Sleep apnoea


There are three types of sleep apnoea:

• Obstructive sleep apnoea (OSA). This is the most common type of apnoea. It occurs due to an obstruction or weakness in the airway that results in the obstruction of airflow to the lungs during sleep. Each obstruction needs to last a minimum of 10 seconds for it to be classified as abnormal. The collapse or narrowing of the upper airway may be a result of several factors, including inherent physical characteristics, excess weight, and alcohol consumption before going to bed.

• Central sleep apnoea. This is caused by a delay in the signal transmitted from the brain to elicit breathing, and is usually part of a brain or cardiac disorder (these disorders often follow after a stroke or cardiac failure). 

• Mixed sleep apnoea. As the name suggests, this type of apnoea is more or less a mixture of the above. It occurs less frequently than obstructive sleep apnoea, but more frequently than central sleep apnoea.

Who gets sleep apnoea?
The prevalence of obstructive sleep apnoea (OSA), the most common type of apnoea, has been estimated to be between 3% and 7% of the male adult population. 

There are multiple risk factors, which include:

  • Male sex
  • Middle age
  • Increased neck circumference
  • Elevated body mass index (BMI)

Symptoms of sleep apnoea

Symptoms of sleep apnoea include:

  • Loud snoring.
  • Waking up still tired and groggy, and struggling to stay awake during the day.
  • Waking up with headaches.
  • Waking up feeling a choking sensation.
  • Gasping or holding your breath during sleep.
  • Waking up sweating and perspiring excessively during sleep.
  • Frequent stopping of breathing during sleep.
  • High blood pressure.
  • Frequently waking at night to urinate (nocturia).
  • Overweight (sometimes) and/or experiencing rapid weight gain. Most people with obstructive sleep apnoea are overweight. This is because the repeat drop in blood oxygen causes the suppression of a chemical called leptin and the increase of a chemical called ghrelin. This combination causes an increase in weight. When this happens, it’s very difficult or impossible to lose weight.
  • Dry mouth upon awakening.
  • Depression.
    Difficulty concentrating during the day.
  • Several trips to the bathroom during the night.
  • Heartburn.
  • Reduced libido.
  • Insomnia. As many as 58% of people with obstructive sleep apnoea (OSA) also have insomnia. Memory problems frequently occur and there’s a seven times raised risk for motor-vehicle accidents in these people. Legally, they should not be behind the wheel of a car. The mood changes aren’t just depression. People with OSA become highly irritable, and it can cause marital break-ups. The memory problems can be so severe as to mimic Alzheimer's disease.
  • Many people consider OSA to be the most important cause of the metabolic syndrome.

What causes sleep apnoea?
In the vast majority of adults with obstructive sleep apnoea (OSA), the airway collapses due to an innate weakness in the tissues comprising the upper airway. 

In a significant minority of adults with OSA, a physical anatomical anomaly is found to be blocking the windpipe – the tongue, the tonsils or the uvula (the little piece of flesh at the very back of the throat). The most common cause in these adults is a collapse of the tongue backwards into the airway. 

Risk factors for sleep apnoea
Studies indicate that 4-5% of women and 8-10% of men over 50 years of age suffer from sleep apnoea. Overweight people, and those with facial deformities that could obstruct their airways, are at greater risk.

An important risk factor is the size of your collar. In a man, if you snore and your collar is greater than 43cm, you probably have obstructive sleep apnoea. In a woman, the figure is 40cm. 

If you’re a snorer, this alone gives you a 50% risk of having obstructive sleep apnoea. If, in addition, you’re tired despite having what appears to be adequate hours in bed, you can confidently bet that you have it. 

Course and prognosis of sleep apnoea
If treated correctly – whether through behavioural changes, continuous positive airway pressure (CPAP), or surgery – a person with sleep apnoea could be successfully treated. Some people are even cured of this debilitating condition, and can once again enjoy a quality life thanks to quality sleep. 

How is sleep apnoea diagnosed?
A sleep test called polysomnography (PSG) is usually done to diagnose sleep apnoea. 

