[Circulatory monitoring in very low birth weight infants using Doppler sonography]

Doppler-ultrasonography measures blood flow velocity, which is proportional to blood flow if the vessel's diameters remain constant. Perfusion of brain, kidneys and gut can thus be estimated by transcutaneous ultrasonography at specific locations on the internal-carotid artery, renal artery and upper mesenteric artery. Cardiac output can be derived from measurements taken on the ascending aorta. The procedures of measurement are easy to learn, but interpretation is more critical. Doppler-ultrasonography has been applied in persistent ductus arteriosus, asphyxia, hyperventilation, brain death, impact of drugs on brain circulation, seizures, hydrocephalus, and shock. Future aims are the development of miniaturized doppler-sensors with low energy output for continuous monitoring, and the definition of guidelines for clinical applications.