尽管不知道接受体外循环心脏手术患者的最佳红细胞输注阈值，但专家一般建议输血量低于8 g / dL的血红蛋白值。 在TRICS III试验中，超过5000名死亡高危成人被随机分配到限制性红细胞输注阈值（血红蛋白<7.5 g / dL输血）或自由阈值（血红蛋白<9.5 g / dL输血）。 任何原因导致的死亡，心肌梗死，卒中或新发的肾功能衰竭伴有透析的复合终点事件的发生率没有差异，而正如预期的那样，输血阈值较高的患者输血率较高。 该试验证实了小规模随机试验的结果，并支持我们的输血实践，将血红蛋白水平维持在8 g / dL以上，并认识到个别患者因素可能会改变此阈值。
BACKGROUND The effect of a restrictive versus liberal red-cell transfusion strategy on clinical outcomes in patients undergoing cardiac surgery remains unclear.
METHODS In this multicenter, open-label, noninferiority trial, we randomly assigned 5243 adults undergoing cardiac surgery who had a European System for Cardiac Operative Risk Evaluation (EuroSCORE) I of 6 or more (on a scale from 0 to 47, with higher scores indicating a higher risk of death after cardiac surgery) to a restrictive red-cell transfusion threshold (transfuse if hemoglobin level was<7.5 g per deciliter, starting from induction of anesthesia) or a liberal red-cell transfusion threshold (transfuse if hemoglobin level was<9.5 g per deciliter in the operating room or intensive care unit [ICU]or was<8.5 g per deciliter in the non-ICU ward). The primary composite outcome was death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis by hospital discharge or by day 28, whichever came first. Secondary outcomes included red-cell transfusion and other clinical outcomes.
RESULTS The primary outcome occurred in 11.4% of the patients in the restrictive-threshold group, as compared with 12.5% of those in the liberal-threshold group (absolute risk difference, -1.11 percentage points; 95% confidence interval [CI], -2.93 to 0.72; odds ratio, 0.90; 95% CI, 0.76 to 1.07; P<0.001 for noninferiority). Mortality was 3.0% in the restrictive-threshold group and 3.6% in the liberal-threshold group (odds ratio, 0.85; 95% CI, 0.62 to 1.16). Red-cell transfusion occurred in 52.3% of the patients in the restrictive-threshold group, as compared with 72.6% of those in the liberal-threshold group (odds ratio, 0.41; 95% CI, 0.37 to 0.47). There were no significant between-group differences with regard to the other secondary outcomes.
CONCLUSIONS In patients undergoing cardiac surgery who were at moderate-to-high risk for death, a restrictive strategy regarding red-cell transfusion was noninferior to a liberal strategy with respect to the composite outcome of death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis, with less blood transfused. (Funded by the Canadian Institutes of Health Research and others; TRICS III ClinicalTrials.gov number, NCT02042898 .).
