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Single channel flow study for diagnosis of OSA

DIAGNOSIS OF OBSTRUCTIVE SLEEP APNOEA/HYPOPNOEA SYNDROME USING A SINGLE CHANNEL FLOW STUDY AT HOME

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Melissa Thomas, Kim Ward, David Hillman
West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Perth WA 6009

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) affects 2-4% of the middle aged population. The diagnostic gold standard is laboratory polysomnography (PSG) but insufficient resources delay OSAHS diagnosis and treatment. Single channel flow study (SCFS) devices utilising nasal pressure measurement could provide a simple, low cost, readily available alternative. Methods: Patients attending for laboratory diagnostic PSG used a microMESAM® SCFS device at home the following night. Apnoea/hypopnoea index (AHI) from automated microMESAM® analysis was compared to that derived from technologist-analysed PSG. Results: To date 10 adult subjects have been recruited (2F: 8M). While positively correlated (r = 0.94, p< 0.001) microMESAM® AHI was significantly less than PSG AHI (28.1±36.7 (mean±SD) vs 38.1±37.9, p< 0.04). Where OSA was defined as PSG AHI ³10, 8 patients had the condition and microMESAM® demonstrated a high positive predictive value (1) but a modest negative predictive value (0.5). Conclusion: microMESAM® appears to be a useful tool to rule in OSA but less useful in ruling it out. Where clinical pretest probability is high, a positive test would allow treatment to proceed while a negative test indicates further investigation by PSG. Given its low relative cost, microMESAM® screening appears a cost-effective option for such patients.

Grant Support: Resmed Travel expenses.

Key words: Screening device, Obstructive Sleep Apnoea, nasal pressure, diagnosis.

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