Objective Cardiogenic oscillations (CO) in airflow signals contain valuable physiological information. However, accurately isolating CO from airflow signals, particularly in individuals with sleep apnea, remains a challenging signal processing problem.

Method We introduce the Optimal Shrinkage-aided Airflow Decomposition Algorithm (OSADA), a novel approach for extracting CO from airflow signals while simultaneously recovering a CO-free, noise-free airflow signal, referred to as diaphragm-driven airflow (DDairflow). The algorithm’s performance is quantitatively evaluated using both a semi-real simulated database and real-world data with benchmark comparisons to existing methods, including the bandpass filter (BPF) and Savitzky-Golay smoothing filters (SGF).

Result For the semi-real database, OSADA significantly outperforms BPF and SGF across multiple performance indices, including the normalized root mean square error (NRMSE) for CO and DDairflow recovery, as well as spectral energy indices of CO. For real-world data, OSADA also achieves superior performance in the data-driven spectral energy index of CO.

Conclusion OSADA is the first algorithm specifically designed for CO recovery from single-channel airflow signals, without relying on additional channels, and is supported by theoretical foundations. Quantitative results suggest robust performance for both CO extraction and DDairflow recovery.

The authors have declared no competing interest.

This study did not receive any funding

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

We assessed the performance of OSADA on real-world data from 22 subjects from a single-center prospective observational study at the sleep center in Taipei Veterans General Hospital, Taipei (VGHTPE), Taiwan, collected from June to December 2023 with Medical Ethics Committee approval (IRB No: 2023-04-003A). The study adhered to the ethical guidelines of the 1975 Declaration of Helsinki

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All data produced in the present study are available upon reasonable request to the authors