Transfusion associated circulatory overload

In transfusion medicine, transfusion associated circulatory overload (aka TACO) is a transfusion reaction (an adverse effect of blood transfusion) that can occur due to a rapid transfusion of a large volume of blood, but can also occur during a single red cell transfusion (about 15% of cases). The fluid volume causes hypervolemia.
Symptoms and signs.
The primary symptoms of TACO are dyspnea, orthopnea, peripheral edema, and rapid increase of blood pressure. TACO must be suspected when there is respiratory distress with other signs, including pulmonary edema, unanticipated cardiovascular system changes, and evidence of fluid overload (including improvement after diuretic, morphine or nitrate treatment), during or up to 24 hours after transfusion.
Diagnosis.
The International Society of Blood Transfusion (ISBT) working party on hemovigilance in collaboration with the International Haemovigilance Network (IHN) and AABB produced new reporting criteria in 2018.
Patients classified with TACO should have acute onset or worsening respiratory distress or evidence of pulmonary edema, or both during or up to 12 hours after transfusion. They should have at least 3 of the following characteristics:
Differential diagnosis.
TACO and TRALI are both respiratory complications following a transfusion. TACO and transfusion related acute lung injury (TRALI) are often difficult to distinguish in the acute situation. TACO is usually associated with hypertension and responds well to diuretics, TRALI is often associated with hypotension and diuretics have a minimal effect. A normal natriuretic peptide level post-transfusion is seen with TRALI but not with TACO.
Prevention.
Transfusion associated circulatory overload is prevented by avoiding unnecessary transfusions, closely monitoring patients receiving transfusions, transfusing smaller volumes of blood at a slower rate, and considering the use of furosemide as a diuretic. A pre-transfusion TACO checklist can be used to assess patients' risk of developing TACO.
Management.
If TACO is suspected, the transfusion is stopped immediately and the person is treated with oxygen, diuretics, and other treatments for heart failure.
Occurrence.
It is difficult to determine the incidence of TACO, but its incidence is estimated at about one in every 100 transfusions using active surveillance, and in one in every 10000 transfusions using passive surveillance. TACO is the most commonly reported cause of transfusion-related death and major morbidity in the UK, and second most common cause in the USA.
The risk increases with patients over the age of 60, patients with cardiac or pulmonary failure, renal impairment, hypoalbuminemia or anemia.