Cardioventilatory Coupling in Resting Human Subjects

Abstract

In 48 conscious resting subjects we examined the temporal coupling of heart beat timing and the onset of inspiration (cardioventilatory coupling), and the relationship between coupling and spectral indices of autonomic function. Using the proportional Shannon entropy (SHα) of the RI‐1 interval (interval between inspiration and the preceding ECG R wave) as a measure of coupling we detected statistically significant coupling in 32 of the 48 subjects. This was confirmed by visual inspection of time series plots of RI intervals, in which coupling was evident as horizontal banding. Coupling resulted in a significant preference for whole number heart rate/respiratory frequency ratios. The strongest coupling was associated with low ventilatory frequency and high heart rate variability in the high (0.15‐0.40 Hz) and low (0.04‐0.15 Hz) frequency ranges, but was not related to blood pressure variability, or to a spectral measure of baroreflex sensitivity (α‐index, low frequency range). There was no difference in coupling strength between males and females. We have previously described cardioventilatory coupling in spontaneously breathing anaesthetised subjects. The current study extends those observations by demonstrating that the qualitative features of coupling seen during anaesthesia are also observed in the conscious state. We conclude that the role of coupling in normal physiological respiratory control needs to be more widely explored.

Physiology of Long Pranayamic Breathing: Neural Respiratory Elements may Provide a Mechanism that Explains How Slow Deep Breathing Shifts the Autonomic Nervous System

“…breathing frequency [45] similar to that found in slow pranayama. Cardioventilatory coupling, found during deep breathing exercises, indicates a synchronization mechanism that coordinates neural and non-neural activity.…”

In vivo cardiac phase response curve elucidates human respiratory heart rate variability

“…It is well known [23][24][25][45][46][47][48]51,52 that the phase of respiration influences the peripheral autonomic nervous system's outflow to the heart. However, till now it has never been shown when exactly this happens inside the cardiac cycle.…”

“…Description of cardiorespiratory interaction in terms of coupling functions yields a new technique for the quantification of respiratory-related HRV. HRV is one of the central tools of psychophysiology and behavioural medicine 44 , and the respiratory component is a significant part of it [23][24][25][45][46][47][48] , representing mainly the vagal or parasympathetic part of the autonomic nervous system influences. Having introduced the time-continuous phase of the ECG, we obtain a continuous description of the HRV via the instantaneous frequency _ j e ðtÞ, instead of the commonly used discontinuous beat-to-beat description.…”

“…Human CRI has been studied for decades [23][24][25][30][31][32][33] . It has gained increased interest due to extensive application of ideas from nonlinear dynamics and information theory to medical problems, for example, to the use of heart rate variability (HRV) as an indicator of autonomic activity.…”

Quantification of Cardiorespiratory Interactions Based on Joint Symbolic Dynamics

“…48 Cardioventilatory coupling (CVC) is another concept, which specifically refers to the influence of timing of breathing on cardiac activity. 17,19,47 CVC is quantified based on the temporary alignment between the R waves of the electrocardiogram (ECG) and inspiratory onsets, using the R-peak to inspiratory-onset interval plot. Galletly and Larsen showed that during anesthesia CVC places the heart beats and inspiratory onsets such that they are maximally affected by vagal modulation of RSA implying common physiological roles and significant relationship between CVC and RSA.…”