Anemia and red blood cell transfusion in neurocritical care.
Crit Care. 2009 Jun 11;13(3):R89
Authors: Kramer AH, Zygun DA
ABSTRACT: INTRODUCTION: Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to "secondary" cerebral injury, anemia may not be as well tolerated among neurocritical care patients. METHODS: The first portion of this paper is a narrative review of the physiological implications of anemia, hemodilution and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations. RESULTS: There have been no randomized controlled trials which have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiological studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiological parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions. CONCLUSIONS: Although hemoglobin concentrations as low as 7 g/dl are well tolerated by most critically ill patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurological implications of transfusion also requires further investigation.
PMID: 19519893 [PubMed - as supplied by publisher]