Fig. 1

Schedule of Assessments and Procedures. X: assessments for all registered patients / •: additional assessments for randomised patients. ¹ Randomisation: as soon as haemoglobin ≤9 g/dl during surgery (=day 0) or day 1, 2, or 3 after surgery, registered consenting patients will be randomised. Re-evaluation of inclusion−/exclusion criteria before randomisation only refers to obvious occurrence of any component of the composite endpoint and any allogeneic blood transfusion after registration (chapter 4.2.2.). No specified diagnostics are scheduled. ^2a Haemoglobin levels will be determined from blood samples (primarily BGA measurement mainly as part of the patient’s usual care) at least daily before randomisation. ^2b Mild drop of haemoglobin < 9 g/dl due to induction of anaesthesia before skin incision is permitted and not an exclusion criteria. ^2c Haemoglobin levels will be determined from blood samples (primarily BGA measurement mainly as part of the patient’s usual care) at any time during or after randomisation until hospital discharge (up to 30 days after surgery; at least every 3 days), and after each transfused unit. Creatinine levels will be determined as part of the patient’s usual care at any time during or after randomisation until hospital discharge (or up to 30 days after surgery; at least every 7 days). ³ Intra-/Postoperative Intervention: Duration of intervention per patient: from intra−/postoperative randomisation until hospital discharge or 30 days after surgery, whichever occurs first. Physicians will be instructed to transfuse RBC units each time haemoglobin is lower than the randomised threshold and as soon as possible. The randomised target post-transfusion Hb level needs to be reached each time within 24 h upon receipt of lab result at the latest