Hyperpnea, or hyperpnoea (forced respiration), is increased volume of air taken during breathing.
[1] It may be physiologic—as when required by oxygen to meet metabolic demand of body tissues (for example, during or after heavy exercise, or when the body lacks oxygen at high altitude or as a result of anemia, or any other condition requiring more respiration)—or it may be pathologic, as when sepsis is severe or during pulmonary edema.
Thus, hyperpnea is intense active breathing as opposed to the passive process of normal expiration.
However, in addition to low oxygen, high carbon dioxide, and low pH levels, there appears to be a complex interplay of factors related to the nervous system and the respiratory centers of the brain that governs hyperpnea.
[3] The word hyperpnea uses combining forms of hyper- + -pnea, yielding "excessive breathing".