Introduction

Successful and safe transfusion practice depends on administering a quality blood component of the right type, in the right amount, in the right way, at the right time to the right patient.¹

Blood components should only be given when the expected benefits to the child outweigh the potential hazards. A range of clinical signs and symptoms viewed within the context of a clinical need is essential for the decision to transfuse. Transfusion triggers include both clinical (symptoms, signs, comorbidities) and laboratory indications; benefit–risk of blood product use requires careful consideration. In the setting of massive haemorrhage whole blood could be used. Otherwise, there is no indication for the use of whole blood when specific component(s) appropriate to a clinical problem are available.

Emphasis on blood component safety, standardisation of appropriate guidelines for use of blood components and informed consent for blood component administration have led to a substantial reduction in the potential risks and complications of their use as well as increasing their appropriate usage. Informed consent with regards to the risks and benefits of blood component therapy needs to be obtained in the light of community concerns about transfusion safety, particularly the potential for infection transmission. The indication, risks, benefits, alternatives to transfusion, parental consent, response to treatment and any adverse event should be clearly documented. In non-urgent situations, parents and mature children can access publications such as ‘Children receiving a blood transfusion: A parents’ guide’² for more information.

Clinical guidelines for use of red blood cells (RBC) in children are consensus rather than evidence based,³ with the latest National Health and Medical Research Council/Australian Society of Blood Transfusion Australian practice guidelines for blood product indication and administration available at www.nhmrc.gov.au, including haemoglobin (Hb) and platelet transfusion threshold triggers.¹ It is recommended that intravenous (IV) access be 22–24G or larger for children receiving blood products through a standard blood administration set primed with normal saline or the blood component. A blood warmer is indicated at flow rates >15 ml kg⁻¹ hr⁻¹ in children and for exchange transfusion in infants; very slow rates are recommended in small children if rapid volume expansion is not required. Blood products should not be warmed to above 41°C.⁴

The rate of administration should not be >5 mL min⁻¹ in the first 15 minutes as severe reactions are most likely to occur then; all blood components should be infused within 4 hours unless fluid overload is a risk. The child and infusion need to be monitored during blood product administration, more closely if unconscious or anaesthetised. A severe reaction requires suspension of blood product administration pending further incompatibility or bacterial contamination checks, consideration of antihistamines/steroids, and be reported to the Australian Incident Monitoring System in Australia or the New Zealand Blood Service.

Whole blood

Whole blood is rarely used, being specifically used for massive blood loss requiring simultaneous restoration of oxygen-carrying capacity and blood volume, haemorrhage with uncontrolled coagulopathy and exchange transfusion. Eight ml kg⁻¹ will increase a child’s haemoglobin concentration by 10 g/dL⁻¹, and administration must be completed within 4 hours to avoid bacterial contamination.

Packed red blood cells (PRBC)

Indications

The child’s Hb level, patient factors, signs and symptoms of hypoxia, ongoing blood loss, risk of anaemia and risk of transfusion should be considered. Each paediatric red cell unit is 25–100 mL (mean volume 50 mL) with a haemoglobin concentration of 100–150 g L^–1. PRBC is indicated if the oxygen-carrying capacity of blood is so reduced that the degree of anaemia poses a risk to the child or there is ongoing blood loss. Transfusion of PRBC in an asymptomatic child is not appropriate in most situations. PRBC transfusion is likely to be appropriate when haemoglobin is less than 70 g L^–1 in critically ill children.⁵ The haemoglobin threshold remains uncertain in stable children with anaemia. Use of PRBC with haemoglobin in the range 70–100 g L^–1 is appropriate if the child is at risk of hypoxia (cardiac, respiratory disease) and should be supported by the need to relieve clinical symptoms and signs. Criteria for PRBC in patients aged less than 4 months are different from those for older children. Infants in the former group have smaller blood volumes, decreased erythropoietin production (especially if premature) and there may be physiological anaemia of infancy.

Additional indications for PRBC include:

• emergency surgery in a child with significant preoperative anaemia;

• sickle cell disease with ischaemic organ events to suppress endogenous Hb production;

• Chronic congenital or acquired anaemia such as B-thalassaemia.

Administration

If stored in optimal conditions, RBC have a shelf life of 35–42 days. In haemorrhagic shock, RBC infusion at an initial volume of 10–20 mL kg^–1 should be considered when loss of blood volume approaches 30% (when hypotension first appears)³ and shock is refractory to non-blood fluid resuscitation. A single Hb level is not reliable in acute haemorrhage.³ If haemorrhage or haemolysis is accompanied by life-threatening hypoxia or rapid Hb decline then uncross-matched group O rhesus negative packed cells may be required. In less urgent cases, type-specific or cross-matched RBC is preferred. Rh type specific blood takes 15 minutes to cross match. If the child has no immediate need for RBC replacement and there is no ongoing bleeding or haemodynamic instability, cross-matched RBC may be administered over 4 hours. The volume required for elective top-up transfusion in mL is:

Weight(Kg) × haemoglobin rise required (gL ⁻¹)×3