Blood products - Vula

Blood Products in Critically ill Children

Shamiel Salie Paediatric Intensive Care Unit Red Cross Children’s Hospital, University of Cape Town

1818 - Extracted 4 ounces of blood from the arm of the patient’s husband with a syringe and successfully transfused it

Anaemia in critically ill children • Causes – Chronic anaemia – Overt and occult blood loss – Bone marrow suppression from diseases/treatment – Inadequate erythropoietin response to anaemia

Red Blood Cell Transfusions • For decades considered to be a low risk with obvious benefits • 10/30 rule

• Restrictive use of blood since the 1980’s

What actually happens in PICU? • 50% of children in PICU’s transfused Bateman: Am J Resp Crit Care Med 2008

• Large variability in clinical practise • Bedside observational studies Gauvin 2000 & Armano 2005

– transfusion threshold ranges from 7 - 11 g/dl

• 30 North American PICU’s – Pretransfusion Hb 9.7 g/dl Bateman: Am J Resp Crit Care Med 2008

Physiological benefits of RBC transfusions • Tissue hypoxia may be due to low Hb concentration, cardiac output or SaO2 • Oxygen delivery exceeds requirements • Adaptive processes as oxygen delivery decreases with anaemia – Increased oxygen extraction – Increased heart rate and stroke volume – Preferential perfusion of head and heart at the expense of splanchnic perfusion

• Altered physiological adaptation to low Hb in critically ill children – Increased metabolic rate in SIRS increases oxygen consumption and lowers reserves – Impaired LV function and vascular tone restricts oxygen delivery and blood redistribution – Infants have high resting heart rates, which limits the ability to increase cardiac output

Microcirculatory effects of transfused RBC • Global increase in oxygen delivery with potentially decreased microcirculatory flow – Increased blood viscousity – Cytokines my cause vasoconstriction – Low levels of 2,3 DPG shifts curve left, impeding oxygen availability – Decreased RBC membrane deformability – Free Hb may bind NO causing vasoconstriction

Immunologic effects of RBC transfusion • Some evidence that it may cause – Immune suppression by altering lymphocyte reactivity – Pro inflammatory: cytokines in unfiltered rbc’s might trigger SIRS or multi organ failure

When should critically ill children be transfused?

• 637 critically ill children • Equivalence of restrictive strategy (Hb 7 • Maintain Hb > 10 in haemodynamically unstable children, those with significant cardiovascular disease and traumatic brain injuries

Conclusions • Advantages to using leukocyte reduced blood

• Platelet transfusion thresholds not evidence based • Prophylactic use of FFP is controversial

Questions