[Change of pulse transit time during stepwise paced breathing]

Area of Science:

• Cardiovascular Physiology
• Respiratory Medicine
• Biomedical Engineering

Background:

• Pulse transit time (PTT) is a non-invasive indicator of cardiovascular function.
• Paced breathing (PB) influences autonomic nervous system activity and cardiovascular parameters.
• Understanding the relationship between PB and PTT is crucial for developing non-pharmacological interventions.

Purpose of the Study:

• To investigate the effect of a stepwise paced breathing (PB) protocol on pulse transit time (PTT) in healthy adults.
• To analyze changes in PTT oscillations and baseline during a controlled PB procedure.
• To explore the potential of PB for blood pressure reduction.

Main Methods:

• Collected electrocardiogram (ECG), respiration, and arterial pulse wave signals from 22 healthy adults.
• Measured PTT as the interval between ECG R-spike and the second derivative peak of the arterial pulse wave.
• Applied Ensemble Empirical Mode Decomposition (EEMD) to PTT to extract respiratory oscillations and baseline trends.

Main Results:

• Respiratory oscillations in PTT increased as the PB rate decreased (7.0-14.0 breaths per minute).
• A majority of subjects (14/22) exhibited an increasing PTT baseline during the PB procedure.
• The stepwise PB protocol induced significant cardiovascular oscillations and an accumulative PTT baseline increase.

Conclusions:

• Stepwise paced breathing can reduce blood pressure, indicated by the increase in PTT baseline.
• The PB protocol effectively modulates cardiovascular oscillations.
• Future research should focus on indices for PB effectiveness and its application in hypertension management.