Blood Transfusion Strategies in Patients Supported by Extracorporeal Membrane Oxygenation

Abstract

Since red blood cell (RBC) transfusion was first performed by English obstetrician James Blundell 200 years ago,[1] it has become one of the most commonly used lifesaving therapies. Historically, RBC transfusion have been viewed as a safe and effective means of treating anemia and improving oxygen delivery to tissues. However, in the early 1980s, transfusion practice began to come under systematic scrutiny.[2,3] The early concern about the safety of blood transfusion revolved around transfusion-related infection. However, the concern about risks of blood transfusion have become diverse and complicated over the last three decades, according to research findings. In the recent literature, blood transfusion has been confirmed as an independent risk factor for mortality, perioperative infection, postinjury multiple organ failure, systemic inflammatory response syndrome, and admission to the intensive care unit(ICU).[4-7] Problems about blood transfusion are particularly important in the critically ill patients. Many data suggest that critically ill patients can tolerate hemoglobin levels as low as 7 g/dL and that a “liberal” RBC transfusion strategy may in fact lead to worse clinical outcomes.[8] Actually, RBC transfusion impairs physiologic control of regional vascular tone, induces coagulopathy and negatively impacts immune function and antioxidant system.[9] The 2012 Cochrane analysis reported that restrictive transfusion strategies were more effective than liberal transfusion strategies in reducing hospital mortality significantly among 6,264 patients from 1986 to 2011.[10,11] As such, newer “restrictive” hematocrit threshold for transfusion (e.g., 21%) are now appreciated to be at least noninferior to more “liberal” hematocrit thresholds (e.g., 30%) for broad array of conditions.[9] The efficacy of transfusion in critically ill pediatric patients has been also questioned as is still uncertain for adult critically ill patients. Lacroix et al. suggested, based on their TRIPICU study, that there was no difference in outcomes of stable critically ill children between restrictive (hemoglobin threshold of 7 g/dL) and liberal (hemoglobin threshold of 9.5 g/dL) transfusion strategies.[12] Subgroup analysis of postsurgical and postcardiac surgical patients from the TRIPICU study revealed similar findings. Among pediatric cardiac surgical patients, greater RBC transfusion volumes are associated with prolonged duration of mechanical ventilation, an increase in nosocomial infection rates and duration of hospitalization.[13,14]