Pereira Tânia, Almeida Pedro R, Cunha João P S, Aguiar Ana
Telecommunications Institute, University of Porto, Portugal.
School of Criminology, University of Porto, Portugal.
Comput Methods Programs Biomed. 2017 Sep;148:71-80. doi: 10.1016/j.cmpb.2017.06.018. Epub 2017 Jun 29.
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.
The electrocardiogram (ECG) signal from 14 volunteers was monitored using the Vital Jacket 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.
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.
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.
尽管存在多种可根据生理指标估算压力的技术，但对其进行细粒度评估仍是生物医学工程面临的一项挑战。压力状况的短期评估克服了长时间压力特征描述的局限性，能够评估现实环境中的行为变化以及压力水平动态。本研究的目的是使用短时间窗口评估时域、频域和非线性心率变异性（HRV）指标以评估压力水平。
14名志愿者在进行标准化压力诱导方案——特里尔社会压力测试（TSST）时，使用生命夹克监测其心电图（ECG）信号。测试了用于HRV分析的220秒至50秒的窗口长度，以评估哪些指标可用于几乎连续地监测压力水平。
HRV指标的一个子集（平均NN间期、相邻NN间期差值的均方根、标准NN间期和NN间期差值大于20毫秒的心搏数百分比）在压力和非压力阶段之间显示出一致的差异，并且在短期分析中显示为评估压力水平的可靠参数。
使用50秒窗口长度分析的平均NN间期指标表明，它是识别TSST四个阶段压力水平最可靠的指标，能够作为心理压力指标对压力效应进行细粒度分析，并深入了解自主神经系统对压力的反应。
