Final answer:
The nurse should instruct the parents to immediately report to the provider if they notice restricted ability to move the toes or swelling of the casted foot when the leg is dependent, as these can be signs of serious complications.
Step-by-step explanation:
Important Observations Post Cast Application
When a toddler has a lower leg cast applied, it is critical for parents to monitor for signs of impeded blood flow or complications related to the cast. The nurse's instructions should emphasize alerting the provider if they observe any restricted ability to move the toes or swelling of the casted foot when the leg is dependent, as these can indicate issues such as a too tight cast or circulation problems. A capillary refill time less than 2 seconds and toes that are deep pink in color are generally signs of good circulation and not typically cause for concern unless there is a drastic change.