Depth of sedation induced by target-controlled infusion of propofol required to inhibit swallowing reflex

Abstract

Objective To determine the depth of sedation induced by target-controlled infusion (TCI) of propofol required to inhibit the swallowing reflex.Methods Thirty-five ASA Ⅰ or Ⅱ healthy volunteers,aged 20-60 yr,with body mass index ＜ 30 kg/m2,were enrolled in the study.Sedation was performed with TCI of propofol.The initial target plasma concentration (Cp) of propofol was set at 2.4 μg/ml and the Cp increased or decreased by 0.2 μg/ml every 5 min until the BIS value reached the predetermined level.The initial Cp of propofol was increased or decreased by 0.3 μg/ml in the next subject according to the BIS value in the previous one.The up-and-down sequential experiment was pedormed.The BIS value was set at 65 in the first subject and the ratio of the BIS value between the two consecutive subjects was 1.1.The BIS value was increased or decreased depending on the occurrence of the swallowing reflex in the previous subject.The half-effective BIS value (BIS50) and 95％confidence interval (CI) of propofol inhibiting the swallowing reflex were calculated by up-and-down sequential method.Results The BIS50 of propofol required to inhibit the swallowing reflex was 64.4 (95％ CI 59.3-69.8).Conclusion The BIS50 and 95％ CI of propofol administered by TCI and required to inhibit the swallowing reflex is 64,4 (59.3-69.8). Key words: Propofol; Conscious sedation; Deglutition; Drug delivery systems