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    Obstructive Sleep Apnoea - Continuous Positive Airway Pressure Therapy

    Where to Seek Treatment
    Singapore General Hospital
    Contributed by Sleep Disorders Unit


    Short sleep arousal can lead to unrefreshing sleep

    Obstructive Sleep Apnoea (OSA) is a condition in which the upper airway collapses repeatedly during sleep. This creates an effect similar to that of being repeatedly choked throughout the night.

    During these episodes, there are recurrent dips in the blood oxygen levels, putting stress on the heart. As a result, sleep is unrefreshing and patients typically feel sleepy and irritable throughout the day.

    What if OSA is left untreated?

    In addition to causing sleep disruption and daytime symptoms, OSA can increase the risks of serious health complications such as:

    • Memory loss
    • Stroke (Almost 70% of people who have had a stroke have OSA)
    • Hypertension (>35% of people with sleep apnoea suffer from hypertension)
    • Diabetes
    • Depression
    • Heart failure and heart attacks (by 2 to 3 times)
    • Risk of motor vehicle accidents (by 7 times)
    • Increased risk of work-related accidents


    • Loud, frequent snoring
    • Cessation of breathing or gasping for air during sleep
    • Excessive daytime sleepiness
    • Unrefreshing sleep
    • Frequent urination at night
    • Erectile dysfunction

    I sleep through the night without recurrent awakenings, does this mean I do not have OSA?

    No. Often, the sleep disturbances caused by OSA are short and intermittent and are insufficient to fully rouse the affected person from sleep completely. These repeated short arousals are however enough to result in unrefreshing sleep and all the adverse health consequences described previously.


    It is best to see a sleep specialist to confirm the diagnosis. In the initial consultation, a thorough sleep history will be taken to assess for OSA. If OSA is suspected, an overnight sleep study is recommended to confirm the diagnosis of OSA.

    What is a sleep study?

    A sleep study or polysomnogram (PSG) is an overnight noninvasive diagnostic test done in a Sleep Laboratory. The PSG monitors the different stages of sleep, heart rhythm, muscle activity, breathing effort and oxygen levels during sleep. The severity of OSA can also be determined.


    A very effective treatment for OSA is Continuous Positive Airway Pressure (CPAP) therapy. CPAP therapy is considered the gold standard and most effective non-surgical treatment for OSA. Depending on the severity of OSA and the upper airway anatomy, other treatment options include weight loss, wearing of appliance during sleep and surgery.

    How does CPAP therapy work?

    Continuous Positive Airway Pressure - OSA treatment

    CPAP therapy works by quietly delivering pressurised air through the nose or mouth to keep the upper airway open and maintain normal breathing during sleep. There are two important parts of the CPAP machine that need to be decided on by careful consultation with your sleep physician prior to using CPAP.

    They are:

    1. The mask:
    CPAP is administered through a mask that seals either the nose, mouth or both the nose and the mouth. There are a variety of masks that can be used. Most of these are made from a soft silicon or gel to maximise comfort. The mask chosen for you will be fitted by the sleep technician to suit your facial structure and breathing habits.

    The first step in choosing the type of mask is to establish how you breathe naturally (through the nose, mouth or both). There are different types of masks to suit different needs, such as:

    • Nasal masks (for nose breathers)
    • Nasal pillows (for nose breathers)
    • Full face masks (for nose and mouth breathers)
    • Oral-nasal masks (for nose and mouth breathers)
    • Oral masks (for mouth breathers)

    In order to optimise the comfort and success of CPAP therapy, it is important to identify and treat any reversible causes of nasal obstruction (e.g. chronic rhinitis, nasal polyps or septal deformities) prior to CPAP therapy.

    2. The Machine:
    Most CPAP machines today are small – about the size of a bedside alarm clock – quiet and relatively portable.

    Modern CPAP devices can deliver a fixed pressure or may have sophisticated software that can detect obstruction and self-adjust the delivered pressure (auto-titrating machines). Excessive pressure can cause air leak and discomfort while insufficient pressure will not effectively treat the sleep apnoea.

    Some devices have special modes that allow you to breathe out more easily, or can deliver a different pressure depending on whether you are breathing in or out.

    The type and setting of each device will need to be individualised for each patient after consultation with your sleep specialist.

    What happens after OSA is treated?

    OSA sufferers who start using CPAP report sleeping better and feeling more energetic and less sleepy during the day. Some report feeling better after the first day of treatment while for others, the improvement may only become apparent after a few weeks of sustained use. The benefits of CPAP include:

    • Improved sleep quality with reduction or elimination of snoring and apnoea
    • Feeling more rested and alert during the day with improved memory and cognition
    • Improved blood pressure control
    • Reduced risks of stroke, heart failure and heart attacks
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