In the scenario of Gary, a nursing assistant caring for Phyllis with a cast, the action that would result in a negative effect on the care of the cast is "using a ruler to scratch the skin under the cast."
Here's why:
1. **Covering the cast when near water:** This is a good practice as it helps to protect the cast from getting wet, which can lead to skin irritation, infection, or damage to the cast material.
2. **Allowing the patient to take a bath:** Allowing the patient to take a bath can be done if the cast is properly covered to prevent water from getting inside and compromising the integrity of the cast.
3. **Preventing the patient from getting the cast dirty:** Keeping the cast clean is essential to prevent infections and maintain overall skin health while the bone is healing.
4. **Using a ruler to scratch the skin under the cast:** This action can introduce foreign objects under the cast, leading to skin irritation, potential infections, or damage to the skin. It's crucial to avoid inserting any objects under the cast as it can harm the patient and interfere with the healing process.
In summary, scratching the skin under the cast with a ruler can have negative consequences, such as skin damage or infection, and should be avoided to ensure proper care and healing of the injured area.
