Shoulder surgery often causes severe pain after the operation. To control this pain, doctors commonly perform a nerve block (interscalene brachial plexus block), which numbs the shoulder area. However, when the effect of a single-injection nerve block wears off, many patients experience sudden, intense pain known as "rebound pain".
One way to prevent rebound pain is to place a thin catheter near the nerves so that local anesthetic can be given continuously for a longer period (continuous nerve block). However, this method is technically demanding and can cause problems such as catheter dislodgement, infection, and inconvenience for patients. Another simpler option is to give a single-injection nerve block together with an intravenous (IV) injection of dexamethasone, a steroid medication known to prolong the effect of nerve blocks and reduce rebound pain.
The purpose of this study is to determine whether a single-injection nerve block combined with IV dexamethasone (5 mg) is not inferior to a continuous nerve block in preventing rebound pain after shoulder surgery. A total of 92 adult patients scheduled for elective shoulder surgery will be randomly assigned to one of the two groups. The main outcome is the rebound pain score, defined as the difference between the last pain score recorded in the recovery room (while the nerve block is still working) and the highest pain score reported within the first 24 hours after the nerve block. The investigators expect that the simpler single-injection method with IV dexamethasone will provide comparable pain control while avoiding the complications and inconvenience of catheter-based continuous nerve blocks.
Adult patients aged 19 to 79 years scheduled for elective shoulder surgery under brachial plexus block and monitored anesthesia care (MAC)
Pre-existing neurological deficit of the brachial plexus
Emergency surgery
American Society of Anesthesiologists (ASA) physical status classification IV or higher
Contraindication or history of hypersensitivity to local anesthetics or dexamethasone
Parallel
Dexamethasone (IV)
DrugIntravenous dexamethasone 5 mg, administered as a single dose after confirmation of adequate sensory and motor block on arrival in the operating room.
Single-shot interscalene brachial plexus block
Procedure/SurgeryUltrasound-guided single-shot interscalene brachial plexus block performed with a 50 mm needle. 0.75% ropivacaine 15-20 mL is injected at the interscalene level. No perineural catheter is placed.
Continuous interscalene brachial plexus block
Procedure/SurgeryUltrasound-guided interscalene brachial plexus block with 0.75% ropivacaine 15-20 mL, followed by placement of a perineural catheter adjacent to the superior trunk. Continuous postoperative analgesia is provided through the catheter using 0.2% ropivacaine (basal rate 5 mL/h, bolus 3 mL, lockout time 30 min) via a patient-controlled analgesia pump.
Rebound Pain Score (RPS)
Difference between the last pain score recorded in the post-anesthesia care unit (PACU) while the nerve block is still effective and the highest pain score reported within the first 24 hours after the nerve block, measured on an 11-point Numerical Rating Scale (NRS; 0 = no pain, 10 = worst pain imaginable). Higher scores indicate more severe rebound pain. Non-inferiority margin: 1.5.
Postoperative pain score (NRS)
Pain intensity at rest and during movement, measured on an 11-point NRS (0 = no pain, 10 = worst pain imaginable).
Peak NRS pain score
Highest pain score reported during each period, on an 11-point NRS.
Incidence of severe rebound pain
Proportion of participants experiencing rebound pain with NRS ≥ 7.
Block duration
Time from completion of the nerve block to the first onset of pain.
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