I believe the culprit is "Pump Head". Not the inflammation thing they mention, not the anesthesia.
Heart lung bypass machines, ECMO systems, they all use non-pulsatile continuous flow pumps. These pumps do not have the same pressure curve and higher pressure pulses that the native circulation does. This causes blood to not make it all the way down to the capillaries, and therefore starves brain tissue that is fed by the smallest of the capillaries.
To solve this problem, a company I helped called Ventriflo has been working to build a pulsatile pump that can be used for both ECMO and cardiopulmonary bypass uses.