Restrictive Transfusion Strategy after Cardiac Surgery

Abstract

Background Recent guidelines on transfusion in cardiac surgery suggest that hemoglobin might not be the only criterion to trigger transfusion. Central venous oxygen saturation (Svo2), which is related to the balance between tissue oxygen delivery and consumption, may help the decision process of transfusion. We designed a randomized study to test whether central Svo2–guided transfusion could reduce transfusion incidence after cardiac surgery. Methods This single center, single-blinded, randomized controlled trial was conducted on adult patients after cardiac surgery in the intensive care unit (ICU) of a tertiary university hospital. Patients were screened preoperatively and were assigned randomly to two study groups (control or Svo2) if they developed anemia (hemoglobin less than 9 g/dl), without active bleeding, during their ICU stay. Patients were transfused at each anemia episode during their ICU stay except the Svo2 patients who were transfused only if the pretransfusion central Svo2 was less than or equal to 65%. The primary outcome was the proportion of patients transfused in the ICU. The main secondary endpoints were (1) number of erythrocyte units transfused in the ICU and at study discharge, and (2) the proportion of patients transfused at study discharge. Results Among 484 screened patients, 100 were randomized, with 50 in each group. All control patients were transfused in the ICU with a total of 94 transfused erythrocyte units. In the Svo2 group, 34 (68%) patients were transfused (odds ratio, 0.031 [95% CI, 0 to 0.153]; P < 0.001 vs. controls), with a total of 65 erythrocyte units. At study discharge, eight patients of the Svo2 group remained nontransfused and the cumulative count of erythrocyte units was 96 in the Svo2 group and 126 in the control group. Conclusions A restrictive transfusion strategy adjusted with central Svo2 may allow a significant reduction in the incidence of transfusion. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Association between in-ICU red blood cells transfusion and 1-year mortality in ICU survivors

“…Recommended transfusion thresholds are a hemoglobin concentration [Hb] < 7 g/dL for stable non-bleeding patients, and [Hb] < 8 g/dL in patients with coexisting cardiovascular disease and those undergoing cardiac or orthopedic surgery [ 13 ]. Restrictive transfusion strategies have been shown to improve short-term outcomes in several patient populations, including cardiac surgery [ 14 , 15 ]. Conversely, the long-term impact of various transfusion strategies remains unknown.…”

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“…24 In Anesthesiology, Zeroual and colleagues described a single-center, single blinded, randomized controlled trial investigating the role of SvO2 in guiding red blood cell (RBC) transfusion in adults after cardiac surgery. 23 Onehundred patients were randomized in the intensive care unit, half received RBC transfusion if their hemoglobin concentration was less than 9 g/dL, and half received RBC transfusion if their SvO2 was less than or equal to 65%, regardless of hemoglobin concentration. Patients were excluded if they exhibited active bleeding defined as greater than one liter of blood loss or having received four or more units of packed RBC within the first 12 hours postoperatively.…”

“…The first study used central venous oxygen saturation (SvO2) as a surrogate for oxygen consumption to guide a more restrictive blood transfusion strategy after cardiac surgery. 23 The second compared restrictive and liberal transfusion strategies in patients with acute myocardial infarction (AMI). 24 In Anesthesiology, Zeroual and colleagues described a single-center, single blinded, randomized controlled trial investigating the role of SvO2 in guiding red blood cell (RBC) transfusion in adults after cardiac surgery.…”

“…The first study used central venous oxygen saturation (SvO2) as a surrogate for oxygen consumption to guide a more restrictive blood transfusion strategy after cardiac surgery. 23 The second compared restrictive and liberal transfusion strategies in patients with acute myocardial infarction (AMI). 24…”

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“…Another recent study in cardiac surgery patients showed a significant reduction in transfusion by following a central venous saturation-guided restrictive strategy. 5 Previously, the TRICS trial in patients for cardiac surgery demonstrated that a restrictive strategy for transfusion based on hemoglobin <7.5 g/dL was noninferior to liberal strategy for those with hemoglobin <9.5 g/dL. 6 After cardiac surgery, blood volume reduction is about 18%, red blood cell volume 38%, while plasma volume only 8%, implying hemoglobin may after all not be the best trigger for transfusion.…”