Final answer:
The most likely cause of the ventilator's high-pressure alarm going off in the patient's home is excessive secretions.
Step-by-step explanation:
The most likely cause of the ventilator's high-pressure alarm going off in the patient's home is excessive secretions. When there are excessive secretions in the airway, it can cause a blockage and lead to increased airway pressure, triggering the high-pressure alarm. This can be resolved by suctioning or clearing the airway of the secretions.