Analysis of influence factors of pharmacodynamics of propofol with target-controlled infusion during anesthetic recovery period

Objective: To explore the pharmacodynamic (PD) characteristics of propofol during anesthetic recovery period with target-controlled infusion (TCI), and to identify the clinical variables related to the PD parameters. Materials and methods: 20 patients scheduled for otolaryngology surgery were enrolled. After the surgery was finished, target effect site concentration was gradually decreased, blood samples were measured at 7 time points and the differences between the target and measured plasma concentration were compared. Observer's assessment of alertness/sedation (OAA/S) and Narcotrend index (NI) were used as two PD indicators by fitting sigmoid E(max )model. Correlations between PD parameter and clinical variables were evaluated. Results: Performance of the TCI system showed a positive bias at the end of the anesthesia sedation period and a negative bias in the anesthetic recovery period. PD parameters (EC50, r) calculated with OAA/S and NI were significantly different, EC50 of OAA/S was lower than EC50 of NI (1.53 +/- 0.70 vs. 2.16 +/- 0.99 mu g/mL), r of OAA/S was higher than r of NI (57.07 +/- 56.39 vs. 4.35 +/- 4.42). Propofol dosage and hemodynamic parameters were significantly correlated with EC50 (()(OAA/S)), lean body weight and gender were significantly conelated with EC50 ((NI)). Conclusion: NI provided a more stable and adequate assessment of the depth of anesthesia than OAA/S, and the influence factors should be taken into account for precise dosing.