Final answer:
For a rattlesnake bite, the nurse should administer an opioid analgesic for pain management, as opioids are routinely used as painkillers. Other treatments like ice, corticosteroids, or elevation are not typically prescribed in this scenario.
Step-by-step explanation:
In the case of treating a client who has sustained a rattlesnake bite to the lower leg, the nurse should expect to administer an opioid analgesic to the client. This is because opioids are used routinely as painkillers, which can help manage the severe pain associated with snake bites. It's important to note that applying ice, initiating corticosteroid therapy, or keeping the leg above the heart level are not standard treatments for a rattlesnake bite, as they may not address the immediate needs of pain management or may even be counterproductive.