Hypocapnia - reduced voltage of carbon dioxide in arterial blood. Occurs by inhalation of pure oxygen and air with low content C02, at atmospheric pressure, dyspnea, hyperventilation of the lungs, forced artificial respiration. If hypocapnia there is oppression respiratory centre, violation of cerebral circulation, poor transfer of oxygen from the blood to the tissues. Breathing gets shallow and rare. To prevent hypocapnia patients give breathe a mixture of oxygen and carbon dioxide (5-7%), which causes stimulation of the respiratory centre.