Brain death in infants: evaluation with Doppler US

In a preliminary study, nine infants with a clinically determined diagnosis of brain death were examined with duplex pulsed Doppler ultrasonography (US) through the anterior fontanelle. Flow velocity measurements were made in the intracranial internal carotid artery and anterior cerebral artery. Resistive index (RI) was calculated in each patient and used as an indicator of diastolic flow. Eight of nine infants showed markedly elevated RI (100%-191%) with reversal of diastolic flow. One infant had low RI (42%-58%) with preserved systolic and diastolic flow until death. The authors believe that the elevation of RI with diastolic flow reversal seen in these patients is a reflection of increased intracranial pressure and is a sign of poor prognosis when present on serial examinations. Cranial duplex pulsed Doppler US is a useful, noninvasive tool in the diagnosis of brain death in infants but must be carefully correlated with clinical examination and other diagnostic tests.