A nurse is caring for a client who is intubated and receiving mechanical ventilation for heroin toxicity. Which of the following assessments is the nurse's priority?

Rationale: A. WBC count: Monitoring the white blood cell count is useful for detecting infection, but heroin toxicity primarily affects the respiratory system. An elevated or normal WBC does not provide immediate information about the client's ventilation or gas exchange status. B. Intake and output: Tracking fluid balance is important for overall patient monitoring, especially in critically ill clients. However, it does not provide direct insight into the effectiveness of mechanical ventilation or the client's oxygenation status. C. ABGs: Arterial blood gases are the priority assessment because they directly measure the client's oxygenation, ventilation (CO₂ removal), and acid-base status. Since heroin toxicity can cause respiratory depression, ABGs are essential to evaluate the effectiveness of mechanical ventilation. D. Blood glucose level: Although monitoring glucose is important in critically ill clients, heroin use is not typically associated with hypo- or hyperglycemia. Blood glucose assessment is not as urgent as evaluating respiratory function in this scenario.