Hernando Alberto, Lazaro Jesus, Gil Eduardo, Arza Adriana, Garzon Jorge Mario, Lopez-Anton Raul, de la Camara Concepcion, Laguna Pablo, Aguilo Jordi, Bailon Raquel
IEEE J Biomed Health Inform. 2016 Jul;20(4):1016-25. doi: 10.1109/JBHI.2016.2553578. Epub 2016 Apr 13.
Respiratory rate and heart rate variability (HRV) are studied as stress markers in a database of young healthy volunteers subjected to acute emotional stress, induced by a modification of the Trier Social Stress Test. First, instantaneous frequency domain HRV parameters are computed using time-frequency analysis in the classical bands. Then, the respiratory rate is estimated and this information is included in HRV analysis in two ways: 1) redefining the high-frequency (HF) band to be centered at respiratory frequency; 2) excluding from the analysis those instants where respiratory frequency falls within the low-frequency (LF) band. Classical frequency domain HRV indices scarcely show statistical differences during stress. However, when including respiratory frequency information in HRV analysis, the normalized LF power as well as the LF/HF ratio significantly increase during stress ( p-value 0.05 according to the Wilcoxon test), revealing higher sympathetic dominance. The LF power increases during stress, only being significantly different in a stress anticipation stage, while the HF power decreases during stress, only being significantly different during the stress task demanding attention. Our results support that joint analysis of respiration and HRV obtains a more reliable characterization of autonomic nervous response to stress. In addition, the respiratory rate is observed to be higher and less stable during stress than during relax ( p-value 0.05 according to the Wilcoxon test) being the most discriminative index for stress stratification (AUC = 88.2 % ).
在一个由接受改良版特里尔社会应激测试诱导的急性情绪应激的年轻健康志愿者组成的数据库中，呼吸频率和心率变异性（HRV）作为应激标志物进行了研究。首先，使用经典频段的时频分析计算瞬时频域HRV参数。然后，估计呼吸频率，并以两种方式将此信息纳入HRV分析：1）将高频（HF）频段重新定义为以呼吸频率为中心；2）从分析中排除呼吸频率落在低频（LF）频段内的那些时刻。经典频域HRV指标在应激期间几乎没有显示出统计学差异。然而，当在HRV分析中纳入呼吸频率信息时，归一化的LF功率以及LF/HF比值在应激期间显著增加（根据Wilcoxon检验，p值<0.05），表明交感神经优势更高。LF功率在应激期间增加，仅在应激预期阶段有显著差异，而HF功率在应激期间降低，仅在需要注意力的应激任务期间有显著差异。我们的结果支持呼吸和HRV的联合分析能更可靠地表征自主神经对应激的反应。此外，观察到应激期间的呼吸频率比放松期间更高且更不稳定（根据Wilcoxon检验，p值<0.05），是应激分层的最具判别力的指标（AUC = 88.2%）。
