Skin conductance responses to auditory stimuli and anticipatory responses before venepuncture in patients premedicated with diazepam or morphine.

We have measured the skin conductance response to innocuous auditory stimuli and the anticipatory response before venepuncture in 45 patients receiving diazepam, morphine or no premedication before general anaesthesia. Subjective ratings of anxiety and sedation were measured using visual analogue scales. Skin conductance was less in subjects receiving diazepam than in the other groups, and the pattern of change of skin conductance in this group indicated superior adaptation to the environment during presentation of the innocuous stimuli compared with the other groups. After warning of venepuncture there was a large increase in skin conductance in all groups. There was a significant relationship between anxiety and skin conductance in unpremedicated patients and those receiving diazepam.