Driving ability in sleep apnoea patients before and after CPAP treatment: evaluation on a road safety platform

Sleepiness is considered to be the major cause of increased traffic accidents in patients with obstructive sleep apnoea syndrome (OSAS). Until now, OSAS patients' driving ability has been assessed using driving simulators, but no assessment in a more natural driving environment has been carried out to date. The aim of the present study was to evaluate driving parameters in OSAS and in controls on a road safety platform, and to compare them with attentional in-laboratory measures before and after continuous positive airway pressure treatment. The parameters measured were: reaction time; distance to stop and number of collisions on the platform; maintenance of wakefulness; and sustained, selective and divided attention in laboratory. Patients exhibited much longer reaction times than controls, leading to a lengthening of the vehicle's stopping distance of 8.8 m at 40 km.h(-1) and to twice the number of collisions. Patients did not demonstrate objective sleepiness or selective and sustained attention deficits. Divided attention deficits were found. However, they did not allow the prediction of real driving impairment. After CPAP treatment, there was no longer any difference between patients and controls regarding driving and attention performances. Driving abilities are significantly impaired in obstructive sleep apnoea syndrome. After continuous positive airway pressure treatment, deficits were normalised. This stresses the importance of evaluating attentional parameters in apnoeic patients and of offering continuous positive airway pressure treatment even to non-sleepy subjects.