Transfusions in the Critically Ill Pediatric Patient

Jelena Roganovic

Disclosures

Pediatr Health. 2010;4(2):201-208. 

In This Article

Indications for Transfusion

For over 40 years, the decision to transfuse RBCs was based upon the 'ten out of 30 rule', which stated that transfusion was indicated in all patients in order to maintain a blood Hb concentration above 10 g/dl and a hematocrit level above 30%.[14] Over the past 10 years, healthcare professionals responsible for children have become much more restrictive in their use of RBC transfusions. For most critically ill children, the only indication for a RBC transfusion is to provide a patient with sufficient RBCs to prevent or reverse tissue hypoxia owing to an inadequate circulating RBC mass and insufficient compensation. Little information exists regarding the level of Hb or hematocrit that should accomplish this, nor the desired final Hb level.[5,15] It is not surprizing that there is no consensus regarding the precise indications for RBC transfusion use in the pediatric age group, and there is evidence of wide variation in transfusion practice worldwide.[1] There is a general agreement that a child's Hb value, although important, should not be the sole deciding factor when considering whether to transfuse RBCs. Accordingly, the decision to transfuse must be based on an assessment of the risks of anemia versus the risks of transfusion. In addition to the individual assessment of any symptomatic anemic child, the duration of anemia must be taken into consideration as well as the extent of trauma or surgery and the probability of blood loss and coexisting conditions such as impaired pulmonary function and inadequate cardiac output.

Acute anemia usually warrants immediate medical attention. Treatment depends on the severity and underlying cause of the anemia. According to restrictive criteria, in normal healthy individuals, a transfusion Hb threshold of 7 g/dl is appropriate and leaves a safety margin over the critical level of 4–5 g/dl.[2] In patients with cardiac disease, as a general guide, the available evidence suggests that it may be safer to maintain the Hb level above 9 g/dl. Transfusion at Hb levels above 10 g/dl is unlikely to be appropriate unless there are specific indications.[2,5]

For children with acute blood loss, maintaining an adequate intravascular volume (including by crystalloid and colloid infusions) is critical to ensure adequate tissue oxygenation. Crystalloid solutions redistribute into the extravascular space by up to 80% and require quantities that are three- to four-times the actual blood loss in order to maintain intravascular volume. In practice, diagnosis of the presence and degree of blood loss is quite difficult, especially in a young and otherwise healthy child that can sustain a relatively large hemorrhage with few external signs of distress. Signs of impending shock, such as pallor and tachypnea, are easily overlooked. With loss of at least 25% of the total blood volume, the signs of cardiovascular compromise (mental alterations, hypotension, coolness of the extremities, weak peripheral pulses and decreased capillary filling) become evident. Transfusion is likely to be appropriate to maintain Hb above 7 g/dl during active bleeding.[5]

For critically ill children who develop anemia, transfusion may be appropriate to control anemia-related symptoms if the Hb level falls below 7 g/dl, with the aim of maintaining the Hb concentration in the range of 7–9 g/dl. A possible exception to this guideline are pediatric patients with known pulmonary and heart disease, where it may be preferable to maintain the Hb level in the range of 9–10 g/dl.[10] The therapeutic goal is to improve oxygen delivery according to the physiological needs of the child, by assessing urine output, skin temperature and the severity of lactic acidosis.[5,10]

There are no universally accepted treatment guidelines for the management of anemia in PICUs, especially for neonates, and practice differs between pediatricians, hospitals and countries. The evidence-based Transfusion Guidelines for Neonates and Older Children of the British Committee for Standards in Haematology are widely used.[16] In these guidelines, transfusion requirements of the neonate are recognized as unique, and special attention is paid to other groups of children who are regularly transfused (e.g., those with thalassemia major and sickle cell disease) and those who have very specific transfusion needs (e.g., children with aplastic anemia, malignancies and cardiac surgery). Suggested transfusion thresholds for infants under 4 months of age are summarized in Table 1.

The US Guidelines for blood utilization review state that the transfusion practice guidelines are not intended to serve as medical indications for transfusion, listing clinical circumstances in which RBC transfusions might be administered. They include conditions for which RBC transfusions are not mandatory but reasonable practice.[17] In addition, RBC transfusions may be indicated in clinical situations that are not listed in the guidelines. The guidelines from Roseff et al. (American Association of Blood Banks [AABB], MA, USA) are more prescriptive (Box 1).[18]

Summarizing published data from the literature, a 'restrictive' transfusion strategy (a Hb threshold of 7 g/dl for RBC transfusion) can safely decrease transfusion requirements in stable critically ill children. In this patient group, there is no benefit of a 'liberal' transfusion strategy (a Hb threshold of 10 g/dl for RBC transfusion). This recommendation is not applicable to premature infants and children with severe cardiopulmonary disease. It should be emphasized that no Hb level can serve as an absolute indicator of transfusion need. Proposals summarized in Box 2, in conjunction with the clinical assessment of a child, could help to achieve a rational decision regarding the appropriateness of transfusion.

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