Cardiorespiratory interactions during resistive load breathing

Area of Science:

• Cardiorespiratory Physiology
• Respiratory Mechanics
• Autonomic Nervous System Function

Background:

• Resistive loads applied to the respiratory system induce changes in breathing patterns and intrathoracic pressure.
• Understanding cardiorespiratory interactions is crucial for assessing physiological responses to respiratory challenges.

Purpose of the Study:

• To investigate the impact of resistive load breathing on cardiorespiratory interactions.
• To quantify changes in heart rate variability (HRV) and respiratory sinus arrhythmia (RSA) in response to altered breathing patterns.

Main Methods:

• Seven healthy subjects were exposed to four different resistive loads in a randomized order.
• Heart rate variability (HRV) spectral power components were analyzed from R-R interval sequences.
• Respiratory sinus arrhythmia (RSA) amplitude and phase were calculated using instantaneous heart rate fitting.

Main Results:

• Resistive loading led to a longer respiratory period and unchanged heart rate.
• Significant increases in heart rate variability (HRV) and alterations in respiratory sinus arrhythmia (RSA) characteristics were observed.
• HRV and RSA parameters showed a linear correlation with the respiratory period.

Conclusions:

• Breathing cycle duration is a critical factor influencing cardiorespiratory interactions.
• Load-induced changes in respiratory period appear to be the primary driver of observed HRV and RSA modifications.
• These cardiorespiratory interactions may be modulated by the time-dependent activation and dissipation of neurotransmitters involved in RSA.