A nurse is evaluating a client who has pleural effusion and is receiving oxygen therapy. For which of the following complications of oxygen therapy should the nurse monitor?

A. Increased partial oxygen levels (PaO2): While oxygen therapy can raise PaO2, this is an expected therapeutic effect, not a complication. Monitoring PaO2 ensures safety, but elevation within therapeutic range is desired. B. Dehydration: Oxygen therapy, especially at higher flow rates, can dry out the mucous membranes of the respiratory tract, leading to fluid loss and dehydration. The nurse should monitor for dry mouth, thickened secretions, and signs of fluid imbalance. C. Hyperthermia: Oxygen therapy does not typically cause an increase in body temperature. Hyperthermia is not a recognized complication of supplemental oxygen administration. D. Hypoxia: Hypoxia is a condition oxygen therapy aims to correct, not a complication of oxygen administration. Persistent hypoxia may indicate ineffective therapy or worsening underlying disease rather than a direct adverse effect of oxygen.