Introduction

What is sleep apnoea?

Sleep apnoea is a disorder in which a person's breathing becomes disrupted while sleeping. Those affected by this sleep disorder experience repeated episodes where they stop breathing. This activates a survival reflex, causing you to wake up so that you can breathe normally again.

Such a disturbance to your sleep cycle can lead to daytime fatigue and other serious health problems, including cardiovascular disease. A timely diagnosis is therefore essential in ensuring you can receive treatment sooner and reduce your risk of developing complications of sleep apnoea. 

Types of sleep apnoea

Obstructive sleep apnoea

Abbreviated to OSA, this is the most common type of sleep apnoea. It is characterised by the intermittent relaxation of throat muscles, causing the tongue to fall backwards and the upper airway to collapse.

Central sleep apnoea

Although less common than OSA, central sleep apnoea, or CSA, also results in disruption to breathing during sleep owing to the failure of an area of the brain, known as the pontomedullary pacemaker, to generate the normal breathing rhythm that causes muscles in the throat to function properly.¹

Complex sleep apnoea syndrome

This is defined as a form of CSA that presents in patients with OSA who are undergoing treatment for this.

Symptoms of sleep apnoea

Do you frequently suffer from morning headaches? Or perhaps you feel excessively tired or irritable during the day? These are just two of the main symptoms of sleep apnoea. Other indications of the disorder include:

• Loud snoring
• Choking or gasping for air during sleep
• Insomnia
• Dry mouth
• Concentration difficulties³

Risk factors for sleep apnoea

Certain characteristics that will increase your chance of developing sleep apnoea. These are:

• Obesity – increased fat deposits in the neck can lead to the airway becoming blocked
• Genetics – sleep apnoea can often be passed down in families
• Anatomic factors – those with an abnormally large tongue, tonsils or neck circumference are more likely to experience sleep apnoea.
• Age – the likelihood of sleep apnoea is greater in those older than 65 years compared to adults in the 30 to 50 years group
• Gender – sleep apnoea is more prevalent in males than females
• Smoking – tobacco can inflame the airway and cause breathing difficulties
• Alcohol – this causes muscles, such as the tongue, to relax, leading to the collapse of the upper airway^2,3

Diagnosis of sleep apnoea

Questionnaires and symptom-scoring scales

Initial symptoms are often the primary consideration in the diagnosis of sleep apnoea. If your doctor suspects you have the condition, screening questionnaires can be used to determine whether further tests are necessary to confirm the diagnosis.

One such example is the STOP-bang questionnaire which gathers information on factors such as tiredness, blood pressure, age, and gender to assess your likelihood of suffering from sleep apnoea.

Another example is the Berlin questionnaire which consists of various questions divided into categories to determine how high your risk of sleep apnoea is.

Symptom-scoring scales, such as NoSAS³ and the Epworth sleepiness scale, can also be useful for the indication of sleep apnoea. The former stands for Neck, Obesity, Snoring, Age, Sex, and uses these factors to determine the chance of sleep apnoea whilst the latter measures your chance of dozing in certain situations to estimate your level of daytime sleepiness.^4,5

Diagnostic tests

Polysomnography

Polysomnography, or a sleep study, is considered the standard diagnostic procedure for sleep apnoea. You stay in a laboratory overnight with video recording and continuous monitoring by a sleep technician. The data generated during this time helps to inform doctors about your sleep stages and breathing patterns, as well as any arousal or movement that you might have experienced while asleep.⁶

Despite the high diagnostic accuracy of polysomnography, the procedure can be costly and time-consuming and requires highly specialised equipment which may not always be available.⁴

Home sleep apnoea testing (HSAT)

As an alternative to polysomnography, HSAT can be used if you have a high probability of sleep apnoea but do not suffer from any comorbidities such as cardiovascular disease or a history of stroke. This test uses simpler machinery so may not be as accurate as polysomnography but can still give a good indication of sleep apnoea through the measurement of parameters including heart rate, body position, oxygen saturation, and airflow.^4,6

Additional diagnostic tools

Mallampati classification is a system which looks for any abnormalities in the oropharyngeal structures which may be affecting airflow. This includes the soft palate, uvula, tonsils, and tongue.^4,5

Nasal congestion is common in sleep apnoea so an exam in which the nasal cavity is assessed for any inflammation or deformity may be carried out.⁵

Imaging studies are useful to check for any defects in the airway structure. A cephalometric x-ray produces a side view of your head and neck and can reveal any changes to the structure of the bone and soft tissue in this area.

