You can ask the patient something along the lines of, "are your ankles normally this big, or do you think your ankles are swelling??" Subjective data can give you clues on what is going on with the patient, though objective data is usually more reliable.
your priority nursing diagnosis would be related to the respiratory system.. probably altered breathing pattern or ineffective airway clearance because of the trach, vent and respiratory failure. another diagnosis to use would be that of altered tissue perfusion due to the anemia and HTN. You could also use altered nutrition due to the gastrostomy tube placement and the NPO status.