Bispectral analysis of the electroencephalogram during induction of anesthesia may predict hemodynamic responses to laryngoscopy and intubation.
The use of electroencephalography as a measure of adequacy of anesthesia has achieved limited success. Our purpose was to determine whether the non-linear properties of the electroencephalogram (EEG) as defined by the bispectral index was a better predictor of autonomic responses to endotracheal intubation during opioid-based anesthesia than the linear statistical properties of the EEG formulated by power spectral analysis. Thirty-nine adults scheduled for elective non-cranial surgery had a continuous EEG recorded during induction of anesthesia and endotracheal intubation. Anesthesia consisted of thiopental and nitrous oxide in oxygen, followed by 1 of 5 randomized opioid dose regimens. The EEG was continuously recorded and blood pressure was measured every minute. All electroencephalographic parameters were derived for the 3 min before and after intubation and were compared to the blood pressure and heart rate responses. Responders were defined by 2 analyses: patients who had a 20% or greater increase (1) in blood pressure or (2) in heart rate to laryngoscopy. Responders and non-responders were compared using Student's unpaired t test, and differences due to dose regimens were examined with logistic regression. Based on the criterion for blood pressure change, there were 27 responders and 12 non-responders. Heart rate changes did not differentiate between the two groups. There was a significant difference between response groups as measured by the bispectral index which distinguished responders from non-responders independently of the amount of drug given. None of the variables of power spectral analysis accurately distinguished responder from non-responder.(ABSTRACT TRUNCATED AT 250 WORDS)
Kearse
L A
LA
Department of Anesthesia and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Manberg
P
P
DeBros
F
F
Chamoun
N
N
Sinai
V
V
D000328:Adult; D000768:Anesthesia, General; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007442:Intubation, Intratracheal; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted