This dissertation protocol proposes a prospective, comparative observational study to evaluate and compare the effectiveness of the Erector Spinae Plane (ESP) block versus intravenous dexmedetomidine for postoperative analgesia in patients undergoing mastectomy. Given the high incidence of moderate-to-severe acute pain and the risk of chronic post-mastectomy pain syndrome, the study addresses a clear knowledge gap, as both techniques are well studied individually but lack direct head-to-head comparison.

The study will be conducted at Kasturba Medical College hospitals and will include ASA I–II female patients aged 18–75 years undergoing elective mastectomy under general anesthesia. A total of 74 patients (37 per group) will be enrolled using convenience sampling. Patients will be allocated to either Group A (ultrasound-guided ESP block at T4 with local anesthetic) or Group B (IV dexmedetomidine loading dose followed by infusion). Standardized general anesthesia will be administered to all patients, and postoperative pain will be assessed using VAS scores at 1, 12, and 24 hours.

The primary outcome is postoperative analgesic efficacy, assessed by duration and intensity of pain relief. Secondary outcomes include the requirement for rescue analgesia and comparison of hemodynamic parameters (heart rate, blood pressure, oxygen saturation, respiratory rate), along with monitoring for adverse effects such as hypotension or bradycardia. Data will be analyzed using appropriate parametric or non-parametric tests, with statistical significance set at p < 0.05.

Overall, the study aims to determine which modality provides longer-lasting analgesia, reduced need for rescue analgesics, and better hemodynamic stability, thereby guiding optimal postoperative pain management strategies for mastectomy patients.