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What is OSA?

Obstructive Sleep Apnea (OSA) is a form of breathing disorder that occurs during sleep.

Patients with OSA have difficulty breathing when they sleep because their upper air passages in the nose and throat collapse and obstruct more easily than those that do not have OSA. This may occur due to nasal blockage, enlarged tonsils, a large tongue (in relation to the mouth) or a small sized jaw.


During these obstructive episodes, the patient is trying to breathe but is unable to because of the obstruction. He may stop breathing partially (hypopnea) or completely (apnea).

During such episodes, the oxygen concentration in the body drops. As a result, the patient's oxygen level in the body decreases. This causes great stress on the heart because it now has to pump harder and faster to supply oxygenated blood to the rest of the body.

If left untreated, this can lead to serious and long-term health consequences as the heart and brain’s blood supply could easily be compromised.

When Does OSA Occur?

Upper airway obstruction from OSA may occur anytime during sleep.

They however occur more often during deep sleep (S3) and dream sleep (REM) because the muscles are more relaxed during these sleep periods.

The patient is trying hard to breathe but is unable to get air into the lungs because of upper airway collapse.

What are the Risks of Obstructive Sleep Apnea?

OSA is fairly common with an estimated 15% of our population suffering from it.

Patients who are more at risk include:

  1. Middle aged males
  2. Overweight individuals
  3. Patients with certain hormone problems (e.g. hypothyroidism)
  4. Patients with enlarged tonsils (e.g. from frequent sore throats)
How is Obstructive Sleep Apnea Diagnosed?

The only way to diagnose OSA accurately is to do an overnight sleep study, which can be done either at home or in the hospital.

Even if screening questionnaires, the patient’s medical history and physical examination all suggest that the patient may have OSA, it is ultimately still not the most reliable and the decision to treat is always based on the sleep study result.

(A sleep study provides information on the number of apneic and hypopneic episodes each night and its effect on the cardiorespiratory system.)

Common Sites of Obstruction

The doctor will examine you with a flexible nasendoscope to determine where the sites of obstruction are. This helps the doctor decide if surgery is necessary, and if so, to predict the surgical success rate.

  1. Nose
  2. Adenoid Tissue (back of the nose)
  3. Soft Palate
  4. Tonsils
  5. Lateral Pharyngeal Walls (side of throat)
  6. Tongue Base
  7. Epiglottis
Treatments for Obstructive Sleep Apnea
  1. Sleep Hygiene
    1. May be sufficient treatment for those with mild OSA
    2. It may include:
      1. Lying on one’s side
      2. Propping one’s back up with a wedge pillow while sleeping
      3. Avoiding alcohol and cigarettes before bedtime
      4. Get regular and sufficient sleep
  2. Weight Loss
    1. Fat deposited within the tongue, muscles and soft tissues of the upper airway and neck increases the risk of them collapsing during sleep
    2. Weight loss and its maintenance is a key component in the management of OSA
  3. Mandibular Advancement Appliance (MAD)
    1. The MAD advances the lower jaw and its contents (tongue) and increases the tension in the muscles that keep the upper airway open during sleep
    2. Only eligible for some patients who snore or who have mild to moderate OSA
  4. Continuous Positive Airway Pressure (CPAP) Device
    1. A device that is worn at night during sleep
    2. The patient wears a mask over his nose (and or mouth) which is connected to the CPAP machine
    3. Air is blown into the mask which splints the upper airway open with a column of air
    4. CPAP has the best treatment outcomes in the management of OSA and is recommended for the majority of patients
    5. However it is also associated with poorer long term compliance rates due to its inconvenience and some discomfort
  5. Surgery
    1. Very individualised; it can be performed on:
      1. The nasal cavity (to reduce nasal obstruction)
      2. The throat (to reduce laxity and increase the dimensions of the upper airway)
      3. The tongue (to reduce volume and also to advance the tongue)
    2. Not all are suitable for surgery
  6. Inspire® Upper Airway Stimulation (UAS) System
    1. A hypoglossal nerve stimulation system implanted beneath the skin to relieve upper airway obstruction during sleep for uninterrupted rest.
    2. Two incisions are made: in the upper right chest where the small hypoglossal nerve stimulator device is placed; and just under the chin where the hypoglossal nerve is located.
    3. The Inspire device consists of a small battery and two small wires, and is controlled with a small, handheld remote for turning on before bed and off in the morning, or pausing during the night if needed.
    4. The Inspire sleep therapy is suitable for moderate to severe Obstructive Sleep Apnea adult patients with an apnea-hypopnea index (AHI) between 15 and 65, who do not benefit from CPAP treatment.
    5. It is not intended for patients with a complete concentric collapse at the level of the soft palate, or those in whom central and mixed apneas make up 25% or more of their apnea-hypopnea index.
Know Your ENT Specialist
Dr Paul Mok
Senior Consultant ENT Surgeon
MBBS, FRCS (Glasgow), FAMS (ORL)

Dr Paul Mok Kan Hwei is a certified specialist in Otolaryngology, Head and Neck Surgery (ENT) and has had a distinguished career in public service for the past 23 years.

He cares for patients with a wide variety of ENT conditions including managing patients with nasal allergies, sinus infections, ear problems and swellings in the head and neck region. His special areas of interests are in Voice, Swallowing and managing patients with Obstructive Sleep Apnea.

Dr Lau Hung Tuan
Consultant ENT Surgeon
MBBS (London), MRCS (Edinburgh), MMed (ORL), FAMS (ORL)

Dr Lau Hung Tuan is a Ministry of Health-accredited ENT specialist in Singapore. He is passionate about finding holistic, tailored and individualised care plans for his patients.

He treats patients with a wide range of ENT conditions, such as sinus infection, nasal allergy, ear problems and neck lumps. His special area of interest is in the sub-specialty field of Snoring and Obstructive Sleep Apnoea (OSA).