D. Schwender et al., MIDLATENCY AUDITORY-EVOKED POTENTIALS AND MOTOR SIGNS OF WAKEFULNESS DURING ANESTHESIA WITH MIDAZOLAM, British Journal of Anaesthesia, 79(1), 1997, pp. 53-58
We have studied midlatency auditory evoked potentials (MLAEP) and moto
r signs of wakefulness during anaesthesia with midazolam in 10 patient
s undergoing elective laparotomy under continuous extradural analgesia
. Anaesthesia was induced with midazolam 0.3 mg kg(-1) and maintained
with midazolam 0.3-0.9 mg kg(-1) h(-1). Motor signs of wakefulness wer
e documented as spontaneous movements and movements after simple comma
nds (open eyes or move arms). MLAEP were recorded continuously awake,
and during anaesthesia until the end of anaesthesia. Latencies of the
peaks V, Na, Pa, Nh and P1 (ms) and amplitudes of the peaks Na/Pa, Pa/
Nb and Nb/P1 (mu V) were measured. Twenty-five movements were observed
during anaesthesia; 15 movements in six patients were in response to
commands. In two patients supplementary isoflurane was given. Latencie
s of the MLAEP peaks Pa, Nb and P1 increased slightly during anaesthes
ia. Amplitudes for Na/Pa, Pa/Nb and Nb/P1 did not change significantly
. The high incidence of motor signs of wakefulness associated with pre
served MLAEP indicated a high level of cortical neural activity and no
ne of the MLAEP variables predicted movement during anaesthesia with m
idazolam.