Driving impairment due to propofol at effect-site concentrations relevant after short propofol-only sedation

Australian guidelines state "Following brief surgery or procedures with short acting anaesthetic drugs, the patient may be fit to drive after a normal night's sleep. After long surgery or procedures requiring longer lasting anaesthesia, it may not be safe to drive for 24 hours or more". The increasing use of the short-acting anaesthetic drug propofol as a solitary sedative medication for simple endoscopy procedures suggests a need to review this blanket policy. Thirty patients presenting for elective day surgery were recruited as volunteers for a pre-procedure driving simulation study and randomised to propofol or placebo arms. Driving ability was assessed at baseline and then, in the propofol group, at three effect-site concentrations. Driving impairment at these concentrations of propofol was compared to that of a third group of volunteers with a blood alcohol concentration of 0.05% (g/100 ml). Driving impairment at 0.2 µg/ml propofol effect-site concentration was not statistically different to placebo. Impairment increased with propofol effect-site concentration (P=0.002) and at 0.4 µg/ml it was similar to that found with a blood alcohol concentration of 50 mg/100 ml (0.05%). Plasma propofol concentrations of 0.2 µg/ml, as might be found approximately an hour after short (<1 hour duration) propofol-only sedation for endoscopy, were not associated with driving impairment in our young cohort of volunteers.