Cardiac determinants of cerebral blood flow during extracorporeal membrane oxygenation.

Doppler recordings of the pericallosal artery (PCA) and echocardiographic examinations were performed on nine infants before, and at 24-, 72-, and 96-hour intervals during extracorporeal membrane oxygenation (ECMO). Systolic indices of left ventricular (LV) function, as well as mean blood flow velocity and pulsatility in the PCA, were measured. Arterial blood gases and blood pressure were monitored. LV cardiac output and LV stroke volume decreased during early ECMO and returned toward baseline as ECMO flow rates decreased. In the PCA, changes in pulsatility paralleled changes in ventricular performance. Pulsatility decreased during early ECMO and returned toward baseline with time. There was an inverse relationship between mean blood flow velocity in the PCA and ventricular function during early ECMO. Mean blood flow velocity increased during early ECMO and returned toward baseline as ECMO flow rates decreased. Early changes in mean blood flow velocity were associated with an initial increase in arterial pO2, pCO2, and mean blood pressure. Total aortic flow (ECMO flow + LV cardiac output in cc/kg), arterial blood gases, and mean blood pressure remained unchanged during prolonged ECMO. These data suggest that the pulsatility of cerebral blood flow is related to cardiac function during partial bypass and that the regulation of cerebral blood flow during prolonged bypass may be dependent on the presence of pulsatile flow.