The aa energy extracted from 20-s photoplethysmogram recordings classified heat-stressed subjects with 79% accuracy, improving to 83% when combined with a traditional heart rate variability index.
Observational
Does time domain analysis of PPG signals accurately detect heat stress in emergency responders?
Time domain analysis of short 20-s PPG recordings, specifically the aa energy, provides a promising and accurate method for monitoring heat stress in emergency responders.
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%.
Elgendi et al. (Fri,) conducted a observational in Heat stress. aa energy extracted from photoplethysmogram (PPG) signals was evaluated on Classification of heat-stressed subjects. The aa energy extracted from 20-s photoplethysmogram recordings classified heat-stressed subjects with 79% accuracy, improving to 83% when combined with a traditional heart rate variability index.