title: Perioperative Red Blood Cell Transfusion: What We Do Not Know.
abstract: OBJECTIVE
  Blood transfusion saves lives but may also increase the risk of injury. The objective of this review was to evaluate the possible adverse effects related to transfusion of red blood cell (RBC) concentrates stored for prolonged periods.
  
  
  METHODS
  The data used in this review were mainly from PubMed articles published in English up to February 2015.
  
  
  METHODS
  Clinical and basic research articles were selected according to their relevance to this topic.
  
  
  RESULTS
  The ex vivo changes to RBC that occur during storage are collectively called storage lesion. It is still inconclusive if transfusion of RBC with storage lesion has clinical relevance. Multiple ongoing prospective randomized controlled trials are aimed to clarify this clinical issue. It was observed that the adverse events related to stored RBC transfusion were prominent in certain patient populations, including trauma, critical care, pediatric, and cardiac surgery patients, which leads to the investigation of underlying mechanisms. It is demonstrated that free hemoglobin toxicity, decreasing of nitric oxide bioavailability, and free iron-induced increasing of inflammation may play an important role in this process.
  
  
  CONCLUSIONS
  It is still unclear whether transfusion of older RBC has adverse effects, and if so, which factors determine such clinical effects. However, considering the magnitude of transfusion and the widespread medical significance, potential preventive strategies should be considered, especially for the susceptible recipients.
authors: Chong
authors: C
authors: Lei
authors: Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors: Li-Ze
authors: LZ
authors: Xiong
mesh_terms: D001793:Blood Preservation / Q000009:adverse effects; D017707:Erythrocyte Transfusion / Q000009:adverse effects*; D004912:Erythrocytes / Q000378:metabolism / Q000502:physiology; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D013997:Time Factors
chemical_list: D009569:Nitric Oxide