Elgendi Mohamed, Fletcher Rich, Norton Ian, Brearley Matt, Abbott Derek, Lovell Nigel H, Schuurmans Dale
Electrical and Computer Engineering in Medicine Group, University of British Columbia and BC Children's Hospital, Vancouver, BC V6H 3N1, Canada.
Department of Computing Science, University of Alberta, Edmonton, AB T6G 2E8, Canada.
Sensors (Basel). 2015 Sep 25;15(10):24716-34. doi: 10.3390/s151024716.
There are a limited number of studies on heat stress dynamics during exercise using the photoplethysmogram (PPG) and its second derivative (APG). However, we investigate the most suitable index from short PPG signal recordings for heat stress assessment. The APG waveform consists of a, b, c and d waves in systole and an e wave in diastole. Our preliminary results indicate that the use of the energy of aa area, derived from PPG signals measured from emergency responders in tropical conditions, is promising in determining the heat stress level using 20-s recordings. After examining 14 time domain features using leave-one-out cross-validation, we found that the aa energy extracted from PPG signals is the most informative feature for classifying heat-stressed subjects, with an overall accuracy of 79%. Moreover, the combination of the aa energy with the traditional Sensors 2015, 15 24717 heart rate variability index of heat stress (i.e., the square root of the mean of the squares of the successive aa intervals) improved the heat stress detection to an overall accuracy of 83%.
关于在运动期间使用光电容积脉搏波描记图（PPG）及其二阶导数（APG）来研究热应激动态变化的研究数量有限。然而，我们从短PPG信号记录中探究用于热应激评估的最合适指标。APG波形在收缩期由a、b、c和d波组成，在舒张期由一个e波组成。我们的初步结果表明，利用从热带条件下应急响应人员测量的PPG信号得出的aa区域能量，在使用20秒记录来确定热应激水平方面很有前景。在使用留一法交叉验证检查了14个时域特征后，我们发现从PPG信号中提取的aa能量是用于对热应激受试者进行分类的最具信息量的特征，总体准确率为79%。此外，将aa能量与传统的热应激心率变异性指标（即连续aa间期平方均值的平方根）相结合，将热应激检测的总体准确率提高到了83%。
