Page 2019 - Hematology_ Basic Principles and Practice ( PDFDrive )

1790 Part XI Transfusion Medicine

donors undergoing apheresis for donation of RBCs, platelets, or PEDIATRIC HEMAPHERESIS
plasma, donors undergoing apheresis for collection of therapeutic
granulocytes are stimulated with steroids and G-CSF before dona- Therapeutic apheresis in pediatrics poses a particular challenge. The
tion. The well-known association of long-term steroid treatment and indications for apheresis in children are limited by a lack of clinical
posterior subcapsular cataracts is likely irrelevant in the context of trial data. Therefore the evidence for therapy in many diseases is
short-term steroid stimulation for donor granulocyte mobilization. extrapolated from trials in adults despite differing patient physiology
However, an increased number posterior subcapsular cataracts has and an age-dependent presentation and natural history of the disease.
been detected in three separate studies including an analysis of 100 For example, hemolytic uremic syndrome is more common in chil-
granulocyte donors compared with age-matched plateletpheresis dren and responds to supportive care; at the other end of the spectrum
donors, suggesting that granulocyte donors may be at increased risk of this disease, TTP is more common in adults and necessitates
for cataract formation. Repeated steroid stimulation for granulocyte plasma exchange.
collection warrants regular ophthalmologic examination and close Similarly the mechanics of apheresis were developed for adults and
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follow up. Serious complications indirectly associated with thera- therefore designed for their larger circulating blood volume. Therefore
peutic apheresis include adverse consequences of large-needle vascular depending on the size of the child, modifications to the apheresis
access; namely, retroperitoneal or pericardial hemorrhage, phlebotomy procedure may be necessary. Central venous catheters are required in
site aneurysm formation, pneumo- or hemothorax, thrombosis, nerve most circumstances because the caliber of peripheral venous access is
damage, and infection. A retrospective review of 381 therapeutic too small to permit adequate blood flow.
plasma exchange procedures at one institution reported an approxi-
mately 1% incidence of severe complications, all of them related to
central venous catheters (see box on Patient Management Issues for Technical Aspects
Therapeutic Apheresis).
In pediatric apheresis, maintenance of isovolemia is essential to
prevent circulatory compromise, particularly in an acutely ill child
Patient Management Issues for Therapeutic Apheresis who may have some degree of cardiac or renal impairment. The
beginning and end of the apheresis procedure involves negative and
Important issues to consider when preparing a patient for therapeutic positive intravascular fluid shifts, respectively. Typically, this has
apheresis, for monitoring the patient during the procedure, and for negligible impact on an adult’s circulation but can represent a sub-
managing the patient after removal from the apheresis device include: stantial proportion of the total blood volume (TBV) of an infant.
Preparation The volume of the patient’s blood required to fill the apheresis circuit
• Volume considerations: Calculate volume to be processed or at the start of the procedure is the extracorporeal volume (ECV).
exchanged; order replacement solutions; assess patient volume Symptomatic hypovolemia becomes increasingly likely as ECV
status. A blood prime may be necessary for children who weigh exceeds 15% of TBV. An ECV of 400 mL represents 8% of the TBV
less than 25 kg. of a 70-kg patient but may be as much as 35% for a 15-kg infant.
• Vascular access: Assess need for apheresis line placement. Note Modification of the apheresis procedure is necessary for safe manage-
that not all large catheters are suitable for apheresis procedures. ment in infants and small children.
• Medications: Evaluate impact of medications (Coumadin, platelet
inhibitory agents, angiotensin-converting enzyme inhibitors) and In adults, the apheresis circuit is primed with saline, which is then
indications to suspend certain medications. Albumin-bound diverted to the collection or waste bag. One option permits return
medications may be depleted by apheresis. of saline prime to the patient, which may be useful for larger children.
• Cell counts: Patient may require transfusion for preprocedure For children who weigh less than 25 kg, a prime with RBCs is often
anemia or thrombocytopenia. necessary to prevent intravascular volume depletion and severe
• Electrolytes: Assess risks for citrate toxicity; order calcium anemia. Upon completion, fluids remaining in the apheresis circuit,
replacement solutions if indicated. typically returned to the adult patient, are not returned in pediatrics
Procedure to avoid a positive fluid shift causing fluid overload.
• Volume considerations: Monitor replacement fluids (saline-to-
albumin ratio). Rapid infusion of refrigerated solutions may cause
hypothermia. PEDIATRIC APHERESIS
• Vascular access: Observe for impaired, intermittent, or obstructed
flow. Kinked tubing can result in hemolysis. Pediatric therapeutic apheresis accounts for about 10% of all apheresis
• Medications: Limitations on blood or citrate flow rate caused procedures performed. The majority of apheresis procedures in
by symptomatic citrate-induced hypocalcemia may necessitate children are erythrocytapheresis for patients with sickle cell disease
addition of anticoagulant to the final apheresis product or and mononuclear cell collections for HPCs to be used in conjunction
inclusion of heparin in the anticoagulant regimen.
• Cell counts: Consider the impact of very high or low cell counts with high-dose chemotherapy. Leukapheresis is performed in symp-
on device settings and procedure efficiency. tomatic leukostasis in acute leukemias, but may not be beneficial as
• Electrolytes: Continually monitor for adverse citrate effects; prophylaxis in hyperleukocytosis. Indications for ECP and LDL-
bolus or continuous intravenous calcium administration may be apheresis follow guidelines discussed earlier. In solid organ rejection,
required. both ECP and therapeutic plasma exchange (TPE) have been used as
Postprocedure Management adjunct treatment modalities with sparse data thus far. As in adults,
• Volume considerations: Review net volume balance and consider TPE is shown to be efficacious in acute and chronic demyelinating
additional infusion or administration of diuretic if needed. neuropathies and in severe refractory myasthenia gravis. TPE may
• Vascular access: The decision to remove the apheresis also benefit children with rare neurologic disorders; pediatric auto-
catheter should include the possibility of additional apheresis immune neuropsychiatric disorders associated with streptococcal
or procedures; monitor for complications associated with infection and Sydenham chorea (SC) are autoimmune neuropsychi-
maintenance or removal of venous catheter. atric disorders that occur rarely after infection with group A
• Medications: Determine when to restart medications; consider the β-hemolytic streptococcal infections. Circulating immune factors
impact of transiently reduced coagulation factor levels. may contribute to the pathogenesis of these diseases. These condi-
• Cell counts: The patient may require transfusion for tions respond to IVIg and plasmapheresis. In a small randomized
postprocedure thrombocytopenia; monitor cumulative red blood study, 50% of patients with SC also responded to plasmapheresis,
cell and platelet loss after repeated procedures.
• Electrolytes: Assess for imbalance postprocedure with attention to and although superior to corticosteroids, treatment with IVIg had
ionized calcium and magnesium as indicated by symptoms. the best response, with 72% of patients having a reduction in symp-
toms of chorea. Small pediatric studies have demonstrated benefit of