Hyperventilation accelerates rise in arterial blood concentrations of sevoflurane in gynecologic patients.

PURPOSE

We investigated whether ventilation volumes affected arterial blood sevoflurane concentration (A (sev)) and its uptake into the body during general anesthesia.

METHODS

Thirty female patients undergoing elective gynecologic surgery were randomly allocated into three groups: hyperventilation, normal ventilation, and hypoventilation. Inspiratory (CI(sev)) and end-tidal ((sev)) sevoflurane concentrations were routinely measured by infrared analysis, and A (sev) were analyzed by gas chromatography for 40 min after intubation. Cardiac index and total peripheral vascular resistance were measured with a Finometer.

RESULTS

During the first 10 min after sevoflurane administration, A (sev) in the hyperventilation group was the highest and differed significantly from those in the normal ventilation group, followed by those in the hypoventilation group. In addition, hyperventilation significantly increased the slope of A (sev) over time in the first 5 min, but there were no differences in slopes in the 5-10, 10-20, and 20-40 min periods, which indicates no difference in sevoflurane bodily uptake among the three groups after 5 min.

CONCLUSION

Hyperventilation accelerated the rate of A (sev) increase immediately after sevoflurane administration, which was time dependent with respect to different alveolar ventilation levels.