Determination of the median effective dose of propofol in combination with different doses of ketamine during gastro-duodenoscopy in children: a randomised controlled trial

Background Propofol is used to induce deep sedation or general anaesthesia for procedures in children. Adjuvants, such as ketamine, are routinely added to reduce the dose of propofol required and propofol-related adverse events. We conducted a randomised controlled trial to determine the effective bolus dose of propofol in combination with ketamine that induces adequate depth of anaesthesia in 50% of children (ED 50 ) undergoing gastro-duodenoscopy. Methods Children were randomised to one of four doses of ketamine: 0 (control), 0.25, 0.5, and 1 mg kg −1 , followed by a dose of propofol according to Dixon's up-and-down methodology. Excessive movement, coughing, gagging, or airway obstruction that prevented endoscope insertion was considered a failure. Results The ED 50 of propofol (median, 95% CI) was greater in the ketamine 0, 0.25, and 0.5 mg kg −1 groups compared with the ketamine 1 mg kg −1 group (6.1, 4.1–8.1; 4.5, 2.9–6; 4.7, 3.1–6.2 mg kg −1 vs 1.1, 0.5–1.8 mg kg −1 , respectively, P −1 . The mean arterial pressure was lower in the ketamine 0 mg kg −1 group compared with the 1 mg kg −1 group during and immediately after the procedure. The ketamine 1 mg kg −1 group experienced a higher incidence of nausea and visual disturbances. Conclusions Ketamine at 0.5–1 mg kg –1 reduces the dose of propofol required to provide general anaesthesia for gastro-duodenoscopy in children and may reduce the incidence of propofol-related changes in haemodynamics. Clinical trial registration NCT 02295553.