PSG remains the gold standard in the diagnosis of OSA as it is accurate and has a low failure rate. However PSG is technically complex and expensive and requires overnight laboratory staffing. Sleep labs may have variable availability in markets outside metropolitan areas. Home sleep apnea testing (HSAT) via portable monitoring (PM) units have become an attractive alternative to lab-based PSG. Clinical judgement is required to determine if PM would be appropriate in a given patient with suspected OSA symptoms. PM may be considered if there is suspected, high pre-test probability that the patient would likely have moderate to severe OSA and the patient is free from medical comorbid health conditions.11 Or it may be employed in situations where PSG is not possible as in cases with patient immobility, critical illness or facility access issues. PM would not be suited for those with comorbid medical conditions and/ or in the face of other sleep disorders, and thus PSG would then be preferable
HSAT requires at least 6 hours’ worth of data. Sleep testing has been classified into 4 levels based on the number of parameters it measures.12
Level 1 – Standard PSG: minimum of 7 parameters: EEG, EOG (electrooculogram), chin EMG, airflow, respiratory effort, oximetry with a technician in attendance.
Level 2 – Comprehensive portable PSG: minimum of 7 parameters: EEG, EOG, chin EMG, airflow, respiratory effort, oximetry. No personnel present. No intervention possible.
Level 3 – Modified portable apnea testing: minimum of 4 parameters from the following: airflow, ventilation, respiratory movement, oximetry and heart rate or ECG. Body position can be objectively measured. No personnel present. No intervention possible.
Level 4 – Continuous single or dual parameter recording: minimum of 1 parameter; usually either airflow or pulse oximetry which can measure oxygen saturation and heart rate. Body position cannot be measured. No personnel present. No intervention possible.
Note that level 3 and 4 PM devices cannot determine sleep staging or sleep disruption. Of interest to the dentist who provides dental sleep medicine services, according to the American Academy of Dental Sleep Medicine Portable Monitoring Task Force, PM may be used to monitor treatment response to non-PAP treatments such as oral mandibular advancement devices, upper airway surgery and weight loss.13 Such patients must have a diagnosis of OSA already made via PSG and the raw data and report signed by a certified sleep physician. HSAT is not meant to screen asymptomatic populations and PM must be ordered by a sleep physician.11
Dependent on region-to-region practices, insurance reimbursement of PM devices may depend on who orders the test, i.e. sleep physician or dentist. A dentist may play a role in identifying patients with subjective symptoms and objective risk factors of OSA and make a referral to a sleep physician.