Increased inspiratory resistance affects the dynamic relationship between blood pressure changes and subarachnoid space width oscillations

Abstract

Background and objectiveRespiration is known to affect cerebrospinal fluid (CSF) movement. We hypothesised that increased inspiratory resistance would affect the dynamic relationship between blood pressure (BP) changes and subarachnoid space width (SAS) oscillations.MethodsExperiments were performed in a group of 20 healthy volunteers undergoing controlled intermittent Mueller Manoeuvres (the key characteristic of the procedure is that a studied person is subjected to a controlled, increased inspiratory resistance which results in marked potentiation of the intrathoracic negative pressure). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography; oxyhaemoglobin saturation with an ear-clip sensor; end-tidal CO2 with a gas analyser; cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a new method i.e. near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the BP and SAS oscillations coupling.ResultsInitiating Mueller manoeuvres evoked cardiac SAS component decline (-17.8%, P<0.001), systolic BP, diastolic BP and HR increase (+6.3%, P<0.001; 6.7%, P<0.001 and +2.3%, P<0.05, respectively). By the end of Mueller manoeuvres, cardiac SAS component and HR did not change (+2.3% and 0.0%, respectively; both not statistically significant), but systolic and diastolic BP was elevated (+12.6% and +8.9%, respectively; both P<0.001). With reference to baseline values there was an evident decrease in wavelet coherence between BP and SAS oscillations at cardiac frequency in the first half of the Mueller manoeuvres (-32.3%, P<0.05 for left hemisphere and -46.0%, P<0.01 for right hemisphere) which was followed by subsequent normalization at end of the procedure (+3.1% for left hemisphere and +23.1% for right hemisphere; both not statistically significant).ConclusionsIncreased inspiratory resistance is associated with swings in the cardiac contribution to the dynamic relationship between BP and SAS oscillations. Impaired cardiac performance reported in Mueller manoeuvres may influence the pattern of cerebrospinal fluid pulsatility.

Changing the Currently Held Concept of Cerebrospinal Fluid Dynamics Based on Shared Findings of Cerebrospinal Fluid Motion in the Cranial Cavity Using Various Types of Magnetic Resonance Imaging Techniques

“…However, strong dynamic changes in the pressure of the CSF are affected mainly through venous channels. 77) Wszedybyl-Winklewska et al 78) showed that increased inspiratory resistance is associated with large swings in the heart-generated dynamic relationship between blood pressure and subarachnoid oscillations in healthy subjects. In particular, if CSF motion reaches a far distance due to respiratory fluctuations, it would indicate that such movements greatly impact substance mobilization, and this would be an essential study that gives significance to the relationship between respiration and CSF motion.…”

“…In particular, if CSF motion reaches a far distance due to respiratory fluctuations, it would indicate that such movements greatly impact substance mobilization, and this would be an essential study that gives significance to the relationship between respiration and CSF motion. 78) All these studies concern the frequency analysis of CSF motion that started around 2015, and future developments and progress are anticipated.…”

The Relationship between Obstructive Sleep Apnea and Alzheimer’s Disease

“…The respiratory effort against collapsed airways during OSA apneic episodes (Mueller maneuver) is associated with elevated intrathoracic and intracranial pressures, and hemodynamic disturbances [176,177]. These have been hypothesized to acutely and repetitively impede the circulation of brain metabolites from ISF into CSF [178], through the glymphatic system, leading to increased Aβ 42 accumulation in the ISF.…”

The Influence of Breathing on the Central Nervous System

“…The difference between the heart and the diaphragm is that the myocardium moves the CRF faster while the diaphragm moves a larger quantity of fluid [ 31 ]. During inhalation, thoracic pressure is reduced, which affects the subarachnoid space through the venous plexus that surrounds the thoracic spine and inside the spinal canal; the decreased thoracic pressure influences the hydrostatic pressure that helps in low venous resistance and paravenous and CRF drainage [ 32 ]. The CRF protects the functions of the central nervous system (CNS), bringing nutrients, collecting metabolic cellular wastes, and regulating cerebral pressure.…”

“…There is some evidence suggesting a reduction in the amount of CRF in motion, if there is a resistance in the respiratory tract or apnea, with a decrease in the subarachnoid space [ 32 , 34 ]. Currently, it is not known what happens with physiotherapic, osteopathic, or manual treatments of the dysfunctional inspiratory muscle and the effect they have on CRF and improving brain function.…”