Extracorporeal membrane oxygenation and cerebral blood flow velocity in newborn infants

Doppler ultrasound was used to study cerebral hemodynamics in the pericallosal artery of 21 newborn infants undergoing extracorporeal membrane oxygenation (ECMO) for intractable respiratory failure. Cerebral blood flow velocity waveforms were obtained pre-ECMO, after every major change in cardiopulmonary bypass flow during ECMO, and post-ECMO. The mean pulsatility index (PI) pre-ECMO was slightly higher than after decannulation, secondary to hypocarbia pre-ECMO. The PI decreased significantly at high (61 to 120 ml/min.kg) cardiopulmonary bypass flows. This was associated with an increase in mean arterial pressure, but not with changes in Hct, PaO2, or PaCO2. A negative curvilinear relationship between the amount of cardiopulmonary bypass flow and PI was found. These data suggest an increase in cerebral blood flow velocity and vasodilation of the cerebral vessels at high cardiopulmonary bypass flows, and may explain the occurrence of intracranial hemorrhage in infants undergoing ECMO.