Older adults with high cerebrovascular risk exhibited smaller reductions in low-frequency oscillation gains during head-up-tilting compared to low-risk adults, suggesting weaker dynamic autoregulation.
Cross-Sectional (n=24)
Does 70° head-up-tilting reveal differences in cerebral-autoregulation measured by LFO gains between older adults at high vs low risk for cerebrovascular disease?
Low-frequency oscillation gains measured by near-infrared diffuse optical instruments during head-up-tilting may serve as valuable biomarkers for early detection of cerebrovascular disease.
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 (HbO 2 ), 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, HbO 2 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.
Bahrani et al. (Sat,) conducted a cross-sectional in Cerebrovascular risk (n=24). High cerebrovascular risk (Framingham risk score >15) vs. Low cerebrovascular risk (Framingham risk score ≤15) was evaluated on Low-frequency oscillation (LFO) gains of cerebral blood flow, oxy-hemoglobin, and deoxy-hemoglobin during head-up-tilting. Older adults with high cerebrovascular risk exhibited smaller reductions in low-frequency oscillation gains during head-up-tilting compared to low-risk adults, suggesting weaker dynamic autoregulation.