Doppler ultrasound in the neonate.

The use of Doppler ultrasound to assess both the changing haemodynamics of the neonatal circulation and the perfusion of the brain is reviewed. The brain is particularly susceptible to both ischaemic and haemorrhagic injury in preterm and asphyxiated infants. However, the unique characteristics of the transitional neonatal circulation, and of the cerebral vasculature, pose considerable problems in the interpretation of Doppler signals from intracranial arteries. A volumetric Doppler method which eliminates some of those problems is discussed. The same method allows full assessment of the cardiovascular status of the newborn infant, including estimation of ductal shunting and left ventricular output. Doppler ultrasound, if used with a full understanding of the inherant assumptions and limitations of the particular methodology, is likely to prove invaluable in investigating pathological cerebral and cardiac vascular events in the newborn.