1. Department of Anaesthesiology Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Goethe University Frankfurt Germany
2. German Red Cross Blood Transfusion Service of Baden‐Wuerttemberg – Hessen Institute of Transfusion Medicine and Immunohematology; University Hospital of Frankfurt Frankfurt Germany
3. Department of Anaesthesiology Intensive Care and Emergency Medicine, Asklepios Clinic Wandsbek Hamburg Germany
4. Department of Anaesthesiology Heidelberg University Hospital Heidelberg Germany