A cone-beam CT, or CBCT scan is slightly advantageous over a cephalometric x-ray in that it is capable of producing a 3D image of the head and thus may be more informative in suspected cases of sleep apnoea. A major drawback is that it is more expensive than a cephalogram albeit it is becoming more widely available in clinical practice.⁵

Treatment of sleep apnoea

 The main aims when treating sleep apnoea are:

• To reduce symptoms
• To improve quality of life
• To reduce complications
• To decrease mortality⁷

Continuous positive airway pressure therapy

Abbreviated as CPAP, this is the first-line treatment for sleep apnoea. It involves wearing a mask covering the nose and mouth and delivering circulating compressed room air to the upper airway through a tubing system. This increase in pressure serves as a ‘splint’ to keep the airway open.

Autotitrating positive airway pressure (APAP) and bilevel positive airway pressure (BPAP) devices may be an alternative to those who cannot tolerate the continuous form of this therapy. The former can adjust the delivered pressure in response to a patient’s changes in airflow whilst the latter can deliver higher pressures during inhalation than exhalation if this is something your doctor deems necessary for you.

This form of treatment is generally very effective in eliminating sleep apnoea and its associated symptoms, albeit the mask can be uncomfortable to wear and thus compliance rates can be low. Your doctor should have a thorough discussion with you regarding sleep hygiene and the importance of strict adherence to this treatment so that you can manage your sleep apnoea in the best way possible and reduce complications.^2,7

Surgical options

If CPAP proves ineffective for you, there are several surgical options which can provide some benefit.

Uvulopalatopharyngoplasty (UPPP)

This is the most common surgical treatment for sleep apnoea and involves the removal of tissue from the upper airway to expand its capacity and thus prevent collapse. UPPP has a high success rate and significantly reduces the apnoea-hypopnoea index (AHI).^2,7

Nasal surgery

Nasal obstruction is a key contributor to sleep apnoea so undergoing surgery to resolve this will improve airflow resistance in the nasal cavity, thus reducing your symptoms.⁵

Tonsillectomy

Normally, removal of the tonsils is performed if you suffer from recurrent infections or cancer in this area. However, research suggests that this procedure could be useful for the treatment of sleep apnoea since abnormally large tonsils can cause the upper airway to become blocked.⁷

Maxillomandibular advancement surgery (MMA)

This procedure is particularly beneficial if the cause of your sleep apnoea is due to a structural abnormality. The jaw is realigned to improve airway space. This, in turn, prevents the tongue from falling backwards and the upper airway from collapsing. Although MMA is a complex operation, the cure rate is quite high, making it a promising treatment option for sleep apnoea.^5,7

Hypoglossal nerve stimulation

This is a more advanced form of surgery whereby a stimulation device is placed near the hypoglossal nerve to improve muscle movement of the tongue. This increases the volume of the upper airway to allow for better airflow.⁷

Lifestyle changes

This involves addressing the risk factors that may worsen sleep apnoea. You may be recommended to:

• Limit your alcohol intake
• Quit smoking
• Lose weight
• Exercise regularly
• Avoid sleeping on your back – when in this position your tongue is more likely to fall backwards and block the airway⁷

Oral appliances

These include mandibular advancement and tongue retention devices which are worn in the mouth to position the lower jaw and tongue in such a way to prevent the airway from collapsing.³ 

Although not as effective as CPAP, oral appliances can be useful if your adherence or tolerance to CPAP is poor.⁵

Summary

Sleep apnoea is a breathing disorder, the most common of which is obstructive sleep apnoea. This particular type is characterised by the regular disturbances of breathing while asleep, due to blockage of the upper airway. Questionnaires and symptom-scoring scales are useful for the initial indication of sleep apnoea, and suspected cases are subsequently confirmed through a sleep study, known as polysomnography.

If you are diagnosed with sleep apnoea, CPAP will likely be the first treatment recommended to you. If ineffective, your doctor may discuss surgical interventions, such as UPPP or tonsillectomy. Finally, it is important to note that adopting a healthy lifestyle can lead to a significant improvement in sleep apnoea symptoms and reduce your chance of developing complications, like cardiovascular disease.