Effects of a Vasoactive Drug (Nylidrin HCl) on the Response of the Electroencephalogram to Hyperventilation

HYPERVENTILATION (HV) may cause slowing of the electroencephalogram (EEG) in human subjects. The physiological basis of the response has been the object of considerable debate for several decades. 1-8 More recent investigations from several sources favor the hypothesis that sufficient HV causes a decreased blood Pco 2 with subsequent cerebral vasoconstriction more marked in the younger age group. This is followed by a significant decrease in cerebral blood flow resulting in cerebral ischemia. The anoxia has been shown to be the factor most highly correlated with the slowing of the EEG in HV. 8 The present study was performed in an attempt to evaluate the response to HV of normal subjects utilizing a vasoactive drug. If the hypothesis described above is correct, prevention of vasoconstriction would decrease the production of slow activity by HV. Nylidrin HC1 is the vasoactive agent used. This agent increases extracranial and cerebral blood flow