- • Snoring, or otherwise noisy respiration in
- • Periods of respiratory pauses (apneas) witnessed
by bed partner or parents.
- • Fragmented sleep or complaints of insomnia.
- • Daytime sleepiness and/or fatigue.
- • Personality changes, intellectual deterioration.
- • Depression.
Although the sleep-related breathing disorders (SRBD) have been
recognized only recently, they are among the most common of all
the respiratory disorders. These conditions occur in all age groups
but are seen most frequently in middle-aged men.
Estimates from epidemiological studies suggest that 1–5% of
the general adult population has obstructive sleep apnea syndrome
(OSAS) as defined by evidence of abnormal breathing during sleep
combined with symptoms of daytime sleepiness. Other studies have
demonstrated that 24% of men and 9% of women aged
30–60 years have an elevated apnea–hypopnea index
(AHI) without symptoms.
The impact of mild asymptomatic and often unrecognized obstructive
sleep apnea (OSA) on other conditions such as hypertension and cardiovascular
disease is an area of extensive research. Population studies indicate
a prevalence of sleep-disordered breathing (SDB) in men that is
two to three times greater than in women. The prevalence increases
throughout the adult years at least until about age 65.
Young T et al: Epidemiology of obstructive sleep
apnea. Am J Respir Crit Care Med 2002;165:1217.
The obstructive sleep-related breathing disorders can be viewed
as manifestations of ever-increasing resistance to airflow in the
upper airway. At one end of the continuum is an airway that is always
patent in all stages of sleep, positions, and airway inflammation.
On the other end is an airway that frequently collapses (obstructive
apnea) whenever the patient sleeps. These events can lead to cortical
and autonomic nervous system arousals and oxygen desaturations,
producing cardiovascular effects. Between these extreme end points
a patient may exhibit primary snoring (without evidence of sleep
disruption or airway obstruction), sleep fragmentation associated
with airflow limitation (and usually snoring) and excessive daytime
sleepiness (EDS) but without overt hypopneas or apneas [known
as the upper airway resistance syndrome (UARS)], and sleep-related hypopneas
associated with arousals and desaturations.
Ventilation occurs when air flows down a gradient of pressure
created when the muscles of respiration contract to create negative
intrapleural pressure. The muscles dilating the upper airway are activated
in a phasic manner allowing the airway to remain open during inspiration.
Most patients with sleep apnea appear to have an anatomically narrowed
airway, whose patency is maintained during wakefulness due to increased
upper airway tone. With sleep onset a normal reduction in airway
tone occurs that leaves the upper airway vulnerable to collapse
during inspiration. The episodes can be associated with oxygen desaturations
and cortical and autonomic arousals. Systemic and pulmonary artery
pressures acutely rise and the heart rate increases. These events
lead to sleep fragmentation and patients with OSA tend to have increased
amounts of light Stage 1 sleep and reduced amounts to ...