Clinical Case Scenario
A 62-year-old male with a history of hypertension and dyslipidemia presents to the emergency department with severe retrosternal chest pain, sweating, and shortness of breath. A 12-lead ECG was performed, suggesting ST-segment elevation Myocardial infarction (STEMI). The patient rapidly deteriorated, developing profound hypotension and signs of cardiogenic shock. The patient’s trachea was intubated and inotrope was started, however, the shock did not reverse and worsened. Due to refractory cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is initiated via the femoral artery and vein. Initial VA-ECMO support provides hemodynamic stability, and the patient is transferred to the intensive care unit (ICU).
Over the next few hours, the ICU team observes that the patient's lower extremities remain warm and well-perfused, with good oxygen saturation readings from the pulse oximeter. However, the patient's upper extremities and face exhibit cyanosis. Arterial blood gas analysis reveals a significant discrepancy with blood drawn from the radial artery (representing upper body oxygenation) shows a lower PaO2 whereas blood drawn from the femoral arterial line (representing lower body oxygenation from the ECMO circuit) shows a higher PaO2.
Which of the following statements is true regarding the phenomenon occurring in this patient?
