Final answer:
If a nursing assistant notices cold fingers on a resident with a cast on the left arm during a bed bath, the next appropriate action would be to notify the nurse in charge.
Step-by-step explanation:
If a nursing assistant notices that the fingers on a resident's left hand are cold, the next appropriate action would be to notify the nurse in charge. Cold fingers may indicate poor circulation, which could be a sign of a more serious underlying issue such as restricted blood flow or nerve damage. The nurse would have the medical expertise to assess the situation and take appropriate measures to ensure the resident's well-being.