There is no consensus among ECMO centers regarding the way to manage weaning from VA-ECMO. Decrease in doses of catecholamine infusion, recovery of a pulse arterial pressure, and improvement of myocardial function assessed with echocardiography are indicating that the patient might be weaned from ECMO. A weaning test has then to be conducted. The only published test at this time consists in a daily transient decrease in ECMO blood flow at 1 L/min during 15 min. Hemodynamic stability and echocardiography parameters, aortic velocity time integral (reflecting cardiac output)>12 cm, left ventricular ejection fraction>20%, and S′ wave at mitral annulus >6 cm/s are predictive of weaning success under this regimen [1]. ECMO explantation is then performed at the patient’s bedside or in the operating room depending on local practice.

Success of weaning from right ventricular dysfunction remains less predictable. Indeed, right ventricular failure can be masked, even during low ECMO blood flow regimens, making the criteria previously described not suitable to predict weaning success or failure, and can occur several hours after ECMO removal. In that case, weaning process consists in a gradual decrease in ECMO blood flow during approximately 10 days, until reaching 1.5–2 L/min. ECMO explantation will be mostly guided by (1) the predictive clinical course of right ventricular dysfunction considering the underlying pathology (usually several days in case of primary graft dysfunction, more progressive and uncertain in case of ischemia); (2) right ventricular aspect and contractility during the 15-min weaning test at 1 L/min; and (3) right ventricular aspect and contractility during a real clamp test during 20 min.

Respiratory function must also be assessed before explantation. A high proportion of patients assisted with venoarterial ECMO exhibits indeed an ARDS, due to initial multiple organ failure. Switching off the sweep gas flow cannot be done during venoarterial ECMO (as it is during venovenous ECMO), as it would create a venoarterial shunt. Weaning test consists in reimplementing a standard mechanical ventilation (tidal volume 6 ml/kg of ideal body weight) and decreasing the pulmonary assistance on ECMO: decrease sweep gas flow to approximately 2 L/min and decrease FiO₂ on ECMO to <50%. Pulmonary compliance and oxygenation are then checked. Patients not stable under this regimen (increase in the plateau pressure, lack of oxygenation) will necessitate a switch from venoarterial to venovenous ECMO. Drainage cannula is left in place, and an additional return cannula is placed in the right jugular vein while arterial cannula is removed.