A Physical Model-Based Approach to One-Point Calibration of Pulse Transit Time to Blood Pressure

• Published in: IEEE transactions on biomedical engineering Vol. 71; no. 2; pp. 1 - 7
• Main Authors: Mousavi, Azin, Inan, Omer T., Mukkamala, Ramakrishna, Hahn, Jin-Oh
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.02.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arteries; Biological system modeling; Biomedical monitoring; Blood pressure; Blood Pressure - physiology; Blood Pressure Determination; bramwell-hill equation; Calibration; cuff-less blood pressure monitoring; Data models; Humans; Mathematical models; Pressure measurement; Pulse transit time; Pulse Wave Analysis; Time measurement; Transit time
• ISSN: 0018-9294; 1558-2531; 1558-2531
• DOI: 10.1109/TBME.2023.3307658

Objective: To develop a novel physical model-based approach to enable 1-point calibration of pulse transit time (PTT) to blood pressure (BP). Methods: The proposed PTT-BP calibration model is derived by combining the Bramwell-Hill equation and a phenomenological model of the arterial compliance (AC) curve. By imposing a physiologically plausible constraint on the skewness of AC at positive and negative transmural pressures, the number of tunable parameters in the PTT-BP calibration model reduces to 1. Hence, as opposed to most existing PTT-BP calibration models requiring multiple (≥2) PTT-BP measurements to personalize, the PTT-BP calibration model can be personalized to an individual subject using a single PTT-BP measurement pair. Equipped with the physically relevant PTT-AC and AC-BP relationships, the proposed approach may serve as a universal means to calibrate PTT to BP over a wide BP range. The validity and proof-of-concept of the proposed approach were evaluated using PTT and BP measurements collected from 22 healthy young volunteers undergoing large BP changes. Results: The proposed approach modestly yet significantly outperformed an empiric linear PTT-BP calibration with a group-average slope and subject-specific intercept in terms of bias (5.5 mmHg vs 6.4 mmHg), precision (8.4 mmHg vs 9.4 mmHg), mean absolute error (7.8 mmHg vs 8.8 mmHg), and root-mean-squared error (8.7 mmHg vs 10.3 mmHg, all in the case of diastolic BP). Conclusion: We demonstrated the preliminary proof-of-concept of an innovative physical model-based approach to one-point PTT-BP calibration. Significance: The proposed physical model-based approach has the potential to enable more accurate and convenient calibration of PTT to BP.