title: Baroreceptor reflex sensitivity in human neonates: the effect of postmenstrual age.
abstract: We performed a cross-sectional study in human infants to determine if indices of R-R interval variability, systolic blood pressure (SBP) variability, and baroreceptor reflex sensitivity change with postmenstrual age (PMA: gestational age+postnatal age). The electrocardiogram, arterial SBP and respiration were recorded in clinically stable infants (PMA, 28-42 weeks) in the quiet sleep state in the first days after birth. (Cross-)spectral analyses of R-R interval series and SBP series were performed to calculate the power of low-frequency (LF, indicating baroreceptor reflex activity, 0.04-0.15 Hz) and high-frequency (HF, indicating parasympathetic activity, individualized between the p-10 and p-90 values of respiratory frequency) fluctuations, and transfer function phase and gain. The mean R-R interval, and LF and HF spectral powers of R-R interval series increased with PMA. The mean SBP increased with PMA, but not the LF and HF spectral powers of SBP series. In the LF range, cross-spectral analysis showed high coherence values (>0.5) with a consistent negative phase shift between R-R interval and SBP, indicating a approximately 3 s lag in R-R interval changes in relation to SBP. Baroreceptor reflex sensitivity, calculated from LF transfer gain, increased significantly with PMA, from 5 (preterm) to 15 ms mmHg-1 (term). Baroreceptor reflex sensitivity correlated significantly with the (LF and) HF spectral powers of R-R interval series, but not with the LF and HF spectral powers of SBP series. The principal conclusions are that baroreceptor reflex sensitivity and spectral power in R-R interval series increase in parallel with PMA, suggesting a progressive vagal maturation with PMA.
authors.affiliation: Máxima Medical Center, Neonatal Intensive Care Unit, PO Box 7777, 5500 MB Veldhoven, the Netherlands. p.andriessen@mmc.nl
authors.forename: Peter
authors.initials: P
authors.lastname: Andriessen
authors.forename: Sidarto Bambang
authors.initials: SB
authors.lastname: Oetomo
authors.forename: Chris
authors.initials: C
authors.lastname: Peters
authors.forename: Barbara
authors.initials: B
authors.lastname: Vermeulen
authors.forename: Pieter F F
authors.initials: PF
authors.lastname: Wijn
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Blanco
mesh_terms: D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D004562:Electrocardiography; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D010275:Parasympathetic Nervous System; D012143:Respiratory Physiological Phenomena; D012890:Sleep; D014630:Vagus Nerve / Q000254:growth & development