Pediatric emergency medicine trisk 2992 2992
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sJIA because acute lymphoblastic leukemia may cause joint pain and swelling, fever,
lymphadenopathy, and HSM that are indistinguishable from findings in sJIA.
In a patient being treated for known sJIA, fever may represent recurrence of JIA, or
it may be because of an intercurrent infection. Fevers in sJIA typically follow the
classic twice daily pattern, with two peaks above 39°C daily, as well as periods at or
below normal without use of antipyretic medications. If there are no localizing signs of
infection, the CBC shows the leukocytosis, thrombocytosis, and anemia typical of JIA,
and the urinalysis is normal, the child may be treated for a presumed JIA flare. Notably,
an acute infection can cause a flare of disease and both entities may coexist. Children
being treated with immunosuppressive medications may require empiric antibiotics or
observation in the hospital until negative culture results allow infection to be excluded.
If the patient has received more than 20 mg of prednisone daily for more than 6 weeks
within the previous 12 months, appropriate coverage with stress doses of steroids (three
times the physiologic dose) is indicated while the infection is being treated.
Fever in sJIA, especially within 6 months of disease onset, occasionally may be
caused by MAS, also known as reactive hemophagocytic lymphohistiocytosis (HLH).
This spectrum of disease will be discussed in greater detail below. This life-threatening
complication is characterized by systemic inflammation with disseminated
intravascular coagulopathy with diffuse microthromboses, cytopenias, hepatic
inflammation, SIRS-type physiology, and CNS changes progressing to seizures or
coma. The cause of MAS is unknown, but it does occur more commonly during viral
illnesses, as well as in children receiving NSAIDs or DMARDs (particularly
sulfasalazine) as treatment. A subset of children with sJIA likely have a genetic
predisposition to MAS as they carry mutations in genes associated with HLH.
Differentiation from sepsis or a flare of JIA may be difficult, although a sudden rise in
hepatic enzymes, ferritin, and triglycerides or a sudden drop in platelets, red blood
cells, or ESR (due to consumption of cellular elements and fibrinogen) is suggestive.
Early diagnosis and a high level of suspicion are essential. Treatment with anakinra,
pulse-dose methylprednisolone (30 mg/kg, maximum 1 g), and/or cyclosporine, as well
as general support measures for DIC, often lead to full recovery. Delayed diagnosis, in
contrast, is accompanied by a reported mortality rate of 20% to 50%.
Cardiac Complications. Cardiac involvement is an important feature of sJIA but is
uncommon in other subtypes of juvenile arthritis. Pericarditis, like other systemic
manifestations of Still disease, most often occurs during the first 2 years of the illness.
Fortunately, pericardial effusions in JIA rarely lead to cardiac tamponade. Valvulitis is
not typical of JIA and should suggest the possibility of acute rheumatic fever or
bacterial endocarditis. Myocarditis is rare but may be seen.
Bed rest and therapy with an NSAID should be adequate for the treatment of mild to
moderate pericarditis due to JIA. Corticosteroids (prednisone 1 to 2 mg/kg/day,
maximum 60 to 80 mg) are indicated for the treatment of noninfectious myocarditis,
