Pediatric emergency medicine trisk 2998 2998
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be excluded only by direct laryngoscopy. Redness and swelling of the arytenoid
eminences may be observed in cricoarytenoid arthritis, rather than the airway
inflammation of croup.
Increasing airway obstruction with severe inspiratory retractions demands urgent
treatment with respiratory support. Large doses of corticosteroids (methylprednisolone,
2 mg/kg/day IV) may control acute inflammation of the joints, thus avoiding
emergency tracheostomy.
HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS AND
MACROPHAGE ACTIVATION SYNDROME
Current Evidence
HLH and MAS are clinically related, life-threatening immune dysregulatory processes.
Although rare, as our understanding of this spectrum of disease grows, more and more
patients are found to suffer from these syndromes. Accordingly, it is important that the
ED physician be aware of these entities, as the prompt recognition and treatment of
HLH and MAS can markedly improve outcomes. While children with known systemic
autoimmune diseases, especially sJIA, SLE, and KD are at increased risk for MAS,
previously healthy children with new disease may present in MAS or HLH as their first
manifestation of their disorders. Both HLH and MAS cause severe illness in children
that is characterized by fever, systemic inflammation, HSM, coagulopathy, cytopenias,
and neurologic complications. When severe, children may demonstrate sepsis-like
physiology that can proceed to cardiopulmonary collapse if untreated. An ill child
presenting to the ED with persistent fever and the above laboratory and physical
examination findings may have hemophagocytic spectrum disease. However, because
the presentation may be nonspecific, other systemic processes, including infection,
malignancy, metabolic disorders, and other autoimmune disorders must be excluded.
While the clinical presentation of HLH and MAS is somewhat nonspecific, these
entities are defined histologically by the phagocytosis of hematopoietic cells by
normal-appearing macrophages in the bone marrow or lymphatic tissue; though it
remains unclear what role, if any, this hemophagocytosis plays in the pathophysiology
of these syndromes. Typically, however, this histopathologic information is not
available to the ED physician at the time of acute presentation. As such, the recognition
of the clinical syndrome as well as identification of at-risk children is essential to
providing exceptional emergency care.
HLH may be genetic or acquired in response to other triggers, most often infections,
especially EBV. Immunocompromised children, either due to iatrogenic causes or other
immune deficiency like HIV or malignancy, remain at increased risk for the
development of HLH. HLH is also associated with specific monogenic
immunodeficiency syndromes, like X-linked lymphoproliferative disease (XLP).
