Abstract: Hypertension affects 1.4 billion adults globally, yet only 23% have their blood pressure (BP) adequately controlled. A critical but underappreciated barrier is the accuracy of BP measurement devices — 75–80% of automated BP devices worldwide lack independent clinical validation, with India ranking worst globally at 97% non-validated upper-arm devices. Existing automated BP devices rely on population-specific empirical calibration coefficients, limiting accuracy in hemodynamically varying populations, particularly pregnant women where altered cardiac output (↑30–50%) and peripheral vascular resistance (↓25–30%) render standard calibration assumptions invalid.

This work presents the development and evaluation of GARBHA monitor — a calibration- free, multimodal BP monitoring system that leverages the physiological signatures embedded in pressure waveform morphology and Korotkoff sound patterns, rather than relying on population-derived empirical coefficients. By combining simultaneous oscillometric and auscultatory acquisition, the system directly exploits pulse morphology and sound onset characteristics to estimate BP — enabling coefficient-free measurement applicable across hemodynamically diverse populations.

The work comprises three studies. First, systematic benchmarking of four Korotkoff detection algorithms two frequency-domain methods (BLE, DFAT) and two morphology- based methods (Cross-Correlation, DTW) across two search strategies (Thresholding and PWLF) on 350 recordings from 155 subjects identified DTW+PWLF as optimal (SBP: 0.3 ± 7.5 mmHg, DBP: −4.6 ± 5.7 mmHg, r = 0.88), confirming superiority of morphology-based over frequency-domain methods. Second, an controlled in-vivo system verification study on 60 subjects across two operators and two days demonstrated strong intra-day repeatability (SBP ICC: 0.89, DBP ICC: 0.70), minimal inter-operator bias (SBP: 0.10 ± 5.40 mmHg, DBP: 0.43 ± 6.64 mmHg), stable inter-day performance (SBP: −0.6 ± 6.8 mmHg, DBP: 0.72 ± 6.20 mmHg, p > 0.05), and overall accuracy (SBP: 5.5 ± 5.75 mmHg, DBP: 4.66 ± 5.57 mmHg).

Third, a Clinical validation of system in 120 pregnant women in an antenatal care setting showed SBP performance against Omron HEM-7361T (clinically validated for use in pregnancy) (−2.1 mmHg ± 6.2 mmHg, r=0.83). DBP showed a systematic offset versus Omron (9.7 mmHg ± 5.8 mmHg, r=0.71).

The proposed system demonstrates that calibration-free BP measurement is achievable with clinical-grade accuracy and operator independence. Importantly, GARBHA showed stronger agreement with the clinically validated Omron HEM-7361T, representing a meaningful step toward validated, accessible BP monitoring for hemodynamically diverse and underserved populations.

Keywords: Blood pressure measurement, Korotkoff sounds, oscillometric method, calibration-free, pregnancy, hemodynamic variability, AAMI validation

All are cordially invited.

Event Details
Title: Development and Evaluation of a Calibration-Free Blood Pressure Monitoring System for Hemodynamically Varying Population
Date: May 15, 2026 at 03:00 PM
Venue: ESB 244 / Google Meet (http://meet.google.com/vdu-fhbc-jsr)
Speaker: Mr. K Shyam Sundar (EE23S060)
Guide: Dr. Mohanasankar Sivaprakasam
Type: MS seminar

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