The convalescent phase begins with the disappearance of clinical symptoms and continues until the ESR returns to normal, usually 6 to 8 weeks after the onset of illness. Beau lines of the fingernails may appear during this phase.
It is particularly important to exclude other causes of fever, notably infection. It is appropriate to obtain blood and urine culturesand to perform a chest x-ray. In the acute phase, inflammatory parameters are elevated, including white blood cell count, C-reactive protein, and the ESR, which can be profoundlyelevated (often >80 mm/hr). Platelet counts may be inappropriately low or normal. A lumbar puncture, if performed toexclude infection, may reveal pleocytosis. Tests of hepatobiliary function may be abnormal. Greatly elevated platelet countsdevelop during the subacute phase. The development of coronary artery aneurysms is monitored by performing two-dimensional echocardiograms, usually during the acute phase, at 2 to3 weeks, and again at 6 to 8 weeks. More frequent echocardiograms and, potentially, coronary angiography are indicated forpatients who develop coronary artery abnormalities.
The diagnosis of KD is based on the presence of fever for more than 5 days without an identifiable source and the presence of four of five other clinical criteria (Table 88-1).
The diagnosis of incomplete (atypical) KD, which occurs more commonly in infants, is made when fever is present for at least 5 days even if only two or three clinical criteria are present, particularly in the presence of coronary artery aneurysms. The diagnosis of KD should be considered in infants younger than 6 months of age with fever for at least 7 days even if no other criteria are present. Because many of the manifestations of KD are found in other illnesses, many diagnoses must be considered and excluded before the diagnosis of KD can be established (Table 88-2).
Intravenous immunoglobulin (IVIG) is the mainstay of therapy for KD, although the mechanism of action is unknown.
Fever of >5 days’ duration associated with at least four* of the following five changes:
One or more changes of the mucous membranes of the upper respiratory tract, including pharyngeal injection, dry fissured lips, injected lips, and “strawberry” tongue
One or more changes of the extremities, including peripheral erythema, peripheral edema, periungual desquamation, and generalized desquamation
Polymorphous rash, primarily truncal
Cervical lymphadenopathy >1.5 cm in diameter
Disease cannot be explained by some other known disease process.
*A diagnosis of Kawasaki disease can be made if fever and only three changes are present in conjunction with coronary artery disease documented by two-dimensional echocardiography or coronary angiography.
Coronary artery thrombosis Peripheral artery aneurysm Coronary artery aneurysms Myocardial infarction Myopericarditis Heart failure Hydrops of gallbladder Aseptic meningitis Irritability Arthritis Sterile pyuria (urethritis) Thrombocytosis (late) Diarrhea Pancreatitis Peripheral gangrene
A single dose of IVIG (2 g/kg over 12 hours) results in rapiddefervescence and resolution of clinical illness in most patients and, more important, reduces the incidence of coronary artery aneurysms. Aspirin is initially given in anti-inflammatory doses (80 to 100 mg/kg/day divided every 6hours) in the acute phase. Once the fever resolves, aspirin isreduced to antithrombotic doses (3 to 5 mg/kg/day as a single dose) and given through the subacute and convalescentphases, usually for 6 to 8 weeks, until follow-up echocardiography documents the absence or resolution of coronary artery aneurysms.