Early Transfusion and Acute Renal Injury, Dr. Johnson

Andrea Johnson, DO

Early Prophylactic Erythrocyte Transfusion May Reduce Perioperative Acute Kidney Injury in Cardiac Surgical Patients

Article: Karkouti K, Wijeysunder DN, Yau TM, McCluskey SA, Chan CT, Wong P-Y, Crowther MA, Hozhabri S, Beattie WS:  Advance Targeted Transfusion in Anemic Cardiac Surgical Patients for Kidney Protection: An unblinded randomized pilot clinical trial. Anesthesiology 2012; 116:613-21

Acute Kidney Injury (AKI) is a common complication in the perioperative period, and occurs in 1/3 of cardiac surgical patients requiring cardiopulmonary bypass (CPB).  AKI, even when mild, has been shown to be a prognostic indicator for both short and long term postsurgical outcomes. Risk factors for post surgical AKI include preoperative anemia and perioperative transfusions. This is thought to be in part due to increased levels of circulating free iron post transfusion, which can catalyze oxidative reactions resulting in oxidative stress to organs and possible organ damage. Patients on CPB are at an increased risk of oxidative stress due to the damage to erythrocytes. Usually, macrophages and transferrin can accomodate for the hemolysis, however this study hypothesized that transfusion may compound the already overloaded system resulting in more free iron levels, thus more kidney damage.

The study by Karkouti et al. [1] evaluates the protective potential of preoperative erythrocyte transfusion on the renal system in patients undergoing CPB. Sixty patients with moderate anemia (hemoglobin 10-12) were randomly selected preoperatively to either receive erythrocyte transfusions 1 to 2 days prior to scheduled surgery or intraoperative transfusions as indicated.

Perioperative anemia and erythrocyte transfusions were lower in the preoperative transfusion group, however rates of AKI were comparable. As expected, postoperative transferrin saturation was significantly increased in the individuals who received their transfusions intraoperative, and increased transferrin saturation was linked to worse renal dysfunction. These results add to the evidence that suggests iron metabolism may contribute to organ dysfunction after major surgery. The study suggests that transfusing patients 1 to 2 days prior to cardiac surgery in which CPB will be necessary may decrease the severity of AKI but not the incidence.

According to this study, preoperative transfusions have shown to decrease perioperative anemia and the need for intraoperative transfusion, and may reduce plasma free iron levels thus resulting in decreased severity of AKI. I chose this article because as anesthesiologists we are committed to our patients healthcare intraoperative and postoperative. It is our responsibility to know how our management preoperative and intraoperative will affect our patient's overall recovery. Follow up studies are warranted, as it was only a single center, pilot trial study in which the proposed protocol still remains a hypothesis. However, the article highlights the importance of preventing oxidative stress on organs in the perioperative period and adds to evidence that altered iron metabolism affects organ dysfunction in the postoperative period.