Attended in-laboratory diagnostic sleep studies (‘type 1 studies’) are needed where contraindications exist or for a second opinion, and require a sleep medicine practitioner or respiratory physician referral to be eligible for Medicare funding. Type 3 and 4 studies measure oxygen saturation and nasal airflow, without electroencephalography; these are not widely available, or Medicare subsidised. Table 1 summarises the indications, advantages and disadvantages of in-laboratory and home sleep studies.15
As shown in Box 2, in an adult with a suggestive history, who meets the Epworth Sleepiness Scale and other questionnaire criteria, GPs are the key healthcare providers for referring patients to get a Medicare subsidised ‘Type 2’ sleep study, providing there are no features that require a sleep physician review (Box 3). In-laboratory studies require a sleep physician review for the study to be Medicare subsidised. Box 3 summarises the patient groups who would benefit from input from a sleep medicine specialist.16
Key results from a sleep study
The key parameters to review in a sleep study report are summarised in Table 2. Building a relationship with local sleep study testing facilities is helpful for consistent results. To check which laboratories in your local area are accredited, see the National Association of Testing Authorities, Australia (NATA) website (www.nata.com.au/accredited-facility) and search by state using the keyword ‘sleep’.
Treatment options for OSA
Unfortunately, OSA is a chronic disease that rarely resolves spontaneously. OSA treatment options include positive airway pressure (PAP), a mandibular advancement splint, surgery, positional therapy and weight loss.
The gold standard treatment for OSA is CPAP. The CPAP machine is a small bedside pump connected to the patient’s upper airway via a mask attached to their face, splinting the airway open. Auto-titrating CPAP (APAP) is a form of CPAP delivered by a device that contains sensors to increase and decrease the pressure in order to maintain a patent airway. Most patients do not require auto-titrating CPAP machines; for more information see our follow-up article about CPAP therapy in a future issue of Medicine Today.
CPAP is indicated in symptomatic moderate to severe OSA, or mild OSA with an oxygen saturation (SpO2) less than 90% for greater than 10% of the night.
CPAP is a highly effective treatment for OSA. There is strong evidence that CPAP therapy for people with OSA improves the AHI and daytime sleepiness, reduces motor-vehicle accident risk, and increases quality of life.17 The number needed to treat to achieve a two-point reduction on the Epworth Sleepiness Scale is only four, with a cost to the healthcare system of only about $550 per person per year.1,18 Another advantage of CPAP therapy is that the CPAP machine can be rented to test for symptom improvement before purchase.
Disadvantages of CPAP therapy include side effects and the cost of the device and mask replacement. Side effects such as nasal congestion and dry mouth are common, and adherence to CPAP therapy of greater than four hours per night is required to obtain ongoing benefits.
Mandibular advancement splints
Mandibular advancement splints advance the lower jaw while the wearer sleeps. They are custom-made by a specialist dentist. The Australasian Sleep Association list of accredited sleep dental services can be found online in the Sleep Services Directory by selecting OSA – Dental Treatment and your location (www.sleep.org.au/public/resources/sleep-directory).