Non-invasive pulse arrival time as a surrogate for oscillometric systolic blood pressure changes during non-pharmacological intervention.

Non-invasive continuous blood pressure monitoring is of longstanding interest in various cardiovascular scenarios. In this context, pulse arrival time (PAT), i.e., a surrogate parameter for systolic blood pressure (change), became very popular recently, especially in the context of cuffless blood pressure measurement and dedicated lifestyle interventions. Nevertheless, there is also understandable doubt on its reliability in uncontrolled and mobile settings.&#xD;Objective: The aim of this work is therefore the investigation whether PAT follows oscillometric systolic blood pressure readings during moderate interventions by physical or mental activity using a medical grade handheld device for non-invasive PAT assessment.&#xD;Methods: A study was conducted featuring an experimental group performing a physical and a mental task, and a control group. Oscillometric blood pressure and PAT were assessed at baseline and after each intervention. Interventions were selected randomly but then performed sequentially in a counterbalanced order. Multivariate analyses of variance were used to test within-subject and between-subject effects for the dependent variables, followed by univariate analyses for post-hoc testing. Furthermore, correlation analysis was performed to assess the association of intervention effects between blood pressure and PAT. &#xD;Results: The study included 51 subjects (31 females). Multivariate analysis of variances showed that effects in blood pressure, heart rate, PAT and pulse wave parameters were consistent and significantly different between experimental and control groups. After physical activity, heart rate and systolic blood pressure increased significantly whereas PAT decreased significantly. Mental activity leads to a decrease in systolic blood pressure at stable heart rate. Pulse wave parameters follow accordingly by an increase of PAT and mainly unchanged pulse wave analysis features due to constant heart rate. Finally, also the control group behaviour was accurately registered by the PAT method compared to oscillometric cuff. Correlation analyses revealed significant negative associations between changes of systolic blood pressure and changes of PAT from baseline to the physical task (-0.33 [-0.63, 0.01], p<0.048), and from physical to mental task (-0.51 [-0.77, -0.14], p=0.001), but not for baseline to mental task (-0.12 [-0,43,0,20], p=0.50) in the experimental group.&#xD;Conclusion: PAT and the used digital, handheld device proved to register changes in blood pressure and heart rate reliably compared to oscillometric measurements during intervention. Therefore, it might add benefit to future mobile health solutions to support blood pressure management by tracking relative, not absolute, blood pressure changes during non-pharmacological interventions.