Unless you do a lot of paediatrics, you often don’t think about the dose of blood products by body weight, and they can sometimes be difficult to find.

• Red Cells: 4ml X kg X Hb g/dL rise required. (1 unit/bag ~ 300mL)  
• Fresh frozen plasma: 10 - 20 ml/kg (1 bag ~ 230mL) 
• Cryoprecipitate: 5-10 ml/kg (1 bag ~ 20mL) 
• Platelets: 10ml/kg (1 unit ~ 60mL. 1 pooled bag = 5 units)
• Tranexamic acid: 100mg/kg then 10mg/kg/hr
• Factor 7: 90mcg/kg
• Prothrombin (factor 9) complex: 1mL/kg (25units/kg)

In the exam and even in real life, if you don’t know, then ring someone! (ie: the haemotologist)

PS - To make it easier to remember: FFP, cryo and platelets are all about 10ml/kg.

Tranfuse blood products with a giving set that has a filter (170 to 230µm). This filters clot and aggregates.

Microaggregate filters (20-40 µm) were used at the bedside in the past to leukodeplete blood products. However, most Australian blood products are now pre-storage leukodepleted. 

• Prolonged R time (slow clotting speed) needs FFP 
• Narrowed Maximum Amplitude (weak clot strength) needs platelets 
• Low A30/60 (low clot stability) needs TXA

The magic number to remember is 4. 

4ml/kg of packed red blood cells will give you an increase of about 1g/dL of haemoglobin. 

For example a 9 kg child with an HB of 5g/dL will need 180ml of red cells to reach an HB of 10. (9kg X 4ml X 5g/L = 180ml)

PS - You can use this formula for adults too.