Transfusion-associated circulatory overload

Transfusion-associated circulatory overload (TACO) is a potentially life-threatening complication associated with the transfusion of blood products. It is characterized by an acute or delayed increase in circulatory volume leading to pulmonary edema, hypertension, and in severe cases, heart failure. TACO is considered one of the top risks associated with blood transfusion, necessitating prompt recognition and management to mitigate morbidity and mortality.

Etiology and Pathophysiology

TACO occurs when the volume of blood or blood products transfused exceeds the circulatory system's capacity to accommodate the increased fluid load. This can lead to elevated hydrostatic pressure in the capillary beds, particularly in the lungs, causing fluid to leak into the alveoli, resulting in pulmonary edema. Risk factors for TACO include advanced age, pre-existing cardiovascular disease, renal insufficiency, and the rapid transfusion of large volumes of blood products.

Clinical Presentation

Patients with TACO may present with symptoms of acute heart failure, including dyspnea, orthopnea, tachycardia, and elevated blood pressure. Physical examination findings may include rales or crackles on lung auscultation, jugular venous distension, and peripheral edema. The onset of symptoms typically occurs within 6 hours of transfusion but can vary from immediately to up to 24 hours post-transfusion.

Diagnosis

The diagnosis of TACO is primarily clinical, supported by the temporal relationship between transfusion and the onset of symptoms. Diagnostic investigations may include chest X-ray to detect pulmonary edema, echocardiography to assess cardiac function, and laboratory tests to evaluate cardiac biomarkers and natriuretic peptides. It is crucial to differentiate TACO from other transfusion-related complications, particularly transfusion-related acute lung injury (TRALI), which has a distinct pathophysiology and management.

Management

The management of TACO involves stopping the transfusion immediately and initiating supportive care measures. These may include supplemental oxygen to alleviate hypoxia, diuretics to reduce fluid overload, and in severe cases, vasodilators or inotropic agents to support cardiac function. Monitoring of vital signs, oxygen saturation, and urine output is essential to assess the response to treatment and guide further interventions.

Prevention

Preventive strategies for TACO focus on identifying at-risk patients and modifying transfusion practices accordingly. These may include limiting the volume and rate of transfusion, using diuretics prophylactically in susceptible individuals, and considering alternatives to transfusion when appropriate. Education of healthcare providers on the recognition and management of TACO is also critical to reducing its incidence and impact.