Transfusion Requirements After Cardiac Surgery - TRACS

Description:

The goal of the trial was to evaluate a strategy of restrictive red blood cell (RBC) transfusion compared with a strategy of liberal RBC strategy among patients undergoing surgery with the use of cardiopulmonary bypass.

Hypothesis:

Restrictive RBC transfusion will be noninferior in preventing death and severe morbidity.

Study Design

  • Randomized
  • Parallel

Patient Populations:

  • Patients at least 18 years of age undergoing surgery with cardiopulmonary bypass

    Number of screened applicants: 1,765
    Number of enrollees: 502
    Duration of follow-up: 30 days
    Mean patient age: 59 years
    Percentage female: 40%
    Ejection fraction: 55% with LVEF ≥60%
    NYHA class: I-7%, II-41%, III-42%, IV-10%

Exclusions:

  • Emergency procedures, ascending and descending thoracic aortic procedures, or LV aneurysm resection
  • Inability to receive blood products
  • Participation in another study
  • Anemia, thrombocytopenia, or coagulopathy
  • Pregnancy
  • Neoplasm
  • Endocarditis
  • Congenital heart defect
  • Hepatic dysfunction
  • End-stage renal disease
  • Inability to provide informed consent

Primary Endpoints:

  • 30-day all-cause mortality or severe morbidity defined as cardiogenic shock, acute respiratory distress syndrome, or renal failure requiring hemodialysis

Secondary Endpoints:

  • All respiratory, cardiac, neurologic, and infectious complications
  • Inflammatory complications
  • Bleeding requiring reoperation
  • ICU and hospital length of stay

Drug/Procedures Used:

Patients undergoing surgery with cardiopulmonary bypass were randomized to a restrictive RBC transfusion strategy if the hematocrit was <24% (n = 249) versus a liberal RBC transfusion strategy if the hematocrit was <30% (n = 253).

Concomitant Medications:

Clopidogrel and anticoagulants were held for at least 5 days prior to surgery. During surgery, unfractionated heparin was administered at a dose of 500 U/kg.

Principal Findings:

Overall, 502 patients were randomized. There was no difference in baseline characteristics between treatment groups. In the restrictive strategy group, the mean age was 59 years, 40% were women, 35% had diabetes, left ventricular ejection fraction (LVEF) ≥60% was present in 55%, median EuroSCORE was 4, and preoperative hemoglobin/hematocrit values were 13.4 g/dl and 39.9%.

Mean hematocrit values in the intensive care unit (ICU) were 28% in the restrictive strategy group versus 32% in the liberal strategy group (p < 0.001). RBC transfusion was performed in 47% versus 78% (p < 0.001), respectively. Most transfusions were given in the operating room or within 3 days of surgery.

The primary outcome, all-cause mortality, cardiogenic shock, acute respiratory distress syndrome, or renal failure requiring dialysis occurred in 11% of the restrictive strategy group versus 10% of the liberal strategy group (p = 0.85).

Mortality occurred in 6% versus 5% (p = 0.93), cardiogenic shock occurred in 9% versus 5% (p = 0.42), acute respiratory distress syndrome occurred in 2% versus 1% (p > 0.99), and renal failure requiring dialysis occurred in 4% versus 5% (p > 0.99), respectively.

In a multivariate model, regardless of treatment strategy, transfusion of more than 5 RBC units was associated with increased mortality.

Interpretation:

Among patients undergoing surgery with cardiopulmonary bypass, a restrictive RBC transfusion strategy was associated with similar outcomes compared with a more liberal transfusion strategy. In the restrictive RBC strategy, the target to transfuse was a hematocrit of 24% and the mean hematocrit value attained in the ICU was 28%, whereas in the liberal RBC strategy, the target to transfuse was a hematocrit of 30% and the mean hematocrit value attained was 32%. Independent of treatment strategy, the transfusion of >5 RBC units was associated with increased mortality.

Many studies have now called into question the practice of transfusing RBCs after invasive procedures to an arbitrary hematocrit target. This study documents that a hematocrit target as low as 24% is safe. Transfusion requirements should be based on evidence of impaired oxygen carrying capacity.

References:

Hajjar LA, Vincent JL, Galas FR, et al. Transfusion Requirements After Cardiac Surgery: The TRACS Randomized Controlled Trial. JAMA 2010;304:1559-1567.

Clinical Topics: Heart Failure and Cardiomyopathies, Acute Heart Failure

Keywords: Hematocrit, Renal Dialysis, Shock, Cardiogenic, Renal Insufficiency, Follow-Up Studies, Hemoglobins, Erythrocyte Transfusion, Respiratory Distress Syndrome, Adult, Stroke Volume, Cardiopulmonary Bypass, Oxygen, Diabetes Mellitus


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