Blood Pressure Estimation Using Pulse Transit Time From Bioimpedance and Continuous Wave Radar

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Devices

Background:

• Accurate blood pressure monitoring is crucial for cardiovascular health management.
• Current methods often rely on invasive techniques or occlusive cuffs, limiting continuous or ambulatory monitoring.
• Estimating blood pressure using pulse transit time (PTT) offers a promising non-invasive alternative.

Purpose of the Study:

• To develop and evaluate a novel system architecture for estimating cuffless blood pressure.
• To utilize pulse transit time (PTT) derived from central arteries for improved accuracy.
• To integrate electrical bioimpedance, electrocardiogram (ECG), and continuous wave radar for PTT measurement.

Main Methods:

• A new system architecture was designed using electrical bioimpedance, ECG, and radar.
• Arterial pulsations were acquired from the aortic arch, carotid, and subclavian arteries.
• PTT and pulse arrival times (PATs) were measured in six healthy males during exercise.
• Linear regression was used to calibrate PAT and PTT with oscillometric blood pressure readings.

Main Results:

• Strong correlations were observed between PAT and systolic blood pressure (SBP) (r = -0.66, p = 0.001).
• Significant correlations were also found between PTT and SBP (r = -0.48, p = 0.0029).
• Individual subject correlation coefficients for PAT-SBP ranged from -0.54 to -0.9.

Conclusions:

• The developed system architecture demonstrates potential for estimating cuffless blood pressure in central arteries.
• Measuring PTT in central elastic arteries may reduce variability caused by peripheral vasomotion.
• The system's discreet sensor design enhances patient acceptability for ambulatory monitoring.