AUTHOR=Favilla Christopher G. , Parthasarathy Ashwin B. , Detre John A. , Yodh Arjun G. , Mullen Michael T. , Kasner Scott E. , Gannon Kimberly , Messé Steven R. 

TITLE=Non-Invasive Respiratory Impedance Enhances Cerebral Perfusion in Healthy Adults

JOURNAL=Frontiers in Neurology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00045

DOI=10.3389/fneur.2017.00045

ISSN=1664-2295

ABSTRACT=<p>Optimization of cerebral blood flow (CBF) is the cornerstone of clinical management in a number of neurologic diseases, most notably ischemic stroke. Intrathoracic pressure influences cardiac output and has the potential to impact CBF. Here, we aim to quantify cerebral hemodynamic changes in response to increased respiratory impedance (RI) using a non-invasive respiratory device. We measured cerebral perfusion under varying levels of RI (6 cm H<sub>2</sub>O, 9 cm H<sub>2</sub>O, and 12 cm H<sub>2</sub>O) in 20 healthy volunteers. Simultaneous measurements of microvascular CBF and middle cerebral artery mean flow velocity (MFV), respectively, were performed with optical diffuse correlation spectroscopy and transcranial Doppler ultrasound. At a high level of RI, MFV increased by 6.4% compared to baseline (<italic>p</italic> = 0.004), but changes in cortical CBF were non-significant. In a multivariable linear regression model accounting for end-tidal CO<sub>2</sub>, RI was associated with increases in both MFV (coefficient: 0.49, <italic>p</italic> &lt; 0.001) and cortical CBF (coefficient: 0.13, <italic>p</italic> &lt; 0.001), although the magnitude of the effect was small. Manipulating intrathoracic pressure <italic>via</italic> non-invasive RI was well tolerated and produced a small but measurable increase in cerebral perfusion in healthy individuals. Future studies in acute ischemic stroke patients with impaired cerebral autoregulation are warranted in order to assess whether RI is feasible as a novel non-invasive therapy for stroke.</p>