Obstructive Sleep Apnoea

• What causes simple snoring and obstructive sleep apnoea?
• What are the effects of Obstructive Sleep Apnoea?
• What tests are available to investigate snoring and obstructive sleep apnoea?
• What happens during a sleep study?
• Obstructive sleep apnoea - what can be done about it?

What causes simple snoring and obstructive sleep apnoea?

There are a number of different causes and aggravating factors for narrowing of the throat which worsens during sleep to cause snoring or obstructive sleep apnoea. Mild throat narrowing will result in snoring, more severe narrowing will lead to obstructive sleep apnoea.

What are the factors and how do they cause problems?

• Obesity or weight gain: obesity, particular around the neck, narrows the upper airways - people tend to gain weight on the inside as well as on the outside.
• Alcohol: drinking alcohol causes greater muscle relaxation during sleep than normally occurs, and hence can result in an abnormally collapsible upper airway. It also decreases arousal responses and may also, when excessive, damage nerve cells in the brain.
• Nose or throat problems:
  • abnormal lumps can narrow the upper airway such as nasal polyps, tonsil and adenoid enlargement, a large tongue or thyroid gland swellings. Hayfever and smoking may lead to narrowed nose passages, thus aggravating snoring or sleep apnoea.
  • simple variations in the shape of the jaw, throat, face or nose result in the fact that some people have a smaller than usual upper airway. These problems can sometimes tend to run in families, and, if you are a snorer or have sleep apnoea, you may well have relations with the same problem.
• Sleeping tablets: medications which causes increased throat muscle relaxation
• Being male: it is interesting to note that OSA and "simple" snoring in young and middle aged people are far more common in men than in women. It certainly occurs in women but less frequently than in men. Women in their reproductive years seem to be protected form sleep apnoea. This is thought to be due to sex hormone differences and their effect on muscle strength and fat distribution (men tend to gain weight around their abdomen and neck, and women around their hips). It could also be due to higher alcolol consumption in men.

OSA and "simple" snoring occur in all age groups. This includes infants, children, adults and the elderly. In children, large tonsils and adenoids are a common cause. The largest affected group, however, is the middle aged population where it is estimated to affect 10% of the population, with males predominating in a ratio of 10:1.

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What are the effects of Obstructive Sleep Apnoea?

The body's oxygen stores can last only a few minutes after breathing stops before damage occurs to thebrain, heart, kidneys and other vital organs. When the flow of fresh air into the lungs is reduced or absent for more than a few seconds, the body's defence mechanisms are alerted as the changes in blood oxyen and carbon dioxide levels stimulate the brain to cause arousal from sleep and to increase ventilation.

The brain is stimulated to wake up, allowing a return of strength to the muscles of the pharynx; this opens the throat and allows air to flow again. Breathing resumes and the blood oxygen and carbon dioxide levels are returned to normal. Return to sleep and another cycle of airway narrowing occurs and the pattern repeats itself. In severe cases this cycle of breathing, apnoea, breathing, apnoea, etc, is repeated every 1-2 minutes.

When the apnoeas and arousals occur frequently (up to 400 per night in some cases), the night's sleep can be very disrupted, resulting in excessive daytime sleepiness the next day. Arousal rarely occurs to full wakefulness so that few, if any, of the events can be remembered the next day. Sometimes the person is fully aroused and wakes with a start and a choking feeling in the throat.

In addition to snoring, people with severe obstructive sleep apnoea may posess a number of the following symptoms:

1. snoring;
2. daytime sleepiness (including car and work accidents);
3. apnoeas or choking;
4. morning headache;
5. intellectual deterioration - poor memory;
6. personality changes - depression;
7. behavioural disorders;
8. restless sleep;
9. bedwetting/passing urine at night;
10. breathlessness at night or day;
11. reduced sexual activity;
12. heart burn at night.

They wake in the morning feeling tired, lethargic, often with a "hangover" sensation. They often remain sleepy throughout the day, tending to fall asleep at inappropriate times, such as while watching TV, eating, reading or driving their car, and frequently they do not recognise that they have this problem. There are many funny stories about such people missing theur bus stop, going to sleep at the dinner table or in the car ath the traffic lights and they are the butt of the family or workplace jokes.

