukin-6 (IL-6), shows a high association with acute pain because they sensitize the nervous system. IL-6 levels in the plasma are detectable 60 minutes after injury, peaking at 4-6 hours, and are proportional to tissue injury.

Increased plasma cortisol concentrations can be detected within 15 minutes following exposure to a stressor. And several biomarkers related to pain have been studying.

Method 50 patients with rotator cuff tears who had undergone arthroscopic rotator cuff repairs were enrolled in this study. Rotator cuff tears were diagnosed by preoperative magnetic resonance imaging, and the size of the rotator cuff was confirmed at the time of arthroscopic operation. Indication for surgery was a symptomatic full-thickness rotator cuff tear or a partial thickness rotator cuff tear of more than 50% thickness in case of failed conservative therapy. Twenty-five patients were randomly allocated to group 1 and received both ISB with 8mL of ropivacaine with 100 μg (1ml) of dexmedetomidine . The other 25 patients were allocated to group 2 and received ISB with 8mL of ropivacaine with 1ml of normal saline.