Page 2055 - Hematology_ Basic Principles and Practice ( PDFDrive )

1824 Part XI Transfusion Medicine

However, patients with CGD are at significant risk for developing TABLE Indications for Extracorporeal Membrane Oxygenation
anti-HLA antibodies from granulocyte transfusions, which can render 121.5 for Neonates and Pediatric Patients
granulocyte transfusions ineffective and can complicate possible
future hematopoietic cell transplants. 13 Neonatal
Meconium aspiration
Respiratory distress syndrome
TRANSFUSION MEDICINE: INDICATIONS IN UNIQUE Persistent pulmonary hypertension
PEDIATRIC POPULATIONS Congenital diaphragmatic hernia
Sepsis
Hemolytic Disease of the Fetus and Newborn Pediatric
Bacterial pneumonia
Hemolytic disease of the fetus and newborn (HDFN) occurs when Viral pneumonia
the mother’s immune system recognizes a foreign, paternally inherited Acute respiratory distress syndrome
antigen on fetal erythrocytes. The incidence of HDFN dramatically Burns
declined after the introduction of Rh immune globulin to prevent Inhalation injuries
sensitization of the mother to RhD. Although introduction of Rh Near drowning
immune globulin has prevented most cases of HDFN due to RhD Sepsis
sensitization, it has not totally eliminated HDFN due to RhD or
reduced HDFN due to other antibodies.
Most significant cases of HDFN are due to antibodies recognizing
antigens other than ABO system antigens. These antibodies should washed before transfusion. Alternatively, antigen-negative units may
be detected in the blood-bank antibody screen of the blood specimen be available. Indeed, major blood centers usually have HPA-1a-neg-
of the pregnant or postpartum woman. Also necessary for diagnosis, ative units available.
the corresponding antigens would be present on fetal or newborn
erythrocytes, or predicted to be present on fetal erythrocytes based on
molecular testing of fetal DNA. The direct antiglobulin test (DAT) of Extracorporeal Membrane Oxygenation
the fetal or newborn’s erythrocytes is usually positive, although it can
be negative in transfused patients. Although antibody titers can be Extracorporeal membrane oxygenation (ECMO) is an intervention
used to help predict the severity of the disease during pregnancy, they in which whole blood is removed from the patient’s venous circula-
are generally not useful in the newborn. After birth, the severity of the tion and circulated through a machine to remove carbon dioxide and
anemia and the resulting hyperbilirubinemia serve as markers for the replenish oxygen before being returned to the patient. This prolonged
severity of HDFN. Rates of rise in bilirubin level are most helpful in intervention is reserved for patients with more than 80% mortality
determining whether an exchange transfusion will be necessary, with risk and those who have been unresponsive to conventional ventilator
increases of 8 to 13 µmol/L/h despite phototherapy indicating that support and medical treatment but still potentially can recover. In
exchange transfusion will likely be necessary. 14 neonates and children, ECMO has become a lifesaving therapy in
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RBCs transfused in utero to the fetus need to be compatible the treatment of multiple disorders; Table 121.5 lists indications
with the ABO type of the fetus and mother and hence are usually for ECMO support in neonates and children. Standardized guidelines
blood group O. They need to lack the antigen(s) to which the for transfusion practice have not been established, resulting in indi-
mother has made antibodies, and they need to be crossmatch compat- vidualized centers establishing their own criteria. In order to prevent
ible with her serum. The RBCs should be irradiated to prevent thrombosis and platelet activation in the extracorporeal circuit which
transfusion-associated graft-versus-host disease (TA-GVHD), and is comprised of extensive tubing, patients are anticoagulated, usually
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cytomegalovirus (CMV) safe to minimize the risk for transfusion- with heparin, resulting in a significant risk of bleeding. Bleeding
transmitted CMV. Relatively fresh RBCs also are usually chosen for during ECMO is a common complication and may be caused by any
these transfusions. of the following factors necessary for operating the ECMO circuit or
Reconstituted whole blood is usually used for neonatal exchange resulting from the thrombogenic surface of the circuit: (1) systemic
transfusions. The blood is prepared by removing most of the preserva- heparinization, (2) platelet dysfunction, (3) thrombocytopenia, (4)
tive solution from an RBC unit and adding plasma, usually so that other coagulation defects, and (5) nonendothelial cell surface lining
the final hematocrit is 40% to 45%. the circuitry. It is recommended that hospital transfusion services
and ECMO staff be in close communication to agree on local
protocols to ensure safe, efficient, and consistent care (Table 121.6
Neonatal Alloimmune Thrombocytopenia provides an example protocol from one institution). Blood prod-
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ucts for ECMO are typically ABO and Rh specific and crossmatch
The pathophysiology of neonatal alloimmune thrombocytopenia compatible for priming. The RBC units for priming circuits are
(NAIT) is similar to that of HDFN in that both involve immune- typically relatively fresh, irradiated, and CMV seronegative and/or
mediated attack and destruction of fetal and neonatal blood cells by leukoreduced.
the mother’s immune system. Unlike HDFN, NAIT often affects a
woman’s first pregnancy. In addition, the antigens involved are due
to polymorphisms on platelet-specific proteins. Although a variety of Trauma
antigens can be implicated, the human platelet antigen-1 (HPA-1)
protein is most frequently implicated in whites, with approximately Hemorrhagic shock requiring massive transfusion can occur in chil-
70% to 80% of cases being due to women who lack the HPA-1a dren. Prothrombin time (PT), activated partial thromboplastin time
antigen making antibodies against HPA-1a that is expressed on fetal (aPTT), and platelet count abnormalities upon emergency room
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platelets. When NAIT is suspected, maternal serum can be tested admission are strongly associated with mortality. Transfusion man-
for antibodies to platelet antigens, and the parent’s or patient’s platelet agement of a pediatric trauma patient often must be guided by the
antigens can be determined by molecular means in which their patient’s estimated blood loss and associated signs and symptoms,
platelet antigens are indirectly determined from their DNA. An such as hypotension or tachycardia, and bleeding. A prospective study
affected infant or fetus may require platelet transfusions. Although found that a ratio of 1 : 1:1 of RBC to plasma to platelet units
random platelets may be of some transient benefit, antigen-negative transfused did not decrease overall mortality but decreased hemor-
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units are best. Maternal platelets lack the antigen, but because the rhagic deaths in trauma patients. The use of such a massive transfu-
plasma contains the pathogenic antibody, the platelet unit should be sion strategy has not been rigorously tested in pediatric patients.