Heart rate variability metrics for fine-grained stress level assessment. (September 2017)

• Record Type: Journal Article
• Authors: Pereira, Tânia; Almeida, Pedro R.; Cunha, João P.S.; Aguiar, Ana
• Is Part Of: Computer methods and programs in biomedicine. Volume 148(2017)
• Page Start: 71
• Page End: 80
• Publication Date: 2017-09
• Subjects: Heart rate variability -- Stress assessment -- Wearable technology -- Trier social stress test; Medicine -- Computer programs -- Periodicals; Biology -- Computer programs -- Periodicals; Computers -- Periodicals; Medicine -- Periodicals; Médecine -- Logiciels -- Périodiques; Biologie -- Logiciels -- Périodiques; Biology -- Computer programs; Medicine -- Computer programs; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.cmpb.2017.06.018
• Languages: English
• ISSNs: 0169-2607

Abstract

Highlights: This study evaluates which HRV metrics allow to distinguish the mental stress levels. We applied the Trier Social Stress Test (TSST) method, a standardized stress-inducing protocol, to 14 volunteers. We measured the ECG signal with a wearable vital signal monitoring device with Medical Device certification. We evaluated HRV metrics in time and frequency domain and non linear analysis in various short-time scales. Wearable device and AVNN using 50 s of windows length analysis, allows a fine-grained analysis of stress effect as an index of psychological stress. Abstract: Background and Objectives: In spite of the existence of a multitude of techniques that allow the estimation of stress from physiological indexes, its fine-grained assessment is still a challenge for biomedical engineering. The short-term assessment of stress condition overcomes the limits to stress characterization with long blocks of time and allows to evaluate the behaviour change in real-world settings and also the stress level dynamics. The aim of the present study was to evaluate time and frequency domain and nonlinear heart rate variability (HRV) metrics for stress level assessment using a short-time window. Methods: The electrocardiogram (ECG) signal from 14 volunteers was monitored using the Vital Jacket TM while they performed the Trier Social Stress Test (TSST) which is a standardized stress-inducing protocol. Window lengths from 220 s to 50 s for HRV analysis were tested in order to evaluate which metrics could be used to monitor stress levels in an almost continuous way. Results: A sub-set of HRV metrics (AVNN, rMSSD, SDNN and pNN20) showed consistent differences between stress and non-stress phases, and showed to be reliable parameters for the assessment of stress levels in short-term analysis. Conclusions: The AVNN metric, using 50 s of window length analysis, showed that it is the most reliable metric to recognize stress level across the four phases of TSST and allows a fine-grained analysis of stress effect as an index of psychological stress and provides an insight into the reaction of the autonomic nervous system to stress.