Intracranial flow patterns in infants undergoing extracorporeal membrane oxygenation: preliminary observations with Doppler US.

Transcutaneous Doppler ultrasound was used to monitor changes in intracranial hemodynamics in 13 infants undergoing extracorporeal membrane oxygenation (ECMO). Recordings for the pericallosal portion of an anterior cerebral artery were obtained before ECMO and daily during ECMO bypass, with use of a range-gated, pulsed Doppler imaging system. Obvious changes occurred with the onset of ECMO: the systolic phase broadened, and diastolic flow velocities markedly increased. The mean pulsatility value, as measured with the Pourcelot pulsatility index, decreased significantly at the start of ECMO and over time during ECMO bypass. Marked increases in the area under the velocity curve (AUTC) were also observed with the institution of ECMO bypass (mean percentage change in AUTC from baseline, 133%). Factors that appeared to affect AUTC included PCO2, mean blood pressure, and ECMO bypass rate. AUTC tended to decrease during the course of ECMO. Although the clinical significance of these findings remains unclear, the data indicate that ECMO bypass is associated with marked changes in intracranial hemodynamics.