What Are the Indications for a Blood Transfusion?

This trial helps support the findings in previous trials, such as TRICC, by showing that a restrictive transfusion strategy using a trigger point of 8 g/dl does not increase mortality or cardiovascular complications and does not decrease functional ability after orthopedic surgery.

TRAC trial: patients after cardiac surgery⁷. The TRAC trial was a prospective randomized trial in 502 patients undergoing cardiac surgery that assigned 253 patients to the liberal-transfusion-strategy group (Hb >10g/dl) and 249 to the restrictive-strategy group (Hb >8 g/dl). In this study, the primary endpoint of all-cause 30-day mortality occurred in 10% of the liberal group and 11% of the restrictive group. This difference was not significant.

Subanalysis showed that blood transfusion in both groups was an independent risk factor for the occurrence of respiratory, cardiac, renal, and infectious complications, in addition to the composite end point of 30-day mortality—again highlighting the risk involved in of blood transfusions.

These results support the other trial conclusions that a restrictive transfusion strategy of maintaining a hematocrit of 24% (Hb 8 g/dL) is as safe as a more liberal strategy with a hematocrit of 30% (Hb 10 g/dL). It also offers further evidence of the risks of blood transfusions and supports the view that blood transfusions should never be given simply to correct low hemoglobin levels.

Cochrane Review. A recent Cochrane Review that comprised 19 trials with a combined total of 6,264 patients also supported a restrictive-strategy approach.⁸ In this review, no difference in mortality was established between the restrictive and liberal transfusion groups, with a trend toward decreased hospital mortality in the restrictive-transfusion group. The authors of the study felt that for most patients, blood transfusion is not necessary until hemoglobin levels drop below 7-8 g/dL but emphasized that this criteria should not be generalized to patients with an acute cardiac issue.

^{click for large version}

Table 2. General guidelines from the AABB for red blood cell transfusions2

Back to the Case

In this case, the patient is doing well post-operatively and has no cardiac symptoms or hypotension. However, based on the new available data from the FOCUS trial, given the patient’s history of CAD, and the threshold of 8 g/dL used in the study, it was recommended that the patient be transfused.

Bottom Line

Current practice guidelines clearly support clinical judgment as the primary determinant in the decision to transfuse.² However, current evidence is growing that our threshold for blood transfusions should be a hemoglobin level of 7-8 g/dl.

Dr. Chang is a hospitalist and assistant professor at Mount Sinai Medical Center in New York City, and is co-director of the medicine-geriatrics clerkship at the Icahn School of Medicine at Mount Sinai. Dr. Torgalkar is a hospitalist and assistant professor at Mount Sinai Medical Center.

References

1. Sharma S, Sharma P, Tyler L. Transfusion of blood and blood products: indications and complications. Am Fam Physician. 2011;83:719-724.
2. Carson JL, Grossman BJ, Kleinman S, et al. Red blood cell transfusion: a clinical practice guideline from the AABB. Ann Intern Med. 2012;157:49-58.
3. Valeri CR, Crowley JP, Loscalzo J. The red cell transfusion trigger: has a sin of commission now become a sin of omission? Transfusion. 1998;38:602-610.
4. Klein HG, Spahn DR, Carson JL. Red blood cell transfusion in clinical practice. Lancet. 2007;370(9585):415-426.
5. Hébert PC, Wells G, Blajchman MA, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. N Engl J Med. 1999;340:409-17.
6. Carson JL, Terrin ML, Noveck H, et al. Liberal or restrictive transfusion in high-risk patients after hip surgery. N Engl J Med. 2011;365:2453-2462.
7. Hajjar LA, Vincent JL, Galas FR, et al. Transfusion requirements after cardiac surgery: the TRACS randomized controlled trial. JAMA. 2010;304:1559-1567.
8. Carson JL, Carless PA, Hébert PC. Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion. Cochrane Database Syst Rev. 2012; 4:CD002042.