Hyperventilation

Overbreathing. Often due to anxiety. Overbreathing causes dizziness, lightheadedness, a sense of unsteadiness and tingling around the mouth and fingertips. Relief can be gotten by breathing in and out of a paper bag (to increase the level of carbon dioxide in the blood). Opposite, hypoventilation or underbreathing.

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Increased alveolar ventilation relative to metabolic carbon dioxide production, so that alveolar carbon dioxide pressure decreases to below normal. SYN: overventilation.

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hy·per·ven·ti·la·tion -.vent-əl-'ā-shən n excessive ventilation specif excessive rate and depth of respiration leading to abnormal loss of carbon dioxide from the blood called also overventilation

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n.

breathing at an abnormally rapid rate at rest. This causes a reduction of the carbon dioxide concentration of arterial blood, leading to dizziness, tingling (paraesthesiae) in the lips and limbs, tetanic cramps in the hands, and tightness across the chest. If continued, hyperventilation may cause loss of consciousness. This sequence of events occurs in the hyperventilation syndrome (HVS), which has been estimated to contribute to 10% of out-patient referrals to hospital.

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hy·per·ven·ti·la·tion (hi″pər-ven″tĭ-laґshən) 1. a state in which there is an increased amount of air entering the pulmonary alveoli (increased alveolar ventilation; see under ventilation). This results in reduction of carbon dioxide tension, eventually leading to alkalosis. See also hyperpnea, tachypnea, and hyperventilation syndrome. 2. abnormally prolonged, rapid, and deep breathing (polypnea), frequently used as a test procedure in epilepsy and tetany.