The primary objective of the study is to demonstrate that the ECCO2R pulsatile configuration prevents the Willebrand factor high molecular weight multimers decrease observed under continuous blood flow configurations.

The secondary objectives are to quantify the CO2 extracorporeal removal in the pulsatile configuration, to describe complications (hemorrhagic, thrombotic and hemolytic), to describe patients' gas exchanges under ECCO2R, to describe the clinical course of the patients under ECCO2R as well as during the whole stay in the Intensive Care Unit (ICU).

A track of major interest to prevent bleeding complications in ECCO2R, and more generally in extracorporeal circulations, is to prevent acquired Willebrand disease. Indeed, a loss of Willebrand factor high molecular weight multimers (Whmwm) is frequently observed in conditions characterized by a continuous blood flow, associated with a high incidence of bleeding. A publication suggested the existence of this phenomenon under ECCO2R achieved through the medical device Hemolung (Alung technology, USA). We preliminary observed an almost constant and early (< 24 hours) decrease in Willebrand factor high molecular weight multimers under ECCO2R. Such a phenomenon is considered as a major factor of hemorrhagic complications. We hypothesize that use of pulsatile extracorporeal blood flow configuration during the full length of ECCO2R therapy, as authorized by the Xenios console (Xenios AG, Heilbronn), would preserve a normal value of Whmwm, mainly by changing the conditions of shear constraints ("shear stress").

Inclusion Criteria:

• Adult patient hospitalized in the Georges Pompidou European Hospital medical ICU
• Patient with or without SARS-CoV-2 infection
• ECCO2R treatment decision made by the medical team (regardless of the FLOW-ECCO2R protocol): mainly ECCO2R to enable ultraprotective ventilation for Acute respiratory distress syndrome (ARDS) patients or to avoid intubation or to shorten invasive mechanical ventilation in Chronic obstructive pulmonary disease (COPD) patients
• Affiliation to a social security regimen
• Informed consent (patient, trusted person, close family) , by default emergency inclusion notified in medical file and pursuance consent sought
• Negative serum or urinary β-hCG for women of child-bearing potential

Exclusion Criteria:

• Known allergy to heparin or to any of the excipients of the specialty used
• History of type II heparin-induced thrombopenia
• Thrombocytopenia (platelet < 100.000/mm3)
• Constitutional hemostasis disease interfering with biological assays
• Organic lesion likely to bleed
• Bleeding manifestations or tendencies linked to disorders of hemostasis
• Intracerebral hemorrhage
• Participation in another interventional research involving human participants
• Pregnant or breastfeeding women
• Protected adults (including individual under guardianship by court order)
• Persons deprived of their liberty by judicial or administrative decision

Individual participant data (IPD) that underlie results in publication could be shared. IPD detailed in the protocol of a planned metaanalysis could be shared

Two years after the last publication

Data sharing must be accepted by the sponsor and the PI based on a scientific project and scientific involvement of the PI team. Collaboration will be fostered.

Data sharing must respect the agreements made with funders.

Teams wishing obtain IPD must meet the sponsor and IP team to present scientific (and commercial) purpose, IPD needed, format of data transmission, and timeframe. Technical feasibility and financial support will be discussed before mandatory contractual agreement.

Processing of shared data must comply with European General Data Protection Regulation (GDPR).