The Influence of Age on Dexmedetomidine Pharmacodynamic

Dexmedetomidine(DEX) is a novel , highly selective α2 adrenergic receptor agonists , and its selectivity for α2 receptor is 1600 times higher than α1.It also could provide dose-dependent sedation , analgesia , anti-anxiety and inhibition of sympathetic nerves and other effects .At earlier time It was approved by the FDA only for short-time sedation during mechanical ventilation of adult patients (\<24h) in ICU. Because of its minimal impact on the respiratory , currently it was more and more widely used to sedate patients undergoing regional anesthesia.Many anesthetic pharmacokinetics and pharmacodynamics are often affected by age and gender,such as the drug sensitivity of propofol and remifentanil is increased with age,while the current study also demonstrated that gender may influence the sedate efficacy of propofol and the sensitivity of muscle loose of rocuronium. Current studies with regard to the effects of age and gender on dexmedetomidine pharmacodynamic are rare. The study is aim to explore the right DEX dose of different Age of patients to produce suitable sedation.Dexmedetomidine be used in patients with combined spinal and epidural anesthesia for sedation,which is monitored by the BIS,during the operation.The relation between BIS values and the depth of sedation for patients is also investigated.