Send to

Choose Destination
Comput Methods Programs Biomed. 2015 Dec;122(3):503-12. doi: 10.1016/j.cmpb.2015.09.021. Epub 2015 Oct 9.

Frequency analysis of photoplethysmogram and its derivatives.

Author information

Electrical and Computer Engineering in Medicine Group, University of British Columbia, Vancouver, British Columbia, Canada; Department of Computing Science, University of Alberta, Edmonton, Canada. Electronic address:
D-Lab, Massachusetts Institute of Technology, Boston, USA.
National Critical Care and Trauma Response Centre, Darwin, Australia.
School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, Australia.
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
Department of Computing Science, University of Alberta, Edmonton, Canada.


There are a limited number of studies on heat stress dynamics during exercise using the photoplethysmogram (PPG). We investigate the PPG signal and its derivatives for heat stress assessment using Welch (non-parametric) and autoregressive (parametric) spectral estimation methods. The preliminary results of this study indicate that applying the first and second derivatives to PPG waveforms is useful for determining heat stress level using 20-s recordings. Interestingly, Welch's and Yule-Walker's methods in agreement that the second derivative is an improved detector for heat stress. In fact, both spectral estimation methods showed a clear separation in the frequency domain between measurements before and after simulated heat-stress induction when the second derivative is applied. Moreover, the results demonstrate superior performance of the Welch's method over the Yule-Walker's method in separating before and after the three simulated heat-stress inductions.


Affordable healthcare; Heat stress; Hot environment

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center