Table 1.

Study exclusion criteria

Exclusion criteria	Justification
Emergency surgery	Inability to randomise/perform study procedures
IgA deficiency	Not ethical to randomise to standard issue RBCs
History of severe recurrent transfusion reaction	Not ethical to randomise to standard issue RBCs
Refusal to receive allogeneic RBCs	Inability to administer intervention of interest
Refusal to provide informed consent	Not ethical to enrol into trial
Prevalent acute lung injury prior to randomization	Inability to adequately assess outcome
Prevalent hydrostatic pulmonary oedema prior to randomization	Inability to adequately assess outcome
Expected hospital stay<48 hours	Incomplete study procedures and outcome data
Not anticipated to survive>48 hours	Incomplete study procedures and outcome data
Previously enrolled in this trial	Violation of the independence assumption
Pulmonary artery catheter placement not planned for the surgical procedure	Inability to assess key physiologic parameters outlined in the study protocol
Use of home oxygen therapy	Inability to assess oxygen use outcome
Complex RBC antibody profiles	Washing not feasible due to testing delays
Need for the use of irradiated RBCs	Intervention contraindicated

Patients will be recruited and enrolled at two academic medical centres in the USA (Mayo Clinic, Rochester, MN; Duke University Medical Centre, Raleigh, NC) with substantial experience in RBC-washing and transfusion management for cardiac surgery. With regards to type of cardiac surgery, study coordinators will screen all adult patients scheduled to undergo coronary artery bypass grafting (CABG) surgery, complex cardiac valve surgery, pericardial resection, and/or ascending aortic surgery in one of the two participating institutions. Eligible patients will be approached before their elective surgical procedure by a member of the study team for informed consent. A study identification (ID) number will be assigned to each study participant and randomization will occur after receipt of informed consent, but before entry to the operating room for the scheduled procedure. Screening logs will be maintained at each site to allow generation of a CONSORT diagram.