Postoperative nausea and vomiting (PONV) is one of the most frequently occurred complications after surgery, and are associated with patients' dissatisfaction after anesthesia and surgery. Orthognathic surgery is widely performed for the correction of dentofacial deformities. Despite of improved anti-emetic prophylaxis, patients undergoing orthognathic surgery are reported to have a high incidence of PONV, especially those after bimaxillary surgery.~It is known that activation of central cholinergic system plays an important role in the development of PONV. Muscarinic antagonists such as scopolamine can block muscarinic receptors in the cerebral cortex and produce anti-emetic effects. Penehyclidine is a new muscarinic antagonists which selectively block M1 and M3 receptors. Our previous study indicated that single-dose of penehyclidine injected before anesthesia induction was associated with a reduced risk of PONV during the first 6 h postoperatively.The mean elimination half-life of penehyclidine following single administration is about 10.35 h. Hence, a single-dose penehyclidine may only produce a short duration of antiemetic effect.~The investigators hypothesize that continuously administrated penehyclidine during perioperative period reduces PONV more effectively than single-dose injection in patients undergoing bimaxillary surgery. The purpose of this study is to investigate the effect of continuous administered penehyclidine in preventing PONV in patients undergoing bimaxillary surgery.
Postoperative nausea and vomiting (PONV) is a common complication after surgery. Patients undergoing orthognathic surgery are reported to have a high rate of PONV, especially those undergoing bimaxillary surgery. Activation of cholinergic system plays an important role in the development of PONV. Penehyclidine is an muscarinic antagonists which selectively block M1 and M3 receptors and is commonly used to decrease oral secretion. The investigators hypothesize that continuously administrated penehyclidine during perioperative period can reduce the incidence of PONV in patients undergoing bimaxillary surgery.