A spontaneously breathing patient has the following arterial blood gas results: pH 7.38 PaCO2 42 mmHg PaO2 76 mmHg HCO3- 24 mEq/L BE 0 mEq/L. Which of the following supplemental oxygen levels is most appropriate?

The appropriate choice for supplemental oxygen level in this scenario is identified due to the patient's arterial blood gas results indicating mild hypoxemia and normal respiratory function. The patient has a PaO2 of 76 mmHg, which is below the normal range (typically above 80 mmHg) but reflecting mild hypoxemia. The pH, PaCO2, and HCO3- levels suggest that there is no significant acid-base disturbance, which further indicates that the patient's respiratory status is stable.

Using a 5 L/min nasal cannula provides a low flow of supplemental oxygen, typically increasing the inspired oxygen concentration (FiO2) to around 40%, which should effectively address the mild hypoxemia without overwhelming the patient's respiratory drive. It allows the patient to receive adequate oxygen while still breathing room air, maintaining a more natural breathing pattern.

This approach is particularly suitable in a spontaneously breathing patient who does not appear to be in respiratory distress but requires some additional oxygenation. A higher flow, such as from a non-rebreathing mask, would deliver too much oxygen and may not be necessary for the degree of hypoxemia present. It could also risk oxygen toxicity or impair the patient's own respiratory mechanisms.

A Venturi mask at