HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Dyken, M. L. Articles by Frayser, R. Search for Related Content PubMed Articles by Dyken, M. L. Articles by Frayser, R.

Cerebral blood flow, oxygen utilization, and vascular reactivity

Internal carotid artery complete occlusion versus incomplete occlusion with infarction

From the Departments of Neurology (Dr. Dyken); Surgery, Section of Neurological Surgery (Dr. Campbell); and Medicine (Dr. Frayser); Indiana University Medical Center, Indianapolis, Indiana 46202

SUMMARYA group of 10 patients with complete occlusion of one internal carotid artery (COG) were compared with a group of 12 patients with cerebral infarction and severe atherosclerosis but no complete occlusion of an internal carotid artery (IOG). The two groups were closely matched clinically and by age, degree of atherosclerosis, time from infarction, cerebral blood flow, and metabolic studies while breathing room air.

After breathing 5% carbon dioxide, the COG had significantly less increase in CBF and decrease in CVR. CMRO₂ decreased in the completely occluded group and increased in the incompletely occluded group. It is postulated that in the area normally supplied by the occluded internal carotid artery there is a large area that functions because the arterioles are maximally dilated. Under normal conditions, cerebral blood flow is maximal but may be decreased to the point where oxygen supply is at a critical level. When 5% CO₂ is inhaled, the increased PaCO₂ directly affects the large amount of brain not involved and dilates the arterioles, so that blood that would normally be shunted into the area of maximum need is now stolen from the collaterals. As this area of brain is already receiving the maximum amount of oxygen that it needs for normal metabolism, the CMRO₂ in this region does not change. In the area of maximum need, however, the flow has decreased far below the critical level, and as oxygen is not available for normal metabolism, the CMRO₂ decreases in this area. Thus, the average cerebral blood flow may not be affected, but the average CMRO₂ will be significantly reduced.

It would seem that vasodilators may be contraindicated in most cases of complete internal carotid artery occlusion and that probably before they are used in any patient CBF, CMRO₂, and CVR responses to 5% carbon dioxide should be determined.

Dr. Dyken's address is Department of Neurology, Indiana University Medical Center, 1100 West Michigan Avenue, Indianapolis, Indiana 46202.

This investigation was supported by Cerebral Vascular Disease Research Center grant PHS NB 06793.

Submitted for publication Feb. 17, 1970; accepted March 2, 1970.