Combination mode of physiological signals for diagnosis of OSAS using portable monitor.

PURPOSE: Portable respiratory monitor (PRM) has been proposed for pre-diagnosis of obstructive sleep apnea syndrome (OSAS). However, discrepant physiological signal combinations were rarely studied for diagnostic assessment of OSAS. This study was designed to evaluate combination modes of key physiological signals collected by portable sensor modules for OSAS screening in comparison with polysomnography (PSG).

METHODS: People with suspected OSAS were submitted to PRM at a sleep laboratory monitoring concurrently with PSG. The diagnostic accuracy was assessed by sensitivity, specificity, Pearson correlation coefficients, kappa statistic, and Bland-Altman plot. Four combination modes of PRM, including mode 1 with single nasal airflow, mode 2 with airflow plus body activity, mode 3 with airflow plus SpO2, tri-combination mode 4 with airflow plus SpO2 plus activity were studied.

RESULTS: Thirty-five subjects (69% men, mean age ± SD, 49 ± 12 years) with averaged apnea-hypopnea index (AHI) of 36 ± 29 events/h were tested. Excluding incomplete recordings, 33 valid samples were analyzed. All PRM modes demonstrated good concordances with PSG in diagnostic outcomes. Tri-combination mode had optimum with sensitivity of 96.5%, specificity of 100%, +LR of 4, -LR of 0.03, and kappa coefficient of 0.85 for screening OSAS holding AHI ≥5. Its Bland-Altman plots also showed the smallest dispersion.

CONCLUSIONS: This study used clinical comparison to demonstrate diagnostic accuracy of PRM with different physiological signal combination. The combination of respiratory airflow, oxygen saturation, and body activity provided sufficiently high accuracy for diagnosing OSAS. Single respiratory airflow sensor as the simplest PRM was also feasible for pre-screening OSAS.