Blood-component therapy in children: SAQ

SAQ 1: Per-kilogram doses, thresholds and the decision for this child

Blood-component therapy transfuses the specific component a child lacks at a weight-based dose, guided by restrictive thresholds and delivered with rigorous safety checks. The four components prepared from one donation are red cells, platelets, fresh frozen plasma and cryoprecipitate, and the British paediatric doses are neonatal red-cell top-up typically 15 mL per kg, platelets 10 to 20 mL per kg, fresh frozen plasma 15 to 20 mL per kg and cryoprecipitate 5 to 10 mL per kg. The philosophy is patient blood management: transfuse the smallest effective dose of the correct component only when the benefit outweighs the risk. ^[2]

For this child, three components are indicated because he is bleeding with deficits on three axes. The platelet count of 8 times ten to the nine per litre with active bleeding falls below the therapeutic threshold, so platelets are given at 10 to 20 mL per kg to a bleeding target (50 for moderate bleeding; 75 to 100 if haemorrhage is major), and the prophylactic threshold of 10 times ten to the nine per litre is the reference for the stable child. The fibrinogen of 1.2 g per litre sits above the usual 1.0 g per litre trigger outside massive haemorrhage but below the massive-haemorrhage target of 1.5 g per litre, so cryoprecipitate is given at 5 to 10 mL per kg if this is treated as major bleeding. The haemoglobin of 62 g per litre with symptomatic anaemia and bleeding justifies red cells using a typical 15 mL per kg top-up or a formula-based volume, not more than 20 mL per kg. ^[10][2]

The restrictive threshold of 70 g per litre for the haemoglobin in the stable critically ill child comes from the TRIPICU trial, which showed a restrictive strategy as safe as a liberal one. The prophylactic platelet threshold of 10 times ten to the nine per litre is the British paediatric recommendation; the AABB guideline uses the same count of 10 in adults. The neonatal platelet threshold is lower still, at 25 rather than 50 times ten to the nine per litre, because the PlaNeT-2 MATISSE trial found the higher threshold caused more bleeding and death in preterm neonates. ^[1][9]