Final answer:
The nurse's first action should be to stop the transfusion, as the client’s symptoms suggest a potentially life-threatening reaction. Subsequent actions include checking vital signs and informing the health care provider, following the emergency protocols for transfusion reactions.
Step-by-step explanation:
When a client complains of chills and headache half an hour after a blood transfusion is initiated, the first action a nurse should implement is C) Stop the transfusion. This immediate response is crucial because the symptoms could indicate an adverse reaction, such as a hemolytic transfusion reaction (HTR), which can quickly escalate to a life-threatening situation.
Once the transfusion is stopped, the nurse should then check the client's vital signs, including their temperature, to assess the severity of the reaction. Following this, it is imperative to alert the health care provider and follow the facility’s protocol for transfusion reactions, which usually includes obtaining urine samples to test for hemoglobinuria and blood samples to check for hemolysis or any ongoing reaction. Given these steps are in the correct order of priority, they ensure prompt and appropriate management to safeguard the patient's health.