Blogger Craig Denmade
Transfusion in the ICU
- 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
Synthetic blood is the answer
- “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
- 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
- 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