Interscalene Blocks

The primary objectives of this present study are to examine whether a continuous interscalene block of a total duration of 48 hours reduces the incidence of rebound pain comparatively to single-shot interscalene block, through the evaluation of the NRS scores at rest and on movement in the postoperative period at 24, 48, 72 and 96 hours as well as the total opioid consumption in the same timeframe for patients undergoing total shoulder arthroplasty. Rebound pain has been defined in some studies as the "the transition from well-controlled pain (numerical rating scale \[NRS\] ≤3) while the block is working to severe pain (NRS ≥7) within 24 h of block performance."

Recent studies have highlighted the comparative advantages of perineural dexamethasone, particularly regarding its safety profile and its ability to prolong analgesia in various peripheral nerve blocks. A recent systematic review demonstrated that perineural administration of dexamethasone significantly extends the duration of analgesia compared to intravenous administration. The mechanism of action of perineural dexamethasone remains unclear. Moreover, there is a lack of research comparing the systemic absorption of local anesthetics administered perineurally with or without dexamethasone, and the systemic absorption and bioavailability of dexamethasone when used as a perineural adjuvant have not been studied. Objective: This study aims to compare plasma concentrations of bupivacaine following a single-shot interscalene block with dexamethasone administered either perineurally or intravenously. Methodology: A prospective, randomized, double-blind trial will be conducted involving 40 patients undergoing shoulder surgery requiring a single-shot interscalene block. Each patient will receive 20 mL of 0.25% bupivacaine combined with 8 mg of dexamethasone administered either perineurally or intravenously. Venous blood samples (5 mL) will be collected at 5, 10, 20, 40, 80, 120, and 240 minutes post-block, and one sample at discharge, to measure plasma concentrations of both enantiomers of bupivacaine (D(+)-bupivacaine and L(-)-bupivacaine) and dexamethasone. Outcomes: The study will compare plasma levels of bupivacaine between groups, characterize the pharmacokinetics of bupivacaine and dexamethasone, and assess block duration and opioid consumption.

This study is evaluating whether the timing of an interscalene nerve block affects pain control and recovery after arthroscopic rotator cuff repair surgery. An interscalene block is commonly used to reduce pain after shoulder surgery. However, it is not known whether administering the block before surgery or after surgery provides better outcomes. Participants undergoing arthroscopic rotator cuff repair are assigned to receive the interscalene block either before the surgical incision or after completion of the procedure. The study compares postoperative pain levels, opioid medication use, length of hospital stay, and ultrasound imaging quality during block administration between the two groups. Functional recovery is also assessed using patient-reported outcome measures during follow-up. The investigators hypothesize that administration of the interscalene block before surgery may provide superior early pain control and reduce postoperative opioid requirements while maintaining similar functional outcomes compared with administration after surgery.