Determination of the median effective concentration (EC50) of propofol during oesophagogastroduodenoscopy in children

Background: Propofol is commonly used to provide anaesthesia for children undergoing oesophagogastroduodenoscopy (OGD). Despite this, the plasma concentration–response relationships for propofol used in this setting have not been established. Methods: In order to determine the EC50 of propofol during OGD, we studied 12 children aged 3–10 years. No premedication was given. Propofol was administered via a target‐controlled infusion system using the STANPUMP software based on a paediatric pharmacokinetic model. The ‘up‐and‐down’ method described by Dixon was used to determine the EC50. Accordingly, the target plasma propofol concentration for each patient, beginning with the second subject, was determined by the response of the previous patient. A patient was considered a ‘responder’ if there was minimal movement and the heart rate (HR) and blood pressure (BP) remained ≤ 120% of baseline during the procedure. Patients who moved excessively, i.e. requiring more than gentle restraint, or who manifest HR and BP >120% of baseline, were considered ‘nonresponders’. Results: The EC50 of propofol during OGD was 3.55 μg·ml–1 in this study. Conclusions: The plasma propofol concentration associated with adequate anaesthesia for OGD in 50% of unpremedicated children is 3.55 μg·ml–1. This concentration is higher than that required for OGD in adult patients.