Final answer:
The appropriate immediate action for a ventilated patient with distress and low oxygen saturation is to provide supplemental oxygen through a non-rebreather mask. CPR is reserved for an unresponsive patient without breathing or heartbeat, and other options like adjusting ventilator settings or administering anti-anxiety medications are not initial steps in this emergency.
Step-by-step explanation:
In the scenario where a young adult on a mechanical ventilator has an alarm sound and shows signs of distress (agitation, ashen skin, diaphoresis) with a lowered oxygen saturation of 78%, it is crucial to take immediate action. Among the listed actions, the most appropriate initial step is administering oxygen through a non-rebreather mask to quickly improve the patient's oxygen levels, as this is directly addressing the hypoxemia and is consistent with the prioritization of airway and breathing in emergency care. Starting cardiopulmonary resuscitation (CPR) may be considered only if the patient is unresponsive and not breathing or if their heartbeat cannot be detected. Decreasing the ventilator settings is not appropriate without further assessment and may worsen the situation if the patient is not receiving adequate ventilation. Providing an anti-anxiety medication does not address the immediate life-threatening issue of hypoxemia. Ensuring oxygen saturation levels are increased is critical in this emergency, as untreated hypoxemia can lead to tissue hypoxia and potentially fatal outcomes.