Authors: Ziad A Elhajjaji, Amar S Basu
Abstract
Orthostatic disorders affect 30% of older adults and increase the risk for falls. The current diagnostic standard, the blood pressure cuff, cannot capture the rapid, multifaceted dynamics of orthostasis physiology, resulting in frequent underdiagnosis. This paper demonstrates multiparameter, real-time measurement of orthostasis using TRACE, an earlobe mounted wearable developed in our group. In prior work, we demonstrated a novel metric called orthostatic hypovolemia (OHV1), the initial loss in cephalic (head) blood volume immediately upon standing. This study significantly advances our prior work by introducing an additional 2 metrics: OHV2, the cephalic blood volume deficit after the body achieves homeostasis after standing; and postural orthostatic tachycardia (POT), the increase in heart rate. The 3 metrics were evaluated in 101 older adults who wore the TRACE device during postural transitions and reported their orthostatic symptoms. Both the OHV2 and POT metrics had significant differences between the symptomatic and asymptomatic groups, with p-values of 0.0219 and 1.2×10−6 respectively. Furthermore, the 3 combined metrics could predict symptomatic and asymptomatic individuals with 87% sensitivity and 80% specificity. To our knowledge, this is the first report of a wearable can predict orthostatic symptoms. These metrics could aid clinicians and patients in the diagnosis and evidence-based management of orthostatic disorders including orthostatic hypotension and dysautonomia.
Access on IEEE: https://ieeexplore.ieee.org/document/10780505