Clinical Validation of rPPG-Enabled Contactless Pulse Rate Monitoring Software in Cardiovascular Disease Patients

Figure 1. Reference devices connected to the subject: The ECG from the Mindray iMEC8 is connected to the subject. The red, green, and yellow circles represent the placement of the three ECG electrodes. The PPG sensor from the Mindray iMEC8 patient monitor and the Masimo MightySat are also connected to the subject. The subject is seated approximately 0.5 m away from the camera setup. The experimental setup includes a PC to control the recording equipment.

Figure 2. Experimental protocol. The entire session lasted approximately 20 min per subject, with the main experimental task consisting of a 6 min video recording during a resting condition.

Figure 3. System diagram: Video frames are used for face/ROI detection and RGB signal extraction, followed by cloud-based signal cleaning and peak detection to estimate vital signs and signal quality from the rPPG waveform.

Figure 4. Data cleaning protocol implemented in this study.

Figure 5. Result of pulse rate (PR) estimation. The left figure shows the predicted PR vs. the reference PR and the right figure shows the corresponding Bland–Altman plot. Different colors correspond to different subjects. The solid red line in the left figure has a slope of 1, indicating perfect prediction. The dashed light in the right figure indicates a standard deviation of 1.96.

Figure 6. Discrepancy between PPG and ECG for pulse rate measurements for subject ID 1 and 31, compared to subject ID 17 and 44 with consistent PPG and ECG.

Figure 7. Screenshot of the subject monitor showing synchronized ECG (green) and PPG (cyan) waveforms. An ectopic beat in the ECG occurs without a corresponding peak in the PPG, resulting in different instantaneous pulse rate readings.

Figure 8. Regression plots of pulse rate (PR) estimation versus PR reference, stratified by device (Upper Left), gender (Upper Right), age (Lower Left), and luminance (Lower Right). Colored dashed lines represent the linear regression fits for different subgroups: (Upper Left) blue: iPhone, orange: iPad; (Upper Right) blue: male, orange: female; (Lower Left) blue: age ≤ 65, orange: age > 65; (Lower Right) blue: luminance ≤ 272, orange: luminance > 272.