Heart rate variability in normal sleeping full-term and preterm neonates

Ontogeny and control of the heart rate power spectrum in the last third of gestation in fetal sheep

“…While a significant correlation has been reported between respiratory frequency and HF power in preterm and fullterm infants (Patzak et al 1996;Rassi et al 2005), it has also been reported that HF power differs significantly between rapid eye movement and non-rapid eye movement sleep in full-term infants, despite continuous breathing in both states (Clairambault et al 1992). Furthermore, there is evidence that in newborn infants the HF power increases steeply in late gestation (at ∼37-38 weeks; Clairambault et al 1992); together, these data strongly imply that changes in HF power primarily reflect neural maturity and activity rather than a simple link with breathing. Finally, the large variability between animals in the present study is consistent with power spectra of healthy, full-term neonates (Baldzer et al 1989).…”

“…In addition, data from preterm and term infants suggest that LF activity still predominates after birth, despite continuous breathing (Clairambault et al 1992;Patzak et al 1996;Regalado et al 2001). While a significant correlation has been reported between respiratory frequency and HF power in preterm and fullterm infants (Patzak et al 1996;Rassi et al 2005), it has also been reported that HF power differs significantly between rapid eye movement and non-rapid eye movement sleep in full-term infants, despite continuous breathing in both states (Clairambault et al 1992). Furthermore, there is evidence that in newborn infants the HF power increases steeply in late gestation (at ∼37-38 weeks; Clairambault et al 1992); together, these data strongly imply that changes in HF power primarily reflect neural maturity and activity rather than a simple link with breathing.…”

“…Based on these findings and observations in newborn infants (Clairambault et al 1992), we originally predicted increased HF power with maturation, consistent with increased parasympathetic activity. Although the LF/HF ratio was lower in the older fetuses, the underlying spectral band data show that in absolute terms there was little HF activity, with no significant increase with maturation.…”

Cardiovascular Consequences of Preterm Birth in the First Year of Life

“…In a later study by the same group in which 3 groups of infants were compared, a preterm group 31-36 wks conceptional age (ConA), an intermediate group 37-38 wks ConA and a term group 39-41 wks ConA the HF power, mid frequency (MF) power, LF power and mean RR interval all increased with age and the differences were more marked in active sleep compared with quiet sleep. In addition, HF power showed the greatest increase from the preterm to term group, while LF power showed equal differences from preterm to intermediate and intermediate to term indicating that there is a steep increase in vagal tone at 37-38 wks ConA which plateaux to term and a steady increase in sympathetic tone from 31-41 wks (Clairambault et al, 1992). In a similar study of preterm infants divided into groups of 25-27, 28-31, and 32-37 weeks GA and studied at term CA compared with full term infants, it was found that all three groups of preterm infants had significantly lower HF power values in quiet sleep compared to the term infants (Patural et al, 2004).…”

“…Autonomic function has been demonstrated to increase with gestational age in the fetus during pregnancy (Gagnon et al, 1987, Karin et al, 1993. The sympathetic arm is believed to develop at a consistent rate throughout gestation, while the parasympathetic arm undergoes a period of accelerated development at around 37 to 38 weeks conceptional age (Clairambault et al, 1992). Autonomic function has been demonstrated to be immature in preterm infants compared with term infants at term corrected age, and this is inversely related to gestational age at birth (Gournay et al, 2002, Lagercrantz et al, 1990.…”