Using a restrictive threshold for blood cell transfusions does not increase the risk of acute kidney injury (AKI) among patients undergoing cardiac surgery with cardiopulmonary bypass, according to a new study.

Previous research has shown that untreated anemia is associated with adverse effects, especially among patients undergoing cardiac surgery who are susceptible to anemia-induced tissue hypoxia, investigators noted in the Journal of the American Society of Nephrology.

Amit X. Garg, MD, of the London Health Sciences Centre and Western University, London, Ontario, Canada, and colleagues studied 4531 participants in the open-label randomized TRICS-III (Transfusion Requirements in Cardiac Surgery–III) trial. The patients underwent cardiac surgery with cardiopulmonary bypass and had a moderate to high risk of perioperative death. The study compared a restrictive and liberal threshold for red blood cell transfusion. With the restrictive threshold, patients would not receive a transfusion unless their hemoglobin level fell below 7.5 g/dL. Using the liberal threshold, patients would be transfused if their hemoglobin fell below 9.5 g/dL in the operating room or intensive care unit or below 8.5 g/dL while in the non-intensive care ward.

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The restrictive-threshold group received significantly fewer transfusions than the liberal-threshold group (average 1.8 vs 2.9 transfusions). AKI developed in 27.7% of the restrictive-threshold group compared with 27.9% of the liberal-threshold group, a non-significant difference between the groups. In addition, the study found no significant between-group difference in the proportion of patients with preoperative chronic kidney disease who experienced AKI (33.6% vs. 32.5%, respectively).

“In higher-risk patients having cardiac surgery with cardiopulmonary bypass, a restrictive approach to red blood cell transfusion resulted in significantly fewer red blood cell transfusions and was as safe as a liberal approach on the risk of AKI,” the authors concluded. “Results were consistent in patients with and without CKD.”

Reference

Garg AX, Badner N, Bagshaw SM, et al. Safety of a restrictive versus liberal approach to red blood cell transfusion on the outcome of AKI in patients undergoing cardiac surgery: A randomized clinical trial. J Am Soc Nephrol. 2019; published online ahead of print.

doi: 10.1681/ASN.2019010004