Haematological considerations: blood products and transfusion

Summary

Blood products

PACKED RED CELLS

One unit contains 250–350 ml unless there is cardiorespiratory compromise; most patients can tolerate a haemoglobin concentration of 8 g/dl comfortably and do not need transfusion.

PLATELET CONCENTRATE

One pool of platelets contains 250–300 ml. A normal adult pool would be expected to raise the platelet count by 20–40 × 10⁹/l.

The cause of thrombocytopaenia should be established before platelets are given. For example platelets are absolutely contraindicated in thrombotic thrombocytopaenic purpura (TTP) unless the patient is bleeding or undergoing invasive procedures prior to plasmapheresis.

Many patients remain haemostatically competent with a platelet count as low as 10 ×10⁹/l before suffering haemorrhagic complications. However, for most surgery the platelet count should be above 50 × 10⁹/l. In high risk surgery (e.g. brain or eye), aim for above 100 × 10⁹/l, whereas for epidural analgesia aim for 80 × 10⁹/l.

FFP (FRESH FROZEN PLASMA)

One bag contains 250–300 ml. The usual dose is 12–15 ml/kg.

Indications:

Replace multiple coagulation factor deficiencies (e.g. liver disease, DIC). To correct coagulopathy associated with massive blood transfusion.

Urgent reversal of warfarin overdose-induced bleeding in association with vitamin K, but only in the absence of prothrombin complex concentrate (PCC).

Replacement of single factor deficiencies (e.g. Factor V) in situations when factor concentrate is unavailable.