Patients undergoing Partial or total mastectomy with axillary LN dissection will receive prior to induction of general anaesthesia ESP block at T4 level at the same side of the surgery. one group will receive ropivacaine 0.375% and the other will get ropivacaine 0.375% with dexmedetomidine 0.5mcg/kg as an adjuvant. time to first narcotic requirement will be documented and therefore an assessment of the duration of action of the block will be made

Background and Objective: Whether partial or complete, mastectomy with axillary lymph node dissection is a painful surgery. Acute postoperative pain management is challenging and crucial due to high chances of it transforming into chronic pain. Erector spinae plane (ESP) block has been shown to be effective in managing post mastectomy pain.Dai et al showed the effectiveness of dexmedetomidine in prolonging the duration of sensory block, motor block and analgesia when dexmedetomidine as an adjunct is added to ropivacaine in brachial plexus block (1). The aim of our study is to show the effectiveness of dexmedetomidine in prolonging the analgesic effect of ropivacaine when added to it in ESP block compared to using ropivacaine alone in patients undergoing mastectomy with axillary lymph node dissection, and to study its impact on postoperative opioid consumption.

Methods: 44 American Society of Anesthesiologist (ASA) physical status classification class I, II and III will be randomly allocated to one of two groups, both receiving a single injection erector spinae plane block at T4 vertebral level using 20ml ropivacaine 0.375% 20 minutes before the induction of anesthesia. The first group will receive 0.5mcg/kg of dexmedetomdine added to the ropivacaine solution. The control group will receive no dexmedetomidine.

Postoperatively, patients in both groups will be receive acetaminophen 1g orally every 6 hours and oxycodone 5 mg orally as needed every 6 hours if VAS is more than 4. Postoperative pain will be measured using Verbal Analogue Scale (VAS) at 0, 1, 2, 4, 6, 12, 18, and 24 hours.

Conclusion: This study will be the first of its kind to investigate the impact of adding dexmedetomidine as an adjunct to ropivacaine in prolonging the ESP block duration in patients undergoing mastectomy with axillary lymph node dissection.

Inclusion Criteria:

1. ASA class I, II and III patients
2. Age range: 18-80 years old
3. Elective partial or unilateral radical mastectomy with sentinel lymph node dissection

Exclusion Criteria:

1. Pregnant woman
2. Bilateral mastectomy.
3. Skin infection at the site of needle puncture
4. Coagulopathy problems
5. Allergy or contraindication to any of the study drugs
6. Recent use of opioid drugs

Biologically female