Microvascular cerebral blood flow fluctuations in association with apneas and hypopneas in acute ischemic stroke

Abstract

In a pilot study on acute ischemic stroke (AIS) patients, unexpected periodic fluctuations in microvascular cerebral blood flow (CBF) had been observed. Motivated by the relative lack of information about the impact of the emergence of breathing disorders in association with stroke on cerebral hemodynamics, we hypothesized that these fluctuations are due to apneic and hypopneic events. A total of 28 patients were screened within the first week after stroke with a pulse oximeter. Five (18%) showed fluctuations of arterial blood oxygen saturation ( $\ge 3\%$ ) and were included in the study. Near-infrared diffuse correlation spectroscopy (DCS) was utilized bilaterally to measure the frontal lobe CBF alongside respiratory polygraphy. Biphasic CBF fluctuations were observed with a bilateral increase of $27.1\%\pm 17.7\%$ and $29.0\%\pm 17.4\%$ for the ipsilesional and contralesional hemispheres, respectively, and a decrease of $-19.3\%\pm 9.1\%$ and $-21.0\%\pm 8.9\%$ for the ipsilesional and contralesional hemispheres, respectively. The polygraph revealed that, in general, the fluctuations were associated with apneic and hypopneic events. This study motivates us to investigate whether the impact of altered respiratory patterns on cerebral hemodynamics can be detrimental in AIS patients.

Keywords: diffuse correlation spectroscopy; diffuse optics; sleep disorders; stroke.