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Updated: Dec 18, 2025
Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies
Published on: November 19, 2020
Diffuse optical assessment of cerebral-autoregulation in older adults stratified by cerebrovascular risk
Ahmed A Bahrani1,2,3, Weikai Kong1, Yu Shang4
1Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA.
Insights
Early detection of cerebrovascular disease (CVD) is crucial. This study found that low-frequency oscillation gains, reflecting cerebral autoregulation, differ between high-risk and low-risk groups, suggesting potential as early CVD biomarkers.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Cardiovascular Research
Background:
- Cerebrovascular disease (CVD) diagnosis is vital for preventing complications.
- Abnormal cerebral microvasculature in CVD can impair cerebral autoregulation (CA).
- Early detection methods for CVD are needed.
Purpose of the Study:
- To investigate low-frequency oscillations (LFOs) of cerebral blood flow (CBF) and hemoglobin concentrations.
- To assess cerebral autoregulation (CA) dynamics using LFO gains in individuals with varying CVD risk.
- To determine if LFO gains can serve as early biomarkers for CVD.
Main Methods:
- A hybrid near-infrared diffuse optical instrument and finger plethysmograph were used.
- Simultaneous measurement of CBF, [HbO2], [Hb], and mean arterial pressure (MAP) during head-up-tilting (HUT).
- Transfer function analysis calculated LFO gains (CA ∝ 1/Gain) in low-risk (FRS ≤15) and high-risk (FRS >15) groups.
Main Results:
- High-risk individuals exhibited lower baseline LFO gains compared to low-risk individuals.
- Lower baseline gains in the high-risk group may indicate compensatory mechanisms for steady-state CA.
- Head-up-tilting revealed smaller LFO gain reductions in the high-risk group, suggesting impaired dynamic CA.
Conclusions:
- LFO gains demonstrate differences between CVD risk groups.
- Impaired dynamic CA was observed in the high-risk group during HUT.
- LFO gains show potential as valuable biomarkers for the early detection of CVD.
Abstract:
Diagnosis of cerebrovascular disease (CVD) at early stages is essential for preventing sequential complications. CVD is often associated with abnormal cerebral microvasculature, which may impact cerebral-autoregulation (CA). A novel hybrid near-infrared diffuse optical instrument and a finger plethysmograph were used to simultaneously detect low-frequency oscillations (LFOs) of cerebral blood flow (CBF), oxy-hemoglobin concentration ([HbO2 ]), deoxy-hemoglobin concentration ([Hb]) and mean arterial pressure (MAP) in older adults before, during and after 70° head-up-tilting (HUT). The participants with valid data were divided based on Framingham risk score (FRS, 1-30 points) into low-risk (FRS ≤15, n = 13) and high-risk (FRS >15, n = 11) groups for developing CVD. The LFO gains were determined by transfer function analyses with MAP as the input, and CBF, [HbO2 ] and [Hb] as the outputs (CA ∝ 1/Gain). At resting-baseline, LFO gains in the high-risk group were relatively lower compared to the low-risk group. The lower baseline gains in the high-risk group may attribute to compensatory mechanisms to maintain stronger steady-state CAs. However, HUT resulted in smaller gain reductions in the high-risk group compared to the low-risk group, suggesting weaker dynamic CAs. LFO gains are potentially valuable biomarkers for early detection of CVD based on associations with CAs.
