A nurse is reviewing data for four children. Which of the following children should the nurse assess first?

A. Severe chest pain in a child with sickle cell anemia may indicate acute chest syndrome, which is a life-threatening complication characterized by pulmonary infarction, infection, or vaso-occlusion. This can rapidly lead to hypoxia, respiratory distress, and organ damage, so the child requires immediate assessment and intervention, making it the highest priority. B. This value is slightly diluted but not immediately dangerous. The child is at risk for dehydration, but there is no acute crisis, so it is lower priority than severe chest pain. C. Fever is expected in roseola and usually self-limiting. The child may be uncomfortable but is not at immediate risk for life-threatening complications. D. This PCO2 is within normal limits (35–45 mm Hg). While asthma can deteriorate quickly, this reading does not indicate respiratory failure, making it a lower priority.