A 3-year-old male who just had a cardiac arrest is now unresponsive. What would be the best action regarding his oxygen therapy?

In this scenario, the best action regarding oxygen therapy for the unresponsive 3-year-old male who just experienced a cardiac arrest is to assist his ventilation. When a patient is unresponsive and has undergone a cardiac arrest, they are likely not breathing adequately, if at all. Oxygen therapy in the form of assisted ventilation is crucial to ensure that oxygen reaches the lungs and is delivered to the body's vital organs.

Assisting ventilation can be accomplished with a bag-Valve-mask (BVM) device which can provide positive pressure ventilation. This ensures that oxygen is not only being delivered but also that carbon dioxide is being expelled from the body, which is vital after a cardiac arrest, as the patient’s metabolic state needs to be corrected to prevent further complications.

While switching to a nasal cannula provides some oxygen, it may not deliver sufficient oxygen to meet the metabolic needs of a patient who is unresponsive. The focus should be on ensuring that adequate ventilation is provided, thus making assisting ventilation the prioritized action in this emergency situation.