Comparing Different Doses of Intravenous Dexamethasone for Prolonging Analgesia After a Single-Shot Ultrasound-Guided Supraclavicular Brachial Plexus Block: A Prospective Randomized Study

Background Supraclavicular brachial plexus block (SCBPB) is a widely used regional anesthesia technique for upper limb surgeries. Intravenous dexamethasone is known to prolong postoperative analgesia, but the optimal dose remains uncertain due to potential side effects like hyperglycemia associated with high doses. This study compares the efficacy of different doses of intravenous dexamethasone in enhancing the duration of analgesia following a single-shot ultrasound-guided SCBPB. Methods This prospective, randomized study included 60 American Society of Anesthesiologists (ASA) grade I-III patients undergoing upper limb surgery. All patients received an ultrasound-guided SCBPB, followed by general anesthesia (GA) and were randomly allocated into four groups using computer-generated randomization: group 1: 0.5% levobupivacaine (20 ml) + 8 mg IV dexamethasone; group 2: 0.5% levobupivacaine (20 ml) + 4 mg IV dexamethasone; group 3: 0.5% levobupivacaine (20 ml) + 2 mg IV dexamethasone; group 4 (control): 0.5% levobupivacaine (20 ml) + IV 0.9% normal saline. Postoperative pain scores (visual analog scale, VAS), duration of analgesia, rescue analgesic requirement, incidence of nausea/vomiting, and blood glucose levels were recorded over 24 hours. Statistical analysis was performed using analysis of variance (ANOVA) and chi-square tests. Results Patients who received IV dexamethasone showed significantly prolonged analgesia compared to the control group (p < 0.001). The duration of analgesia in the 8 mg group was 13.8 ± 1.5 hours, compared to 11.2 ± 1.3 hours (4 mg), 9.4 ± 1.2 hours (2 mg), and 6.8 ± 1.1 hours in the control group. This represents a 103% increase in analgesia duration with 8 mg dexamethasone compared to the control. The incidence of postoperative nausea and vomiting (PONV) was lower in dexamethasone groups (p = 0.02). However, 8 mg dexamethasone was associated with transient hyperglycemia (p = 0.04), with blood glucose levels peaking at 185 ± 12 mg/dL compared to 145 ± 10 mg/dL in the control group. Conclusion Intravenous dexamethasone significantly prolongs analgesia following SCBPB, with 8 mg providing the longest duration (103% increase vs. control). However, 4 mg may offer a balance between efficacy and minimal side effects, particularly in avoiding postoperative hyperglycemia.