Blood Transfusion in ICU

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

STRATEGIES TO MINIMISE BLOOD TRANSFUSION REQUIREMENTS

• stopping bleeding early
• stop unnecessary anticoagulation and antiplatelet agents
• minimising venesection
• use blood conservation devices when sampling from arterial lines
• correct the lethal triad of hypothermia, acidosis and coagulopathy
• GI prophylaxis and enteral nutrition
• haemantinics: Fe2+, B12, folate, nutrition
• use tranexamic acid early in traumatic haemorrhage
• consideration of EPO therapy
• consider use of FVIIA

DETERMINANTS OF TRANSFUSION TRIGGERS

Transfusion triggers are dependent on many variables:

1. evidence of bleeding and stability of patient
2. reason for admission (trauma, GIH)
3. patient wishes (Jehovah’s witness)
4. comorbid conditions (such as ischaemic heart disease)

BLEEDING

Other controversial issues include the prophylactic use of erythropoeitin, routine use of filters / leukodepletion of red cells prior to transfusion, reinfusion of autologous blood (eg cell saver), and the approach to those patients unwilling to be transfused.  A strategy should also be in place to deal with the potential complications associated with massive transfusion (eg coagulopathy).

• lower threshold to transfuse
• adults: aim to keep Hb > 100 g/L until bleeding controlled
• trauma patient:

-> haemostatic resuscitation: early products in a 1-2:1:1 ratio (RBC:platelets:plasma)
-> permissive hypotension
-> damage control surgery
-> avoid hypothermia, acidosis and coagulopathy

NON-BLEEDING

• based on TRICC 1999 and current NBA guidelines in transfusion in critical care:
  — Hb <70 is usual trigger for transfusion (though patients who are well compensated may not need transfusion)
  — 70 to 100 should be transfused if evidence of ischemia or impaired oxygen delivery
  — Hb >100 rarely if ever need transfusion
• post CAGS Hb 80 is non-inferior to Hb 90
• higher thresholds if elderly or ischemic heart disease (e.g. Hb 100)
• permissive approach also shown to be acceptable in hip fracture patients

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

• transfusion of RBCs >2-3 weeks old may have additional risks due to storage lesions
• See Storage Lesions

Leucodepletion

• all RBCs for transfusion in Australia and New Zealand are now leukodepleted
• this is thought to decrease many transfusion risks; the highest quality evidence available is based only on observational data
• See Leukodepleted blood

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

• ? Hb target of 100

Use of autologous blood if possible

• use cell saver device

Patients who refuse transfusion (e.g. Jehovah’s Witnesses)

• prevent bleeding and anemia
• consider EPO
• consider blood substitutes

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, leukodepleted blood

References and Links

LITFL

• CCC — Storage Lesions
• CCC — Transfusion literature summaries

FOAM and web resources

• Maryland CC Project – Giora Netzer – Blood Transfusion Strategies in the Modern Era (2014)