Final answer:
For a child diagnosed with Reye's syndrome, the nursing care plan should include creating a quiet atmosphere with dimmed lighting because it helps reduce brain swelling and does not aggravate the condition unlike aspirin which is contraindicated.
Step-by-step explanation:
Reye's syndrome is a serious condition that affects the liver and brain, especially after viral infections like influenza or chickenpox, in children and teenagers. Given this information and understanding the association between aspirin use and the development of Reye's syndrome during viral infections, the best nursing intervention to include in a care plan for a child with Reye's syndrome would be to provide a quiet atmosphere with dimmed lighting. This is because a calm environment can help reduce the metabolic demand on the brain and potentially lessen the severity of symptoms. Encouraging physical activity would not be suitable due to the need for brain rest, and administering aspirin for pain relief is contraindicated due to the risk of worsening the syndrome. High-sugar foods are also not relevant to managing the symptoms of Reye's syndrome.