Bispectral index and regional cerebral oxygen saturation during propofol/N2O anesthesia.
OBJECTIVE
A study was undertaken to compare the influence of midazolam, isoflurane, and aminophylline (which may antagonize anesthetic action) on bispectral index (BIS) and regional cerebral oxygen saturation (rSO(2)) during propofol/N(2)O anesthesia, and to test the hypothesis that the drug-induced changes in BIS values are accompanied by a change in rSO(2).


METHODS
General anesthesia was administered to 36 patients with a continuous infusion of propofol to maintain a BIS value of 40 +/- 5. After baseline recordings, patients were randomly assigned to receive either midazolam, isoflurane, or aminophylline. Bispectral index values, rSO(2) using near-infrared spectroscopy, and hemodynamic parameters were recorded for 60 min.


RESULTS
Midazolam (0.05 mg x kg(-1)) significantly decreased the BIS from 47.8 +/- 5.4 to 35.0 +/- 4.5 at five minutes after injection (P < 0.001 vs control) during propofol anesthesia, whereas the rSO(2) was unchanged. Similarly, isoflurane (1.1% end-tidal) decreased the BIS from 42.5 +/- 7.5 to 27.8 +/- 6.9 (P < 0.001) without affecting rSO(2). In contrast, aminophylline (3 mg.kg(-1)) was associated with an increase in BIS from 41.6 +/- 2.1 to 48.3 +/- 9.2 at five minutes after injection (P < 0.05) without affecting rSO(2).


CONCLUSIONS
Midazolam or isoflurane-induced decreases in the BIS during propofol anesthesia were not accompanied by a decrease in rSO(2). Aminophylline significantly increased the BIS score during propofol anesthesia, suggesting that aminophylline can antagonize, at least in part, the sedative actions of propofol.
Kanemaru
Yoshinori
Y
Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi City 371-8511, Japan.
Nishikawa
Koichi
K
Goto
Fumio
F
D000328:Adult; D000368:Aged; D000628:Aminophylline / Q000494:pharmacology; D000704:Analysis of Variance; D000768:Anesthesia, General / Q000379:methods; D018685:Anesthetics, Inhalation / Q000097:blood / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000097:blood / Q000494:pharmacology; D001993:Bronchodilator Agents / Q000494:pharmacology; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004569:Electroencephalography / Q000187:drug effects* / Q000379:methods*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D008874:Midazolam / Q000494:pharmacology; D008875:Middle Aged; D009609:Nitrous Oxide / Q000097:blood / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood*; D015742:Propofol / Q000097:blood / Q000494:pharmacology*; D013997:Time Factors
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D001993:Bronchodilator Agents; D000628:Aminophylline; D007530:Isoflurane; D009609:Nitrous Oxide; D008874:Midazolam; D010100:Oxygen; D015742:Propofol