Short term heart rate variability in healthy neonates: normative data and physiological observations.

Background: The measurement of heart rate variability (HRV) reveals information on the functional state of the autonomic nervous system (ANS). Moreover, several diseases are known to be accompanied by a reduction in HRV. Currently, there are no data on HRV within larger samples of healthy neonates.

Aim: This study was initiated to establish normative data of HRV parameters and to assess physiological observations in healthy newborn infants.

Study Design: We performed 10 min recordings of HRV in 80 healthy neonates. We computed time domain parameters. Furthermore power spectrum analysis was calculated by Fourier Transformation in 3 frequency bands. The total power as well as the peak frequencies was estimated for each band.

Results: The normative data of each HRV parameter for healthy newborns are presented as mean, standard deviation and the 5th and 95th percentiles. Increasing postnatal age is accompanied by a significant (p<0.05) elevation of HRV parameters. Baroreceptor loop fluctuations were delayed from 0.1 Hz (adults) to 0.07 Hz in healthy newborns. A respiratory peak according to respiratory sinus arrhythmia (RSA) as it is common in adults was not detectable.

Conclusions: Normative data of HRV allows the interpretation of clinical data in neonatal diseases affecting the ANS. Moreover, we observed physiological deviations in healthy newborns in comparison to adults.