Blood Transfusions

A transfusion is not a single treatment. The component must replace the specific deficit. Red cells increase oxygen-carrying capacity. In a stable, non-bleeding adult weighing about 70 kg, one unit is approximately 287 mL and usually raises haemoglobin by about 10 g/L. Red cells do not correct thrombocytopenia or isolated clotting-factor deficiency. Platelets are used for clinically significant bleeding or selected prophylactic and procedural thresholds in thrombocytopenia. They are not routine treatment for immune thrombocytopenic purpura, heparin-induced thrombocytopenia, or thrombotic thrombocytopenic purpura; the underlying disorder can destroy or consume the transfused platelets. Plasma supplies multiple clotting factors. It must be ABO-compatible, although it does not need to be group-identical. A usual adult dose is 10–15 mL/kg, approximately three to four units, when clinically significant coagulopathy requires replacement. Cryoprecipitate is concentrated in fibrinogen, with approximately 366 mg per 10 ± 2 mL unit. A common starting dose is one unit per 10 kg for clinically significant bleeding with acquired hypofibrinogenaemia, often when fibrinogen is below 1.0 g/L; higher targets may apply in obstetric or cardiac surgery. Cryoprecipitate is not the preferred...