• George D Politis, Christopher J Stemland, Ravi K Balireddy, Julie Brockhaus, Kevin R Hughes, Matthew D Goins, and Timothy L McMurry.
• Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA 22908, USA. Electronic address: gdp8a@virginia.edu.
• J Clin Anesth. 2014 Feb 1;26(1):25-35.

Study ObjectiveTo determine, for two different age groups, the effect of duration of sevoflurane administration on the amount of propofol needed when performing tracheal intubation.DesignClassic Dixon's Up-and-Down sequential method.SettingUniversity based operating rooms.Patients106 ASA physical status 1 and 2 patients aged one to 11 years.InterventionsPatients were allocated to the 1-6 year (≥ 12 and < 72 mos) and 6-11 year (≥ 72 and < 132 mos) age groups. Midazolam 0.5 mg/kg was given orally to the 1-6 year group, and all patients were induced with 8% dialed sevoflurane and 67% nitrous oxide (N2O), with N2O discontinued and sevoflurane dialed to 5% after one minute and 1.5 minutes for the younger and older age groups, respectively. Intravenous access was obtained and propofol was promptly administered. Propofol dose was determined according to age group and whether propofol was given 2-4, 4-6, or 6-8 minutes after the start of sevoflurane induction, with Dixon's Up and Down Method used separately for each specific age/time group. Tracheal intubation conditions one minute after propofol were evaluated.MeasurementsIsotonic regression determined propofol ED50 estimates for excellent tracheal intubation conditions, and linear regression determined the effect of propofol dose on change in systolic blood pressure (SBP).Main ResultsEstimated propofol ED50 doses for 1-6 year olds, with 95% confidence intervals (CIs), were 1.48 mg/kg (0.80, 2.03), 0.00 mg/kg (0.00, 0.38), and 0.07 mg/kg (0.00, 0.68) in the 2-4, 4-6, and 6-8 minute groups, respectively, with estimated differences between the 2-4 minute group versus the 4-6 and 6-8 minute groups being 1.47 mg/kg (95% CI = 1.04, 2.06) and 1.41 mg/kg (95% CI = 0.74, 2.04), respectively. Estimated propofol ED50 doses for 6-11 year olds, with 95% CIs, were 2.35 mg/kg (1.97, 2.45) and 2.33 mg/kg (1.59, 2.45) in the 2-4 and 4-6 minute groups, respectively. Diminutions in SBP at one minute and two minutes after propofol administration were dose dependent for children 1-6 years of age, decreasing 5.3% and 8.1% for each 1 mg/kg of propofol, respectively.ConclusionThe amount of propofol needed to supplement sevoflurane in children 1-6 years of age can be expected to decrease after 4 minutes of sevoflurane.Copyright © 2014 Elsevier Inc. All rights reserved.

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