Comparison Of Analgesic Efficacy of Continuous Perineural Catheter, Liposomal Bupivacaine, And Dexamethasone as An Adjuvant For Interscalene Block In Total Shoulder Arthroplasty: A Triple Blinded Randomized Controlled Trial.

Abstract

Background: Interscalene catheters (ISC) are considered as the gold standard for perioperative pain control after total shoulder arthroplasty (TSA). Liposomal bupivacaine (LB) for interscalene blocks (ISB) or the addition of dexamethasone to ISBs have both presented as additional options for extended analgesia. We aimed to compare the efficacy of LB to a single shot ISB (SISB) with added dexamethasone to an ISC. We hypothesized that a single injection of LB or an ISB with a dexamethasone will provide non-inferior duration and quality of analgesia compared to ISC.

Methods: A single centered triple blinded randomized controlled trial evaluated patients undergoing elective primary TSA. Patients were randomized to 3 groups, Group A (control): 0.5% bupivacaine 15 ml with a rescue catheter left in situ (0.125% bupivacaine infusion), Group B: 0.5% bupivacaine 14 ml with 4mg (1 ml) dexamethasone with a catheter left in situ (saline infusion), Group C: 10 ml of liposomal bupivacaine (133 mg) with 0.5% bupivacaine 5 ml, with a catheter left in situ (saline infusion). The primary outcome was the worst NRS (numeric rating scale) measured on arrival to PACU, 6 hours, 12 hours, 24 hours, and 36 hours postoperatively. Secondary outcomes recorded were time to first analgesic request, intraoperative opioid consumption, total inpatient opioid consumption, arm weakness, arm numbness, time of analgesia duration, time of motor recovery, sensory testing using pinprick on POD1, Q36, Q48, hand strength assessment using dynamometer POD1, Q36, Q48, PACU and hospital length of stay.

Results: We analyzed 72 patients in 3 groups (Group A 24, group B 24, Group C 24). The pre-surgery physical function scores were similar between groups. The change in postoperative pain was not different among the three groups. All 3 groups demonstrated an increase in the postoperative values, a change that was not statistically significant between groups. Likewise, no difference in the mental function score was seen within or between groups. No differences in sleep quality or satisfaction were seen among groups (P values 0.405 and 1.00, respectively). No adverse events were reported in all groups.

Conclusions: No significant difference was demonstrated between a single injection ISB with dexamethasone, a LB injection and an ISC. Given the equivalence in analgesia provided with these three modalities, providers should carefully consider the option that best fits each patient. Thus, a single injection of LB or single injection of bupivacaine with dexamethasone provides similar analgesic efficacy compared to ISC.