The nurse provides care for a client with chronic obstructive pulmonary disease (COPD). Administering high doses of oxygen may produce what result ？（）
A．Increased respiratory drive.
B．Diminished respiratory drive.
C．A mismatch between ventilation and perfusion.
D．A profound decrease in partial pressure of arterial carbon dioxide (PaCO2).
参考答案：B
解析：
A client with COPD who has had an elevated PaCO2 level for a prolonged time no longer depends on changes in carbon dioxide level to regulate the respiratory drive. The client with COPD depends on hypoxia or lower partial pressure of arterial oxygen level changes to regulate respirations. If high levels of oxygen are administered, the client will lose his hypoxic respiratory drive, causing respirations to decrease or even stop. As the respirations decrease, the PaCO2 levels elevate. COPD leads to a mismatch between ventilation and perfusion. The alveoli enlarge and overdistend, decreasing the surface area of alveoli to capillary ratio. Increasing the oxygen level won't increase the ventilation-perfusion mismatch.