A client in acute respiratory failure is classified as having ventilatory failure. The nurse understands that which finding is a potential extrapulmonary cause of ventilatory failure?

A. Amyloidosis can affect the lungs or heart and may contribute to respiratory failure, but this is generally considered a pulmonary or systemic disease causing intrapulmonary problems rather than an extrapulmonary cause of ventilatory failure. B. Pneumothorax is a pulmonary cause of respiratory failure. It directly impairs lung expansion and gas exchange by causing air to accumulate in the pleural space. C. Pulmonary edema is another pulmonary cause of respiratory failure. It occurs due to fluid accumulation in the alveoli, impairing oxygenation and ventilation. D. Opioid analgesic overdose is an extrapulmonary cause of ventilatory failure. Opioids depress the central nervous system, particularly the medullary respiratory centers, leading to hypoventilation, decreased tidal volume, and elevated arterial CO₂ (hypercapnia). This is a classic example of ventilatory failure caused by a neurologic or pharmacologic extrapulmonary issue, rather than intrinsic lung disease.