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Baroreceptor reflex sensitivity in human neonates: the effect of postmenstrual age
Peter Andriessen1, Sidarto Bambang Oetomo, Chris Peters
1Máxima Medical Center, Neonatal Intensive Care Unit, PO Box 7777, 5500 MB Veldhoven, the Netherlands. p.andriessen@mmc.nl
Insights
Baroreceptor reflex sensitivity and R-R interval variability increase with postmenstrual age in infants, indicating developing parasympathetic activity. This suggests progressive vagal maturation in newborns.
Area of Science:
- Neonatal physiology
- Autonomic nervous system development
- Cardiovascular regulation
Background:
- Infant autonomic nervous system (ANS) development is crucial for cardiovascular stability.
- Understanding changes in baroreceptor reflex sensitivity (BRS) with postmenstrual age (PMA) is vital for assessing neonatal health.
- Limited data exists on the maturation of BRS and its relationship with R-R interval and systolic blood pressure (SBP) variability in early infancy.
Purpose of the Study:
- To investigate the changes in R-R interval variability, SBP variability, and BRS with increasing postmenstrual age (PMA) in human infants.
- To determine the relationship between these cardiovascular parameters and PMA in the first days after birth.
- To explore the association between BRS and spectral powers of R-R interval and SBP series.
Main Methods:
- Cross-sectional study involving clinically stable infants (PMA 28-42 weeks) in quiet sleep.
- Recording of electrocardiogram, arterial SBP, and respiration.
- Utilizing (cross-)spectral analysis to calculate low-frequency (LF) and high-frequency (HF) spectral powers, transfer function phase, and gain for R-R interval and SBP series.
Main Results:
- Mean R-R interval and LF/HF spectral powers of R-R interval series increased significantly with PMA.
- Mean SBP increased with PMA, but SBP variability (LF/HF powers) did not show significant changes.
- Baroreceptor reflex sensitivity (BRS), derived from LF transfer gain, increased from 5 ms/mmHg in preterm to 15 ms/mmHg in term infants.
- BRS showed significant correlation with R-R interval spectral powers (LF and HF), but not with SBP spectral powers.
Conclusions:
- Baroreceptor reflex sensitivity and R-R interval spectral powers increase in parallel with postmenstrual age in infants.
- These findings suggest a progressive maturation of vagal activity and baroreceptor function with increasing PMA.
- The results highlight the dynamic development of autonomic cardiovascular regulation during early neonatal life.
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.
