Novel Application of a Force Sensor during Sit-to-Stands to Measure Dynamic Cerebral Autoregulation Onset

Abstract

Purpose: Current sit-to-stand methods measuring dynamic cerebral autoregulation (dCA) do not capture the precise onset of the time delay (TD) response. Reduced sit-to-stand reactions in older adults and individuals post-stroke could inadvertently introduce variability, error, and imprecise timing. We applied a force sensor during a sit-to-stand task to more accurately determine how TD before dCA onset may be altered. Methods: Middle cerebral artery blood velocity (MCAv) and mean arterial pressure (MAP) were measured during two sit-to-stands separated by 15 minutes. Recordings started with participants sitting on a force-sensitive resistor for 60 seconds, then asked to stand for two minutes. Upon standing, the force sensor voltage immediately dropped and marked the exact moment of arise-and-off (AO). Time from AO until an increase in cerebrovascular conductance (CVC = MCAv/MAP) was calculated as TD. Results: We tested the sensor in 4 healthy young adults, 2 older adults, and 2 individuals post-stroke. Healthy young adults stood quickly and the force sensor detected a small change in TD compared to classically estimated AO, from verbal command to stand. When compared to the estimated AO, older adults had a delayed measured AO and TD decreased up to ~50% while individuals post-stroke had an early AO and TD increased up to ~14%. Conclusion: The transition reaction speed during the sit to stand has the potential to influence dCA metrics. As observed in the older adults and participants with stroke, this response may drastically vary and influence TD.

Hippocampal blood flow rapidly and preferentially increases after a bout of moderate-intensity exercise in older adults with poor cerebrovascular health

“…Interactions of aging and age-related vascular health with cerebrovascular autoregulation under behavioral conditions, e.g. aerobic exercise (Palmer et al, 2022) and positional transfers (Sorond et al, 2010; Whitaker et al, 2022), may explain the presence of this CBF hypoperfusion effect immediately after exercise in older adults in the present study. Older individuals may possess poor age-related cerebrovascular regulation under states of physiologic stress (Claassen et al, 2021; Ward et al, 2018), which are differentially regulated across brain regions and between individuals (Brassard et al, 2021).…”

Force Sensor Reduces Measurement Error during Sit-to-Stand Assessment of Cerebral Autoregulation

“…While previous studies have shown the ability to implement an accelerometer to detect the angle and speed of the sit-to-stand, [8][9][10][11][12][13][14] we are the first to implement a custom force sensor to improve the temporal accuracy of the TD response. 15 Our methodology uses a force sensor to simultaneously measures the sit-to-stand reaction time with the physiological dCA response. 15 We have reported on the ability to implement a force sensor to identify a defined moment of transition between sitting and standing, or arise-and-off (AO).…”

“…15 Our methodology uses a force sensor to simultaneously measures the sit-to-stand reaction time with the physiological dCA response. 15 We have reported on the ability to implement a force sensor to identify a defined moment of transition between sitting and standing, or arise-and-off (AO). 15 Traditionally, the TD response is calculated from the time in which individuals are verbally told to stand up from a seated position.…”

“…15 We have reported on the ability to implement a force sensor to identify a defined moment of transition between sitting and standing, or arise-and-off (AO). 15 Traditionally, the TD response is calculated from the time in which individuals are verbally told to stand up from a seated position. However, in our prior work, we describe the methodology to accurately identify the exact moment of transition during a sit-to-stand recording and show how AO may potentially differ in older adults and individuals post-stroke.…”

“…However, in our prior work, we describe the methodology to accurately identify the exact moment of transition during a sit-to-stand recording and show how AO may potentially differ in older adults and individuals post-stroke. 15 Therefore, the objective of this study was to determine whether implementing a force sensor to detect the exact moment of AO would significantly improve the accuracy of the TD response compared to the traditional estimation of TD from the verbal command to stand. We hypothesized that using a force sensor to measure AO to calculate the TD response during a sitto-stand measure of dCA would be significantly more accurate than the estimated TD response from the verbal command to stand in healthy young adults, older adults, and individuals with stroke.…”