Adverse reactions

Abstract

Blood transfusions in the United States are safer now than they have ever been with approximately 300,000 blood products being transfused to children in the United States each year (Strauss, Am J Dis Child 145:904-911, 1991). However, the transfusion of blood products is not without its risk. Transfusions have been associated with bronchopulmonary dysplasia (Collard, Med Hypotheses 66:355-364, 2006; Cooke et al., Eur J Pediatr 156:47-50, 1997) and retinopathy of prematurity in the neonatal population (Cooke et al., Eur J Pediatr 52:833-836, 1993; Sacks et al., Pediatrics 68:770-774, 1981; Sullivan et al., Transfusion 42:1253-1260, 2002) and are an independent predictor of death (Hebert et al., Am J Respir Crit Care Med 155:1618-1623, 1997). Transfusion reactions are infrequent in infants less than 4 months old as their immature immune systems make them less susceptible to alloimmunization to red cells or human leukocyte antigens (HLA). However, when they do occur, transfusion reactions in neonatal patients differ from that of adult patients due to their age, small blood volume, immature organ and immune function, and wide variation in physiologic response to stressors. Adults, by contrast, show relatively uniform and predictable responses to these variables. In addition, many neonatal patients requiring the transfusion of blood products tend to be those who are more ill and have a longer length of hospital stay than their adult counterparts. For example, most neonatal transfusions occur in extremely low-birth-weight infants (1000 g) who are being treated in the neonatal intensive care unit (NICU) with low-birth-weight neonates being one of the most frequently transfused patient populations in the tertiary care medical center (Neonatal Transfusion Guidance 2012). One study found that the rate of transfusion complications in the pediatric population is 10.7 per 1000 products transfused compared to 2.5 per 1000 products transfused in adults (Andreu et al., Transfusion 42:1356-1364, 2002). While transfusion in healthy infants might be postponed until their anemia becomes symptomatic, seriously ill neonates are often transfused in order to reach a target hemoglobin level regardless of symptoms (Levy et al., Pediatrics 91:523-529, 1993). Not only are patients with a severe illness more likely to receive a transfusion during their hospital stay, but they are also more likely to experience a transfusion reaction when compared to those with a minor illness (Slonim et al., Transfusion 48:73-80, 2008). Factors such as iatrogenic blood loss from repeated phlebotomy and physiologic anemia of infancy in preterm infants contribute to neonatal patients requiring frequent, small-volume transfusions in contrast to transfusion indications in older patient populations. One study found that on average, pediatric patients received between 1 and 12 transfusions during any single hospitalization with 17.5 % of these transfusions occurring in neonates less than 30 days old (Slonim et al., Transfusion 48:73-80, 2008). Of all of the pediatric patients transfused, 0.95 % of them experienced a complication with an average of 1.6 complications per patient with neonates accounting for 7.6 % of these transfusion complications (Slonim et al., Transfusion 48:73-80, 2008). Currently, data on blood product use, transfusion complications, and effects on clinical outcomes remain scarce for the neonatal patient population. Packed red blood cell transfusions are one of the most widely utilized medical interventions, but criteria for when to infuse in neonates are based on expert opinion and recent evidence-based medicine. No single clinical parameter is available to determine the best time to transfuse, and therefore no consensus is available, and transfusion practices vary (Kasat et al., Blood Transfus 9:86-94, 2011). The decision to transfuse is often dependent on the patient's clinical signs and symptoms. However, these signs and symptoms can also be a result of the patient's underlying condition. Transfusion guidelines have been implemented in many NICUs in order to decrease the number of transfusions and have been found to decrease exposure of very low-birth-weight neonates to donor blood products. In contrast, NICUs without strict transfusion guidelines are twice as likely to transfuse. Therefore, measures such as developing unit-specific transfusion guidelines, decreasing blood sampling, and using in-line blood gas and chemistry monitors are recommended in order to reduce the number of unnecessary transfusions, thereby reducing the incidence of transfusion reactions. Because some adverse reactions to transfusion cannot be accurately predicted or entirely prevented, it is important for clinicians to be aware of the risks associated with transfusion and to discuss these risks with the patient or their caregiver while obtaining informed consent. In addition, the healthcare professional that is administering the blood product must be aware of the signs and symptoms of a possible transfusion reaction and be prepared to intervene as necessary. After a transfusion reaction is suspected to have occurred, a laboratory investigation should take place and the records retained in order to help prevent transfusion reactions in the future. This chapter will discuss the complex and unique factors associated with neonatal transfusion adverse reactions.