Dose Response Curves of Plasma Concentration 50 of Propofol Target-Controlled Infusion for Supraglottic Airway Devices: A Randomized Controlled Trial

Objective: We aimed to determine the plasma concentration 50 (CP50) of propofol target controlled infusion (TCI) for successful insertion of four types of supraglottic airway devices (SGD). Material and Methods: This prospective parallel randomized controlled, double blinded, superiority trial was conducted in June 2012 following approval by the Ethics Committee of the Faculty of Medicine, Prince of Songkla University, Thailand. Effect-site concentrations (Ce) of propofol TCI were determined by the modified Dixon’s up-and-down method. After equilibration was established between the plasma and effect-site concentrations, a SupremeTM, ProSealTM(control groups), I-gelTM or Laryngeal Tube Suction IITM devices were inserted. The CP50 was determined by dose response logistic curves presented as means and 95% confidence intervals (CI). The General Estimating Equation was used to determine factors associated with hemodynamic changes. Results: The Ces of TCI propofol requirements in the SupremeTM, ProSealTM, I-gelTM and Laryngeal Tube Suction IITM groups were 5.8, 4.8, 5.6, and 5.8 μg/ml, respectively (effect size [95% CI]: 0.22 [0.06, 0.51], p-value 0.036). The CP50 [95% CIs] in the SupremeTM, ProSealTM, I-gelTM and Laryngeal Tube Suction IITM groups were 5.8 [-0.01, 11.6], 4.9 [3.3, 6.5], 5.7 [5.0, 6.3] and 5.5 [4.7, 6.4] μg/ml, respectively. Heart rates and systolic blood pressure were significantly higher in the Laryngeal Tube Suction IITM group than in the ProSealTM (p-value<0.01) and I-gelTMgroups (p-value<0.01 Conclusion: The ProSealTM and I-gelTM are preferred over the SupremeTM and Laryngeal Tube Suction IITM devices due to the lower CP50 and hemodynamic changes.