Restrictive versus liberal transfusion strategies for older mechanically ventilated critically ill patients: a randomized pilot trial.
Tim Walsh and colleagues successfully conducted a pilot study comparing a liberal transfusion threshold of 9 g/dL to restrictive transfusion threshold of 7 g/dL in 100 intensive care unit patients with hemoglobin levels less than 9 g/dL. All patients required mechanical ventilation for > 96 hours, were > 55 years of age, and were expected to need mechanical ventilation at least 24 hours post randomization.
The trial recruited well, created a meaningful difference in hemoglobin levels, and had relatively few protocol violations. At 30 days, there were 12 deaths (23.5%) in the restrictive group and 16 deaths (32.7%) in the liberal group; relative risk, 0.72 (0.38 to 1.36). At 180 days there was a trend favoring restrictive transfusion group (19 vs. 27 deaths); relative risk, 0.68 [95% CI, 0.44–1.05]. Given the small sample size, these results should be viewed as hypothesis generating. The limitations of the trial included that only 3% of ICU patients were enrolled and the difference in red blood cell transfusions was relatively small between the groups. This well conducted pilot demonstrates the feasibility of definitive trial.