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The paper analyzes anesthesiological maintenance of infusion therapy, optimal criteria for effective brain protection, complications and mortality in 42 patients during operations on the ascending portion and arch of the aorta under deep hypothermic circulatory arrest. For this purpose, the patients were divided into 2 groups: Group 1 comprised 20 patients operated on before 1998; Group 2 included 22 patients operated on in 1998 to 2001. In both groups, circulatory arrest lasted 44 +/- 7 min. The patients were cooled to a temperature of 13.5 +/- 0.5 degrees C, to 15 +/- 0.6 degrees C in the nasopharynx. The duration of cooling was 58 +/- 5 and 73 +/- 6 min, respectively; that of warming-up was 70 +/- 8 and 83 +/- 6 min. Investigations have indicated that determination of the optimum brain cooling requires a complex assessment of central temperature values, electroencephalographic monitoring (visual estimation of a curve and quantitative characteristics), SjbO2 and cerebral metabolism. The investigations have shown that the procedure for anesthesiological maintenance and cerebral metabolism is safe and effective even in patients with arrested circulation lasting longer than 60 min. The operative mortality does not depend on the use of circulatory arrest under deep hypothermia and on its duration. Hemodynamic instability due to bleeding, as well as myocardial infarction, marked hemodilution during extracorporeal circulation are major factors that cause an increase in the rates of incidence of complications and mortality. The procedure used for anesthesiological maintenance and infusion therapy, decreased blood loss, and a reduction in the incidence of myocardial infarction could significantly reduce operative mortality. The fact that there were no neurological complications even during prolonged (80-min) circulatory arrest has shown that the brain-protective procedure including both general and regional cooling is reliable and to the extent of the indicated criteria. So is pharmacological protection.

Bioelectric activity and metabolism of the brain were studied during surgery on the aorta with deep hypothermal arrest of circulation. The study included 9 patients (7 men and 2 women) aged 13 to 66 years. The mean duration of circulation arrest under deep hypothermia was 48.6 (from 19 to 77) min. Before circulation arrest the patients were cooled to nasopharyngeal temperature of 13.5 +/- 0.5 degrees C and rectal temperature of 15 +/- 0.6 degrees C. Deep hypothermia involved the disappearance of bioelectrical activity and decrease of the spectral power of all EEG frequency bands. The most notable changes in the hemoglobin saturation of the blood in the internal jugular vein bulb (SibO2) were observed during artificial circulation and hypothermal arrest of circulation. Cooling of patients led to a gradual increase of its values. Before deep hypothermal arrest of circulation SjbO2 was as high as 98.4 +/- 0.4%. Over the period of circulation arrest its level dropped to 85.7 +/- 4.8%. Subsequent warming led to its further decrease, and by the end of artificial circulation it was as initially. The content of carbon dioxide in the blood flowing from the brain increased from 17.0 +/- 0.9 to 31.7 +/- 4.7 mm Hg over the period of heart arrest, which may be indicative of the continuing metabolic processes in the brain under conditions of deep hypothermia and justifies the additional drug protection and local hypothermia of the head.

Monitoring of brain metabolism is used to assess the adequacy of brain cooling during operations performed under conditions of deep hypothermal perfusion and temporary arrest of circulation. Such monitoring consists in continuous recording of hemoglobin saturation of the blood flowing from the brain by fiberoptic oximetry and testing of blood samples collected from the upper internal jugular bulb. A patient is described, who had been operated with good results under conditions of deep hypothermal perfusion and 30-min arrest of circulation.