Obstructive sleep apnoea (OSA) is a condition where the walls of the throat relax and narrow during sleep, interrupting normal breathingHistory
History of Sleep Apnea
Sleep apnea was first mentioned in medical literature in 1965, although the condition was recognized long before the medical causes were known. These first reports of the condition in a medical context described individuals with severe cases of sleep apnea resulting in severely decreased blood oxygen levels, increased carbon dioxide production and congestive heart failure.
Prior to that time, an early 20th century physician coined the term Pickwickian syndrome, probably a reference to a description by Charles Dickens, in his novel The Pickwick Papers, which accurately describes symptoms associated with sleep apnea.
In 1981, a non-surgical treatment was developed for sleep apnea in the first CPAP, or continuous positive airway pressure device. By the late 1980s, the formerly bulky and noisy devices were replaced by quieter, streamlined designs.
The resulting availability of an effective treatment was the catalyst for a push by the medical community to raise awareness about sleep-disordered breathing and identify those who could benefit from treatment. Specialized sleep clinics common today cropped up as public awareness of the condition and other sleep disorders rose. A study conducted in 1993 found that nearly one in fifteen Americans are affected by at least moderate sleep apnea.
Today obstructive sleep apnea is a serious but highly treatable condition that is well understood with a broad support network existing for individuals with the disorder. Talk to a doctor about the various treatment plans and ways to alleviate the symptoms associated with sleep apnea.
There are two types of breathing interruption characteristic of OSA:
- apnoea – where the muscles and soft tissues in the throat relax and collapse sufficiently to cause a total blockage of the airway; it is called an apnoea when the airflow is blocked for 10 seconds or more
- hypopnoea – a partial blockage of the airway that results in an airflow reduction of greater than 50% for 10 seconds or more
As many people with OSA experience episodes of both apnoea and hypopnoea, doctors sometimes refer to the condition as obstructive sleep apnoea-hypopnoea syndrome, or OSAHS.
The term "obstructive" distinguishes OSA from rarer forms of sleep apnoea, such as central sleep apnoea, which is caused by the brain not sending signals to the breathing muscles during sleep.
What happens in OSA?
People with OSA may experience repeated episodes of apnoea and hypopnoea throughout the night.
During an episode, the lack of oxygen triggers your brain to pull you out of deep sleep – either to a lighter sleep or to wakefulness – so your airway reopens and you can breathe normally.
After falling back into deep sleep, further episodes of apnoea and hypopnoea can occur. These events may occur around once every one or two minutes throughout the night in severe cases.
Most people with OSA snore loudly. Their breathing may be noisy and laboured, and it is often interrupted by gasping and snorting with each episode of apnoea.
These repeated sleep interruptions can make you feel very tired during the day. You'll usually have no memory of your interrupted breathing, so you may be unaware you have a problem unless a partner, friend or family member notices the symptoms while you sleep.
Symptoms of obstructive sleep apnoea
If you have obstructive sleep apnoea (OSA), you may not realise it yourself. The condition is often first spotted by a partner, friend or family member who notices problems while you sleep.
Signs of OSA in someone sleeping can include:
- loud snoring
- noisy and laboured breathing
- repeated short periods where breathing is interrupted by gasping or snorting
Some people with OSA may also experience night sweats and may wake up frequently during the night to urinate.
If you have OSA, you may have no memory of your interrupted breathing during the night. However, when you wake up you are likely to feel as though you have not had a good night's sleep.
Signs of OSA while you are awake can include:
- not feeling refreshed after waking up
- feeling very sleepy during the day
- poor memory and concentration
- headaches, particularly in the morning
- irritability and mood swings
- lack of interest in sex (loss of libido
- in men, erectile dysfunction
When to seek medical advice
You should see your GP if you think you might have OSA, as treatment can help reduce the potential impact of the condition on your quality of life.
It can also reduce your risk of potentially serious problems, such as high blood pressure, serious accidents caused by tiredness (such as a car crash), strokes, heart attacks and an irregular heartbeat (such as atrial fibrillation).
