OBSTRUCTIVE  SLEEP  APNOEA
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Obstructive Sleep Apnoea (OSA) is the most common of the respiratory sleep disorders.
 
During sleep, in those with OSA, the muscles of the upper airway relax and are ‘sucked in’ during inspiration, obstructing breathing in the throat – obstruction may be partial or complete and last from 10 seconds to 2 minutes. During this time the blood oxygen levels may fall significantly. The episode of obstruction usually terminates in arousal from sleep with choking or gasping sounds. OSA is usually associated with loud snoring. Episodes of obstruction may occur many hundreds of times per night.
The poor quality and fragmentation of sleep, along with periods of low oxygen levels, are often associated with waking unrefreshed from a night’s sleep, morning headache, irritability, dry mouth, daytime sleepiness and impairment of normal functioning. Patients often fall asleep when inactive e.g. watching TV, reading, or driving and at traffic lights.

In recent times the significance of OSA has become more apparent – of particular concern :

-          Excessive daytime sleepiness and impaired concentration and mental functioning is associated with an increased risk of car accidents ( from 2 to 7 times more collisions in those with OSA compared to other drivers) and industrial accidents

-          Increased incidence of depression with a possible causative relationship

-          Increased blood pressure – 45% of those with OSA have high blood pressure – treating OSA results in a reduction in blood pressure

-          Severe OSA is associated with an increase in ischaemic heart disease and abnormal heart rhythm – in particular nocturnal atrial fibrillation and periods of slowing of the heart or the heart stopping for several seconds

-          Increased risk of stroke and death

-          OSA may cause insulin resistance and increase the risk of diabetes

Overall mortality is increased in moderate or severe OSA – predominantly from cardiac causes, stroke and motor vehicle accidents

OSA may occur at all ages, including children, but is more common with increasing age – it is twice as common in men. The more overweight the person, the greater the risk, with 30% of obese males and between 50% and 98% of morbidly obese (BMI more than 40) affected. The larger the neck size the greater the risk.
People with a receding jaw, large tongue or tonsils or of Asian descent have a higher risk as their facial structure is such that their tongue can more readily fall backward during sleep with resultant throat obstruction.
Alcohol, relaxant medications, nasal obstruction and sleeping on the back are all aggravating factors as is active or passive smoking.

Assessment
The diagnosis of OSA is usually suggested by a history of loud snoring with periods of breathing cessation and choking, along with daytime drowsiness. Daytime sleepiness can be measured using the Epworth Sleepiness Scale where a score of more than 9/24 is significant.

Sleep studies can be undertaken to confirm the diagnosis and exclude other less common   respiratory sleep disorders. These studies may be undertaken in specialised hospital based overnight sleep units or by portable home sleep studies.
To be eligible for direct referral for home sleep studies at least 2 of the following must be  present :
- loud snoring
- being observed to stop breathing during sleep
- excessive daytime fatigue or drowsiness
- elevated blood pressure or being treated for high blood pressure
Sleep Unit studies are more comprehensive, but less convenient than home studies - home studies have been shown to be of most use in confirming a suspected case.
Home sleep studies can be arranged by the St Agnes doctors and the unit fitted at the St Agnes Medical Centre.

Treatment
- Weight loss
- Avoiding alcohol at night
- CPAP                        
are the usual first line treatments.

CPAP is a positive pressure mask and compressor system which is worn during sleep – the machine gently blowing air into the nose and mouth ‘splinting’ the upper airway open and thus preventing obstruction. The mask is usually individually fitted and adjusted by qualified sleep specialist physicians or sleep technicians.
The concept of wearing a mask at night is quite ‘off putting’ for most people, but is tolerated by the majority of them with an often rapid and dramatic improvement in the quality of their sleep and life more generally.

Alternatives to CPAP include :
- ‘mandibular advancement’ splints – mouthguards fitted by specialised dentists designed to hold the tongue forward while asleep. They are effective in around 50% of mild to moderate SOA cases.
-  surgery to the palate or throat to hold the tongue more forward

Avoiding sleeping on the back or with the neck bent forward and not smoking also helps.

*Successful treatment of OSA reverses the serious cardiac and stroke risk.

*Commercial drivers cannot maintain their licence if they have OSA unless their OSA is successfully managed on an ongoing basis.

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