Is a low transfusion threshold safe in critically ill patients with cardiovascular diseases? (Reprinted from Critical Care Medicine, vol 29, pg 227-234, 2001)

Objective: To compare a restrictive red blood cell transfusion strategy wit h a more liberal strategy in volume-resuscitated critically ill patients wi th cardiovascular disease. Setting: Twenty-two academic and three community critical care units across Canada. Study Design: Randomized controlled clinical trial. Study Population: Three hundred fifty-seven critically ill patients with ca rdiovascular diseases from the Transfusion Requirements in Critical Care tr ial who had a hemoglobin concentration of <90 g/L within 72 hrs of admissio n to the intensive care unit. Interventions: Patients were randomized to a restrictive strategy to receiv e allogeneic red blood cell transfusions at a hemoglobin concentration of 7 0 g/L (and maintained between 70 and 90 g/L) or a liberal strategy to recei ve red blood cells at 100 g/L (and maintained between 100 and 120 g/L). Results: Baseline characteristics in the restrictive (n = 160) and the libe ral group (n = 197) were comparable, except for the use of cardiac and anes thetic drugs (p <.02). Average hemoglobin concentrations (85 +/- 6.2 vs. 10 3 +/- 6.7 g/L; p <.01) and red blood cell units transfused (2.4 =/- 4.1 vs. 5.2 +/- 5.0 red blood cell units; p <.01) were significantly lower in the restrictive compared with the liberal group. Overall, all mortality rates w ere similar in both study groups, including 30-day (23% vs. 23%; p = 1.00), 60-day, hospital, and intensive care unit rates. Changes in multiple organ dysfunction from baseline scores were significantly less in the restrictiv e transfusion group overall (0.2 +/- 4.2 vs. 1.3 +/- 4.4; p =.02). In the 2 57 patients with severe ischemic heart disease, there were no statistically significant differences in all survival measures, but this is the only sub group where the restrictive group had lower but nonsignificant absolute sur vival rates compared with the patients in the liberal group. Conclusion: A restrictive red blood cell transfusion strategy generally app ears to be safe in most critically ill patients with cardiovascular disease , with the possible exception of patients with acute myocardial infarcts an d unstable angina.