Patient Dyspnea Under Veno-arterial Extracorporeal Circulation

Rationale: Patients with severe heart failure increasingly benefit from extracorporeal circulatory assistance (Extracorporeal Membrane Oxygenation - ECMO) that completely replaces the function of the heart and is in addition to mechanical ventilation (veno-arterial ECMO). In clinical practice, some of these patients have been found to be dyspneic, although circulatory assistance ensures satisfactory hematosis. Indeed, nearly half of the patients undergoing mechanical ventilation in intensive care have a generally intense dyspnea. In addition to the immediate discomfort caused by dyspnea, which can be assimilated to pain, this symptom is associated with a prolonged duration of mechanical ventilation and contributes to the genesis of neuropsychological sequelae of resuscitation such as post-traumatic stress syndrome. Objectives : 1. To study the effectiveness and impact of an increase in ECMO sweep gas flow through the membrane lung or positive tele-expiratory pressure (PEP) on dyspnea in patients under ECMO. 2. To understand the mechanism involved in this relief of dyspnea. Methods: in 30 patients of Intensive Care Unit, dyspnea will be evaluated by psychophysiological scales and scores as well as by neurophysiological tools (electromyography of inspiratory muscles) during sweep gas flow through the membrane lung incrementation and PEP increase. Ethical framework: Changes in ventilation parameters and ECMO will be performed in the usual manner, without additional or unusual diagnostic, treatment or monitoring procedures. Expected results and outlook: the investigators hypothesize that half of the patients on veno-arterial ECMO have dyspnea related to pulmonary edema. Therefore, an increase in PEP would alleviate this dyspnea. The investigators hypothesize that by using a relief method related to increased sweep gas flow through the membrane lung, the investigators can reduce the discomfort without inducing any associated complication. This study will improve the