CYCLIC VARIATION PATTERN OF CEREBRAL BLOOD-FLOW VELOCITY AND POSTCONCEPTIONAL AGE

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 refle ct the degree of immaturity of autoregulation - a speculation to be te sted. In a cross-sectional study 15 infants (gestational age 26-40 wee ks, postconceptional age (PCA) 26-42 weeks, age 1-99 days were investi gated. We performed a 10 min pulsed Doppler tracing on an internal car otid artery by means of a computer controlled 5 MHz Duplex device. Sys tolic velocity (Vs) was recorded pulse by pulse. After appropriate dat a transformation, in all infants the Fast Fourier Transform of the tim e course of Vs revealed the presence of a 2-5/min cyclic variation pat tern (one sample z-test, P < 0.0001). There was no significant correla tion between proportionate spectral power of the 2-5/min frequency ban d and either PCA (r = 0.23, P = 0.42) or age (r = 0.41, P = 0.13). Bet ween 26 and 42 weeks PCA, the cycling phenomenon is constant thus not reflecting cerebral maturation, and its presence does not mean immatur ity of cerebral autoregulation.