An article published in Emergency Medicine Clinics of north America discussed the evaluation of dehydration in children and reviewed the literature on physical findings of dehydration. 

The authors stated that pediatric dehydration is a common presentation in emergency departments and there exists a wide practice variation in treatment. Dehydration can be treated with oral, nasogastric, subcutaneous or intravenous fluids. Additionally, most children with dehydration can be successfully rehydrated through the oral route. Careful selection of oral rehydration solutions has been advocated.

Children with dehydration are divided into severity subgroups by percent of weight lost during the illness. Based on the severity of dehydration, rehydration strategy and solutions or fluids are to be chosen. Moreover, intravenous fluids are employed to manage severe dehydration;in such cases, isotonic solutions should be used to avoid iatrogenic hyponatremia.

Source: Emergency Medicine Clinics of north America.2018 May;36(2):259-273. doi:10.1016/j.emc.2017.12.004.