[The electroencephalogram and somatosensory evoked potentials following intravenous administration of 0.5 mg/Kg ketamine].
Because of its analgesic potency without affecting consciousness, low-dose ketamine (0.5 mg/kg) has been advocated for traumatized patients in order to ensure the possibility of neurological assessment. This study describes the effects of 0.5 mg/kg ketamine on spontaneous and evoked brain electrical activity.


METHODS
Nine unpremedicated, healthy volunteers aged 22-35 years and free of CNS-active drugs took part in the study. The EEG was recorded from C3P3, C4P4, and vertex versus linked earlobes (Cz/A1-A2) (bandpass: 1-45 Hz). For artefact control the electro-oculogram (EOG) was recorded from supra- and infraorbital electrodes with the same filter settings. EEG and EOG were stored on magnetic tape and were digitized off-line (sampling rate: 100/s) followed by Fourier transformation (epoch-length: 5.2 s). Somatosensory evoked potentials (SEP) were elicited by constant current pulses at the median nerve near the wrist. Recording sites were at the cervical spine (Cv6), the ipsi- and contralateral somatosensory projection area, and the vertex (Cz) vs a frontal reference (Fz). Bandpass: 10-2000 Hz, stimulation frequency: 4 Hz, twofold motor threshold, analysis time: 100 ms. Electrocardiogram, blood pressure, and arterial oxygen saturation (pulse oximeter) were monitored continuously. After an adaptation session of 30-45 min, 0.5 mg ketamine was administered intravenously. EEG and SEP were recorded for the following 45-60 min. Data were subjected to analysis of variance (ANOVA) and Scheffé-test if appropriate (P less than or equal to 0.05).


RESULTS
All subjects lost consciousness within 45-110 s (mean: 70 s) after administration of ketamine. Mean blood pressure levels increased by about 20% and heart rate by about 10% after 5-10 min.(ABSTRACT TRUNCATED AT 250 WORDS)
Kochs
E
E
Abteilung für Anaesthesiologie, Universität-Krankenhaus Eppendorf, Hamburg.
Blanc
I
I
Werner
C
C
Schulte am Esch
J
J
D000328:Adult; D001921:Brain / Q000187:drug effects*; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D005260:Female; D006801:Humans; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male
D007649:Ketamine
Elektroenzephalogramm und somatosensorisch evozierte Potentiale nach intravenöser Gabe von 0.5 mg/kg Ketamin.