Hyperpnea is increased depth and rate of breathing. It may be physiologic—as when required to meet metabolic demand of body tissues (for example, during or after exercise, or when the body lacks oxygen at high altitude or as a result of anemia)—or it may be pathologic, as when sepsis is severe.
Tachypnea is sometimes distinguished from hyperpnea when tachypnea is meant as rapid and shallow breaths, whereas hyperpnea is meant as rapid and deep breaths. This distinction is not always followed; the words can be synonymous. Similarly, some speakers maintain a distinction between hyperpnea and hyperventilation, whereby in hyperpnea, the increased breathing rate is desirable as it meets the metabolic needs of the body, but in hyperventilation, the rate of ventilation is inappropriate for the body's needs (except in metabolic acidosis, when CO
2 needs to be breathed off). The resulting decrease in CO
2 concentration results in the typical symptoms of light-headedness, tingling in peripheries, visual disturbances etc., whereas in hyperpnea in the contradistinguished sense, there are generally no such symptoms. This distinction, too, is not invariably followed.