Hyperventilation: a practical guide

Abstract

The term 'hyperventilation' is incorrectly applied by most physicians to a range of vague and imprecise clinical presentations. It is often used in cases of breathlessness when no clear respiratory disorder has been diagnosed, when the patient repeatedly reports complaints that do not fit any precise diagnostic category, and when there are abnormalities of respiratory pattern. Almost invariably, it is used to imply that there is an ill-defined underlying psychiatric cause for the symptoms. This is not necessarily correct. The precise physiological definition of hyperventilation is breathing in excess of metabolic requirements. It invariably implies arterial hypocapnia (reduced arterial partial pressure of carbon dioxide, PaCO 2), which can be documented by arterial or end-tidal measurements. Hyperventilation is a clinical finding and not a disease. It implies increased respiratory drive, which can have many causes and is thus no different from other abnormal biochemical measures for which the cause must be sought. The term ‘hyperventilation syndrome’ was first used to describe patients with a combination of organic and psychiatric symptoms, but has since been used in so many different contexts that it has no universally agreed meaning. In the author's opinion, it should not be used.