全身麻醉课件.ppt

General anesthesia Ma Ling Department of Anesthesiology Shengjing Hospital, China Medical University Tel:What is general anesthesia? A. pain relief (analgesia) B. blocking memory of the procedure (amnesia) C. producing unconsciousness D. inhibiting normal body reflexes to make surgery safe and easier to perform E. relaxing the muscles of the body Definition General anesthesia is anesthetics-induced reversible suppression on CNS, and has the following manifestations: producing unconsciousness pain relief (analgesia) blocking memory of the procedure (amnesia) inhibiting normal body reflexes to make surgery safe and easier to perform relaxing the muscles of the body Course of General Anesthesia Route of Action Inhalation anesthetics Through airway Maintenance (most); induction (some) Most are halogenated hydrocarbons Mechanism: interact with the brain cell membrane, details are not clear How to compare anesthetic potency? MAC (minimum alveolar concentration) 最低肺泡有效浓度 The concentration (at 1atm) required to prevent movement in 50% of subjects following a surgical stimulus Oil-gas partition coefficient Anesthetic potency MAC MAC is also an index for depth of anesthesia Inhalational anesthesia Lower MAC higher potency How to determine its controllability? Blood-gas partition coefficient (solubility) The lower the blood-gas partition coefficient the easier for the partial pressure in alveolar, blood and brain to get equilibrium the easier to control its concentration in brain Physicochemical property (1) oil-gas partition coefficient anesthetic potency MAC (2) blood-gas partition coefficient controllability Which has the best anesthetic potency?Which takes effect fastest? FA: alveolar concentration of anestheticFI: inspired concentration of anesthetic FA /FI shows the increasing rate of an