Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions

Abstract

Respiration disturbs cardiovascular and cerebrovascular controls but its role is not fully elucidated. Methods: Respiration can be classified as a confounder if its observation reduces the strength of the causal relationship from source to target. Respiration is a suppressor if the opposite situation holds. We prove that a confounding/suppression (C/S) test can be accomplished by evaluating the sign of net redundancy/synergy balance in the predictability framework based on multivariate autoregressive modelling. In addition, we suggest that, under the hypothesis of Gaussian processes, the C/S test can be given in the transfer entropy decomposition framework as well. Experimental protocols: We applied the C/S test to variability series of respiratory movements, heart period, systolic arterial pressure, mean arterial pressure, and mean cerebral blood flow recorded in 17 pathological individuals (age: 64±8 yrs; 17 males) before and after induction of propofol-based general anesthesia prior to coronary artery bypass grafting, and in 13 healthy subjects (age: 27±8 yrs; 5 males) at rest in supine position and during head-up tilt with a table inclination of 60°. Results: Respiration behaved systematically as a confounder for cardiovascular and cerebrovascular controls. In addition, its role was affected by propofol-based general anesthesia but not by a postural stimulus of limited intensity. Conclusion: The C/S test can be fruitfully exploited to categorize the role of respiration over causal variability interactions. Significance: The application of the C/S test could favor the comprehension of the role of respiration in cardiovascular and cerebrovascular regulations.

Dynamic Temporal Relationship Between Autonomic Function and Cerebrovascular Reactivity in Moderate/Severe Traumatic Brain Injury

“…The sympathetic nervous system seems to attenuate the CO 2induced increases in CBF (Jordan et al, 2000), which can be mediated by ventilation in the ICU. Though it has been noted that powerful actions of mechanical ventilation induces periodical modifications of the intrathoracic pressure, modulating venous return which has shown to alter cardiovascular and cerebrovascular interactions (Innes et al, 1993;Elstad et al, 2011;Porta et al, 2021). With literature assessing the relationship between PEEP and cerebral reactivity in pigs, demonstrating that static PEEP improved the assessment of impaired/intact cerebrovascular reactivity (Brady et al, 2012;Fraser et al, 2013).…”

Respiratory Sinus Arrhythmia is Mainly Driven by Central Feedforward Mechanisms in Healthy Humans

“…We thus propose that the arterial baroreflex had no change in input and did not contribute to our results. Porta et al have found that respiration affects the cardiac baroreflex pathway by reduction of baroreflex sensitivity ( Porta et al, 2000 ; Porta et al, 2012 ; Porta et al, 2022) . Similarly, when baroreceptor stimuli occur during inspiration, the respiratory gate renders the vagal cardiac motoneuron unresponsive ( Eckberg, 2003 ).…”

Dynamic effects of cholinergic blockade upon cerebral blood flow autoregulation in healthy adults

“…In this latter paper, the first application of Laguerre expansions to this problem was also reported. The use of multivariate autoregressive methods was recently presented in connection with the effects of respiration to this system ( Porta et al, 2022 ).…”

“…We note that the term “cerebral autoregulation” (CA or CAR) has been used by the peer community to describe the dynamic relation between ABP and CFV in the extensive literature on this matter [e.g. ( Aaslid et al, 1989 ; Paulson et al, 1990 ; Tiecks et al, 1995 ; Panerai, 1998 ; Zhang et al, 1998 ; Panerai et al, 1999 ; van Beek et al, 2008 ; Mitsis et al, 2009 ; Porta et al, 2022 )]. The term “cerebral flow autoregulation” (CFA) is used in this paper to draw the distinction with those previous studies with regard to the use of a second input (CO2) accounting for the contemporaneous effects on CFV of spontaneous changes in blood CO2 tension, as well as to make the object of autoregulation explicit.…”