This page explains what a contrast extravasation is, how it is treated, and symptoms to watch for. DOWNLOADABLE PDF: Contrast Extravasation.
The amount of fluid a child needs depends on many factors including their age, their gender, the weather and how much physical activity they do, but generally they should aim to drink about 6-8 glasses of fluid per day (on top of the water provided by food in their diet).
My daughter, 13 1/2 months old, drinks 3 bottles a day, one with her breakfast (6 oz, cereal then drinks the rest of the bottle) one at nap time (6 oz) and one at bedtime (8oz).