On admission to the pediatric intensive care unit, he had a temperature of 102°F; heart rate, 120 bpm; respirations, 32 breaths per minute; blood pressure, 120/62 mm Hg; and oxygen saturation, 93% to 95% on a fraction of inspired oxygen of 1.0. Findings from physical examination revealed a capillary refill time of 2 to 3 seconds, full distal pulses, and warm extremities. His pharynx was congested without exudate, retropharyngeal swelling, or uvular displacement. He had bilateral nontender cervical lymph nodes measuring 2 to 3 cm. His abdomen was mildly distended, the liver enlarged, and the bowel sounds hypoactive. The skin had no petechiae or purpura, but erythema was present over the lateral aspect of his left proximal fibula.