Final answer:
The nurse's first action for a client with an aspirin overdose should be to monitor intake and output every hour to manage fluid balance and electrolyte levels. The patient's lab data suggest respiratory alkalosis and hypokalemia, which are typical of aspirin toxicity.
Step-by-step explanation:
The nurse's first action for a client who has just been admitted with an overdose of aspirin and presents with lab data indicating PaO2 95, PaCO2 30, pH 7.5, and K 3.2 mEq/L should be focused on addressing the aspirin overdose and its effects. In this scenario, the patient's pH level indicates respiratory alkalosis, likely due to hyperventilation, a common reaction to aspirin overdose. The client also shows hypokalemia with a potassium level of 3.2 mEq/L. The first action by the nurse should be C. Monitor intake and output every hour to assess fluid balance and electrolyte levels, which can be altered due to the aspirin toxicity and compensation for the alkalosis. Preparing to administer oxygen (choice D) may not be necessary with a PaO2 of 95, as it indicates adequate oxygenation. Observing the respiratory rate trends (choice B) is also important, but it is secondary to monitoring the client's fluid and electrolyte status. Assisting the client to breathe into a paper bag (choice A) would increase PaCO2 and could be harmful in this situation.