Hemodynamic Effects of Intradermal Methylene Blue During Breast Surgery Under General Anesthesia

All eligible patients will receive an intradermal injection of 5 mL of 1% methylene blue into the quadrant of the breast where the tumor is located or into the subareolar region prior to skin incision, as part of the standard sentinel lymph node mapping procedure during elective breast surgery. After injection, the site will be massaged for 10 minutes to facilitate lymphatic uptake. The procedure will be performed under general anesthesia, and all other aspects of perioperative care will follow standard clinical practice.