Vasomotor Reactivity in Premature Neonates at Term

Abstract

In order to assess the specific sympathetic reactivity in premature infants at term, we designed a study to evaluate the peripheral vasomotor response of such infants when exposed to auditory challenges. Testing was performed in 29 premature neonates at term in both quiet and active sleep during a morning session. Two types of noises were used (click and continuous tones) at three frequencies (250, 1,000 and 6,000 Hz) and at three intensities (60, 85 and 110 dBA). Vasomotor response was studied by analyzing with Mathlab^® software the variability of the plethysmographic wave of the oxymetric pulse. No behavioral awakening was observed in response to any stimulation. When a tachycardia or a bradycardia reaction to the stimuli was observed, all neonates responded with a vasoconstriction. The global mean of the vasoconstrictive response was 18.45%. The overall ANOVA on the vasomotor response revealed significant effects for sleep stages (t: 1.98; p < 0.05), for frequency (t: 3.3; p < 0.001) and for intensity of noise (t: 3.01; p < 0.03) but no significant response with heart rate variability. From these results, we could conclude that the assessment of the vasomotor response is a very sensitive procedure to determine the reactivity of the autonomic nervous system in neonates, and could be used to study such vegetative responses in other stressful situations with good accuracy.

Spectral Analysis of Heart Rate Variability: An Emerging Tool for Assessing Stability During Transition to Extrauterine Life

“…To test the hypothesis that preterm neonates measured at term continue to exhibit more sympathetic reactivity, researchers exposed them to auditory challenges when asleep to evaluate their peripheral vasomotor response (Ducrocq et al, 2002). The stimuli produced a strong reactivity, resulting in vasoconstriction manifested as either a heart rate deceleration or acceleration, although the overall mean heart rate did not change.…”

Statistical Modeling of Heart Rate Variability to Unravel the Factors Affecting Autonomic Regulation in Preterm Infants

“…However, in septic infants, reduced HRV, even though obvious to the eye, may not be fully captured by SDNN 12 . This is because, unlike healthy adults, who exhibit a heart rate (HR) pattern with an equal number of decelerations and accelerations, preterm infants are susceptible to transient pathophysiological decelerations in HR 13 . Such decelerations potentially result in substantially large values of SDNN, even in the absence of the small increases and decreases in HR that characterizes healthy HRV, and which SDNN was initially designed to capture 2 .…”