Extracorporeal blood purification is a supportive therapy in the management of patients with sepsis or vasoplegic shock. The pathophysiology of sepsis is based on an inappropriate host response to infection. Certain medical devices with higher adsorption capacity make it possible to limit this inappropriate response and could thus improve the hemodynamics of patients in septic or vasoplegic shock. The preliminary experience of the investigators from clinical data of vasopressor withdrawal in pediatric patients treated with oXiris shows a 50% reduction in the vasopressor score, Vaso Inotropic Score (VIS), for 40% of patients within 24 hours following the start of treatment. Similar results were found in adult patients treated for severe COVID-19 or vasoplegic shock by the other centers participating in the study. Cytokine purification is an important physiological effect of purification membranes. However, this may not fully explain the rapid hemodynamic improvement of patients treated with an oXiris membrane. The role of angiotensin metabolites (Ang 1-5, 1-7, 1-9) in the systemic vascular tone of patients has been recently discussed. The administration of angiotensin 2 in vasoplegic shock in adults helps correct hypotension. In the group of patients with increased renin, this treatment was associated with a reduction in mortality. Indeed, increased renin associated with dysfunction of Angiotensin Converting Enzyme (ACE) leads to an accumulation of Angiotensin 1 which degrades to Ang 1-7. The hypothesis f the investigators is that the concentration of Ang 1 and Ang 1-7 is elevated in cases of vasoplegic shock and that the clearance of these vasodilator peptides by blood purification is associated with clinical improvement.