TY - JOUR
T1 - Effects of propofol, etomidate, midazolam, and fentanyl on motor evoked responses to transcranial electrical or magnetic stimulation in humans
AU - Kalkman, C. J.
AU - Drummond, J. C.
AU - Ribberink, A. A.
AU - Patel, P. M.
AU - Sano, T.
AU - Bickford, R. G.
PY - 1992
Y1 - 1992
N2 - The effects of propofol, etomidate, midazolam, and fentanyl on motor evoked responses to transcranial stimulation (tc-MERs) were studied in five healthy human volunteers. Each subject, in four separate sessions, received intravenous bolus doses of propofol 2 mg·kg-1, etomidate 0.3 mg·kg-1, midazolam 0.05 mg·kg-1, and fentanyl 3 μg·kg-1. Electrical tc-MERs (tc(e)-MERs) were elicited with anodal stimuli of 500-700 V. Magnetic tc-MERs (tc(mag)-MERs) were elicited using a Cadwell MES-10 magnetic stimulator at maximum output. Compound muscle action potentials were recorded from the tibialis anterior muscle. Duplicate tc(e)-MERs and tc(mag)-MERs were recorded before and up to 30 min after drug injection. Reproducible baseline tc(e)- MERs (amplitude 4.7 ± 0.43 (SEM) mV, latency 29.4 ± 0.35 ms) and tc(mag)- MERs (amplitude 3.7 ± 0.43 mV, latency 31.1 ± 0.39 ms) were obtained in all subjects. Pronounced depression of tc(e)-MER amplitude to 2% of baseline values (P < 0.01) was observed 2 min after injection of propofol. Thirty minutes after injection of propofol, amplitude depression to 44% of baseline (P < 0.05) was still present, despite an apparent lack of sedation. Midazolam caused significant (P < 0.01) amplitude depression, e.g., tc(mag)-MER to 16% of baseline values 5 min after injection. Significant depression persisted throughout the 30-min study period. Fentanyl did not cause any statistically significant amplitude changes in this small population. Etomidate caused significant but transient depression of tc-MER amplitude. However, there was considerable intersubject variability. Latency did not change significantly after any drug. The magnitude of drug-induced MER changes was similar for magnetic and electrical stimulation, although in two instances, at the peak of drug-induced depression, tc(mag)-MERs were absent when tc(e)-MERs were recordable. Since amplitude depression after etomidate was less pronounced and of shorter duration, etomidate may be preferable to propofol as an induction agent when tc-MER monitoring is indicated. Similarly, fentanyl may be preferable to midazolam as an intravenous supplement.
AB - The effects of propofol, etomidate, midazolam, and fentanyl on motor evoked responses to transcranial stimulation (tc-MERs) were studied in five healthy human volunteers. Each subject, in four separate sessions, received intravenous bolus doses of propofol 2 mg·kg-1, etomidate 0.3 mg·kg-1, midazolam 0.05 mg·kg-1, and fentanyl 3 μg·kg-1. Electrical tc-MERs (tc(e)-MERs) were elicited with anodal stimuli of 500-700 V. Magnetic tc-MERs (tc(mag)-MERs) were elicited using a Cadwell MES-10 magnetic stimulator at maximum output. Compound muscle action potentials were recorded from the tibialis anterior muscle. Duplicate tc(e)-MERs and tc(mag)-MERs were recorded before and up to 30 min after drug injection. Reproducible baseline tc(e)- MERs (amplitude 4.7 ± 0.43 (SEM) mV, latency 29.4 ± 0.35 ms) and tc(mag)- MERs (amplitude 3.7 ± 0.43 mV, latency 31.1 ± 0.39 ms) were obtained in all subjects. Pronounced depression of tc(e)-MER amplitude to 2% of baseline values (P < 0.01) was observed 2 min after injection of propofol. Thirty minutes after injection of propofol, amplitude depression to 44% of baseline (P < 0.05) was still present, despite an apparent lack of sedation. Midazolam caused significant (P < 0.01) amplitude depression, e.g., tc(mag)-MER to 16% of baseline values 5 min after injection. Significant depression persisted throughout the 30-min study period. Fentanyl did not cause any statistically significant amplitude changes in this small population. Etomidate caused significant but transient depression of tc-MER amplitude. However, there was considerable intersubject variability. Latency did not change significantly after any drug. The magnitude of drug-induced MER changes was similar for magnetic and electrical stimulation, although in two instances, at the peak of drug-induced depression, tc(mag)-MERs were absent when tc(e)-MERs were recordable. Since amplitude depression after etomidate was less pronounced and of shorter duration, etomidate may be preferable to propofol as an induction agent when tc-MER monitoring is indicated. Similarly, fentanyl may be preferable to midazolam as an intravenous supplement.
KW - Anesthetics, intravenous: etomidate; fentanyl; propofol; midazolam
KW - Magnetic stimulation
KW - Monitoring, evoked potentials: motor evoked potentials
KW - Transcranial stimulation
UR - http://www.scopus.com/inward/record.url?scp=0026605352&partnerID=8YFLogxK
U2 - 10.1097/00000542-199204000-00003
DO - 10.1097/00000542-199204000-00003
M3 - Article
C2 - 1550274
AN - SCOPUS:0026605352
SN - 0003-3022
VL - 76
SP - 502
EP - 509
JO - Anesthesiology
JF - Anesthesiology
IS - 4
ER -