Supraclavicular block with Mepivacaine vs Ropivacaine, their impact on postoperative pain: a prospective randomised study.

Background: Supraclavicular block (SCB) with long-acting local anaesthetic is commonly used for surgical repair of distal radial fractures (DRF). Studies have shown a risk for rebound pain when the block fades. This randomised single-centre study aimed to compare pain and opioid consumption the first three days post-surgery between SCB-mepivacaine vs. SCB-ropivacaine, with general anaesthesia (GA) as control.

Methods: Patients (n = 90) with ASA physical status 1-3 were prospectively randomised to receive; SCB with mepivacine 1%, 25-30 ml (n = 30), SCB with ropivacaine 0.5%, 25-30 ml (n = 30) or GA (n = 30) with propofol/fentanyl/sevoflurane. Study objectives compared postoperative pain with Numeric Rating Scale (NRS) and sum postoperative Opioid Equivalent Consumption (OEC) during the first 3 days post-surgery between study-groups.

Results: The three groups showed significant differences in postoperative pain-profile. Mean NRS at 24 h was significantly lower for the SCB-mepivacaine group (p = 0.018). Further both median NRS and median OEC day 0 to 3 were significanly lower in the SCB-mepivacaine group as compared to the SCB-ropivacaine group during the first three days after surgery; pain NRS 1 (IQR 0.3-3.3) and 2.7 (IQR 1.3-4.2) (p = 0.017) and OEC 30 mg (IQR 10-80) and 85 mg (IQR 45-125) (p = 0.004), respectively. The GA-group was in between both in pain NRS and median sum OEC. Unplanned healthcare contacts were highest among SCB-ropivacaine patients (39.3%) vs. SCB-mepivacaine patients (0%) and GA-patients (3.4%).

Conclusions: The potential benefit of longer duration of analgesia, associated to a long-acting local anaesthetic agent, during the early postoperative course must be put in perspective of potential worse pain progression following block resolution.

Trial Registration: NCT03749174 (clinicaltrials.gov, Nov 21, 2018, retrospectively registered).