Pharmacodynamics of propofol for smooth exchange of tracheal tube for a laryngeal mask airway after surgery in elderly patients / 中华麻醉学杂志

ABSTRACT

Objective To investigate pharmacodynamics of propofol for smooth exchange of tracheal tube for u laryngeal mask airway after surgery in elderly patients. Methods Twenty elderly patients, ASA Ⅰ or Ⅱ, aged 65-70 yr, scheduled for elective laparoscopic cholecystectomy were enrolled in this study. Anesthesia was induced with propofol, atracurium and remifentanil. The patients were mechanically ventilated after the trachea was intubated. Anesthesia was maintained with propofol combined with remifentanil. After surgery, a predetermined propofol concentration was achieved and a steady state maintained for at least 5 min. The target plasma concentration of propofol at which the laryngeal mask airway following tracheal extubation was attempted was determined by Dixon's up-and-down method with 0.5 μg/ml as the step size, The probit model was used to calculate the EC_(50) and EC_(95) and 95% confidence interval (95% CI) of propofol for inhibiting patient's response induced by smooth excharge of tracheal tube. Results The EC50 of propofol to achieve laryngeal mask airway following tracheal extubation was 2.79 μg/ml (95% CI 2.44-3.04 μg/ml) and EC_(50) 3.61 μg/ml (95% CI 3.27-4.78 μg/ml). Conclusion The target plasma concentration of propofol for laryngeal mask airway following tracheal extubation in elderly patients is 3.61 μg/ml.