Page 2053 - Hematology_ Basic Principles and Practice ( PDFDrive )

1822 Part XI Transfusion Medicine

permit this. If this is done without medical reason, it offers no TABLE Guidelines for Transfusion of Red Blood Cells in
benefit and there are potential risks. Although directed donors need 121.1 Infants Less Than 4 Months of Age
to go through the same screening and infectious disease testing
process as all allogeneic blood donors, some studies suggest that 1. Hematocrit <20% with low reticulocyte count and symptomatic
directed donors have a slightly higher risk for infectious disease anemia (tachycardia, tachypnea, poor feeding)
transmission. 2. Hematocrit <30% and
In addition, directed donors may be a poor choice for immunologic a. On <35% oxygen hood, or
reasons. For example, if a neonate has alloimmune thrombocytopenia b. On oxygen by nasal cannula, or
or anemia, the pathologic antibody is a passively acquired maternal c. On continuous positive airway pressure and/or intermittent
antibody directed against inherited paternal antigens. In this case, mandatory ventilation on mechanical ventilation with mean
blood donated by the father would be recognized by the antibody in airway pressure <6 cm of water, or
the baby’s circulation and cleared just as the neonate’s own platelets d. With significant tachycardia or tachypnea (heart rate >180 beats
or erythrocytes are cleared. Another example in which immune per minute for 24 hours or respiratory rate >80 breaths per
concerns make directed donors a poor choice involves transplants. minute for 24 hours)
Some patients may require a future tissue or bone marrow trans- e. With significant apnea or bradycardia (more than six episodes in
plant, and blood relatives often serve as the best donors for such 12 hours or two episodes in 24 hours requiring bag and mask
transplants. However, prior transfusions from relatives may sensitize ventilation while receiving therapeutic doses of
the patient’s immune system to antigens present on the tissues of methylxanthines), or
blood relatives, complicating those potential tissue or bone marrow f. With slow weight gain (<10 g/day observed over 4 days while
transplants. receiving >100 kcal/kg/day)
3. Hematocrit <35% and
a. On >35% oxygen hood, or
TECHNICAL CONSIDERATIONS/MECHANICAL DEVICES b. On continuous positive airway pressure/intermittent mandatory
ventilation with mean airway pressure >6–8 cm of water
Smaller pediatric patients require small transfusions administered at 4. Hematocrit <45% and
slow rates. Aliquots of components often need to be prepared. This a. On extracorporeal membrane oxygenation (ECMO), or
can be performed by collecting blood into collection bags intercon- b. With congenital cyanotic heart disease
nected with sterile tubes or by attaching additional containers to a RBC, Red blood cell.
standard blood component by using a sterile docking device that
produces a sterile weld between two separate tubing sets.
Blood components must be filtered to remove microaggregates
before transfusion. For an adult patient, this is normally accomplished are based on experience rather than evidence-based medicine (Table
by transfusing the component through a filter contained within the 121.1). An ongoing study (http://clinicaltrials.gov/01702805)
blood administration set. These standard blood administration sets has the promise of providing definitive evidence to inform RBC
7
are not ideal for transfusing small patients because 20 to 40 mL of transfusion practice in this population. One prospective random-
the component is lost in the dead space of the administration set. ized clinical trial found equivalent clinical outcomes in neonates
Pediatric microaggregate filters with much smaller dead space are transfused with fresh RBCs stored for less than 7 days as those
available. transfused with standard-issue RBCs with a mean age of 14.6 days,
For nonbleeding patients, blood components are generally trans- although some have criticized the generalizability of the study
fused at a rate of no more than 5 mL/kg/h. For infants, this corre- results. 8,9
sponds to a lower rate than can be regulated by most standard
infusion pumps. Hence these transfusions are usually performed
using syringe pumps, with the blood component aliquot being Older Infants, Children, and Adolescents
transferred to a syringe for the transfusion. Often the blood bank
prepares aliquots of a blood component through a pediatric microag- RBC transfusion indications for infants older than 4 months and
gregate filter directly into a syringe, eliminating the need for bedside for young children are similar to those of adults. However, there
microaggregate filtration. are several noteworthy differences between children and adults:
total blood volume, ability to tolerate blood loss, and age-specific
hemoglobin levels (Table 121.2). In infants, RBC transfusions are
TRANSFUSION MEDICINE: GENERAL primarily given for surgical losses, anemia of chronic diseases, and
INDICATIONS AND DOSING malignancies. Infants inherently have lower hemoglobin levels than
adults and remain asymptomatic at lower hemoglobin concentra-
Indications for RBC Transfusion in Neonates, tions, especially if the anemia occurs gradually. Even with these
Children, and Adolescents physiologic differences, general transfusion-trigger guidelines for
pediatric intensive care unit patients are similar to those for adults,
with a transfusion trigger of 7 g/dL of hemoglobin for hemody-
Neonates Less Than 4 Months Old namically stable patients being shown to be safe for these patients.
10
This threshold has also been found to be safe for hematopoietic
11
RBC transfusions are more commonly administered to hospitalized progenitor cell (HPC) transplant patients. The usual dose of RBCs
neonates than any other pediatric patient age-group, and RBCs are is 10 to 15 mL/kg. There is no evidence that pediatric patients
the component most often transfused in this population. Symptom- benefit from transfusion of RBCs of a particular age, although it is
atic anemia is the major indication for simple transfusion and an currently the subject of a multicenter study (http://clinicaltrials.gov/
RBC transfusion should be considered when the venous hemoglobin 01977547).
is less than 13 g/dL in the first 24 hours of life or when a neonate
has lost approximately 10% of his/her blood volume. A transfusion
dose of 10–15 mL/kg of RBCs should yield an increase in the neonate Platelets
of 2–3 g/dL of hemoglobin after transfusion.
Two randomized clinical trials of premature infants in neonatal Platelet transfusion support in pediatric patients is usually intended
intensive care units, examining restrictive versus liberal RBC transfu- as a prophylactic strategy to prevent bleeding (Table 121.3). The
5,6
sion practices, had conflicting results. Therefore most guidelines prophylactic platelet transfusion thresholds in premature infants are