Prophylactic transfusions reduce perioperative needs
MedWire News: Giving blood transfusions to anemic patients before rather than during cardiac surgery may reduce their need for perioperative transfusion, with its associated harmful effects, a pilot study suggests.
The study, which appears in Anesthesiology, was an unblinded randomized trial involving 60 patients with anemia (hemoglobin 10-12 g/dL) who were scheduled to undergo cardiac surgery. The patients were randomly assigned to receive 2 units of erythrocytes 1-2 days before surgery or to receive transfusions perioperatively as needed.
It is thought that blood transfusion increases the amount of circulating free iron, which contributes to oxidative stress. Prophylactic transfusion "would allow time for the transfused erythrocytes to recover from the deleterious changes that they undergo during storage and the kidneys to recuperate from the harmful effects of the transfused erythrocytes before they are exposed to the myriad of surgical stressors that occur during cardiac surgery," say the researchers.
During surgery, the nadir hemoglobin level was significantly higher in patients given prophylactic transfusions than in those given them as needed, at 8.3 versus 7.6 g/dL. Consequently, patients in the prophylactic group received a median of 0 units of perioperative erythrocytes, whereas those in the as-needed group received 2 units.
Prophylactic transfusion did not affect patients' risk for acute kidney injury (>25% fall in estimated glomerular filtration rate), with this occurring in 11 patients in each group. One patient in each group required dialysis.
However, in a subgroup of 35 patients, postoperative transferrin saturation levels were significantly lower in those given prophylactic rather than as-needed transfusions, indicating that the blood of patients in the prophylactic group had an increased capacity to bind free iron.
Transferrin saturation was greater than 80% in five patients; three were in the as-needed group and two were in the prophylactic group but did not complete their transfusions until just before surgery. All of these patients developed acute kidney injury, compared with eight of 30 patients with lower transferrin saturation levels.
"These findings suggest that a large-scale randomized trial of prophylactic erythrocyte transfusion in anemic patients undergoing cardiac surgery is feasible and warranted," say Keyvan Karkouti (University of Toronto, Ontario, Canada) and team.
In an accompanying editorial, Jean-Louis Vincent and Christophe Lelubre (Erasme Hospital, Brussels, Belgium) describe the findings as "highly interesting and challenging."
They note: "Some physicians will certainly have concerns about this 'preventative' use of blood transfusions. However, it is interesting to note that the total amount of blood transfused was not significantly greater in patients who received a preoperative transfusion."
Vincent and Lelubre say: "This study is not really about whether to give more or fewer transfusions - if you need a transfusion, you will receive it sooner or later - but about the timing of transfusion."
The editorialists caution that it is too soon to start debating the merits of prophylactic transfusion, after just one single-center pilot study. But they say: "These results add to the mounting evidence that altered iron metabolism may contribute to organ dysfunction after major surgery."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012
By Eleanor McDermid