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Transfusion requirements in critical care. A pilot study. Canadian Critical Care Trials Group
P C Hébert1, G Wells, J Marshall
1Critical Care Program, University of Ottawa (Ontario), Canada.
Objective:
To evaluate the effects of a restrictive and a liberal red blood cell (RBC) transfusion strategy on mortality and morbidity in critically ill patients.
Study Design:
Multicenter, prospective, randomized clinical trial.
Patient Population:
Sixty-nine normovolemic critically ill patients admitted to one of five tertiary level intensive care units with hemoglobin values less than 90 g/L within 72 hours of admission.
Interventions:
Patients were randomly allocated to one of two RBC transfusion strategies. Hemoglobin values were maintained between 100 and 120 g/L in the liberal transfusion group and between 70 and 90 g/L in the restrictive group.
Results:
Primary diagnosis and mean +/- SD age (58.6 +/- 15 vs 59.0 +/- 21 years and Acute Physiology and Chronic Health Evaluation II score (20 +/- 6.2 vs 21 +/- 7.2) were similar in the restrictive and liberal groups, respectively. Daily hemoglobin values averaged 90 g/L in the restrictive group vs 109 g/L in the liberal group (P < .001). The restrictive group received 2.5 U per patient compared with 4.8 U per patient in the liberal group. This represents a 48% relative decrease (P < .001) in RBC units transfused per patient. The 30-day mortality rate was 24% in the restrictive group compared with 25% in the liberal group; the 95% confidence interval around the absolute difference was -19% to 21%. Similar observations were noted for intensive care unit mortality (P = .76) and 120-day mortality (P > .99). In addition, survival analysis comparing time until death in both groups did not reveal any significant difference (P = .93) between groups. Organ dysfunction scores were also similar (P = .44).
Conclusion:
In this small randomized trial, neither mortality nor the development of organ dysfunction was affected by the transfusion strategy, which suggests that a more restrictive approach to the transfusion of RBCs may be safe in critically ill patients. However, the study lacked power to detect small but clinically significant differences. Therefore, further investigations of RBC transfusion strategies are warranted.