Eur. Phys. J. B (2017) 90: 191
https://doi.org/10.1140/epjb/e2017-80378-x

Regular Article

The effect of respiratory oscillations in heart rate on detrended fluctuation analysis

Division of Fetal and Transitional Medicine, Fetal Medicine Institute, Children’s National Health System, 111 Michigan Ave, NW, Washington, DC 20010, USA

^a e-mail: rgovinda@childrensnational.org

Received: 7 March 2017
Received in final form: 27 June 2017
Published online: 11 October 2017

Abstract

Characterization of heart rate using detrended fluctuation analysis (DFA) is impeded by respiratory oscillations. In particular, the short-term exponent measured from 15 to 30 beats is compromised in the DFA. We reconstruct respiratory signal from electrocardiograms and attenuate the respiratory oscillation in the heart rate using a frequency-dependent subtraction approach. We validate this method by applying it to an electrocardiogram signal simulated using a coupled differential equation with the respiratory oscillation modelled using a sine function. The exponent estimated using the proposed approach agreed with the exponent incorporated in the model within a narrow range. In contrast, the exponent obtained from the raw data deviated from the expected value. Furthermore, the exponents obtained for the raw heart rate are smaller than the exponents obtained for the respiration oscillation attenuated heart rate. We apply this approach to heart rate measured from 12 preterm infants that were being treated for prematurity related complications. As observed in the simulated data, we show that compared to the raw heart rate, the respiratory oscillation attenuated heart rate shows higher short-term exponent (p < 0.001).