Blood Products in Critically ill Children

Shamiel SaliePaediatric Intensive Care UnitRed 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?

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) and

liberal strategy (Hb <9.5)• No difference in MODS, death, icu stay and sepsis• 44% reduction in blood transfusions• 50% of study children transfused

• 838 critically ill adults• Restrictive strategy (Hb<7) and liberal strategy (Hb <9)• Restrictive group had 54% fewer rbc units• Decrease mortality in adults who were less sick• Possible exceptions: unstable angina and MI’s

• 1269 Kenyan children hospitalized for malaria English, Lancet 2002

– RBC transfusion decreased mortality in severe anaemia,

<4g/dl

or if Hb < 5g/dl and dyspnoeic

- some benefits to keep Hb > 5 in hospitalized children

• Haemodynamically unstable children: Hb > 10• De Oliveira et al (Intens. Care Med. 2008)

– children with severe sepsis

– significant reduction in 28 day mortality

(11% vs 39%, p=0.002) and new organ failure

– targeting SVC sats > 70% using fluids, inotropes and blood transfusions keeping Hb > 10g/dl

• Similar outcomes in adults using goal directed therapy Rivers et al, NEJM 2001

• Children with severe congenital heart disease and traumatic brain injuries might need higher Hb’s

Transfusion related acute lung injury (TRALI)

• Aetiology poorly understood

• Diagnostic criteria– Acute lung injury occurring within 6 hours

of a transfusion – No signs of fluid overload– Bilateral lung infiltrates on cxr

• Usually resolves within 48 hours

Leukocyte reduced RBC’s

• Reduces leukocytes by up to 99%

• reduces the number of cell associated viruses: cmv, herpes and ebv

• May reduce transmission of prions and parasites and incidence of TRALI

Fresh Frozen Plasma

Platelets

• Thrombocytopenia and qualitative platelet defects impairs ability to form platelet plugs

• Risk of massive bleeding when platelet count < 10 and IVH when platelets <1

• No scientific basis for keeping platelets > 20

Cryoprecipitate

• Rapid increase in fibrinogen levels in patients with DIC and active bleeding

• Meta-analyses of 24 studies, 1419 patients

• 6% increase in mortality or

‘1 death for every 17 patients given albumen’

• Meta-analysis of 55 trials, 3504 patients

• No difference in mortality

• Nearly 7000 patients

• No significant difference in mortality

• Similar rates of secondary outcomes– Survival time, organ dysfunction, duration of

mechanical ventilation, length of icu and hospital stay

• Albumin to saline ratio 1: 1.4

Conclusions

• Stable critically ill children can support an 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