Haemoglobin – who needs it?

Blogger Craig Denmade

Transfusion in the ICU

Tim Walsh

Summary/Key messages

  • Blood saves lives!
  • What is the impact of transfusion strategy on mortality?
  • Old vs fresh blood – Walsh et al CCM 2004
  • RCT – trend to better outcomes with restrictive strategy. Safe & may be better.
  • TRICC trial; Hb 70 vs 100, trend to harm with higher Hb
  • (Other evidence to support argument… Presenter slides needed as too many to capture)
  • More blood to augment oxygen delivery associated with harm
  • Transfusion in UGIB (barca/Villanova) liberal group worse outcomes
  • Septic shock population – higher Hb through transfusion does not confer benefit
  • Cardiac surgery population – restrictive strategy signalling harm
  • Areas of uncertainty: cardiovascular disease population, cardioresp co- & acute morbidity
  • Evidence to demonstrate harm with restrictive strategy in IHD/cardiovasc population
  • More ACS in pts with chronic CHD & restrictive strategy (under review)
  • Red cell storage: We don’t need fresh blood in ICU
  • Conclusions: HB trigger 70 appropriate & safe, higher triggers in acute coronary disease, chronic CVD uncertainty – individualise care

References/Further reading

Synthetic blood is the answer

Chris Cooper

Summary/Key messages

  • “Safe” haemoglobin-based blood substitute
  • Creating a haemoglobin genetically to exist outside RBC
  • Lab research – use E.coli to produce Hb, lyse then purify
  • Toxicity of Hb in plasma: binds NO – ‘good’ radicals, redox cycle – ‘bad’ radicals, free haem complement activation
  • Mimic haptoglobin? No.
  • Current direction: Haemoglobin as a true ascorbate peroxidase
  • Making haemoglobin less reactive outside RBC
  • Tyrosine mutations, in-vitro data encouraging
  • Engineered protein exhibits normal oxygen carriage
  • Beginning in-vivo studies

Intravenous iron is the answer

Shaman Jhanji

Summary/Key messages

  • Not discussing PREVENT trial (elective major surgery), focussing on critical care patients
  • Many patients anaemic before arriving in ICU (Vincent JAMA 2002)
  • Anaemia during ICU stay & at discharge Walsh ICM 2005
  • Bleeding, venepuncture, anaemia chronic disease
  • Nutrient deficiencies 10-14% Fe deficient
  • Hepcidin – is iron of any use to our patients?
  • Critical care anaemia due to Fe deficiency or inflammation induced hepcidin increases?
  • Measuring iron def – iron studies not helpful
  • Data suggests iron could be useful in our patients
  • Size of the problem? Lasocki Crit care 2014 (prevalence iron def)
  • Iron and risk infection – free iron risk factor for sepsis
  • Modern iron preparations (lower levels free iron) – data suggests not increased infection
  • Clinical data in ICU patients limited – no increase in haemoglobin but reduction in RBC transfusion (iron dose too low?)
  • IRONMAN trial ongoing – higher dose iron on ICU
  • Anaemia common, our patients likely Fe deficient, iron may reduce transfusion need

 

Q&A

  • Transfusion threshold in TBI – individualised care as data lacking
  • Transfusion and duration MV – some subgroup analysis data but uncertainty, hypothesis: improved oxygen carriage > quicker wean, recovery: anaemia and fatigue persists post-ICU
  • Animal kingdom (evolutionary Hb level, normal/physiological Hb): Is the ‘holy grail’ out there?
  • Define chronic cardiovascular disease? Need clear definition in order to assign to treatment groups eg. Liberal vs restrictive