Brain tumors may alter the relationship between bispectral index values and propofol concentrations during induction of anesthesia.
OBJECTIVE
To compare propofol-predicted effect-site concentrations (PropCe) and bispectral index (BIS) of the electroencephalogram during induction of anesthesia in patients with small brain tumors and to analyze BIS and PropCe at loss of consciousness (LOC).


METHODS
Prospective investigation.


METHODS
Operating theater of a university hospital.


METHODS
26 ASA physical status I and II patients, 13 of whom were scheduled for nontumor spinal surgeries, and the other 13, for brain surgery for small brain tumor removal.


METHODS
Anesthesia was induced with a propofol 1% constant infusion rate of 200 mL/h until LOC.


METHODS
BIS, PropCe, heart rate, and mean arterial pressure were analyzed at the beginning of the propofol infusion and every 30 seconds during induction.


RESULTS
The BIS values were significantly higher in patients with brain tumors in the period from 150 to 210 seconds, with PropCe similar to patients without brain tumors. Loss of consciousness occurred 3.6 +/- 0.8 minutes in patients without brain tumors and 3.9 +/- 0.7 minutes in patients with brain tumors. No differences were observed between groups in the time to LOC (3.6 +/- 0.8 in group 1 vs 3.9 +/- 0.7 in group 2) or in BIS at LOC (48.7 +/- 11.4 in group 1 vs 58.6 +/- 21.7 in group 2).


CONCLUSIONS
For similar propofol concentrations, patients with small brain tumors show higher BIS values on induction of anesthesia with propofol.
Ferreira
David A
DA
CECAV, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal. davidor@utad.pt
Nunes
Catarina S
CS
Lobo
Francisco
F
Casal
Manuela
M
Antunes
Luís M
LM
Amorim
Pedro
P
D000328:Adult; D000704:Analysis of Variance; D000768:Anesthesia, General; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D001932:Brain Neoplasms / Q000503:physiopathology*; D003243:Consciousness / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D004576:Electromyography / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage*; D011446:Prospective Studies; D013997:Time Factors
D018686:Anesthetics, Intravenous; D015742:Propofol