Final answer:
In an emergency where a patient is found gasping with the endotracheal tube in hand, the nurse should immediately manually ventilate the patient with 100% oxygen to ensure proper oxygenation before further steps are taken.
Step-by-step explanation:
When the nurse responds to a ventilator alarm and finds the patient gasping and holding the endotracheal tube (ET) in hand, the next action that should be taken by the nurse is to manually ventilate the patient with 100% oxygen. This is an emergency situation where the patient's airway has been compromised, and they are at significant risk of hypoxemia. Immediate manual ventilation will assist in providing adequate oxygenation and maintaining tissue perfusion while further assistance is on the way.
As the situation demands immediate intervention, activation of the rapid response team may be an essential subsequent step following initial stabilization of the patient's breathing. Reinsertion of the endotracheal tube is a critical procedure that would typically be performed by a healthcare provider with the appropriate skill set. Reassurance will be important for patient care but should follow after addressing the immediate need for oxygenation.