There are two kinds of tests:

A detailed, overnight PSG done in hospital involves monitoring brain waves, muscle tension, eye movement, respiration, oxygen level in the blood, and audio monitoring (for snoring and gasping). This provides your doctor with detailed information about the physiological impact of obstructive sleep apnoea (OSA) on various parameters. It’s the gold standard diagnostic test for OSA.

More recently, home OSA sleep testing has become popular. These tests don’t measure brain activity or muscle tone, and is reserved for individuals who have obvious high risk factors for OSA and no evidence of other co-morbidities (other co-occurring conditions). 

How is sleep apnoea treated?
The treatment of sleep apnoea depends on the type and the severity of the condition. In this article, we will focus on the treatment of obstructive sleep apnoea (OSA), the most common type.

There are three broad treatment options for OSA:

1. Non-invasive ventilation: CPAP, APAP and BiPAP
2. Dental oral appliance therapy (OAT)
3. Surgery

1. Non-invasive ventilation: CPAP, APAP and BiPAP
Continuous positive airways pressure (CPAP), automatic positive airways pressure (APAP), and bi-level positive airways pressure (BiPAP) are different types of devices that enable the airway to remain open by blowing pressurised air into the airway while you’re asleep.

CPAP was the initial technology developed to keep the airway open during sleep. However, further development of technology and sensors enabled the developed of a device that automatically detects the pressure required to maintain an open airway and prevent collapse.

This treatment is APAP. Some people who have severe, complex OSA and those with central sleep apnoea require treatment with BiPAP. This regulates breathing in and breathing out. CPAP and APAP are considered gold standard treatments for moderate to severe OSA.

2. Dental oral appliance therapy (OAT)
Dental OATs are mouth-guard-type devices that are worn during sleep. They should be made by a qualified dentist who has experience in sleep medicine and sleep apnoea. These devices work by holding the lower jaw and tongue forward during sleep.
Dental OAT devices are usually indicated for people with mild OSA or those with positional OSA (where the OSA is much worse when lying on your back).

3. Surgery for OSA
Some people have facial deformities that may be the cause of their sleep apnoea. It simply may be that their jaw is smaller than it should be or that they have a smaller opening at the back of the throat. Others have enlarged tonsils, a large tongue, or some other tissues that are partially blocking the airway. 

Fixing a deviated septum may help to open the nasal passages. Removing the tonsils and adenoids or polyps may also help. Other surgical treatments include removing excess tissue to clear the airway, or moving the upper and lower jaw forward.
Success of treatment is measured by the reduction of respiratory disturbances.

If untreated, the personal and professional life of someone who has sleep apnoea could suffer considerably. The risk of a heart attack or stroke also rises. 

Sleep apnoea: when to visit a doctor
When your partner starts complaining about your snoring, you keep waking up tired and groggy, and it’s detected that you gasp for air during sleep, you should see a doctor about your condition. If you wake up during the night with the sensation of being choked, you need to get medical advice. 

Children should never snore at all. If a child snores, and there are complaints of attention problems at school, the tonsils should be examined and removed if they’re obstructing the airway. This is frequently more effective in treating inattention than using medications like methylphenidate (Ritalin).

Sleep apnoea is a potentially life-threatening condition that requires immediate medical attention. The risks of undiagnosed obstructive sleep apnoea include heart attack, stroke, impotence, irregular heartbeat, high blood pressure, and heart disease. Obstructive sleep apnoea is associated with a 23 times raised risk for a heart attack. You’re uninsurable if you have it.

In addition, obstructive sleep apnoea causes daytime sleepiness that can result in accidents, lost productivity and interpersonal relationship problems.

Visit the South African Sleep Society to find to a sleep clinic near you. 

How can sleep apnoea be prevented?
Follow these steps to prevent obstructive sleep apnoea, the most common type:

  • Follow a healthy lifestyle.
  • Keep your body mass index (BMI) below 24 – i.e. maintain a healthy weight.
  • Seek medical attention early if you snore or experience daytime tiredness.

Reviewed by Dr Irshaad Ebrahim, specialist neuropsychiatrist in sleep disorders at The London Sleep Centre and The Constantia Sleep Centre. FRCPsych. April 2018.

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