Final answer:
Guardians of a toddler with a new cast should report signs of infection such as increased redness, swelling, warmth, or fever, as well as any indications of poor circulation, including color changes or decreased sensation in the affected limb.
Step-by-step explanation:
The nurse should instruct the guardians to report any finding that indicates potential complications, such as increased redness, swelling, pain, fever, or warmth at the site of the cast, which could signify an infection. Signs of poor circulation such as pallor, blue or gray skin, coldness, or a decrease in sensation or movement below the cast are also critical to report. If the toddler develops any systemic symptoms like a fever, which could indicate a more severe problem like infection, it is essential to seek medical attention immediately. This is particularly important because children can sometimes have difficulty communicating their discomfort, and guardians need to be vigilant for non-verbal signs of distress.