The alkaline shift of blood Ph together with marked metabolic acidosis in the liquor were found postoperativery in 42 patients operated upon the colon and small intestine at the height of postoperative psychosis. The patients developed tachipnoe up to 32-36 per minute, followed with a great energy expenditure. As a consequence, artificial pulmonary ventilation (APV) at the hyperventilation regime was administered to a part of the patients to correct acidosis of the liquor. Postoperative psychotic patients need an early administration of the APV at the hyperventilation regime, which is one of effective methods of correcting liquor acidosis in the complex therapy of psychoses.