Final answer:
The nurse should use a non-rebreather mask for the client with viral pneumonia showing pulse oximeter readings of 79% - 88%, as it provides the highest concentration of oxygen up to 95-100%, which is crucial for treating significant hypoxemia.
Step-by-step explanation:
To address the question of which oxygen delivery system a nurse should initiate to provide the highest concentration of oxygen to a client with viral pneumonia and fluctuating pulse oximeter readings between 79% - 88%, the answer is the non-rebreather mask. A non-rebreather mask can deliver up to 95-100% oxygen concentration and has a reservoir that allows for the storage of oxygen, providing the patient a larger reservoir of oxygen to inhale. This is essential for patients who are experiencing significant hypoxemia, as indicated by the client's pulse oximeter readings, which are well below the normal range of 95-100%. Other options such as nasal cannula, Venturi mask, or simple face mask offer lower oxygen concentrations (24-50%, 24-60%, and 40-60%, respectively).
It is crucial for the nurse to monitor the client's oxygen saturation levels closely after initiating the non-rebreather mask to ensure that oxygenation improves and maintains at a therapeutic level. In the presence of insufficient ventilation, the body's mechanisms attempt to redirect blood flow to more adequately ventilated alveoli, as low partial pressure of oxygen in the alveoli hinders efficient diffusion across the respiratory membrane.