What is Sleep Apnoea?

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By Dr Simon Kyle

'Sleep apnoea', or 'sleep apnea', is a general term covering three distinct conditions: 'Obstructive sleep apnoea' (OSA), 'Central sleep apnoea' (CSA) and 'Complex' or 'Mixed' sleep apnoea.

Intermittent or mild bouts of sleep apnoea may occur during periods of illness, for example as a result of a throat infection, and tend not to require treatment. However, forms of long-term or severe sleep apnoea can result in dangerously low levels of blood oxygen and therefore require prompt medical attention.

Obstructive sleep apnoea is…
OSA is the most commonly diagnosed form of sleep apnoea, being characterized by things such as restlessness during sleep, snoring and sleepiness during the daytime amongst other, less common symptoms.

Snoring – the vibration of respiratory structures due to obstructed air movement while asleep – is often considered to be the most recognizable symptom in those suffering from sleep apnoea. However, it is actually when snoring stops that breathing may be most obstructed, with the throat becoming too constricted to allow enough air to flow through the airway to make a sound. These breathing events (called apnoeas [complete cessation of airflow] or hypopneas [50% reduction in airflow]) may occur several times per hour, and can result in arousal from sleep. It is for this reason that snoring is not a sure sign of sleep apnoea and that louder snoring is not necessarily more likely to be caused by severe obstruction due to OSA.

Risk factors for developing obstructive sleep apnoea include having a Body Mass Index (BMI) of 40 or more, a neck circumference (in men over 17in), smoking and drinking alcohol regularly. Older adults, men, and people with diabetes are also known to be more likely to suffer from OSA, although it may still be found in both women and children.

How to sleep with sleep apnoea?
Simply implementing lifestyle and behavioral changes may help improve OSA; however, the most effective treatment is seen as a result of the use of a Continuous Positive Airway Pressure or 'CPAP' machine. CPAP machines are used to open up the airways and keep blood oxygen at a healthy level by maintaining a flow of air to the lungs delivered through a facial mask.
Individuals whose OSA isn't helped by the use of a CPAP machine, or find the machines too uncomfortable, may be offered a range of surgical procedures to widen their airway or remove and tighten soft-tissue in the throat.

Central sleep apnoea is…
CSA, also known as 'Cheyne-Stokes respiration', differs from OSA in that it involves an imbalance of the brain's respiratory control centers during both sleep and wakefulness. Low blood oxygen therefore occurs as a result of failures in the brain's feedback mechanisms rather than being due to physical obstructions as seen in OSA. Sufferers of CSA do not struggle to breathe during sleep but may be seen to cycle between periods of fast and slow breathing in order to compensate for drops in blood oxygen known as 'hypoxaemia'.

The effects of CSA will differ between sufferers depending on how severe their apnea is but tends to present milder symptoms unless the condition exists alongside other health problems such as those with the heart or nervous system.

'Complex' or 'mixed' sleep apnoea is…
People seen to have a combination of OSA and CSA may receive a diagnosis of 'complex' or 'mixed' sleep apnoea. It is currently thought that it is possible for people suffering from long-term, severe OSA to develop CSA as a result of damage to the brain's feedback mechanisms. Research is ongoing into the relationship between OSA and CSA, with much left to be understood about 'complex' or 'mixed' apnoeas.

Please consult your doctor if you believe you might be suffering from sleep apnoea.

Filed under: Sleep disorders