Transfusion and Anaemia in Critically Ill Adults (BSH 2012)


General ITU – Threshold <70, Target 70-90

Sepsis – early Target 90-100, later Target 70-90

Neuro – TBI Target 70-90, SAH Target 80-100, Stroke Target >90

IHD – Stable Target >90, ACS Target >80




20-30% of patient admitted to ITU have an Hb <90g/l

After 7 days, 80% of ITU patients have an Hb <90g/l

ITU accounts for 10% of annual blood use




Global oxygen delivery (DO2) is a product of cardiac output and arterial O2 concentration

Tissue hypoxia can occur as the result of a problem at any stage in the oxygen cascade – airway, pulmonary, cardiac, vascular flow etc.

Anaemia reduces oxygen carrying capacity

When tissue DO2 falls, compensatory mechanisms increase oxygen extraction up to a point

Once compensation is overwhelmed, O2 transport becomes directly proportional to O2 supply and tissue hypoxia becomes much more likely to occur.

Healthy individuals can maintain O2 supply down to a Hb of 40-50g/l


Transfusion Triggers


General ITU Population

TRICC Study 1999

  • Liberal <100g/l trigger v.s. Restrictive <70g/l trigger

  • Restrictive group received 54% fewer RBC units, and 33% no blood at all

  • No global difference in mortality

  • Patients <55 y.o. and those who were less ill (APACHE <20) had lower mortality with restrictive strategy. NNT = 13.

TRACS 2010 (cardiac surgery) and FOCUS 2011 (elective hip surgery) made the same conclusions


Alternatives to Red Cell Transfusion


Blood Sampling Techniques to reduce iatrogenic blood loss

  • Typically approx.. 40ml blood loss per day

  • Use of paediatric bottles reduces blood loss without affecting assay quality.



  • Critically ill patients do not produce a physiological increase in Epo production

  • Epo is not licensed for critically ill patient with anaemia due to no difference in patient outcomes and a concern over increased VTE risk


Iron Therapy

  • Evidence of absolute iron deficiency is absent in most ITU patients

  • Iron supplementation not recommended due to lack of randomized trials and concern over increased susceptibility to infection

  • Typical Iron profile in ITU

    • Serum iron – decreased

    • Total Iron Binding Capacity – Decreased

    • Ferritin – Increased

    • Transferrin – Decreased

    • Soluble Transferrin – Normal


Adverse Effects of RBC Transfusion in Critical Care



  • Acute respiratory distress with pulmonary oedema, tachycardia, increased BP and a positive fluid balance after blood transfusion


  • Onset of pulmonary oedema within 6 hours of blood transfusion, hypoxia and bilateral pulmonary infiltrates on CXR.

  • Results from anti-neutrophil antibodies (leukoagglutinins) present in the donor plasma

RBC Storage Duration

  • Red cell storage process depletes 2,3 DPG, impairing oxygen release

  • Also depletes nitric oxide and causes membrane changes with decreased deformability, which combined limit capillary transit.

  • However no evidence to support need for ‘fresher’ blood in ITU patients


Severe Sepsis Patients


Early hours of sepsis

  • Low SVCO2% and high lactate indicative of tissue hypoxia

  • Transfusion to Hb approx. 100g/l associated with improved survival, but in trials that had many intensive interventions being tested at once.

Later stages of sepsis

  • As per TRICC trial, can use <70g/l as transfusion trigger


Neuro Critical Care


Difficult – increase Hct —> increased oxygen carrying capacity, but also viscosity which may in itself reduces delivery to cerebral microvasculature.


Traumatic brain injury

  • Target 70-90g/l, increased to >90g/l if cerebral ischaemia present


  • Target 80-100g/l

Ischaemic Stroke

  • Target >90g/l


Ischaemic Heart Disease on ITU


Stable Angina – Hb >70g/l but transfusion >100g/l has uncertain benefit

ACS – Hb >80-90g/l