Normative Values for Heart Rate Variability Indices in Healthy Infants in the Emergency Department

Heart rate variability (HRV) has been used as a marker of cardiovascular health and a risk factor for mortality in the adult and paediatric populations, and as an indicator of neonatal sepsis. There has been an increasing interest in using short-term (5-minutes) HRV to identify infants <90 days of life with serious bacterial infections. However, there has not been any normative data range reported for short-term HRV indices in this infant population. We conducted a prospective observational study of short-term HRV analysis of well infants <90 days of life in the emergency department (ED) setting. 108 infants with complete data [51.9% male, median age 9 days (inter-quartile range 4-35 days)] were included. We found that heart rate (HR) is correlated with heart rate variability. Thus, normalisation of HRV parameters was done to remove their dependence on HR. We then provided a normative reference range of widely used short-term HRV time-domain, frequency-domain, and non-linear HRV metrics in our cohort. We produced a HRV calculator for evaluation of these short-term HRV variables in young infants in ED settings that can be used for future clinical research.