Why is there a risk of cerebral hypoxia with ECMO?

Why is there a risk of cerebral hypoxia with ECMO?

Venoarterial extracorporeal membrane oxygenator  or ECMO is a potential lifesaving intervention in those with refractory cardiogenic shock. But there is a potential risk of cerebral hypoxia because of upper body hypoxemia. Upper body is perfused by the left ventricular output which can be hypoxemic if there is pulmonary edema. Lower body is perfused with oxygenated blood from the ECMO [1].

Reference

1. Rab T, Ratanapo S, Kern KB, Basir MB, McDaniel M, Meraj P, King SB 3rd, O’Neill W. Cardiac Shock Care Centers: JACC Review Topic of the Week. J Am Coll Cardiol. 2018 Oct 16;72(16):1972-1980.