Cyclic variation pattern of cerebral blood flow velocity and postconceptional age

Abstract

In preterm neonates, the risk for intracerebral haemorrhage is linked to immaturity of cerebral autoregulation. The preterm's 2-5/min cyclic variation pattern of cerebral blood flow velocity is thought to reflect the degree of immaturity of autoregulation--a speculation to be tested. In a cross-sectional study 15 infants (gestational age 26-40 weeks, postconceptional age (PCA) 26-42 weeks, age 1-99 days were investigated. We performed a 10 min pulsed Doppler tracing on an internal carotid artery by means of a computer controlled 5 MHz Duplex device. Systolic velocity (Vs) was recorded pulse by pulse. After appropriate data transformation, in all infants the Fast Fourier Transform of the time course of Vs revealed the presence of a 2-5/min cyclic variation pattern (one sample z-test, P < 0.0001). There was no significant correlation between proportionate spectral power of the 2-5/min frequency band and either PCA (r = 0.23, P = 0.42) or age (r = 0.41, P = 0.13). Between 26 and 42 weeks PCA, the cycling phenomenon is constant thus not reflecting cerebral maturation, and its presence does not mean immaturity of cerebral autoregulation.

Effect of dexamethasone therapy on cerebral and ocular blood flow velocity in premature infants studied by colour Doppler flow imaging

“…We analysed only patients with stable blood flow velocity patterns, but cyclic variations in CBFV [1,22] cannot be ruled out completely without longer periods of observation. Nevertheless, our results should not be influenced by such variations because cyclic variations affect systolic and diastolic blood flow velocity similarly [1] and the RI remains unchanged.…”

Low frequency cerebral arterial and venous flow oscillations in healthy neonates measured by NeoDoppler

“…At the time, LFO in neonates was thought to represent an immature cerebral autoregulatory system, that was dampened with age ( 5 , 6 ). In contrast, in a cross-sectional study including 15 preterm and term neonates, LFO was found to be independent of PNA ( 11 ). In the latter study, oscillations were measured over a longer time scale (10 min) than previous studies, which also captures very LFO (approximately 0.02 Hz) ( 11 ).…”

“…In contrast, in a cross-sectional study including 15 preterm and term neonates, LFO was found to be independent of PNA ( 11 ). In the latter study, oscillations were measured over a longer time scale (10 min) than previous studies, which also captures very LFO (approximately 0.02 Hz) ( 11 ). In a longitudinal study including 10 preterm infants, the same research group found that although LFO was independent of PNA, LFO tended to be reduced in the early postnatal period ( 14 ).…”

“…In a longitudinal study including 10 preterm infants, the same research group found that although LFO was independent of PNA, LFO tended to be reduced in the early postnatal period ( 14 ). Similarly, Menke et al ( 10 ) found that preterm neonates had few LFO directly after birth, and that the presence of LFO increased significantly during the first 96 h. This might indicate an initially impaired autoregulation in preterm neonates in the period they are known to be in greatest risk of intracranial complications ( 2 , 10 , 11 ). Physiological changes in CBF beyond the transitional period cannot be assumed based on our study.…”

“…In adults, LFO in cerebral oxygenation measured with near-infrared spectroscopy (NIRS) appear to be related to increased reactivity of the microvasculature and, potentially, increased compliance and autoregulatory capacity ( 18 ). LFO in arterial CBF have been observed in both preterm ( 5 – 14 ) and term ( 5 , 7 , 8 , 11 , 12 ) neonates, but the significance in these age groups is not known. In neonates, LFO in venous CBF have not yet been described in publications.…”