SeminarAdult obstructive sleep apnoea
Introduction
Obstructive sleep apnoea is a common disorder of repetitive pharyngeal collapse during sleep.1 Pharyngeal collapse could be complete (causing apnoea) or partial (causing hypopnoea). Disturbances in gas exchange lead to oxygen desaturation, hypercapnia, and sleep fragmentation, which contribute to the consequences of obstructive sleep apnoea—eg, cardiovascular, metabolic, and neurocognitive effects. Although several treatments exist, they are often either poorly tolerated or only partially alleviate abnormalities. Thus, improvement of patient adherence to existing treatments and development of new treatments (or combinations of treatments) are needed. In view of the obesity pandemic, the propensity for pharyngeal collapse and therefore the number of cases of obstructive sleep apnoea are likely to rise.
The landmark study investigating the prevalence of obstructive sleep apnoea was the 1993 Wisconsin Sleep Cohort Study.2 This study reported that the prevalence of obstructive sleep apnoea—defined as more than five apnoeas or hypopnoeas per h of sleep plus excessive daytime sleepiness—was 4% in middle-aged men and 2% in middle-aged women (age 30–60 years). Subsequent studies suggest that prevalence in high-income countries is higher than previously reported (10% in women and 20% in men),3, 4 perhaps a result of worsening obesity and improving technology over time.5 Obstructive sleep apnoea is a global health problem; Brazil and several Asian countries have the same, if not higher, prevalence as the USA and Europe, despite less overall obesity.6, 7
Section snippets
Diagnosis and definitions
Patients with obstructive sleep apnoea report snoring, witnessed apnoeas, waking up with a choking sensation, and excessive sleepiness.1 Other common symptoms are non-restorative sleep, difficulty initiating or maintaining sleep, fatigue or tiredness, and morning headache.8 Indicators include a family history of the disease or physical attributes suggestive of obstructive sleep apnoea—eg, a small oropharyngeal airway or markers of obesity (eg, large neck circumference).9
The best test for
Pathophysiology and risk factors
Traditionally, obstructive sleep apnoea was considered to be primarily a problem of upper airway anatomy, where craniofacial structure or body fat decreased the size of the pharyngeal airway lumen, leading to an increased likelihood of pharyngeal collapse.21 During wakefulness, the airway is held open by the high activity of the numerous upper airway dilator muscles, but after the onset of sleep, when muscle activity is reduced, the airway collapses.22, 23 Although this sequence probably occurs
Consequences
Randomised trials have shown that obstructive sleep apnoea causes sleepiness based on significant improvements in symptoms with continuous positive airway pressure compared with controls.63 People with obstructive sleep apnoea are more likely to have motor vehicle accidents (perhaps up to seven-times as many as those without the disease64). This risk might be mitigated, at least in part, by treatment.65 Obstructive sleep apnoea also affects quality of life and different aspects of health
Management
Nasal continuous positive airway pressure is the treatment of choice for adults with obstructive sleep apnoea.98 It was first reported as an effective means of preventing collapse of the pharyngeal airway in 1981.99 The mechanism of continuous positive airway pressure is debated, but probably involves maintenance of a positive pharyngeal transmural pressure so that the intraluminal pressure exceeds the surrounding pressure.33 Continuous positive airway pressure also increases end-expiratory
Prevention
Although many risk factors for obstructive sleep apnoea are fixed, weight loss (though diet and exercise), and avoidance of cigarettes, alcohol, and other myorelaxant drugs can be beneficial.5, 86 Results of a randomised controlled trial5, 86 show that a 10 kg reduction in bodyweight can yield a reduction in apnoea–hypopnoea index of roughly five events per h. Obstructive sleep apnoea resolved in 63% of patients with mild disease, whereas only 13% of patients with severe obstructive sleep
Future directions
Future treatments for obstructive sleep apnoea are likely to be targeted to the cause of disease since the disease occurs for different reasons in different patients (figure 3). For patients with a low arousal threshold, sedatives or hypnotics might be useful, whereas for patients with unstable ventilatory control, oxygen or acetazolamide might improve obstructive sleep apnoea.28 Palate surgery will probably help patients with anatomical problems at the level of the velopharynx.141 For patients
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Adverse events associated with device assisted hyoid and tongue base suspension for obstructive sleep apnea
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2024, The Lancet Regional Health - Western PacificChronic intermittent hypoxia attenuates noradrenergic innervation of hypoglossal motor nucleus
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