Coupling between Blood Pressure and Subarachnoid Space Width Oscillations during Slow Breathing

Abstract

The precise mechanisms connecting the cardiovascular system and the cerebrospinal fluid (CSF) are not well understood in detail. This paper investigates the couplings between the cardiac and respiratory components, as extracted from blood pressure (BP) signals and oscillations of the subarachnoid space width (SAS), collected during slow ventilation and ventilation against inspiration resistance. The experiment was performed on a group of 20 healthy volunteers (12 females and 8 males; BMI =22.1±3.2 kg/m2; age 25.3±7.9 years). We analysed the recorded signals with a wavelet transform. For the first time, a method based on dynamical Bayesian inference was used to detect the effective phase connectivity and the underlying coupling functions between the SAS and BP signals. There are several new findings. Slow breathing with or without resistance increases the strength of the coupling between the respiratory and cardiac components of both measured signals. We also observed increases in the strength of the coupling between the respiratory component of the BP and the cardiac component of the SAS and vice versa. Slow breathing synchronises the SAS oscillations, between the brain hemispheres. It also diminishes the similarity of the coupling between all analysed pairs of oscillators, while inspiratory resistance partially reverses this phenomenon. BP–SAS and SAS–BP interactions may reflect changes in the overall biomechanical characteristics of the brain.

Cardio-respiratory interactions in response to lower-body negative pressure

“…Under external perturbations to hemodynamic homeostasis such as head-up tilt and sit-to-stand tests, the importance of the interplay between respiration, heart rate and blood pressure in maintaining arterial blood pressure has been well documented in the literature (Novak et al 1993, Censi et al 2003, Porta et al 2011, Silvani et al 2017, Gruszecka et al 2021. Thus, understanding such interactions and their physiological role in maintaining blood pressure homeostasis could help with monitoring the progression of blood loss as well as identifying individuals with low tolerance to hemorrhage.…”

Neural Cross-Frequency Coupling Functions in Sleep

“…Arguably, the greatest recent interest for coupling functions is coming from neuroscience [25]. These works have encompassed the theory and inference of a diversity of neural phenomena, levels, physical regions, and physiological conditions [26,27,28,29,30,31,32,33]. When the coupling functions describe the interactions between brainwave oscillations with distinctive frequency intervals, then one refers to neural crossfrequency coupling functions [31].…”

Mild poikilocapnic hypoxia increases very low frequency haemoglobin oxygenation oscillations in prefrontal cortex

“…They are very suitable for studying interaction of oscillatory processes in physiology e.g., cardiorespiratory or cardiovascular interactions [ 22 , 23 ]. Recently, Gruszecka et al [ 24 ] studied the respiratory–cardiac coupling of the blood pressure and cerebrospinal fluid signals. Another interesting study was carried out by [ 25 ].…”