Validity of Ultra-Short-Term HRV Analysis Using PPG-A Preliminary Study

Area of Science:

• Biomedical Engineering
• Physiological Monitoring
• Wearable Technology

Background:

• Continuous heart rate variability (HRV) monitoring via wearables aids physiological status assessment and disease prevention.
• Evaluating the accuracy of photoplethysmography (PPG) devices against electrocardiography (ECG) is crucial for reliable HRV analysis.

Purpose of the Study:

• To assess the agreement of HRV features between a commercial PPG wearable (Bora Band) and reference ECG.
• To validate ultra-short-term HRV measurements as a surrogate for short-term HRV analysis.

Main Methods:

• Acquired simultaneous PPG (Bora Band) and ECG recordings from 5 healthy subjects over 18 nights.
• Extracted time-domain, frequency-domain, nonlinear, and visibility graph HRV features from 5 min 30 s and 1 min 30 s durations.
• Compared PPG-derived HRV features against ECG reference using correlation, Bland-Altman plots, Cliff's delta, and equivalence testing.

Main Results:

• 37 out of 48 HRV features showed agreement between PPG and ECG in short-term recordings.
• 16 HRV features demonstrated strong correlation, minimal bias, and statistical equivalence in ultra-short (1 min 30 s) recordings.
• The Bora Band demonstrated valid and reliable HRV measurements across short and ultra-short durations.

Conclusions:

• The Bora Band provides accurate and dependable HRV measurements using PPG technology.
• Ultra-short-term HRV analysis is a valid approach, comparable to short-term analysis, for physiological monitoring.
• Wearable PPG devices show promise for accessible, continuous health status monitoring and disease prevention.