Blood-pressure-induced oscillations of deoxy- and oxyhemoglobin concentrations are in-phase in the healthy breast and out-of-phase in the healthy brain

Abstract

Abstract. We present a near-infrared spectroscopy (NIRS) study of local hemodynamics in the breast and the brain (prefrontal cortex) of healthy volunteers in a protocol involving periodic perturbations to the systemic arterial blood pressure. These periodic perturbations were achieved by cyclic inflation (to a pressure of 200 mmHg) and deflation (at frequencies of 0.046, 0.056, 0.063, 0.071, and 0.083 Hz) of two pneumatic cuffs wrapped around the subject's thighs. As a result of these systemic perturbations, the concentrations of deoxy-and oxyhemoglobin in tissue (D and O, respectively) oscillate at the set frequency. We found that the oscillations of D and O in breast tissue are in-phase at all frequencies considered, a result that we attribute to dominant contributions from blood volume oscillations. In contrast, D and O oscillations in brain tissue feature a frequency-dependent phase difference, which we attribute to significant contributions from cerebral blood flow oscillations. Frequency-resolved measurements of D and O oscillations are exploited by the technique of coherent hemodynamics spectroscopy for the assessment of cerebrovascular parameters and cerebral autoregulation. We show the relevant physiological information content of NIRS measurements of oscillatory hemodynamics, which have qualitatively distinct features in the healthy breast and healthy brain. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Dynamic cerebral autoregulation estimates derived from near infrared spectroscopy and transcranial Doppler are similar after correction for transit time and blood flow and blood volume oscillations

“…On the other hand, we assume the constant phase shift to be 0 if blood volume oscillations are dominant, as has been suggested previously. 14,15 Although blood flow oscillations are usually dominant in brain tissue, 28 a mixture of both blood flow and blood volume oscillations may be present, as has been previously reported in the literature, which may result in a constant phase difference in between 0 and 180 . 29,30 Figure 1 illustrates these effects on simulated data.…”

“…Furthermore, the OxyHb-HHb phase difference spectrum during REST and DB was compatible with dominance of blood flow oscillations, which is typical for brain tissue and atypical for extracranial tissue. 28 NIRS is also a focal measurement and since we only measured in the MCA territory, we cannot generalise our findings to other vascular territories, which precludes investigation of regional heterogeneity of cerebral autoregulation. Finally, the reproducibility of the findings has not yet been established, and longer measurements may be needed to evaluate if the NIRS-based autoregulation estimates and transit time and blood flow/volume estimates are stable over time and react similarly to repeated challenges.…”

Frequency-resolved analysis of coherent oscillations of local cerebral blood volume, measured with near-infrared spectroscopy, and systemic arterial pressure in healthy human subjects

“…The data for nine of the female subjects (nn. 13–21) have been previously analyzed for a comparison of the relative phase and amplitude of oxyhemoglobin and deoxyhemoglobin concentration oscillations in brain and breast tissue [29].…”

Axial variation of deoxyhemoglobin density as a source of the low-frequency time lag structure in blood oxygenation level-dependent signals

“…Moreover, associated 77 sLFOs in blood flow and velocity have been found (Killip, 1962;Fagrell et al, 1977) and, 78 later, transcranial Doppler ultrasonography and optical methods confirmed their traces 79 within the brain (Giller et al, 1999;Obrig et al, 2000). This optically detected sLFO was 80 found in both oxy-and deoxy-Hb with an interesting phase difference exclusively observed 81 in the brain (Rayshubskiy et al, 2014;Tgavalekos et al, 2016). Additionally, sLFOs were 82 found in electroencephalographic recordings, for which arterial vasomotion was suggested 83 as the origin (Nikulin et al, 2014), although it is unclear how the vasomotion accounts for 84 the fMRI signal mainly from the capillary bed.…”