Alfentanil used to supplement propofol infusions for oesophagoscopy and bronchoscopy

46 patients undergoing rigid oesophagoscopy and (or) bronchoscopy

Alfentanil 10 micrograms/kg just before rapid sequence induction with propofol, followed by suxamethonium 1 mg/kg and infusions of suxamethonium 10 mg/minute and propofol (10 mg/kg/hour for 10 minutes, 8 mg/kg/hour for 10 minutes and then 6 mg/kg/hour thereafter)

Saline just before rapid sequence induction with propofol, followed by the same suxamethonium and propofol infusions

Cardiovascular stability (arterial pressure and heart rate) and rate of recovery (assessed using critical flicker fusion threshold)surrogate