Snoring and Obstructive Sleep Apnoea
What are snoring and sleep apnoea in children?
When a child is awake the muscles in the throat are subconsciously working to keep the throat and airway passages open. However, when children fall asleep the muscles throughout their body relax, including those in the throat. When these throat muscles (tongue base/soft palate/pharyngeal constrictors) relax they can narrow the airway. For most people though, there is still plenty of space to breathe easily.
If the throat muscles relax more and narrow the airway further, then snoring can occur. Snoring is the sound generated by vibration of the throat muscles during breathing.
Approximately 2-3% of children in the country have a more severe version of snoring called obstructive sleep apnoea. This occurs when further relaxation/collapse of the throat muscles leads to temporary blockage of the breathing passages (apnoeas). In this situation the body will partly (or fully) wake the child up, in order for the muscles to open the airway and allow breathing to return to normal. However, when the child then returns to deeper sleep the same problems of airway obstruction often recur. This creates a cycle of deeper sleep and obstructed airways, followed by partial waking with return to normal breathing (often seen as a large gasp of air).
Normal sleep in a child involves several specific sleep cycles each night, fluctuating between light and deep sleep, as well as REM sleep (dream sleep). This pattern is important for effective processing of information, brain development and memory, and allowing the child to feel happy and energised the following day. Sleep apnoea disrupts these normal sleep cycles, as the body has to wake itself regularly to maintain adequate breathing.
What causes sleep apnoea in children?
Any factor which narrows a child’s upper airway can make sleep apnoea more common. The most common causes are enlarged tonsils and adenoids, or swollen lining inside the nose (rhinitis). Other factors include obesity, cranio-facial syndromes (such as Achondroplasia or Crouzon Syndrome), ethnicity (being Afro-Caribbean increases the chance), metabolic or neuro-muscular problems (such as cerebral palsy).
Problems caused by Snoring and Sleep Apnoea
Many of the symptoms of sleep apnoea are related to the disruption of sleep, which then causes a reduced quality of sleep. Therefore children may sleep for a good number of hours, but if the quality of sleep is reduced it may not be enough to keep up with their rapid development. If severe, sleep apnoea can cause excessive strain on the heart as it works harder to pump blood.
More recently it is understood that even snoring, without sleep apnoea, can cause significant symptoms. As a result the threshold for treatment has reduced.
Problems from snoring or sleep apnoea include:
Ongoing need to nap during the day
Reluctance to wake up/get up in the morning
Hyperactivity or poor behaviour
Significant variability in mood
Impaired growth (height or weight)
How can I tell if my child has sleep apnoea?
The most commonly seen symptom is significant snoring most of the night. Additional features seen may include:
Unusual head positioning (helping to open their own airway)
Increased work of breathing (sucking-in of the chest; and sucking-in low in the front of the neck )
Gasping for air
Frequent waking from sleep
With experience, it is possible to diagnose sleep apnoea for most children in clinic, based on the history and examination findings. Video of a child sleeping is often very helpful. However, for some children with mild symptoms, or those with severe symptoms and other complex medical problems, sleep testing may be helpful. Two main techniques exist for this, Pulse Oximetry and Polysomnography, and both aim to assess the disruption to normal breathing while the child is asleep.
This uses a simple finger probe to measure Oxygen levels (saturation) throughout the night while the child is sleeping, and can often be done at home. The small machine records the data, which is then analysed by the Sleep Team. The presence of oxygen de-saturations (drops in Oxygen level) is often a marker of breath holding and apnoeas.
The limitation of this test is that it can miss a significant number of children who do in fact have sleep apnoea. This is called a high false-negative rate.
This is a more detailed test, and requires children to be admitted to a special Sleep Department, where their sleep is monitored overnight. Oxygen and Carbon Dioxide levels are monitored, as well as chest and stomach movement, snoring volume, and other parameters. Polysomnography is considered the “gold standard” test, but is generally only available in specialist Children’s Centres.
The limitation is that sleep apnoea severity can fluctuate, even over a few weeks. Any sleep test is therefore a “snap-shot” on one night, and not necessarily representative of an average.
Severity of Obstructive Sleep Apnoea
Sleep apnoea severity is described as the number of times per hour a child’s airway is partly/fully obstructed. This is called the apnoea/hypopnoea index (AHI). This correlates with the degree of impact on sleep. Other measurements in the sleep study, such as the 3% Oxygen dip rate, can also be helpful.
Normal - AHI less than 1
Mild Obstructive Sleep Apnoea - AHI 1-5
Moderate Obstructive Sleep Apnoea - AHI 5-10
Severe Obstructive Sleep Apnoea - AHI over 10
The treatment for sleep apnoea should focus on the underlying cause. Many children will have a short period of sleep apnoea in association with an upper respiratory infection, when the tonsils and adenoids are temporarily enlarged, and the nose is blocked. However, if the sleep returns to normal after resolution of the infection, then usually no treatment is required. If the problems are more long standing, then there may be medical and surgical treatment options.
Many children with sleep apnoea will eventually grow out of their symptoms, as their throat enlarges and their tonsils and adenoids gradually shrink in size. Often the challenge is knowing when this improvement may occur, but a period of waiting is reasonable to allow for this. In my experience if symptoms have been present for six months, early improvement is unlikely.
If the source of airway obstruction is swelling of the lining of the nose, often related to allergy, then medical treatment may be effective. A combination of non-drowsy antihistamine by mouth, and a topical steroid nasal spray (with minimal systemic absorption), can reduce the swelling inside the nose and improve the airway and sleep quality.
For many children with sleep apnoea, the main contributing factor is enlarged tonsils and/or adenoids. If conservative treatment is unsuccessful, then surgery is usually very effective in resolving the symptoms swiftly. Even children with additional severe medical problems contributing to sleep apnoea (such as cerebral palsy), will often gain great benefit from.
If the nasal lining remains swollen even after medical treatment, then there is a surgical option to shrink down this mucosa (Coblation reduction of inferior turbinates) and improve the nasal airflow. This can be combined with tonsil and adenoid surgery if needed.