1. BLOOD TRANSFUSIONS
Dr. Tamara Wagenheim

2. INTRODUCTION RBC Transfusion dates back to 17th century
70 years ago – mainstay of clinical practice
Huge advances in surgical and medical practice
1980’s concerns of transfusion related infection

3. RBC transfusion - rationale
O2 delivery = cardiac output x O2 content
Restore oxygen delivery, preventing tissue hypoxia
Treatment of anaemia

4. ANAEMIA
Risk – harm caused by decrease in the O2 carrying capacity and plasma volume
Common in critically ill
Causes:
1. Phlebotomy: “ nosocomial anaemia”
“medical vampires”
2. Occult blood loss
3. Inappropriate production of RBC : blunted EPO
response

5. ADVANTAGE VS DISADVANTAGE
ADVANTAGES
1. TREATMENT OF ANAEMIA
2.RESTORE RC MASS, PREVENTING TISSUE HYPOXIA
DISADVANTAGES
1.TRANSFUSION RISKS
2.ADVERSE EFFECTS OF RC STORAGE

6. TRANSFUSION: WHO?? WHEN??
CRIT study - Transfusion triggers drive transfusion decisions
Downward revision of infusion trigger
TRICC trial by Hebert et.al :
liberal( 10g/dl) vs restrictive(7g/dl) transfusion threshold
Overall hospital mortality lower in the restrictive group
30 day mortality lower in those < 55yrs
Patients with active ischaemic cardiac disease benefited from liberal transfusion threshold
Therefore TRICC study showed 7g/dl threshold- most appropriate transfusion threshold in critically ill patients

7. EFFECTS OF STORED BLOOD
Storage of blood – cause of increase morbidity and mortality
Increased duration of storage associated –
Increase mortality
Increased length of hospital stay
Multi organ system failure
Impaired o2 utilization
Increased incidence of infection:- nosocomial infection
-TRIM
WBC and accumulation of WBC derived cytokines- increase morbidity and mortality

8. Effects of stored blood cont.
Morphologic and biochemical changes
ATP deprivation:
– loss of surface/ volume ratio
increase osmotic fragility
loss of deformity
2,3, DPG depletion
WBC- increase haemolysis, and k leakage
RBC adhesion with increased storage duration

9. RISKS OF BLOOD TRANSFUSIONS
1. INFECTIONS: viral, bacterial
2. MISMATCH: ABO incompatibility
3. METABOLIC: acidosis, hyperkalaemia
4. HYPOTHERMIA
5. TRALI
6. DILUTIONAL COAGULOPATHY

10. VIRAL TRANSMISSION HIV
1982/83- first transfusion related HIV infection
1985- implementation of HIV ab test
1995- p24 antigen
HEPATITIS B: hep b surface ag test led to decrease
in transfusion transmitted hep b
HEPATITIS C: HCV antibody test
HEPATITIS A: uncommonly ass. with blood transfusions
CMV: oncology patients

11. BACTERIAL INFECTIONS Most common organism – Yersinia enterocolitica
Bacterial contamination of platelets – common
RARELY- EBV, Lyme Disease, Brucellosis, Toxoplasmosis, Chagas Disease, West Nile Virus

12. MISMATCH
Mistransfusion- blood transfused to other than the intended recipient
USA: 1 in , 1 in in UK
50 % errors in clinical arena
30 % lab errors

13. TRALI Transfusion Related Acute Lung Injury
Acute respiratory distress syndrome within 4 hours after transfusion
Dyspnoea and hypoxaemia
Approximately 1 in 5000 transfusions
Mechanisms:
1. Donor antibodies react with recipients neutrophils –
increased permability of pulmonary microcircultaiom
2. Storage of blood – rise of reactive lipid products

14. SUMMARY Anaemia is common in critically ill patients
Increased morbidity and mortality associated with anaemia and transfusions
Transfusion trigger of 7g/dl is most appropriate for critically ill patients
Transfusion trigger of 10g/dl for patients with active ischaemic cardiovascular disaese
Duration of RBC storage may have adverse effects
Advances in blood safety, esp transfusion transmitted viral infections
Consider alternatives to RBC transfusion