When a patient bleeds they lose whole blood, but we also see a reduction in Hb concentration. The reason for this is apparently ‘transcapillary filling’ which always sounded to me like it could be bullshit (see earlier post).
Every so often we have a patient who has had their coagulopathy corrected before the insertion of a central line. Although this is done with the best of intentions, it’s not my own practice and I think it increases rather than reduces risk. In fact, it’s one of those areas where I’ve always thought there’s an evidence base, but until writing this was never sure where I heard/read it.
The avoidance of tissue hypoxia is one of the mainstays of the management of sepsis. A logical hypothesis would be that increasing oxygen delivery through transfusion may be of use (although this hypothesis ignores the fact that in the patient with sepsis it is mitochondrial dysfunction and oxygen uptake that tends to be the problem, not delivery). Clearly profound anaemia would not be beneficial, but the question is how low is too low? Transfusion is not without risks, so if there is not a benefit to transfusion it should be avoided.
The TRICC trial has reassured us that allowing a Hb of >7 is acceptable (and probably beneficial) in the critically ill. Bleeding patients were excluded from that study however, and critical care evidence based practice rarely translates to a change outside of the ICU. It is as if critical care is somehow a different world!
The paper to be discussed compared a liberal transfusion trigger (of 9g/dl) to a restrictive strategy of 7g/dl in patients with UGI bleeding.
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Dr Peter Hersey & Dr Laura O'Connor