Correct Answer: A

Rationale: Performing immediate gastric lavage is the appropriate action for a client with severe lithium toxicity, indicated by a plasma lithium level of 2.1 mEq/L. Gastric lavage can help reduce the client's lithium level by removing the unabsorbed drug from the stomach.

Correct Answer: B

Rationale: Tremors may occur as a result of excessive stimulation of beta2 receptors in skeletal muscles when using Albuterol. It is important to educate the parent about potential adverse effects to ensure proper monitoring and management of the adolescent client's medication regimen.

Correct Answer: C

Rationale: The interaction between oxycodone and ibuprofen results in an increase in the expected therapeutic effect of both medications. Oxycodone is a narcotic analgesic, while ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). They work through different mechanisms but complement each other in pain management. When taken together, they can enhance the pain-relieving effects of each other, providing better pain relief for the client.

Correct Answer: D

Rationale: To prevent Otitis Externa, the nurse should instruct the client to tip the head to the side to allow water to drain out after showering or swimming. This helps to prevent moisture buildup in the ear canal, reducing the risk of developing Otitis Externa, commonly known as swimmer's ear.

Correct Answer: B

Rationale: The client's serum calcium level is below the expected reference range, indicating hypocalcemia. Calcium carbonate, an oral form of calcium, is used to increase serum calcium levels to the expected range in cases of hypocalcemia. It helps correct the deficiency by supplementing calcium in the body.