Design: A prospective, randomized, controlled study. Setting: Single-center university hospital. Participants: The study included 168 patients undergoing thyroid surgery under general anesthesia with endotracheal intubation.~Interventions: The patients were allocated randomly into the following 3 groups: the control group: patients will be injected intravenously 5ml of normal saline 15 minutes before anesthesia and another 5ml of normal saline was injected intravenously when the incision was washed and sutured；the pre-tramadol group: patients will be injected intravenously 5ml of tramadol (1mg / kg) 15 minutes before anesthesia and 5ml of normal saline was injected intravenously when the incision was washed and sutured. the post-tramadol group: patients will be injected intravenously 5ml of normal saline 15 minutes before anesthesia and 5ml of tramadol (1mg / kg) was injected intravenously when the incision was washed and sutured. Postoperatively, all patients will receive standard treatment.
Post operative sore throat after general anesthesia with endotracheal intubation is a common problem causing dissatisfaction and discomfort to the patients. The investigators want to study the effect of tramadol on postoperative sore throat in general anesthesia with endotracheal intubation.