RECOMMEND Platform Trial

PLATFORM INCLUSION CRITERIA: * Patients receiving ECMO * Patients enrolled in the EXCEL Registry - NCT03793257 PLATFORM EXCLUSION CRITERIA: * Treating clinician regards death as imminent and inevitable * Treating clinician determines it is not in the patient's best interests RBC TRANSFUSION DOMAIN INCLUSION CRITERIA: • Aged 18 years or older RBC TRANSFUSION DOMAIN EXCLUSION CRITERIA: * Contraindication to RBC transfusion (including known patient preference) * Limitations of care put in place either through patient wishes or the treating medical teams. * Participant has already received ECMO \>12 hours. The start of ECMO is defined as the time of initiation of extracorporeal blood flow unless ECMO was initiated during a surgical intervention in which case the start of ECMO is defined as the arrival time into the initial ICU (post-surgery) * The treating physician anticipates that ECMO treatment will cease before the end of tomorrow * The treating physician deems the study is not in the patient's best interest * The treating physician has concern regarding patient ability to tolerate restrictive or liberal transfusion trigger thresholds * Actively listed for a solid organ transplant and has not yet received one * Suspected or confirmed to be pregnant * Previous ECMO treatment during the same hospital admission