A client who is 12 hour post-op becomes confused and says: 'Giant sharks are swimming across the ceiling.' Which assessment is necessary to adequately identify the source of this client's behavior?

Pulse oximetry. A sudden change in mental status in any post-op client should trigger a nursing intervention directed toward respiratory evaluation. Pulse oximetry would be the initial assessment. If available, arterial blood gases would be better. Acute respiratory failure is the sudden inability of the respiratory system to maintain adequate gas exchange which may result in hypercapnia and/or hypoxemia. Clinical findings of hypoxemia include these findings which are listed in order of initial to later findings: restlessness, irritability, agitation, dyspnea, disorientation, confusion, delirium, hallucinations, and loss of consciousness.