Stages of Anesthesia

Abstract

Narcotic, analgetic, and neuroleptic substances used in anesthesiology for general anesthesia cause a continuous reversible suppression of all or individual structures of the CNS (holencephalic and telencephalic narcotics). The changes in the level of consciousness and in the vegetative functions during the induction, maintenance, and termination of anesthesia are at all times related to the actual depth of anesthesia. The various stages of anesthesia can thus be clinically classified, as was first described by Guedel in 1920 [5]. In the course of anesthesia with holencephalic drugs, these stages are basically passed through in a similar sequence — analgesia with complete alertness, loss of consciousness, coma due to narcotic overdose, and intoxication. The time leading up to the individual stages and their duration depends on the type of narcotic agent and its specific appearance and disappearance in the CNS. In modern anesthetic techniques with combinations of several anesthetic-narcotic relaxing substances, the individual stages of anesthesia are frequently varied in their clinical manifestations and thus can be less easily distinguished than with the monoanesthetic formerly used.