Intraperitoneal Dexamethasone Spraying on Vagal Nerve-Rich Areas for Prevention of Hoarseness After Upper Abdominal Surgery

The goal of this clinical trial is to evaluate whether intraoperative spraying of dexamethasone onto the abdominal vagal nerve-rich areas can prevent postoperative hoarseness in patients undergoing elective upper abdominal surgery. The main questions it aims to answer are: * Does intraoperative topical dexamethasone spraying reduce the incidence of postoperative hoarseness after upper abdominal surgery? * Does postoperative intravenous dexamethasone accelerate recovery in patients who develop hoarseness? Researchers will compare a dexamethasone group (intraoperative spraying of 10 mg dexamethasone in 10 mL normal saline) to a placebo group (intraoperative spraying of 10 mL normal saline alone) to see if dexamethasone reduces the rate of postoperative hoarseness. Participants will: * Undergo voice assessment (GRBAS scale) and voice recording before surgery and daily for 10 days after surgery. * Be randomly assigned to receive either dexamethasone or placebo sprayed onto the surgical field at the end of the operation. * If hoarseness develops in the placebo group, be randomly assigned again to receive either intravenous dexamethasone (5 mg daily for 3 days) or placebo.