Rationale: Obstructive sleep apnea (OSA) is a common but underdiagnosed disorder. There is a need for validated simpler modalities such as single-channel monitors to assist diagnosis of OSA.
Study objectives: To assess data sufficiency, agreement, and diagnostic accuracy of nasal airflow measured by a single-channel pressure transducer device (Flow Wizard, DiagnoseIT, Sydney, Australia) compared to attended full polysomnography (PSG) on the same night for OSA diagnosis.
Design: Cross-sectional study.
Setting: Laboratory.
Participants: Subjects with possible OSA referred to the sleep laboratory for PSG were eligible.
Methods: Nasal airflow was measured by a pressure transducer in the laboratory concurrently with PSG.
Results: Of 226 eligible subjects who consented, 221 (97.8%; 151 males, 70 females) completed the protocol. With nasal airflow measurement, 5.3% of subjects had insufficient data, compared with 2.2% on PSG. The mean difference between PSG AHI and NF RDI was -6.2 events/h with limits of agreement (+/- 2 standard deviation [SD]) of 17.0 events/hr. The accuracy of the Flow Wizard for diagnosing severe OSA (PSG AHI > 30) was very good (area under the ROC curve [AUC] 0.96; 95% confidence interval [CI] 0.92 to 0.99) and for diagnosing OSA (PSG AHI > 5) was good (AUC, 0.84; 95% CI, 0.77 to 0.90). There was no difference in the rate of data insufficiency and accuracy between males and females.
Conclusion: Nasal flow measured by a nasal pressure transducer has a low rate of data insufficiency, good agreement, and high accuracy compared to PSG for diagnosing OSA in the monitored sleep laboratory setting.