OVERVIEW
- anaemia common in ICU
- tendency to more restrictive strategy c/o increased morbidity associated with transfusion
- general attempts to minimize the requirement for blood transfusion should be pursued:
-> stopping bleeding early
-> stop unnecessary anticoagulation
-> minimising venesection
-> treat hypothermia and acidosis
-> GI prophylaxis
-> Fe2+
-> nutrition
-> consideration of EPO therapy
-> use of FVIIA
- transfusion triggers are dependent on many variables:
1. evidence of bleeding and stability to patient
2. reason for admission (trauma, GIH)
3. patient wishes (Jehovah’s witness)
4. co-morbid conditions (such as ischaemic heart disease)
BLEEDING
- lower threshold to transfuse
- adults: aim to keep Hb > 80 g/L until bleeding controlled
- trauma patient:
-> haemostatic resuscitation: early products in a 1:1:1 ratio (RBC:platelets:plasma)
-> permissive hypotension
-> damage control surgery
-> avoid hypothermia, acidosis and coagulopathy
NON-BLEEDING
- controversial
TRICC trial (NEJM, 1999)
- critically ill, normovolaemic, non-bleeding
- MRCT
- n = 838
- restrictive (70g/L) vs liberal groups (100g/L) as transfusion thresholds
- no difference in mortality
- increased complications in liberal strategy group (APO, ARDS)
- under powered (so the study was unlikely to find a difference anyway)
- prior to leukodepletion
TRACS trial (JAMA, 2010)
- post cardiac surgical patients
- RCT
- n = 502
- HCT 30% vs HCT > 24%
- no difference in mortality and severe morbidity
- large separation between groups not achieved
- high base line event rate
- number of RBC’s transfused was an independent risk factor for clinical complications
CONTROVERSIAL ISSUES
Storage lesions
- increased peri-operative complications
- organ failure
- sepsis
- mortality
- VTE
Old vs New blood
- decreased deformability -> impedes microvascular flow
- depletion of 2, 3 DPG -> left shifted oxy-Hb dissociation curve -> reduces O2 delivery
- increased adhesiveness and aggregability
- reduced concentration of NO
- reduced ATP -> reduced ability to maintain biconcave shape
- accumulation of proinflammatory bioactive substances
- haemolysis over time
- progressive increase in K+ concentration (20mmol/L @ day 28) -> despite this hyperkalaemia uncommon complication
- progressive acidaemia (pH 6.7 @ day 28)
- hypomagnasaemia
- citrate exposure -> hypocalcaemia
Leucodepletion
- decreases risk of TRALI
- reduction in non-haemolytic transfusion reactions
- reduction in CMV transmission
- improved chance of finding an organ transplant match if required
- reduction in storage lesion effect
- reduction in graft vs host disease
- reduction in mortality after universal leukodepletion in cardiac surgical, orthopaedic and trauma populations (Hebert, JAMA, 2003)
EPO
- decreases transfusion requirements
- increased thrombotic complications
- being investigated in trauma and traumatic brain injury
FVIIa
- stops bleeding but increased risk of thrombosis and embolic disease
Undefined threshold for IHD patients
AN APPROACH
- minimise transfusion requirements using other means
- if bleeding: transfuse aggressively until bleeding controlled (avoid hypothermia, acidosis and coagulopathy).
- if not bleeding: restrictive strategy in those who can tolerate it and more liberal in those that have evidence of ischaemic end-organ dysfunction.
- ideally use new, leucodepleted blood
About Chris Nickson
