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Department of Sleep Medicine
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Last Updated:
24 May, 2005

Obstructive Sleep Apnoea/Hypopnoea Syndrome (OSAHS)

What is OSAHS?
Limited (home) sleep study
    Continuous Positive Airway Pressure (CPAP)  
    Mandibular repositioning splint  
    Weight loss  
    Chronic Non-invasive Ventilation (Bi-level therapy)  

What is OSAHS?

  • Obstructive Sleep Apnoea / Hypopnoea Syndrome is a relatively common disorder affecting approximately 4% of middle-aged men and 2% of middle-aged women.
  • There are many symptoms associated with this disorder among the most common being snoring and daytime sleepiness.
  • Factors predisposing a person to OSAHS include being male, carrying excessive body weight (particularly in the neck) and a back set jaw. Their absence however does not exclude a diagnosis of OSAHS.

The symptoms of OSAHS are caused by a cycle of events that can happen hundreds of times every night.


Cycle of events

Falling asleep -> snoring -> airway narrowing -> increased effort to breath in -> wake from sleep (can be with loud snore / choking sensation)
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Daytime symptoms
Daytime fatigue
Difficulty concentrating
Decreased libido

Night time symptoms
Unrefreshing sleep
Restless sleep
Choking episodes
Getting up to the toilet frequently

Consequences of sleep disruption in patients with OSAHS

Frequent wakings = sleep disruption so increased sleepiness and risk of road accidents, also increased blood pressure leads to increased risk of stroke and heart attack.
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  • Diagnosis of Obstructive Sleep Apnoea/Hypopnoea Syndrome (OSAHS) is made by overnight monitoring to detect events characterising the syndrome.
  • This can take place either in the Department of Sleep Medicine with a test called overnight polysomnography or at home; a home study. All sensors are attached to the surface of the skin only, so undergoing a sleep study is painless.



One of the bedrooms

This overnight study takes place at the Department of Sleep Medicine in one of seven specially equipped sound-proofed single bedrooms.

  • Sleep quality, chest and abdomen movements, heart-rate, oxygenation, snoring and leg movements are all monitored.
  • Specialist nurses place electrodes on the face and scalp, nasal cannulae over the lip, bands around the chest and abdomen, sensors on the legs and an oxygen sensor on a finger.
  • These sensors are all plugged into a box which feeds signals into a computer.
  • Sleep specialist nurses on duty will watch the signals and if a diagnosis of OSAHS is made in the early part of the night the patient may be commenced on CPAP treatment the same night.
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Limited (home) sleep study

A sleep study in the patients' own home can be carried out using portable recording equipment.



Embletta case


Hypno-PTT case
  • The equipment includes a breathing sensor attached to the lip, sensors to monitor heart rate, bands around the chest and a plaster-like oxygen sensor over a finger.
  • These allow breathing movements, oxygen levels, heart rate, and snoring to be recorded.
  • The patients attend the Department in the daytime to be given instruction on how to use the equipment. The following morning the equipment is returned and the information collected overnight is downloaded onto a computer.

This type of study allows the patients to sleep in their own enviroment. However a polysomnography in the Department may be required if more information on sleep quality is needed.

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Continuous Positive Airway Pressure (CPAP)

Benefits of CPAP

The CPAP pump operates by maintaining a constant pressure of air through a nose/full face mask whilst the patient is asleep. This results in splinting the throat open and preventing its closure whilst asleep (the cause of sleep apnoea). Partial throat closure during sleep results in snoring and this is also alleviated by a CPAP pump.

Use of the CPAP pump will allow free breathing during sleep to allow for a normal sleep pattern and a restful sleep. Regular use of the CPAP pump will result in other positive long-term effects including improved mood, memory, concentration and better quality of life. There is increasing evidence that CPAP also improves blood pressure and helps to prevent heart attacks and strokes.

CPAP education

Prior to undergoing an overnight CPAP trial, all patients thought to require CPAP are invited to attend a session of CPAP education. Attendance of a partner or housemate together with the patient is strongly encouraged. CPAP education is generally carried out by one of the sleep specialist nurses and allows each patient individually to adjust to the idea of CPAP. The education session takes place in the sleep lab and normally runs for about an hour. It involves:

This will involve:
  1. Watching a DVD about sleep apnoea and CPAP (which has been produced by the Dept of Sleep Medicine). There should be adequate time for questions and discussion with the sleep nurse afterwards.
  2. Having a mask fitting to ensure the most appropriate and comfortable mask is used during the CPAP trial.
  3. Using the CPAP machine whilst awake.
CPAP machine
We have found that patients and their partners benefit greatly from attending CPAP education.



CPAP trial

  • When the patient comes in for their CPAP trial investigation, they will be asked to wear one of the masks trialled at the CPAP education session.
CPAP mask
  • During the night, measurements will be recorded by the CPAP machine that will enable us to determine what pressure the CPAP pump will need to be set at. This will ensure that any breathing problems can be effectively corrected.
  • In the morning after the CPAP trial, the machine will be downloaded to a computer, which will show the optimal pressure and any potential problems with mask leak etc.
  • The sleep nurse specialist will then set the optimal pressure for the CPAP machine which the patient then takes home.
  • Every patient will be given an appointment for review in OPD1 (Outpatient Dept 1, Ground Floor). This will be in approximately six months from the date of the CPAP trial.
  • Patients are encouraged to contact the nursing staff before then if they are having any problems using CPAP.
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Mandibular repositioning splint

  • If you are diagnosed with simple snoring, or mild sleep apnoea, you may be treated using a mandibular repositioning splint, or MRS (sometimes also referred to as a mandibular advancement device, or MAD).
  • This is a dental appliance, similar to a gumshield, which is worn over the teeth while you are asleep. It acts by holding the lower jaw and tongue forward, which in turn increases the space at the back of the throat, reducing the narrowing of the airway which can lead to snoring.
  • The MRS is made individually for you by an orthodontist using impressions made of your teeth and jaw.
  • An MRS may not be suitable for you if you have none or very few of your own teeth.
Mandibular repositioning splint
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Weight loss

Symptoms of sleep apnoea are generally worsened in people who are overweight and studies have shown that weight loss reduces the degree of sleep disordered breathing at night.
It is therefore very important that weight is kept within the normal range. Consultation with a dietitian may be necessary to assist in safe and sensible weight loss.
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Chronic Non-invasive Ventilation (Bi-level therapy)

Our clinic sees a wide variety of patients who require bi-level ventilation at night.

These include patients with: chest wall disorders (e.g. kyphoscoliosis; post-TB surgery); neuromuscular disorders; obesity-hypoventilation.

Patients are reviewed on a regular basis.


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