Spectral analysis of heart rate variability in premature infants

Abstract

We studied the effect of gestational age, birth weight, postmenstrual age and selected neonatal morbidities on the heart rate power spectra in preterm infants (birth weight 1075 [840, 1230] grams, gestational age 27 [26, 30] weeks). Age at testing was 6 (3, 11) days. Birth weight, gestational age and postmenstrual age were positively correlated with low frequency power (0.03–0.39 Hz) with correlation coefficients of 0.59, 0.54 and 0.53 respectively (p<0.05); high frequency power (0.4–1.0 Hz) [r-value 0.54, 0.58 and 0.50 respectively] (p<0.05); and total power [r-value 0.41, 0.38 and 0.41 (p<0.05) respectively]. No significant effect on heart rate power spectra was observed for intraventricular hemorrhage, mechanical ventilation or methylxanthine use. Our data indicates increased heart rate variability with maturation and no major effect of the neonatal morbidities studied at the time when infants were physiologically stable.