Efficient inspired concentration of sevoflurane for vital capacity rapid inhalation induction (VCRII) technique.
OBJECTIVE
To evaluate the efficient inspired concentration of sevoflurane for a vital capacity rapid inhalation induction (VCRII) technique with respect to induction time, characteristics, and acceptability.


METHODS
Prospective study.


METHODS
Medical college hospital.


METHODS
68 unpremedicated healthy adult volunteers were assigned to one of four groups in order of sequential entry of informed consent.


METHODS
3%, 4.5%, 6%, or 7.5% concentrations of sevoflurane were administered for 5 minutes (3% and 4.5%) or 3 minutes (6% and 7.5%) using a single breath technique.


RESULTS
The mean induction time required with 3%, 4.5%, 6%, or 7.5% sevoflurane was 120 +/- 26 sec, 79 +/- 18 sec, 52 +/- 15 sec, or 47 +/- 17 seconds, respectively. Each induction time was significantly different from the others (p < 0.05) except for that between 6% and 7.5%. There appeared to be a direct inverse relationship between the mean induction time and the logarithm of inspired concentration of sevoflurane, but this relationship did not extend beyond concentrations above 6%. Blood pressure decreased by approximately 18% from baseline at the end of inhalation of the drug, and heart rate remained constant in all groups. Except of one subject in the 7.5% group, no coughing was observed and laryngospasm, breath-holding, and secretions were not seen in any subjects. Slight limb movement was observed in a few subjects in each group. All subjects except one in the 3% group would accept undergoing a similar procedure again.


CONCLUSIONS
Sevoflurane 6% can be recommended for VCRII, but increasing the concentration higher than this does not markedly shorten the induction time and thus seems to add little benefit.
Yurino
M
M
Department of Anesthesiology and Resuscitology, Asahikawa Medical College, Hokkaido, Japan.
Kimura
H
H
D000328:Adult; D000769:Anesthesia, Inhalation / Q000009:adverse effects; D004987:Ethers / Q000009:adverse effects / Q000378:metabolism*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008738:Methyl Ethers; D011446:Prospective Studies; D012016:Reference Values; D000077149:Sevoflurane; D016037:Single-Blind Method; D013997:Time Factors
D004987:Ethers; D008738:Methyl Ethers; D000077149:Sevoflurane