In fact sleepiness is really a medical condition and can be very dangerous for people with sleep apnoea who have a markedly increased incidence of car accidents, work accidents, and sick days. However, if this sleepiness is due to sleep apnoea, it can be effectively treated with sleep apnoea treatment and a normal sleeping pattern can be re-established. There are, of course, many other causes of daytime sleepiness (refer below), and these need to be distinguished from sleep apnoea by your doctor.

Causes of Excessive Daytime Sleepiness:

• Sleep apnoea syndromes
• Narcolepsy
• Insomnia
• Shifts in the body's natural rhythm: shift work or jet lag.
• Nocturnal myoclonus or restless legs syndrome
• Blood disorders eg. anaemia - low blood count
• Depression
• Drug and alcolol dependency
• Hormone disturbance eg. thyroid, diabetes
• Sleep deprivation eg. parenthood
• Unknown

Sometimes the problem of sleep apnoea is raised because the person's sleep partner notices that in addition to snoring, the sufferer has periods of apnoea (ie obstructed breathing) during sleep, and a very restless sleep pattern. This can be a cause of great concern to the partner who lies awake fearful that breathing might not start again. Thus, some sufferers are actually brought along to the doctor by their bed partner.

The repeated arousals in sleep apnoea disrupt the quality of sleep and thus deprive one of good quality sleep and the associated oxygen deprivation can result in slow mental functioning, poor memory, depression and loss of libido, as well as daytime sleepiness.

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What tests are available to investigate snoring and obstructive sleep aponoea?

The first step is for you to discuss your snoring or sleep problem with your own doctor. It is a good idea to take your sleeping partner, if you have one, to the doctor with you, to fill in the gaps regarding what happens to you when you are asleep.

Following a through history and examination by your doctor, you may be referred to a specialist in sleep disorders. Here again a detailed history and examination of the chest, heart, blood pressure, nose and throat and nervous system will be performed. If necessary, the advice of a surgeon may be sought regarding any nasal or throat problems. It is generally accepted by those working in the area that a sleep study or polysomnogram should be performed before a diagnosis is made. In addition, breathing tests and blood tests (to test oxygen levels, haemoglobin levels, and thyroid gland function) are usually performed.

Sleep studies are performed in a sleep unit or laboratory usually consisting of a number of private, quiet, single rooms with simple non-invasive equipment used to monitor brain, heart, lung and other organ activity during sleep. Staff attach monitoring leads to the patient, prior to sleep, then work in an adjacent room to observe recordings.

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What happens during a sleep study?

The activities of the body monitored during a sleep study usually include:

1. body oxygen level by measuring light transmission through the ear lobe or finger with an "oximeter";
2. airflow at nose or mouth
3. chest and abdomen movements
4. heart activity also known as electrocardiogram (ECG)
5. brain activity also known as electroencephalogram (EEG)
6. muscle activity also known as electromyogram (EMG)
7. eye activity also known as electrooculogram (EOG)

During the sleep study you will sleep in a bedroom usually adjacent to a room in which most of the recording equipment is operating, and a trained nurse or scientist stays all night.

In special circumstances when specfic problems are suspected or being investigated, other measurements may be made, such as blood pressure, leg movements, or carbon dioxide levels.

A number of the other causes of daytime sleepiness can be distinguished from sleep apnoea by a sleep study.

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Obstructive sleep apnoea - What can be done about it?

A sleep study will diagnose and determine the severity of your sleep apnoea, and your doctor will discuss with you the available treatments most suitable for you.

If you have mild obstructive sleep apnoea then your doctor might suggest:

1. weight reduction
2. reducing alcohol intake
3. reducing nasal stuffiness, with nasal sprays or occasionally nasal surgery
4. stopping or reducing sleeping or sedating tablets
5. improving lung function (increasing asthma treatment, ceasing smoking)

If you have moderate or severe obstructive sleep apnoea, then he might suggest:

1. a nasal "CPAP" mask and pump (Continuous Positive Airway Pressure = CPAP)
2. Nose or throat surgery
3. Other treatments - mouth guards, anti snoring pillows, corks or tennis balls sewn into your pyjamas coat black & wrist band stimulators.

Certainly, sleeping on your side may lessen the tendency for apnoeas as there will be less tendency for the tongue to fall back against the back wall of your throat, but it is difficult to prevent people from rolling over on to their back during sleep.

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