BLOOD TRANSFUSIONS Dr. Tamara Wagenheim

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

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

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

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

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

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

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

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

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

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

MISMATCH Mistransfusion- blood transfused to other than the intended recipient USA: 1 in 14000 , 1 in 18000 in UK 50 % errors in clinical arena 30 % lab errors

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

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