Sleep Apnoea - A Driving Simulator To Assess The Risk Of Falling Asleep At The W

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Sleep Apnoea - A Driving Simulator To Assess The Risk Of Falling

Asleep At The Wheel

http://www.medicalnewstoday.com/medicalnews.php?newsid=32843

Sleep apnoea can lead to daytime sleepiness, which in turn increases

the risk of road accidents. In an article to be published in

November's ERJ, German researchers show that a driving simulator

could allow easy, objective assessment of the accident risk. They

also confirm the potential road safety benefits of the standard

treatment provided to sleep apnoea sufferers.

Road accidents are now one of the leading causes of death in

developed countries. And, while accusing fingers are rightly being

pointed at speed and alcohol, sleepiness at the wheel also plays a

significant role, which may be seriously underestimated.

Since daytime sleepiness is one of the main signs of sleep apnoea,

sufferers from the condition are thus particularly vulnerable. They

are thought to have an accident rate between two and seven times

higher than that of the general population.

In view of this, doctors are tending increasingly (and in some

countries have an obligation) to make judgements about their apnoeic

patients' safety at the wheel. But how is the risk to be judged

objectively, and with what diagnostic tool? Maritta Orth and her

team, of Bergmannsheil University Hospital in Bochum, Germany,

recommend a driving simulator, such as the C.A.R.® (Computer Aided

Risk Simulator), which was used in the study they publish in

November's ERJ.

Simulator more effective than neuropsychological tests

The German team tested the driving performance of 31 patients with

obstructive sleep apnoea. The simulator placed the subjects in

monotonous driving conditions for 60 minutes at an average virtual

speed of 100 kilometres/hour (62 miles/hour). Various weather

conditions (wind, sunshine, rain, snow, etc.) and a range of

obstacles (such as animals, pedestrians and other vehicles) were

integral to the simulation.

The results obtained by Orth and her colleagues show first of all

that, on average, untreated apnoea sufferers experienced

2.7 " accidents " (collisions with other vehicles or pedestrians,

veering off the carriageway) in such a driving simulation, with a

further 12.4 lapses of concentration. The ERJ study also demonstrates

the ineffectiveness of neuropsychological tests or polysomnographic

tracing to predict increased accident risk. No correlation could be

demonstrated between driving performance and polysomnographic

parameters or neuropsychological test results.

Positive airway pressure's effectiveness confirmed

Most importantly, the German study shows that the usual treatment for

sleep apnoea, namely continuous positive airway pressure (CPAP),

delivered through a mask worn over the nose and mouth at night, can

significantly improve safety behind the wheel.

Orth's team measured apnoeic subjects' driving performance before

treatment and then two and 42 days after the start of treatment.

The results in November's ERJ are unambiguous: not only were

attention and alertness improved after 42 days' treatment, as were

sleepiness scores and polysomnographic traces; but a safer driving

performance could be seen even before the other improvements. The

comparative accident rate fell sharply as soon as treatment began

(2.7 before the start of CPAP, 1.5 after two days and 0.9 at 42

days).

In parallel to these results, the German team emphasises the

qualities of the simulator used in the study, which it found

particularly well suited to this type of investigation.

" The C.A.R.® driving simulator is the best tool for comparing

obstructive sleep apnoea sufferers' driving abilities before and

under CPAP " , the authors state. Its scope appears very broad: already

tested for multiple sclerosis sufferers, it could be used to assess

the road safety implications of many other conditions. It could also

prove useful in evaluating the effect of drug treatments on driving

performance.

Title of original article:

Driving simulator and neuropsychological testing in OSAS before and

under CPAP therapy

EUROPEAN RESPIRATORY JOURNAL (ERJ), Vol. 26, No 5

http://erj.ersjournals.com