Transfusion-associated dyspnea--shadow or substance?

New Zealand Blood Service Haemovigilance uses International Society of Blood Transfusion/International Haemovigilance Network definitions to categorize transfusion reactions (TR). Transfusion-associated dyspnoea (TAD) is a category for TR with respiratory features (TRRF) that do not fit definitive entities. TRRF, including TAD, are clinically significant. TR classified as TAD were reviewed. We found that many TAD may have been transfusion-associated circulatory overload. Better information in TR reports and refining TR diagnostic criteria may result in less misclassification of TRRF. TAD may represent mild, atypical or overlap entities, and there may be a residuum of cases with currently unexplained pathophysiology.