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 ∼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.
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机译:我们对人类婴儿进行了一项横断面研究,以确定R–R间隔变异性,收缩压(SBP)变异性和压力感受器反射敏感性的指标是否随月经年龄(PMA:胎龄+出生年龄)而变化。在出生后第一天,处于安静睡眠状态的临床稳定婴儿(PMA,28-42周)记录了心电图,动脉SBP和呼吸。进行了R-R间隔序列和SBP序列的(跨)光谱分析,以计算低频(LF,指示压力感受器反射活动,0.04–0.15 Hz)和高频(HF,指示副交感神经活动,个体化)的功率呼吸频率的p-10和p-90值之间的波动)以及传递函数的相位和增益。 R–R间隔序列的平均R–R间隔以及LF和HF频谱功率随PMA的增加而增加。平均SBP随PMA增加,但不随SBP系列的LF和HF光谱功率增加。在低频范围内,互谱分析显示高相干性值(> 0.5),并且在R–R间隔和SBP之间存在一致的负相移,表明R–R间隔相对于SBP约有3 s的滞后。由LF转移增益计算得出的压力感受器反射敏感性随着PMA的增加而显着增加,从5(早产)增加到15 ms mmHg -1 sup>(足月)。压力感受器反射敏感性与R–R间隔序列的(LF和)HF频谱功率显着相关,但与SBP系列的LF和HF频谱功率无显着相关。主要结论是,RR间隔系列中的压力感受器反射敏感性和频谱功率与PMA平行增加,提示PMA逐渐进行迷走神经成熟。
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