2010 BC Guide in Determining Fitness to Drive

complex problem solving, andshort-term recall of verbal and spatial information.Sleep monitoring is used to confirm a diagnosis of OSAHS. The preferred test used in diagnosisis nocturnal polysomnography. This test involves monitoring a number of physiologicalfunctions such as brain activity, respiration, heart activity, and oxygenation of the blood while anindividual is sleeping. A diagnosis of sleep apnea is based on the apnea-hypopnea index (AHI),where apnea is defined as a cessation of airflow lasting at least 10 seconds and hypopnea isdefined as a reduction in airflow with a decline in blood oxygen level lasting at least 10 seconds.Generally, an individual is diagnosed with sleep apnea if they have greater than 5apnea/hypopnea episodes per hour of sleep.There are a number of scales used to measure the severity of OSAHS. A scale based on the AHIdescribes the following levels of severity: Mild: 5 to 14 events per hour Moderate: 15 to 30 events per hour Severe: more than 30 events per hour.Although nocturnal polysomnography is considered to be the best test for the diagnosis ofOSAHS, a number of other tests may be used by sleep specialists to assist in evaluation ordiagnosis. Overnight oximetry is similar to polysomnography, but only measures oxygen leveland heart rate. Results from overnight oximetry alone are not considered adequate to diagnoseOSAHS.A number of tests are used to evaluate daytime sleepiness. These include the Maintenance ofWakefulness Test (MWT), the Multiple Sleep Latency Test (MSLT), and the Epworth SleepinessScale (ESS). MWT measures the level of daytime drowsiness based on how long a person canremain awake during the day under controlled conditions. The MSLT is similar to the MWT, butmeasures how long it takes a person to fall asleep when taking daytime naps, rather than howlong they can stay awake. The ESS is a subjective test in which a person is asked to rate on ascale of 1 to 4 the likelihood that they would fall asleep in different situations, such as whenwatching TV, riding in a car, and engaging in conversation.Treatment options for OSAHS include: lifestyle changes such as weight loss, alcohol abstinence, or change in sleep position the use of oral appliances the use of a nasal continuous positive airway pressure (CPAP) device, bariatric surgery (for morbidly obese individuals), and in rare cases, corrective upper airway surgery.CPAP is the most effective treatment, and the only one which has been shown to reduce the riskof motor vehicle crashes. A CPAP machine blows heated, humidified air through a short tube toa mask worn by the individual while sleeping. As the individual breathes, air pressure from theCPAP machine holds the nose, palate, and throat tissues open.342