Facilities & Services
The Adelaide Institute for Sleep Health is affiliated with the Flinders Medical Centre and Flinders University. AISH provides a public sleep service based at the Repatriation General Hospital, a private sleep service at Ashford Hospital and an additional sleep service in Darwin.
Accredited by the Australasian Sleep Association and The Thoracic Society of Australia and New Zealand, the sleep laboratory offers a 7-bed facility equipped with state-of-the-art patient monitoring facilities.
The AISH team consists of a highly qualified and experienced team of physicians, specialist nurses, sleep technologists and scientists all working to provide diagnosis and treatment of sleep apnoea and other sleep disorders, and conduct cutting edge sleep research.
Types of Sleep Study
- Diagnostic Sleep Study. Read more
- CPAP (Continuous Positive Airway Pressure) Study. Read more
- BiPAP (Bi-level Positive Airway Pressure). Read more
- Multiple Sleep Latency Test (MSLT). Read more
- Maintenance of Wakefulness Test (MWT). Read more
Diagnostic Sleep Study
Diagnosis of OSA usually involves an overnight stay in the Sleep Laboratory for a sleep study (polysomnography) to establish the presence and severity of OSA. Polysomnography involves the measurement of several neurolophysiological parameters by trained sleep technologists. The parameters measured include:
- Electroencephalography (EEG): measures the electrical activity of the brain derived from leads (electrodes) on the scalp. This allows for the recognition of different stages of sleep such as Slow Wave Sleep and Rapid Eye Movement (REM) Sleep.
- Electro-oculogram (EOG): electrode cups placed near the eyes to detect and record eye movements which are used to distinguish between different sleep stages (e.g. the rapid eye movements of REM sleep).
- Electromyogram (EMG): electrodes usually placed on the chin are used for the measurement and recording of muscle activity. One utility of this measurement is to distinguish between REM and other stages of sleep.
- Electrocardiograph (ECG): recording of cardiac cycle, including heart rate and rhythm.
- Position: sleep posture is an important measurement as snoring or and apnoeas are often worse when sleeping on the back.
- Leg sensors: placed on the anterior tibialis (shin) muscle to detect PLM (Periodic Limb Movements).
- Vibration sensor: placed over the throat of patients to detect snoring.
- Pulse oximetry: provides estimates of arterial oxyhaemoglobin saturation (SaO2) by utilising selected wavelengths of light to noninvasively determine the saturation of oxyhaemoglobin in the blood.
- Breathing (as measured by nasal pressure): reduction or absence of pressure (i.e. breathing through the nose) is used to detect apnoeas.
- Thoracic and abdominal respiratory effort: measured by inductive plethysmography (reduction or absence of respiratory effort is used to detect apnoeas).
- Transcutaneous CO2 monitoring: a sensor placed on the skin to measure levels of carbon dioxide in the bloodstream.
AISH also offers assessment and treatment of sleep disorders for Repatriation General Hospital inpatients. Our inpatient service may involve the use of ambulatory polysomnography, pulse oximetry and transcutaneous CO2, standard and autotitrating CPAP therapy and bi-level ventilation (see below for description).
CPAP (Continuous Positive Airway Pressure) Study
Diagnosis of moderate-severe sleep apnoea usually results in a follow-up CPAP trial in the sleep laboratory. During this trial, the measurements recorded during the diagnostic study are repeated, to assess the effectiveness of CPAP therapy. A CPAP machine generates air pressure directed through the nasal passages and into the throat. Air pressure is delivered through a mask that fits over the nose and/or mouth, and is worn while sleeping. The pressure holds the throat open and prevents snoring, apnoeas and other breathing irregularities. Sleep technologists in the laboratory manually adjust the pressure to relieve patients of these breathing irregularities while monitoring the neurological and physiological parameters previously described.
BiPAP (Bi-level Positive Airway Pressure)
Bi-level ventilation is another form of positive airway pressure management. Unlike CPAP, Bi-level ventilation (or BiPAP) provides two separate pressures, an expiratory positive airway pressure (EPAP) and an inspiratory positive airway pressure (IPAP). The EPAP is set lower than the IPAP. Whilst the EPAP maintains airway patency during exhalation, the IPAP provides additional ventilatory support during inspiration. This form of therapy is most commonly applied only during sleep to treat sleep hypoventilation that may occur in patients with conditions such obesity hypoventilation syndrome, hypoventilation related to neuromuscular disorders such as motor neurone disease or chest wall abnormality, and in selected cases of COPD/OSA overlap.
Multiple Sleep Latency Test (MSLT)
The MSLT (Multiple Sleep Latency Test) measures sleep propensity and may be used as an objective measure of excessive daytime sleepiness. The diagnosis of narcolepsy often incorporates characteristic findings from a MSLT. The test takes place during the day, and consists of 5 opportunities to sleep during the day. Patients are asked to lie quietly in a dimly lit room and to attempt sleep. The time it takes to fall asleep and the type of sleep recorded during these naps provide useful diagnositic information for the clinician.
Maintenance of Wakefulness Test (MWT)
The MWT is a different form of daytime test that may be used to objectively measure excessive daytime sleepiness. It measures patients' ability to stay awake in a soporific environment. The patient is asked to sit upright in a chair in a dimly lit room and to remain awake for 40 minutes. The test is conducted 4 times across the day at 2 hourly intervals.