Germinal matrix hemorrhage–intraventricular hemorrhage (GMH-IVH) is the most common variety of neonatal intracranial hemorrhage and is characteristic of the premature infant. The importance of the lesion relates not only to its high incidence but also to the essential gravity of the larger forms of IVH and their attendant complications. Moreover, the major forms of brain injury of the premature infant occur most commonly in the context of IVH, either as an apparent consequence of the IVH or as an associated finding.
Transcranial Doppler (TCD) ultrasonography has been extensively performed in preterm infants to evaluate alterations in cerebral hemodynamics, and studies in the literature have suggested that systolic and diastolic flow velocities of the anterior cerebral artery are related to physio-pathological mechanisms of hemorrhages and hypoxic-ischemic events.
Cerebral blood flow (CBF) in unhealthy preterm newborns is not auto-regulated, being therefore correlated to any change in systemic blood flow. During the early transitional period, the use of left or right ventricular output for measurement of systemic blood flow may not be accurate because of blood shunting across the patent ductus arteriosus (PDA) and foramen oval. Consequently, measurement of cardiac input via the superior vena cava (SVC) has been suggested as a proxy for global central blood flow in the transitional period.