摘要：

There is a multidirectional continuum of anesthetic states, some represented by CNS excitation and others by depression. The reticular activating system is influenced by all anesthetics, some inhibiting its action (Stage III) and some hyperexciting the system which results in a function disorganization (Stage II C). In both cases the result is a loss of the arousal response. Some agents traverse both excitation and depression i.e. diethyl ether (Stages I, II, III); others induce Stage II—catalepsia i.e. trichlorethylene, nitrous oxide, ketamine, γ-hydroxybutyrate, phencyclidine and ethrane; while others induce no Stage II but progress directly frorn the excitement of Stage I to Stage III i.e. halothane and barbiturates. Cataleptic agents may induce further CNS excitation manifested by seizures i.e. γ-hydroxybutyrate, phencyclidine, trichlorethylene, and ethrane. The functional definition of surgical anesthesia is : A state induced by a drug which makes the patient relatively unresponsive to painful stimuli and amnestic. Thus the patient does not respond during surgery and cannot recall what happened. This can be achieved by CNS stimulation or depression. The anesthetic state induced by ketamine can be described as a cataleptic anesthetic state.

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