Sleep apnoea symptoms
Obstructive sleep apnoea/hypopnoea syndrome
The obstructive sleep apnoea syndrome is a condition in which unwanted daytime sleepiness results from recurrent episodes of upper airway obstruction during sleep. Obstructive sleep apnoea is present when the patient has had more than 5 episodes of apnoea per hour that each last at least 10 seconds (i.e. an apnoea hypopnoea index (AHI) of more than 5).
The prevalence of obstructive sleep apnoea is critically dependent on the disease definition, age, sex and body mass index (BMI) of the population studied. In a US-based population study, using an AHI of 5 or more, the obstructive sleep apnoea/hypopnoea syndrome was estimated to be present in 24% of men (24 000 per 100 000) and 9% of women (9 000 per 100 000). Using the stricter criteria of AHI 5 or more and daytime sleepiness, more recent epidemiological studies estimate the prevalence to be approximately 4% (4000 per 100 000) in men and 2% (2000 per 100 000) in women.
In susceptible individuals, complete or partial collapse of the pharyngeal airway brings about apnoea or hypopnoea during sleep. Consequently, oxygen saturation drops and arousal occurs briefly, allowing a few deep breaths to be taken. Sleep is resumed and the cycle repeats (up to 60 to 100 times an hour). The patient may awake feeling unrefreshed and suffer with daytime somnolence.
The primary defect is a small and collapsible airway; contributing factors include a small jaw, large tonsils and increased soft tissues of the oropharynx (obesity). Population risk factors for this condition are increasing age, male sex and obesity.
Scope of disease
Obstructive sleep apnoea syndrome is a relatively new diagnosis, and morbidity related to this disease is still being studied. Epidemiological studies have reported a causal relationship between obstructive sleep apnoea and hypertension; current studies are evaluating the benefits of treatment on hypertension. Other complications are impaired cognitive function, altered mood and personality, ventilatory failure and an increased risk of road traffic accidents.
The cardinal symptoms are excessive daytime somnolence, snoring and mood changes. Additional symptoms that may be noticed by the partner are apnoea, choking during sleep and poor concentration. Less common features are nocturia and erectile dysfunction.
On examination the patient is often obese (BMI >30 kg/m2) with a small mandible, crowded oropharynx, hypertension and a large neck size (more than 42 cm). Nasal patency and the size of the tongue and uvula should be assessed.
Clinical assessment should also include the Epworth score to quantify the severity of daytime somnolence . Patients should also be screened for coexisting diseases such as COPD, hypothyroidism, Marfan's syndrome and acromegaly.
No initial investigations are required to diagnose obstructive sleep apnoea.
Sleep studies are indicated for unwanted daytime somnolence (Epworth Score greater than 10), snoring associated with hypertension or cardiovascular disease, or when uvulopalatoplasty is considered for snoring.
The patient is attached to pulse oximetry and abdomen and ribcage movement monitors as well as airflow monitors (through the nose and mouth). If there is doubt as to the diagnosis of obstructive sleep apnoea, or if narcolepsy or restless legs syndrome is being considered, full polysomnography is performed. During sleep, an EEG is also recorded, and the pattern of rapid eye movements (REM) may suggest narcolepsy or periodic leg movement syndrome (arousals in association with limb movement).
Currently weight loss is the only intervention strategy associated with improved outcome. Other measures include avoiding alcohol at night, elevation of the foot of the bed, and positional therapy to stop the patient lying on his or her back (e.g. a tennis ball sewn into the pyjama jacket).
Nasal continuous positive airway pressure ventilation (CPAP)
The indications for CPAP are an apnoea - hypopnoea index (AHI) > 15 events/hour accompanied by excessive daytime sleepiness, impaired cognition, mood disorders, insomnia or documented cardiovascular disease (including hypertension, ischaemic heart disease and stroke).
A CPAP mask is worn over the nose (or nose and mouth) and a ventilator blows air continuously at a fixed pressure (usually around 10 cm of water). This keeps the airway open during sleep and prevents desaturation and arousal. Problems with CPAP include nasal bridge pressure sores, claustrophobia, nasal congestion, sneezing and disrupted sleep. Many adjustments are usually required to optimize treatment (minimize air leaks), and it may be some time before patients and their carers are able to cope and use it successfully.
Mandibular advancement splints
A mandibular advancement splint is an option for patients with mild obstructive sleep apnoea or those intolerant of CPAP (it is not as effective as CPAP for patients with severe disease). The splint is a personalized device made by an orthodontist which pulls the mandible forward, keeping the airway open during sleep.
Uvulopalatopharyngoplasty may be an option for highly selected patients; at present results are no better than with the use of a mandibular splint. Laser uvulopalatoplasty reduced the level of snoring in mild obstructive sleep apnoea, but improvements to the apnoea hypopnoea index and symptoms are minor compared to no treatment
Tracheostomy is seldom required, and is used only as a last resort in the treatment of obstructive sleep apnoea.
Patients are expected to have a normal life expectancy, currently treatment aims are intended to minimize behavioural and cardiovascular morbidity.
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