title: Stimulus processing during apparent unconsciousness in anesthetized volunteers.
abstract: Return of motor-responses upon request as an indicator of stimulus processing during apparent unconsciousness in general anesthesia was studied in 8 healthy, male volunteers during prolonged inhalation of nitrous oxide. First the minimal effective concentration of nitrous oxide was established for each volunteer, based upon continued absence of motor-responses to repeated verbal commands. One week later this concentration of nitrous oxide was administered for a 3-hr. period; return of motor-responses after at least 30 min. of absence was considered a sign of so-called unconscious perception. Four volunteers showed return of motor-response within the 3 hr. of exposure, but two of these had been rather restless throughout the session. Results indicate that unexpected processing of information by patients may occur during presumed unconsciousness after a prolonged inhalation of nitrous oxide in general anesthesia.
mesh_terms: D000328:Adult; D000768:Anesthesia, General; D001143:Arousal / Q000187:drug effects; D001364:Awareness / Q000187:drug effects*; D003071:Cognition / Q000187:drug effects*; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000187:drug effects; D009609:Nitrous Oxide; D009619:Nociceptors / Q000187:drug effects; D013067:Speech Perception / Q000187:drug effects*; D014474:Unconsciousness / Q000523:psychology*
chemical_list: D009609:Nitrous Oxide