Time delay correction of the synchrogram for optimized detection of cardiorespiratory coordination

Area of Science:

• Physiology
• Biomedical Engineering
• Nonlinear Dynamics

Background:

• The cardiorespiratory synchrogram is a graphical tool for assessing phase-locking between cardiac and respiratory systems.
• The original method involves observing respiratory phase at specific cardiac phase instants.

Purpose of the Study:

• To introduce an adaptive delay into the cardiac oscillator of the cardiorespiratory synchrogram.
• To investigate the impact of this adaptive delay on cardiorespiratory phase coordination analysis.

Main Methods:

• An adaptive delay was incorporated into the cardiac oscillator, maximizing cross-correlation with respiration.
• Phase coordination was analyzed in 13 healthy subjects across supine and upright postures.
• The performance of the modified synchrogram was compared to the original algorithm.

Main Results:

• Cardiorespiratory coordination significantly decreased in the upright posture compared to supine.
• The adaptive delay method increased the average detection of cardiorespiratory coordination (11.9% to 18.9% in supine).
• The adaptive delay reduced the standard deviation of coordination percentage (5.1% to 4.4% in supine).

Conclusions:

• The inclusion of an adaptive delay significantly improves the performance of the cardiorespiratory synchrogram technique.
• This enhancement leads to more robust detection and reduced variability in cardiorespiratory coordination measurements.
• The findings suggest the adaptive delay method offers a more sensitive approach to analyzing cardiorespiratory interactions.