Pre-oxygenation enhances induction with sevoflurane as assessed using bispectral index monitoring.
BACKGROUND
Several methods may enhance the inhalational induction of anesthesia. In this randomized double-blind study, we evaluated the speed of induction of anesthesia with sevoflurane with or without pre-oxygenation.


METHODS
Fifty-four patients scheduled for hysteroscopy received for 10 min air or 100% oxygen via a facemask followed by > or = 7% sevoflurane in 100% oxygen. During the first 300 s of sevoflurane administration, bispectral index (BIS) values were recorded every 30 s in all patients. In 14 patients, seven in each group, BIS, endtidal CO(2), tidal volume, respiratory rate, SpO(2), and heart rate were recorded every minute during the pre-induction period and every 30 s during the first 5 min of sevoflurane administration.


RESULTS
The BIS, endtidal CO(2), tidal volume and respiratory rate did not differ between the oxygen or air breathing groups (P = 0.696, P = 0.999, P = 0.388, and P = 0.875, respectively), though the oxygen group exhibited lower tidal volumes by 16-20%. The SpO(2) and heart rates were higher in the oxygen breathing group (P < 0.001 and P = 0.042, respectively). During sevoflurane administration, BIS values were lower in the oxygen group vs. the group breathing air, in particular at 90, 120, 150, 180 and 210 s (P = 0.001, P = 0.001, P = 0.001, P = 0.001 and P = 0.030, respectively). The endtidal CO(2) and the tidal volumes between the groups did not differ. The two groups differed in the SpO(2) and the heart rates during induction (P = 0.004 and 0.003, respectively).


CONCLUSIONS
Before sevoflurane administration, breathing 100% oxygen for 10 min enhances induction of anesthesia with sevoflurane.
Fassoulaki
A
A
Department of Anesthesiology, Aretaieio Hospital, Medical School, University of Athens, Athens, Greece. fassoula@aretaieio.uoa.gr
Petropoulos
G
G
Kottis
G
G
Sarantopoulos
C
C
D000759:Adjuvants, Anesthesia / Q000008:administration & dosage*; D000328:Adult; D018685:Anesthetics, Inhalation; D004311:Double-Blind Method; D004569:Electroencephalography; D005260:Female; D006801:Humans; D015907:Hysteroscopy; D008738:Methyl Ethers; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000008:administration & dosage*; D000077149:Sevoflurane; D013990:Tidal Volume
D000759:Adjuvants, Anesthesia; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D010100:Oxygen