EFFECT OF NITROUS-OXIDE ON CEREBRAL BLOOD VELOCITY WHILE RECLINING AND STANDING

Cerebral blood velocity (CBV) (measured with transcranial Doppler, TCD ) and other physiological and rating scale indices were measured befor e, during, and after inhaling a mixture of 40% nitrous oxide/oxygen an d 40% nitrogen/oxygen, given during two separate visits in 7 normal ma le volunteers. During nitrous oxide/oxygen but not nitrogen/oxygen inh alation, CBV and euphoria increased significantly with minimal changes in other physiological indices except an increase in pulse rate after nitrous oxide/oxygen. In another 7 male volunteers, similar measureme nts were obtained while lying down and standing lip during nitrous oxi de/oxygen mixture and nitrogen/oxygen mixture inhalations, given durin g two separate visits. Nitrous oxide/oxygen inhalations produced signi ficant CBV increase, which showed nonsignificant decrease of no clinic al significance during standing up. There were no significant postural changes in blood pressure. Standing up during nitrous oxide/oxygen in halation was associated with significant though mild dizziness. (C) 19 97 Society of Biological Psychiatry.