Abstract

In transfusion medicine, transfusion associated circulatory overload (TACO) is a transfusion reaction (an adverse effect of blood transfusion) that occurs due to a rapid transfusion of a large volume of blood.

There is still no single agreed reporting definition for TACO. The International Society of Blood Transfusion (ISBT) working party on hemovigilance in collaboration with the International Haemovigilance Network (IHN) produced new draft reporting criteria in 2016.

These draft criteria are: acute onset or worsening respiratory distress during or up to 12 hours after transfusion, plus two or more of the following:

- Evidence of acute or worsening pulmonary edema (by physical examination or chest imaging)

- Evidence of unanticipated cardiovascular system changes (tachycardia, hypertension, jugular venous distension, peripheral edema)

- Evidence of fluid overload (positive fluid balance, response to diuretic therapy with clinical improvement, change in the patient’s weight in the peri-transfusion period)

- Elevation in natriuretic peptide (NP) levels (e.g. brain-natriuretic peptide (BNP), N-terminal (NT)-pro BNP) to greater than 1.5 times the pre-transfusion value

Symptoms

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 | Differentiation from TRALI

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.

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 diuretics. A pre-transfusion TACO checklist can be used to assess patients' risk of developing TACO.

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.