title: Non-Invasive Respiratory Impedance Enhances Cerebral Perfusion in Healthy Adults.
abstract: 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 H2O, 9 cm H2O, and 12 cm H2O) 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 (p= 0.004), but changes in cortical CBF were non-significant. In a multivariable linear regression model accounting for end-tidal CO2, RI was associated with increases in both MFV (coefficient: 0.49,p< 0.001) and cortical CBF (coefficient: 0.13,p< 0.001), although the magnitude of the effect was small. Manipulating intrathoracic pressurevianon-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.
authors.affiliation: Department of Neurology, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Favilla
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Ashwin B
authors.initials: AB
authors.lastname: Parthasarathy
authors.affiliation: Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA; Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.affiliation: Department of Neurology, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Mullen
authors.affiliation: Department of Neurology, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Kasner
authors.affiliation: Department of Neurology, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Gannon
authors.affiliation: Department of Neurology, University of Pennsylvania , Philadelphia, PA , USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Messé
keywords: cerebral blood flow; cerebral blood flow measurement; cerebral hemodynamics; diffuse correlation spectroscopy; near-infrared spectroscopy; respiratory impedance; transcranial Doppler