Final answer:
The nurse's best action would be to check oxygen saturation and notify the health care provider. Decreased lung sounds and decreased lung expansion are signs of pneumonia, a respiratory infection.
Step-by-step explanation:
The nurse's best action would be to check oxygen saturation and notify the health care provider. Decreased lung sounds and decreased lung expansion are signs of pneumonia, a respiratory infection. Checking oxygen saturation will help determine the severity of the hypoxemia and notifying the health care provider is important to ensure appropriate treatment.