Laurie Tay, aged 52 years presents to your general practice complaining of fatigue. Recently he has fallen asleep at work during a meeting and was embarrassed. He states that he feels he needs to lie down most afternoons to have a rest if possible. A few days ago he fell asleep at the traffic lights and was beeped at by cars. You know doesn't smoke and is happily married and works as an account manager in a major bank. However, his weight has increased over the past few years and he is now obese with a body mass index of 32.
Excessive daytime sleepiness is the principal symptom and snoring is virtually universal. The patient usually feels that he or she has been asleep all night but wakes unrefreshed. Bed partners report loud snoring in all body positions and will often have noticed multiple breathing pauses (apnoeas). Difficulty with concentration, impaired cognitive function and work performance, memory loss, depression, irritability, impotence and nocturia are other features. In examination, look for associated clinical features of obesity, hypertension and heart failure.
Provided that the sleepiness does not result from inadequate time in bed or from shift work etc., any person who repeatedly falls asleep during the day when not in bed, who complains that his or her work is impaired by sleepiness, or who is a habitual snorer with multiple witnessed apnoeas should be referred to a sleep or respiratory specialist.
Epworth Sleepiness Scale:
A more quantitative assessment of daytime sleepiness can be obtained by questionnaire.
Overnight studies:
Overnight studies of breathing, oxygenation and sleep quality (polysomnography) are diagnostic but the level of complexity of investigations will vary depending on the probability of diagnosis, differential diagnosis and resources. The current threshold for diagnosing the sleep apnoea/hypopnoea syndrome is 15 apnoeas/hypopnoeas per hour of sleep, where an apnoea is a 10-second or longer breathing pause and a hypopnoea a 10-second or longer 50% reduction in breathing.
Excessive daytime sleepiness is the principal symptom and snoring is virtually universal. Difficulty with concentration, impaired cognitive function and work performance, depression, irritability and nocturia are other features.
2-4% of the middle-aged population suffer from recurrent upper airway obstruction during sleep. Due to the daytime sleepiness, especially in monotonous situations, this results in a threefold increased risk of road traffic accidents and a ninefold increased risk of single-vehicle accidents.
How likely are you to doze off or fall asleep in the situations described below? Use the following scale to choose the most appropriate number for each situation:
Situations:
Normal subjects average 5.9 (SD 2.2) and patients with severe obstructive sleep apnoea average 16.0 (SD 4.4)
Narcolepsy is a rare cause of sleepiness, occurring in 0.05% of the population, and is associated with cataplexy (when muscle tone is lost in fully conscious people in response to emotional triggers), hypnagogic hallucinations (hallucinations at sleep onset) and sleep paralysis. Idiopathic hypersomnolence occurs in younger individuals and is characterised by long nocturnal sleeps.
Lack of sleep:
Sleep disruption:
Sleepiness with relatively normal sleep:
Psychological/psychiatric:
Overnight oxygen saturation trace helps in both diagnosing and managing sleep apnoea syndrome. In a typical example, the baseline night shows the trace of a patient during a night when he slept without CPAP and had 53 apnoeas plus hypopnoeas/hour and marked oxygen desaturation. The subsequent night when he slept with a CPAP of 10 cm H₂O delivered through a tight-fitting nasal mask abolished his breathing irregularity and awakenings and improved his oxygenation.