Hyperventilation in the dental chair.

An anxious patient may experience an uncontrollable increase in ventilatory effort, far in excess of the body's metabolic needs, to such a degree that profound changes are induced in the cardiovascular and neurological systems. This abnormal drive to breathe rapidly leads to a reduction in the tension of carbon dioxide in alveolar gas and arterial blood and to mild alkalosis. The outward expression of these disturbances can be alarming for both patient and dentist, but for the physiologist searching for underlying mechanisms it is intriguing. The cursory coverage of this subject in some textbooks and lecture courses is regrettable when one considers that hyperventilation is not uncommon in a dental patient. This article examines the causes, signs, symptoms and management of acute hyperventilation.