Goal-Directed Fluid Therapy for Patients Undergoing Oro-Maxillofacial Surgery

Orthognathic surgery, one kind of Oro-maxillofacial surgery, is a complicate surgery that undergoes several hours with nasotracheal intubation general anesthesia. To limit blood loss during operation, the patients are often under intentional hypotension. However, the intentional hypotension may confuse with hypovolemic induced low blood pressure. The hypothesis is using flotrac (to measure stroke volume variation) to keep the patients hemodynamics stable under Tridil and propofol infusion and avoid over-infusion of crystalloid or colloid and prevent hypovolemia induced postoperative nausea and vomiting.