Phase-Rectified Signal Averaging to Evaluate ANS Development in Premature Infants

Aim: Heart Rate Variability (HRV) is determined by the autonomic nervous system (ANS) and a low value of this parameter is related to neurological pathologies and infants mortality. This study aims to assess the utility and the advantages of HRV analysis by means of phase-rectified signal averaging (PRSA), a technique that obtains curves that are useful to determine the development of the ANS in preterm infants, with less obtrusive monitoring compared to electroencephalography. Methods: For a preliminary study, 24-hour ECGs were taken in NICU at the University Hospital in Leuven, from 12 babies: 4 were term, 4 were born preterm but reached a term postmenstrual age, and 4 were preterm. Heart rate tracks of segments of 27 minutes were extracted and analyzed with the PRSA technique. The curves obtained were quantified by the slope and by an acceleration/deceleration related parameter (AC/DC). Two independent analyses on acceleration and deceleration were carried out to visualize the effects of the sympathetic and parasympathetic system separately. Moreover, the immediate response and the response after 5 seconds were taken into account. Results and Conclusion: All the results were compared and validated with traditional HRV parameters. The results of slope and AD/DC in both types of analysis are promising in providing a simple parameter to assess neurological development deficiency in order to allow faster and preventive intervention. Further studies are needed in a larger populatio