DCDA-Net: Dual-convolutional dual-attention network for obstructive sleep apnea diagnosis from single-lead electrocardiograms

Obstructive sleep apnea (OSA) is a breathing-related chronic disease in which the soft palate and tongue collapse and block the upper airway for at least 10 s during sleep. It can lead to many heart diseases such as hypertension, myocardial infarction, and coronary heart syndrome if not detected early. Artificial intelligence has facilitated the diagnosis of many diseases in healthcare. Polysomnography is a widely used but unpleasant, time-consuming, technically demanding, and financially expensive procedure to detect OSA. Some previous methods have detected OSA using time-domain information from an electrocardiogram (ECG), whereas others have used frequency-domain information. The limitations of these two approaches can be handled using the data's time–frequency representation. Nevertheless, there is room for enhancing the detection accuracy of OSA using the time–frequency representation approach. Therefore, we propose a novel technique that takes the ECG signal and detects R-peaks from the QRS complexes. Afterward, we interpolate those R-peaks by linear interpolation and get an interpolated-R signal. Then we magnify the interpolated-R signal corresponding to the apnea and normal frequency ranges. After magnification in the time domain, we transformed the magnified version into a scalogram. We also transformed the original one-minute ECG signal into a spectrogram after denoising. Overall, we used ECG signals to generate scalograms and spectrograms for 2 dimensional convolutional neural network (2D CNN) to classify obstructive sleep apnea. For apnea classification, we proposed a dual convolutional dual attention network (DCDA-Net) that includes a dual convolutionally modified inception module, a spatial attention module, and a channel attention module. Finally, we apply a support vector machine to the probability scores obtained from DCDA-Net based on the scalogram and spectrogram. Extensive experimental results using the open PhysioNet apnea ECG dataset confirm the effectiveness of our method in terms of accuracy and F1 score of 98% and 97.5%, respectively, which outperforms state-of-the-art methods.