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.
Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi City 371-8511, Japan.
Yoshinori
Y
Kanemaru
Koichi
K
Nishikawa
Fumio
F
Goto
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