Transfusion Requirements in Cardiac Surgery

This is a multi-centre randomized controlled pilot trial of two transfusion strategies in high risk patients having cardiac surgery. This study will be conducted in 7 Canadian centers and 1 American centre. Patients allocated to a "restrictive" transfusion strategy will receive a red cell transfusion if their hemoglobin is 75 g/L or less intraoperatively and postoperatively. Patients allocated to a "liberal" transfusion strategy will receive red cell transfusion if their hemoglobin concentration is 95 g/L or less intraoperatively and postoperatively in the intensive care unit, and less than 85 g/L on the ward.

The primary objectives of this study are to determine 1) enrollment rates (patients enrolled/patients eligible), 2) consent rates (consent obtained/patients approached); and 3) protocol adherence (incidence and reasons for non adherence, lack of consent, rates of contamination and utilization of co-interventions). The secondary objectives are to determine 1) the mortality rate and the rate of the composite outcome for morbidity of renal, cardiac, neurological and infectious adverse events; 2) the proportion of missing data as a measure of the feasibility of the case report form; and 3) the proportion of blood products utilized (red cells, platelets and plasma).

The results of the multicentre pilot study will be used to 1) maximize enrollment rates to ensure timely completion of recruitment of a definitive large randomized controlled trial, 2) maximize adherence rates, 3) determine event rates for sample size estimation for a definitive study, and to 4) optimize the case report form.