Incorporating QRS complex and T wave features with PPG signals improved blood pressure estimation, achieving average SBP MAEs of 6.57 mmHg and 6.21 mmHg compared to 7.87 mmHg with P wave addition.
Does the addition of specific ECG characteristic waveforms (P wave, QRS complex, T wave) to PPG signals improve the accuracy of continuous blood pressure estimation using convolutional neural networks?
Incorporating QRS complex and T wave features from ECG signals alongside PPG significantly improves the accuracy of continuous blood pressure estimation models.
Non-invasive continuous blood pressure monitoring is of great significance for the preventing, diagnosing, and treating of cardiovascular diseases (CVDs). Studies have demonstrated that photoplethysmogram (PPG) and electrocardiogram (ECG) signals can effectively and continuously predict blood pressure (BP). However, most of the BP estimation models focus on the waveform features of the PPG signal, while the peak value of R-wave in ECG is only used as a time reference, and few references investigated the ECG waveforms. This paper aims to evaluate the influence of three characteristic waveforms in ECG on the improvement of BP estimation. PPG is the primary signal, and five input combinations are formed by adding ECG, P wave, QRS complex, T wave, and none. We employ five common convolutional neural networks (CNN) to validate the consistency of the contribution. Meanwhile, with the visualization of Gradient-weighted class activation mapping (Grad-CAM), we generate the heat maps and further visualize the distribution of CNN's attention to each waveform of PPG and ECG. The heat maps show that networks pay more attention to the QRS complex and T wave. In the comparison results, the QRS complex and T wave have more contribution to minimizing errors than P wave. By separately adding P wave, QRS complex, and T wave, the average MAE of these networks reaches 7.87 mmHg, 6.57 mmHg, and 6.21 mmHg for systolic blood pressure (SBP), and 4.27 mmHg, 3.65 mmHg, and 3.73 mmHg, respectively, for diastolic blood pressure (DBP). The results of the experiment show that QRS complex and T wave deserves more attention and feature extraction like PPG waveform features in the continuous BP estimation.
Ma et al. (Wed,) conducted a other in Blood pressure estimation. Addition of ECG characteristic waveforms (QRS complex and T wave) to PPG vs. PPG with P wave or PPG alone was evaluated on Mean Absolute Error (MAE) for systolic and diastolic blood pressure. Incorporating QRS complex and T wave features with PPG signals improved blood pressure estimation, achieving average SBP MAEs of 6.57 mmHg and 6.21 mmHg compared to 7.87 mmHg with P wave addition.