Part 1: The cardiorespiratory parameters and somatosensory evoked potentials (SEP) were assessed in six healthy volunteers during the induction and steady state anesthesia with XeS. Following denitrogenation with 100% oxygen, 75% XeS with oxygen was administered by fitted mask for 15 minutes to spontaneously breathing subjects. The induction occurred promptly and was characterized by a significant increase in minute ventilation (MV), tachycardia, increase in blood pressure, and short agitation. During the steady state of anesthesia, the MV was still higher than before anesthesia (p < 0.05). The cortical components of SEP were significantly depressed by XeS, with amplitude being more affected than latency.

Part 2: The cerebral blood flow velocity (FV) in the middle cerebral artery together with cardiovascular parameters were assessed during 70% XeS inhalation in ten patients initially anesthetized with propofol. The propofol anesthesia significantly reduced FV but delivery of XeS resulted in its gradual increase. It appears that the vasodilatory effect of XeS on cerebral circulation can be attenuated by background propofol anesthesia and moderate hyperventilation.

Keywords: Anesthetics, propofol, xenon, cerebral blood flow, evoked potentials, doppler sonography

Applied Cardiopulmonary Pathophysiology 7: 161-165, 1998

Wlodzimier Lewelt, M.D.
Medical College of Virginia of VCU
PO Box 980541
Richmond, VA 23298-0541
USA