Your GP can check for other possible reasons for your symptoms, and can arrange for an assessment of your sleep to be carried out through a local sleep centre
Causes of obstructive sleep apnoea
Obstructive sleep apnoea (OSA) is caused by the muscles and soft tissue in the back of your throat collapsing inwards during sleep.
These muscles support your tongue, tonsils and soft palate (the tissue at the back of the throat used in speech, swallowing and breathing).
Some loss of stability in these muscles and tissues is normal while you sleep, but in most people this doesn't cause any breathing problems.
In cases of OSA, the relaxation of these muscles and soft tissues causes the airway in your throat to narrow or become totally blocked.
This interrupts the oxygen supply to your body, which triggers your brain to pull you out of deep sleep so your airway reopens and you can breathe normally.
There are a number of things that can increase your risk of developing OSA, including:
- being overweight – excessive body fat increases the bulk of soft tissue in the neck, which can place a strain on the throat muscles; excess stomach fat can also lead to breathing difficulties, which can make OSA worse
- being male – it is not known why OSA is more common in men than in women, but it may be related to different patterns of body fat distribution
- being 40 years of age or more – although OSA can occur at any age, it is more common in people who are over 40
- having a large neck – men with a collar size greater than around 43cm (17 inches) have an increased risk of developing OSA
- taking medicines with a sedative effect – such as sleeping tablets or tranquillisers
- having an unusual inner neck structure – such as a narrow airway, large tonsils, adenoids or tongue, or a small lower jaw
- alcohol – drinking alcohol, particularly before going to sleep, can make snoring and sleep apnoea worse
- smoking – you are more likely to develop sleep apnoea if you smoke
- the menopause (in women) – the changes in hormone levels during the menopause may cause the throat muscles to relax more than usual
- having a family history of OSA – there may be genes inherited from your parents that can make you more susceptible to OSA
- nasal congestion – OSA occurs more often in people with nasal congestion, such as a deviated septum (where the tissue in the nose that divides the two nostrils is bent to one side) or nasal polyps, which may be a result of the airways being narrowed
Diagnosing obstructive sleep apnoea
Obstructive sleep apnoea (OSA) can usually be diagnosed after you've been observed sleeping at a sleep clinic, or by using a testing device worn overnight at home.
If you think you have OSA, it's important to visit your GP in case you need to be referred to a sleep specialist for further tests and treatment.
Before seeing your GP, it may be helpful to ask a partner, friend or relative to observe you while you are asleep if possible. If you have OSA, they may be able to spot episodes of breathlessness.
It may also help to fill out an Epworth Sleepiness Scale questionnaire. This asks how likely you'll be to doze off in a number of different situations, such as watching TV or sitting in a meeting. The final score will help your doctor determine whether you may have a sleep disorder.
An online version of the Epworth Sleepiness Scale can be found on the British Lung Foundation website.
Seeing your GP
When you see your GP, they will usually ask you a number of questions about your symptoms, such as whether you regularly fall asleep during the day against your will.
Your GP will also carry out a physical examination and some tests, including a blood pressure test. A blood test is also likely to be arranged. These will help rule out other conditions that could explain your tiredness, such as hypothyroidism (an underactive thyroid gland).
The next step is to observe you while you are asleep. To do this, your GP will need to refer you to a local sleep centre. These are specialist clinics or hospital departments that help treat people with sleep disorders. The Sleep Apnoea Trust Association has a list of NHS sleep clinics in the UK.
Observing your sleep
The sleep specialists at the sleep centre may first ask you about your symptoms and medical history, and they may also carry out a physical examination.
This may include measuring your height and weight to work out your body mass index (BMI), as well as measuring your neck circumference. This is because being overweight and having a large neck can increase your risk of OSA.
The sleep specialists will then arrange for your sleep to be assessed overnight, either by spending the night at the clinic or taking some monitoring equipment home with you and bringing it back the next day for them to analyse.
Testing at home
In many cases, the sleep centre will teach you how to use portable recording equipment while you sleep at home.
