Comparison of Bupivacaine-Dexmedetomidine and Bupivacaine-Dexamethasone in PENG Block for Post-operative Analgesia in Hip Surgeries

Background: Pain management strategies such as systemic medications, local infiltration, neuraxial anesthesia, and peripheral nerve blocks have been widely studied, but each approach has certain limitations. The PENG block was introduced to provide postoperative pain relief and reduce reliance on opioids. Objectives: To compare the analgesic effectiveness of combining bupivacaine with either dexmedetomidine or dexamethasone in PENG block for patients undergoing hip surgery. We hypothesized that dexmedetomidine would provide superior analgesic outcomes compared to dexamethasone. Methods: Sixty patients underwent spinal anesthesia using hyperbaric bupivacaine. Afterward, each patient received a PENG block using one of two pre-prepared syringes labeled according to group allocation. Patients were randomly divided into two groups: Group A received 20 mL of 0.25% bupivacaine with 1 µg/kg dexmedetomidine, whereas group B received the same volume of 0.25% bupivacaine combined with 8 mg dexamethasone. Results: There was an increase in the Numerical Rating Scale (NRS) of pain in both groups within a period of 24 hours, but a statistically significant increase was observed in group B compared to group A according to the NRS of pain after 30 minutes in the PACU (median 0 vs. 0, P = 0.002), after 4 hours (2 vs. 1, P = 0.011), after 8 hours (4 vs. 3, P = 0.006), and after 24 hours (5 vs. 3, P < 0.001) at the ward. Additionally, group A demonstrated a significantly longer time to the first analgesic request (13.87 ± 2.92 hours vs. 8.93 ± 3.74 hours, P < 0.001) and a reduced overall opioid requirement during the first 24 hours (8.17 ± 2.78 mg vs. 16.00 ± 5.63 mg, P < 0.001). The incidence of adverse effects did not differ significantly between the two groups. Conclusions: The addition of dexmedetomidine to bupivacaine in the PENG block resulted in a significantly prolonged time to the first analgesia request, lower postoperative pain scores, and reduced opioid consumption over 24 hours compared to dexamethasone. Although both adjuvants were effective, dexmedetomidine provided clinically more meaningful and sustained analgesia.