Final answer:
The nurse should administer pain medication and utilize non-pharmacological interventions to help alleviate the client's incisional pain.
Step-by-step explanation:
According to the gate-control theory of pain, the nurse should take action to help close the 'gate' in the spinal cord that is allowing the pain signals to reach the brain. One effective action the nurse can take is to administer pain medication, such as opioids or nonsteroidal anti-inflammatory drugs (NSAIDs), to help alleviate the client's pain. Additionally, the nurse can use non-pharmacological interventions, such as applying ice or heat to the incision site or using relaxation techniques, to help reduce the perception of pain.