The equipment you are given may include:
- a breathing sensor
- sensors to monitor your heart rate
- bands that are placed around your chest
- oxygen sensors that are put on your finger
The equipment records oxygen levels, breathing movements, heart rate and snoring through the night.
If more information about sleep quality is required by the sleep centre, a more detailed investigation called polysomnography will be required, which will be carried out at the sleep centre.
Testing at a sleep centre
The main test carried out to analyse your sleep at a sleep centre is known as polysomnography.
During the night, several different parts of your body will be carefully monitored while you sleep.
Electrodes (small metallic discs) and bands will be placed on the surface of your skin and different parts of your body. Sensors will also be placed on your legs, and an oxygen sensor will be attached to your finger.
A number of different tests will be carried out during polysomnography, including:
- electroencephalography (EEG) – this monitors brain waves
- electromyography (EMG) – this monitors muscle tone
- recordings of movements in your chest and abdomen
- recordings of airflow through your mouth and nose
- pulse oximetry – this measures your heart rate and blood oxygen levels
- electrocardiography (ECG) – this monitors your heart
Sound recording and video equipment may also be used.
If OSA is diagnosed during the early part of the night, you may be given continuous positive airway pressure (CPAP) treatment. CPAP involves using a mask that delivers constant compressed air to the airway and stops it closing, which prevents OSA.
Once the tests have been completed, staff at the sleep centre should have a good idea about whether or not you have OSA. If you do, they can determine how much it is interrupting your sleep and recommend appropriate treatment.
Determining the severity of OSA
The severity of OSA is determined by how often your breathing is affected over the course of an hour. These episodes are measured using the apnoea-hypopnoea index (AHI).
Severity is measured using the following criteria:
- mild – an AHI reading of 5 to 14 episodes an hour
- moderate – an AHI reading of 15 to 30 episodes an hour
- severe – an AHI reading of more than 30 episodes an hour
Current evidence suggests treatment is most likely to be beneficial in people with moderate or severe OSA, although some research has suggested treatment may also help some people with mild OSA.
Treating obstructive sleep apnoea
Common treatments for obstructive sleep apnoea (OSA) include making lifestyle changes and using breathing apparatus while you sleep.
OSA is a long-term condition and many cases will require lifelong treatment.
In most cases of OSA, you will be advised to make healthy lifestyle changes, such as:
- losing weight if you are overweight or obese
- stopping smoking if you smoke
- limiting your alcohol consumption, particularly before going to bed – men should not regularly drink more than three to four units a day and women should not regularly drink more than two to three units a day
- avoiding sedative medications and sleeping tablets
Losing weight, reducing the amount of alcohol you drink and avoiding sedatives have all been shown to help improve the symptoms of OSA.
Although it's less clear whether stopping smoking can improve the condition, you'll probably be advised to stop for general health reasons.
Sleeping on your side, rather than on your back, may also help relieve the symptoms of OSA if you have been diagnosed with the condition.
Continuous positive airway pressure (CPAP)
As well as the lifestyle changes mentioned above, people with moderate to severe OSA will usually need to use a continuous positive airway pressure (CPAP) device.
This is a small pump that delivers a continuous supply of compressed air to you through a mask that either covers your nose or your nose and mouth. The compressed air prevents your throat closing.
CPAP can feel peculiar to start with and you may be tempted to stop using it. But people who persevere usually soon get used to it and their symptoms improve significantly.
CPAP is available on the NHS and is the most effective therapy for treating severe cases of OSA. As well as reducing symptoms such as snoring and tiredness, it can also reduce the risk of complications of OSA, such as high blood pressure.
Possible side effects of using a CPAP device can include:
- mask discomfort
- nasal congestion, runny nose or irritation
- difficulty breathing through your nose
- headaches and ear pain
- stomach pain and flatulence (wind)
Earlier versions of CPAP also often caused problems such as nasal dryness and a sore throat. However, modern versions tend to include humidifiers (a device that increases moisture), which helps to reduce these side effects.
