The Detrended Fluctuation Analysis (DFA) is extensively used to probe the correlation structure of heart rate fluctuations and to investigate differences between healthy and diseased populations that could justify its use as a valid prognostic tool. My research on respiratory influences on the DFA of short-term heart rate fluctuations showed that breathing frequency strongly affects the assessment of the short-term correlation exponent. Specifically, my co-authors and I have been able to formally explain and empirically demonstrate that slow breathing leads to high values of the scaling exponent, indicating stronger correlations embedded in the process, while the opposite holds for rapid breathing patterns. This finding has important implications for the use of measures derived from the DFA method in medical diagnosis.
1. Perakakis P., Taylor M., Martinez-Nieto E., Revithi I., Vila J. (2009). Breathing frequency bias in fractal analysis of heart rate variability. Biological Psychology 82, 82–88.