Transfusion-associated circulatory overload

Transfusion-associated circulatory overload (TACO) is cardiogenic pulmonary oedema due to infusion of rapid or large volume blood product. TACO is a frequent, serious, but under-recognized complication of haemotherapy. Presenting symptoms include dyspnoea, cyanosis, tachycardia and increased blood pressure. Pedal oedema, headache, chest tightness and dry cough are additional manifestations. Chest radiographs reveal pulmonary oedema and cardiomegaly. Vulnerable patients are the very young and persons over 60 years. While rapid infusion or massive transfusion are frequently the precipitating factors, relatively small volumes (1-2 units) are sufficient to trigger the congestive heart failure. Both haeme and non-haeme fluids account for the positive fluid balance. Fresh-frozen plasma (FFP) and autologous red blood cells have been implicated as well. Consequences include longer length of intensive care unit and hospital stay. The fatality rate has been reported to be 1-3%, but this may understate the true rate. The incidence has been reported to be 1-8% in orthopaedic surgical populations. In general hospital populations a range of 1 : 708-1 : 4075 red blood cell transfusions is associated with TACO. In the intensive care setting, an incidence of I : 356 components has been demonstrated. TACO is frequently confused with transfusion-related acute lung injury (TRALI). In some cases, TRALI and TACO may co-exist. A potentially important diagnostic tool is brain natriuretic peptide. Brain natriuretic peptide is elevated in TACO and a post-transfusion-to-pre-transfusion ratio of 1.5 is indicative of the diagnosis. The test has a sensitivity of 81% and a specificity of 89%. Treatment includes supplementary oxygen, diuretics, placing the patient in a sitting position and therapeutic phlebotomy in 250-ml increments. While rapid infusion is believed to be a contributing factor, optimal infusion rates for the non-emergency situation have not been determined. TACO has been observed with flow rates between 0.9 and 48.1 ml/min. Preventive measures include use of evidence-based transfusion and controlled-rate infusion. Measures that insure the use of standardized blood components, such as derived through apheresis, are likely to favourably impact the incidence of this complication.