If CPAP causes you discomfort, inform your treatment staff as the device can be modified to make it more comfortable. For example, you can try using a CPAP machine that starts with a low air pressure and gradually builds up to a higher air pressure as you fall asleep.
Mandibular advancement device (MAD)
A mandibular advancement device (MAD) is a dental appliance, similar to a gum shield, sometimes used to treat mild OSA. They are not generally recommended for more severe OSA, although they may be an option if you are unable to tolerate using a CPAP device.
An MAD is worn over your teeth when you are asleep. It is designed to hold your jaw and tongue forward to increase the space at the back of your throat and reduce the narrowing of your airway that causes snoring.
Off-the-shelf MADs are available from specialist websites, but most experts do not recommend them, as poor-fitting MADs can make symptoms worse. It is recommended you have an MAD made for you by a dentist with training and experience in treating sleep apnoea.
MADs are not always available on the NHS, so you may need to pay for the device privately through a dentist or orthodontist.
An MAD may not be suitable treatment for you if you do not have many (or any) teeth. If you have dental caps, crowns or bridgework, consult your dentist to ensure that they will not be stressed or damaged by an MAD.
Surgery to treat OSA is not routinely recommended because evidence shows it is not as effective as CPAP in controlling the symptoms of the condition. It also carries the risk of more serious complications.
Surgery is usually only considered as a last resort when all other treatment options have failed, and if the condition is severely affecting your quality of life.
A range of surgical treatments have been used to treat OSA. These include:
- tonsillectomy - where the tonsils are removed if they are enlarged and blocking your airway when you sleep
- adenoidectomy – where the adenoids (small lumps of tissue at the back of the throat, above the tonsils) are removed if they are enlarged and are blocking the airway during sleep
- tracheostomy - where a tube is inserted directly into your neck to allow you to breathe freely, even if the airways in your upper throat are blocked
- weight loss (bariatric) surgery - where the size of the stomach is reduced if you are severely obese and this is making your sleep apnoea worse
Surgery to remove excess tissue in the throat to widen your airway (uvulopalatopharyngoplasty) used to be a common surgical treatment for OSA, but it is performed less often nowadays.
This is because more effective treatments are available, such as CPAP. This type of surgery can mean you are unable to use a CPAP device properly in the future if you need to.
Soft palate implants
Soft palate implants make the soft palate (part of the roof of the mouth) stiffer and less likely to vibrate and cause an obstruction. The implants are inserted into the soft palate under local anaesthetic.
The National Institute of Health and Care Excellence (NICE) has said soft palate implants are safe, but they are not currently recommended for treating OSA as there is a lack of evidence about their effectiveness.
However, this form of treatment is recommended for treating snoring associated with OSA in exceptional cases.
Complications of obstructive sleep apnoea
Obstructive sleep apnoea (OSA) can sometimes lead to further problems, such as high blood pressure, if it is not treated.
High blood pressure
Evidence suggests OSA can lead to high blood pressure (hypertension).
Maintaining a healthy weight, exercising regularly and eating a healthy, balanced diet can all help prevent high blood pressure, as can the appropriate treatment of OSA, such as using breathing apparatus while you sleep.
Road traffic accidents
As someone with poorly controlled OSA can experience excessive daytime sleepiness, they have an increased risk of being involved in a life-threatening accident, such as a car crash. Their risk of having a work-related accident also increases.
Research has shown someone who has been deprived of sleep because of OSA may be up to 12 times more likely to be involved in a car accident.
If you are diagnosed with OSA, it may mean your ability to drive is affected. It is your legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that could have an impact on your driving ability.
Once a diagnosis of OSA has been made, you should not drive until your symptoms are well controlled.
OSA has also been linked to an increased risk of developing type 2 diabetes. This is a lifelong condition that causes a person's blood sugar (glucose) level to become too high. It may occur in people with OSA if your body becomes less able to break down glucose properly.
However, it is not clear whether people develop diabetes as a direct result of OSA, or whether it is the result of an underlying cause of the condition, such as obesity.