Short-term inhalation of sevoflurane during induction of general anesthesia can inhibit the A-line ARX index response to intubation: a randomized trial.

Background: Monitoring hypnotic depth is used to prevent awareness during general anesthesia. We used the A-line ARX index (AAI) to assess the effect of shortterm inhalation of sevoflurane in the prevention of intubation-induced inadequate hypnotic depth during anesthetic induction.

Methods: Thirty patients were randomly divided into the sevoflurane and non-sevoflurane groups, both of which were given 3 μg kg⁻¹ fentanyl, 4 mg kg⁻¹ thiamylal, and 0.2 mg kg⁻¹ cis-atracurium intravenously to induce general anesthesia. The sevoflurane group then inhaled 6% sevoflurane and 4 L/min O₂ for 3 minutes, whereas the non-sevoflurane group was given 4 L/min O₂ alone. Both groups were intubated 3 minutes after induction. Measurements of the AAI, non-invasive blood pressure, and heart rate were performed every minute, starting 3 minutes prior to induction until 9 minutes after intubation.

Results: Intubation induced a significant AAI elevation in the non-sevoflurane group (47.13 ± 20.88, 48.13 ± 20.05, 40.87 ± 15.86 and 31.27 ± 15.26 at 1, 2, 3 and 4 minutes after intubation, respectively, vs. 17.67 ± 6.44 at 3 minutes after induction; p < 0.05), whereas the AAI remained unchanged for the sevoflurane group following intubation. Moreover, the non-sevoflurane group demonstrated higher AAI values after intubation compared with the sevoflurane group. There were no significant differences in blood pressure and heart rate between the two groups throughout the study.

Conclusion: Adding 6% sevoflurane with 4 L/min O₂ for 3 minutes during the induction period prevented inadequate hypnotic depth caused by intubation but was not sufficient to inhibit fluctuations in hemodynamics.