Method for determining time delay between beat-to-beat blood pressure signal and pulse arrival time

An apparatus comprising:

• a pulse arrival time (PAT) calculator configured to receive a raw electrocardiography (ECG) signal of a subject from an ECG device and a raw blood pressure (BP) signal of the subject from a BP waveform detector, calculate a beat-to-beat ECG signal, a beat-to-beat pulse wave signal, and calculate a beat-to-beat PAT signal that is measured as a time delay between the beat-to-beat ECG signal and the beat-to-beat pulse wave signal;
• a BP calculator configured to receive the raw BP signal and calculate a beat-to-beat BP signal;
• an interpolator configured to interpolate the beat-to-beat PAT signal and the beat-to-beat BP signal and generate an interpolated beat-to-beat PAT signal and an interpolated beat-to-beat BP signal;
• a time delay corrector configured to calculate a subject-specific phase difference between the interpolated beat-to-beat PAT signal and the interpolated beat-to-beat BP signal;
• and
• a BP-PAT relationship estimator configured to assess a subject-specific relationship between the interpolated beat-to-beat PAT signal and the interpolated beat-to-beat BP signal.