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Reducing PCV by venesection

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Removal of red cells by venesection is the most rapid way to decrease red cell mass; the volume and frequency has to be graded to the individual.It can be used to control the haemotocrit (Hct) levels. The target is to maintain the haemotocrit levels at less than 0.45 (1).

The volume and frequency has to be graded to the individual’s size and comorbidities (1). In young, fit adults, up to 450 ml can be removed at intervals of 2-3 days. In older patients, smaller volumes at less frequent intervals are recommended.

If volume depletion is a major concern, an isovolaemic procedure can be carried out: an equivalent volume of crystalloid solution is administered to replace the volume of whole blood withdrawn.

The viscosity of the blood may make venesection difficult due to repeated clotting, even with a wide-bore needle. Alternatives include a venesection pack with citrated anticoagulant or IV heparin infusion.


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