What are reasons why patients might hyperventilate during a hospital visit?

Stress ; breathing: An increase in one's breathing rate is what typically occurs when one is under stress. Certain individuals are more prone to hyperventilation when under stress. Even without being under stress, predisposed individuals are already breathing more rapidly, or are engaging in mouth breathing, or are engaging in thoracic as opposed to diaphragmatic breathing. They are already close to hyperventilation.