[Changes in cerebral circulation in patients with coronary heart disease during myocardial revascularizing operations...

Twenty-five patients with coronary heart disease were examined in the preperfusion stage of myocardial revascularing operations under extracorporeal circulation. All the patients received combined anesthesia with xenon (Xe) as minimum flow anesthesia with flow of gases: oxygen, 0.4 l/min; Xe, 0.9 to 0.4 l/min. Cerebral circulation was investigated by transcranial Doppler study. The following parameters of the circulation: maximum systolic and diastolic blood flow velocities and pulsatile index were bilaterally estimated, by insonating the middle cerebral artery (MCA). When the concentration of Xe was as high as 50-60%, systolic and diastolic blood flow velocities along the MCA increase and the pulsatile index decreased. Opposite results were obtained 8 minutes after Xe feed was stopped. The findings provide evidence that Xe increases cerebral circulation and has a significant hypnotic effect. The increased systolic and diastolic blood flow velocities with the decreased peripheral resistance index in the MCA suggest that Xe diminishes peripheral vascular resistance in the pial arteries of the brain.