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

Abstract

Introduction: Novel implementation of a force sensor during a sit-to-stand measure of dynamic cerebral autoregulation (dCA) has been shown to measure the exact moment an individual stands up from a chair, called arise-and-off (AO). Traditional measures estimate time delay (TD) before the onset of the dCA response from the verbal command to stand. We hypothesized that using a force sensor to measure AO would significantly improve the accuracy of the TD measure compared to estimating from verbal command. Methods: Middle cerebral artery blood velocity (MCAv) and mean arterial pressure (MAP) were measured simultaneously during three sit-to-stand measures of dCA. Participants were seated for 60 seconds, then performed a sit-to-stand and the force sensor detected AO. TD was calculated as the time from AO until an increase in cerebrovascular conductance (CVC = MCAv/MAP). TD was also calculated from verbal command to stand. Results: Sixty-five participants completed the study: twenty-five young adults (age 25±2 years), twenty older adults (age 61±13 years), and twenty individuals with stroke (age 60±13 years). There was a significant difference in TD when using AO compared to estimating (F-value=49.9, p<0.001). Estimated TD introduced ≈17% measurement error. Average TD measurement error was not related to age (r =-0.04, p=0.76) or history of stroke (r=0.01, p=0.96). Discussion: The addition of a force sensor to detect AO during a sit-to-stand procedure showed a significant difference in the TD dCA measurement. Our data support the implementation of a force sensor during sit-to-stand dCA measures in healthy adults across all ages and after stroke.