Opioid Free Versus Opioid Based Anaesthesia for Free Flap Reconstruction Surgery of the Breast: A Phase III Multicentric Randomized Controlled Study.

Inclusion Criteria: 1. Women aged 18 or older. 2. Patients with a French health insurance coverage (having a French social security number). 3. Patient eligible for free flap reconstruction surgery of the breastunder general anaesthesia. 4. Patient who has given written consent to participate in accordance with the regulations. 5. Having a negative blood pregnancy test for patients of childbea ring age. Exclusion Criteria: 1. Allergy or intolerance to any of the drugs (dexmedetomidine, remifentanil, lidocaine, propofol, dexamethasone, kétamine, ketoprofen, nefopam, paracetamol, morphine, ropivacaine, droperidol, ondansetron). 2. Known history of heart failure, arrhythmias and/or ischemic heart disease and/or severe renal insufficiency. 3. Pulse below 50bpm during anaesthesia consultation and/or under beta blocker treatment. 4. Treatment with ACEI/ARB. 5. Severe asthma. 6. Symptomatic gastric or duodenal ulcer with or without treatment. 7. Baseline systolic blood pressure \< 100 mmHg. 8. Chronic preoperative pain and/or use of WHO ladder step 2 or 3 analgesics preoperatively. 9. Patient already included in another therapeutic trial evaluating an experimental molecule. 10. Persons deprived of liberty or under guardianship. 11. Patients with suspected difficulties in assessing pain on a scale. 12. Inability to undergo trial medical monitoring due to geographic, social or psychological reasons.