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Acute Blood Loss |
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Broad guidelines for fluid replacement are: ¨ Loss of <15% blood volume— never transfuse ¨ Loss of 15—30% blood volume— replace intravascular volume with crystalloid +/- colloid ¨ Loss of 30—40% blood volume— rapid intravascular volume replacement with crystalloid +/- colloid. Red blood cells may be required according to principles below ¨ Loss of > 40% - rapid intravascular volume replacement and urgent red cell transfusion
There is no universal ‘trigger’ for red cell transfusion. Individual patient factors and clinical circumstances must be taken into account. The appropriate target haemoglobin level and rate of blood loss should be taken into account when considering the need for red cell transfusion. Broad guidelines are: ¨ Red cell transfusion is not indicated when estimates of actual and anticipated haemoglobin levels are > 10g/dL ¨ Red cell transfusion is always indicated when the haemoglobin level is < 6g/dL. Transfuse according to ongoing red cell loss. If otherwise stable, transfuse 2 units and reassess. ¨ The decision to transfuse patients with haemoglobin levels between 6—10g/dL must be made on an individual basis. Clinicians often transfuse red cells despite evidence that this is not justified. ¨ Some patients will not tolerate acute anaemia and will require a haemoglobin level of > 8g/dL. These include patients who are over 65 years old or have a compromised cardiovascular or respiratory system.
Post-operative Blood Transfusion The same target values for haemoglobin levels should be applied as for acute blood loss. The practice of routinely ‘topping-up’ a patient post-operatively to achieve a haemoglobin level above 10g/dL is strongly discouraged. Patients should be transfused on the basis of clinical need. Asymptomatic patients with post-operative anaemia should be commenced on oral iron. The haemoglobin may be expected to rise at a rate of 0.1g/dL/day. |
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Following acute blood loss, the effects of anaemia must be considered separately from those of hypovolaemia. Acute anaemia is tolerated much more than hypovolaemia and initial fluid resuscitation and restoration of perfusion should be with crystalloid and/or colloid. The decision to give red cells depends on the degree of anaemia and the patients’ underlying health. |