[Chronic hyperventilation syndrome].
Hyperventilation syndrome is a frequent, but poorly understood clinical entity. The clinical expression is a rich combination of respiratory, cardiac and neurological signs which can simulate various organic diseases. Hypocapnia remains the primum movens for most authors although the relationship with psychiatric situations, in particular in anxious patients, is increasingly emphasized. The diagnosis is currently based on the elimination of diseases associated with hyperventilation, then on Nijmegen's questionnaire and is confirmed by the reproduction of the same clinical picture in a voluntary hyperventilation test. Respiratory function tests offer little information. Treatment is based on combining rehabilitation therapy focused on the diaphragm and on relaxation. Specialized care may be needed in psychiatric patients.