Oxygen Extraction Fraction at Maximally Vasodilated Tissue in the Ischemic Brain Estimated from the Regional CO2 Responsiveness Measured by Positron Emission Tomography

• Published in: Journal of cerebral blood flow and metabolism Vol. 8; no. 2; pp. 227 - 235
• Main Authors: Kanno, Iwao, Uemura, Kazuo, Higano, Schuichi, Murakami, Matsutaro, Iida, Hidehiro, Miura, Shuichi, Shishido, Fumio, Inugami, Atsushi, Sayama, Ichiro
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.04.1988; Lippincott Williams & Wilkins
• Subjects: Adolescent; Adult; Aged; Arterial Occlusive Diseases - metabolism; Arterial Occlusive Diseases - physiopathology; Biological and medical sciences; Brain - physiopathology; Brain Ischemia - metabolism; Brain Ischemia - physiopathology; Carbon Dioxide - metabolism; Carotid Artery Diseases - metabolism; Carotid Artery Diseases - physiopathology; Carotid Artery, Internal; Cerebral Arteries; Cerebrovascular Circulation; Child; Female; Humans; Male; Medical sciences; Middle Aged; Neurology; Oxygen - metabolism; Tomography, Emission-Computed; Vascular diseases and vascular malformations of the nervous system; Vasodilation; Autoregulation; Hemodynamics; CO2 responsiveness; Cerebral blood flow; Positron emission tomography; Oxygen extraction fraction; Human; Brain; Cerebral infarction; Oxygen; Nervous system diseases; Carbon dioxide; Exploration; Cerebrovascular disease; Vasodilation
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1038/jcbfm.1988.53

The oxygen extraction fraction (OEF) at maximally vasodilated tissue in patients with chronic cerebrovascular disease was evaluated using positron emission tomography. The vascular responsiveness to changes in PaCO2 was measured by the H215O autoradiographic method. It was correlated with the resting-state OEF, as estimated using the 15O steady-state method. The subjects comprised 15 patients with unilateral or bilateral occlusion and stenosis of the internal carotid artery or middle cerebral artery or moyamoya disease. In hypercapnia, the scattergram between the OEF and the vascular responsiveness to changes in PaCO2 revealed a significant negative correlation in 11 of 19 studies on these patients, and the OEF at the zero cross point of the regression line with a vascular responsiveness of 0 was 0.53 ± 0.08 (n = 11). This OEF in the resting state corresponds to exhaustion of the capacity for vasodilation. The vasodilatory capacity is discussed in relation to the lower limit of autoregulation.