Blood-component therapy in children: Viva

Opening question: the principles and the doses

Blood-component therapy transfuses the specific component a child lacks at a weight-based dose, guided by the restrictive philosophy of patient blood management. One donation is centrifuged into four targeted components: red cells to carry oxygen, platelets to plug bleeding, fresh frozen plasma to supply clotting factors and cryoprecipitate to deliver fibrinogen. The per-kilogram doses are red cells 10 to 15 mL per kg over two to four hours, platelets 10 to 20 mL per kg, fresh frozen plasma 10 to 15 mL per kg and cryoprecipitate 5 to 10 mL per kg. A red cell transfusion of 10 to 15 mL per kg raises the haemoglobin by about 20 to 30 g per litre, and a platelet transfusion of 10 to 20 mL per kg raises the count by about 20 to 40 times ten to the nine per litre. [2]

Branch 1: the restrictive thresholds

The thresholds have fallen over three decades as the trials showed less is usually as good. The TRIPICU trial of Lacroix established the restrictive haemoglobin of 70 g per litre in the stable critically ill child, and the Cochrane review of Carson confirmed the safety of restrictive red cell thresholds across the populations studied. The prophylactic platelet threshold is 10 times ten to the nine per litre in the stable child, rising to 50 with bleeding or a procedure, and the neonatal platelet threshold is 25 rather than 50, because the PlaNeT-2 MATISSE trial of Curley found the higher threshold caused more death or major bleeding. [1][7][9]

Branch 2: the massive-transfusion protocol

This bleeding child needs the immediate activation of a massive-transfusion protocol, a pre-agreed pathway that delivers red cells, plasma and platelets in a balanced ratio while the source is controlled. Red cells are given at 10 to 20 mL per kg, fresh frozen plasma at 10 to 15 mL per kg and platelets at 10 to 20 mL per kg, with cryoprecipitate at 5 to 10 mL per kg for a fibrinogen under 1.5 g per litre. Tranexamic acid is given within three hours of the bleed, the child is warmed, the acidosis is corrected and the calcium is replaced, because the hypothermia, the acidosis and the hypocalcaemia each worsen the coagulopathy. [4][2]

Branch 3: special products and reactions

The special products are selected for the right child: leucodepleted components are the default, cytomegalovirus-negative components for the intrauterine, neonatal and immunocompromised recipient, and irradiated components for the profoundly immunocompromised to prevent graft-versus-host disease. K-negative red cells protect the girl from sensitisation, and phenotype-matched red cells prevent alloimmunisation in the chronically transfused. The commonest serious reaction is transfusion-associated circulatory overload, and the first step in any reaction is to stop the transfusion and keep the line open with saline, support the circulation, and return the unit to the laboratory. [2]