Introducing Contactless Blood Pressure Assessment Using a High Speed Video Camera

Area of Science:

• Biomedical Engineering
• Physiological Monitoring
• Medical Imaging

Background:

• Blood pressure (BP) estimation traditionally relies on pulse transit time (PTT) derived from body-worn sensors.
• Photoplethysmogram (PPG) signals are commonly used to detect pulse wave propagation time for PTT calculation.
• Existing methods require physical contact, limiting continuous and unobtrusive monitoring.

Purpose of the Study:

• To introduce a novel methodology for contactless registration of image-based PPG (iPPG) and image-based PTT (iPTT).
• To assess the feasibility of utilizing iPTT for blood pressure estimation in vivo.
• To determine the correlation between contactless iPTT and traditional BP measurements.

Main Methods:

• Developed a system for contactless iPPG and iPTT generation using a high-speed camera (420 fps).
• Registered iPPG signals from head and palm areas simultaneously.
• Calculated iPTT as the time lag between pulse waves from two iPPG signals.
• Measured BP using a verified monitor during rest, exercise peak, and recovery in healthy volunteers.

Main Results:

• Achieved an average inter-person correlation of 0.85 ± 0.08 between PTT and iPTT.
• Demonstrated a significant correlation range (0.70 to 0.95, p < 0.05) between PTT and iPTT.
• Found an average inter-person correlation of -0.80 ± 0.12 between systolic BP (SBP) and iPTT.
• Observed strong intra-individual correlations between iPTT and BP (0.632 to 0.960, p < 0.05).

Conclusions:

• A high-speed camera system can potentially enable unobtrusive, contactless monitoring of BP changes.
• The developed methodology successfully generates approximations of pulse transit time.
• Initial results show high intra-individual correlation between iPTT and BP, warranting further investigation.