Major bleeding is defined as a loss of 20% or more of blood volume. The main aim is to prevent hypovolaemic shock. Restore blood volume initially with crystalloid or colloid solutions to maintain adequate blood flow, BP, and hence tissue oxygenation. Red cell concentrate (RCC) transfusion is indicated when signs of hypovolaemia and/or hypoxia (e.g. compensatory tachycardia, hypotension) occur.